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homework-jianmu/source/libs/tdb/src/sqlite/pager.c

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/*
** 2001 September 15
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** This is the implementation of the page cache subsystem or "pager".
**
** The pager is used to access a database disk file. It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file. The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
*/
#include "sqliteInt.h"
// #include "wal.h"
// /*
// ** Macros for troubleshooting. Normally turned off
// */
// #if 0
// int sqlite3PagerTrace=1; /* True to enable tracing */
// #define sqlite3DebugPrintf printf
// #define PAGERTRACE(X) if( sqlite3PagerTrace ){ sqlite3DebugPrintf X; }
// #else
// #define PAGERTRACE(X)
// #endif
// /*
// ** The following two macros are used within the PAGERTRACE() macros above
// ** to print out file-descriptors.
// **
// ** PAGERID() takes a pointer to a Pager struct as its argument. The
// ** associated file-descriptor is returned. FILEHANDLEID() takes an sqlite3_file
// ** struct as its argument.
// */
// #define PAGERID(p) (SQLITE_PTR_TO_INT(p->fd))
// #define FILEHANDLEID(fd) (SQLITE_PTR_TO_INT(fd))
#define PAGER_OPEN 0
#define PAGER_READER 1
#define PAGER_WRITER_LOCKED 2
#define PAGER_WRITER_CACHEMOD 3
#define PAGER_WRITER_DBMOD 4
#define PAGER_WRITER_FINISHED 5
#define PAGER_ERROR 6
// #define UNKNOWN_LOCK (EXCLUSIVE_LOCK+1)
// /*
// ** The maximum allowed sector size. 64KiB. If the xSectorsize() method
// ** returns a value larger than this, then MAX_SECTOR_SIZE is used instead.
// ** This could conceivably cause corruption following a power failure on
// ** such a system. This is currently an undocumented limit.
// */
// #define MAX_SECTOR_SIZE 0x10000
// typedef struct PagerSavepoint PagerSavepoint;
// struct PagerSavepoint {
// i64 iOffset; /* Starting offset in main journal */
// i64 iHdrOffset; /* See above */
// Bitvec *pInSavepoint; /* Set of pages in this savepoint */
// Pgno nOrig; /* Original number of pages in file */
// Pgno iSubRec; /* Index of first record in sub-journal */
// int bTruncateOnRelease; /* If stmt journal may be truncated on RELEASE */
// #ifndef SQLITE_OMIT_WAL
// u32 aWalData[WAL_SAVEPOINT_NDATA]; /* WAL savepoint context */
// #endif
// };
// /*
// ** Bits of the Pager.doNotSpill flag. See further description below.
// */
// #define SPILLFLAG_OFF 0x01 /* Never spill cache. Set via pragma */
// #define SPILLFLAG_ROLLBACK 0x02 /* Current rolling back, so do not spill */
// #define SPILLFLAG_NOSYNC 0x04 /* Spill is ok, but do not sync */
struct Pager {
u8 exclusiveMode; /* Boolean. True if locking_mode==EXCLUSIVE */
u8 journalMode; /* One of the PAGER_JOURNALMODE_* values */
u8 useJournal; /* Use a rollback journal on this file */
u8 noSync; /* Do not sync the journal if true */
u8 fullSync; /* Do extra syncs of the journal for robustness */
u8 extraSync; /* sync directory after journal delete */
u8 syncFlags; /* SYNC_NORMAL or SYNC_FULL otherwise */
u8 walSyncFlags; /* See description above */
u8 tempFile; /* zFilename is a temporary or immutable file */
u8 noLock; /* Do not lock (except in WAL mode) */
u8 readOnly; /* True for a read-only database */
u8 memDb; /* True to inhibit all file I/O */
u8 memVfs; /* VFS-implemented memory database */
/**************************************************************************
** The following block contains those class members that change during
** routine operation. Class members not in this block are either fixed
** when the pager is first created or else only change when there is a
** significant mode change (such as changing the page_size, locking_mode,
** or the journal_mode). From another view, these class members describe
** the "state" of the pager, while other class members describe the
** "configuration" of the pager.
*/
u8 eState; /* Pager state (OPEN, READER, WRITER_LOCKED..) */
u8 eLock; /* Current lock held on database file */
u8 changeCountDone; /* Set after incrementing the change-counter */
u8 setSuper; /* Super-jrnl name is written into jrnl */
u8 doNotSpill; /* Do not spill the cache when non-zero */
u8 subjInMemory; /* True to use in-memory sub-journals */
u8 bUseFetch; /* True to use xFetch() */
u8 hasHeldSharedLock; /* True if a shared lock has ever been held */
Pgno dbSize; /* Number of pages in the database */
Pgno dbOrigSize; /* dbSize before the current transaction */
Pgno dbFileSize; /* Number of pages in the database file */
Pgno dbHintSize; /* Value passed to FCNTL_SIZE_HINT call */
int errCode; /* One of several kinds of errors */
int nRec; /* Pages journalled since last j-header written */
u32 cksumInit; /* Quasi-random value added to every checksum */
u32 nSubRec; /* Number of records written to sub-journal */
// Bitvec *pInJournal; /* One bit for each page in the database file */
int fd; /* File descriptor for database */
int jfd; /* File descriptor for main journal */
int sjfd; /* File descriptor for sub-journal */
// i64 journalOff; /* Current write offset in the journal file */
// i64 journalHdr; /* Byte offset to previous journal header */
// sqlite3_backup *pBackup; /* Pointer to list of ongoing backup processes */
// PagerSavepoint *aSavepoint; /* Array of active savepoints */
// int nSavepoint; /* Number of elements in aSavepoint[] */
// u32 iDataVersion; /* Changes whenever database content changes */
// char dbFileVers[16]; /* Changes whenever database file changes */
// int nMmapOut; /* Number of mmap pages currently outstanding */
// sqlite3_int64 szMmap; /* Desired maximum mmap size */
// PgHdr *pMmapFreelist; /* List of free mmap page headers (pDirty) */
// /*
// ** End of the routinely-changing class members
// ***************************************************************************/
// u16 nExtra; /* Add this many bytes to each in-memory page */
// i16 nReserve; /* Number of unused bytes at end of each page */
u32 vfsFlags; /* Flags for sqlite3_vfs.xOpen() */
// u32 sectorSize; /* Assumed sector size during rollback */
// Pgno mxPgno; /* Maximum allowed size of the database */
// i64 pageSize; /* Number of bytes in a page */
// i64 journalSizeLimit; /* Size limit for persistent journal files */
char *zFilename; /* Name of the database file */
char *zJournal; /* Name of the journal file */
// int (*xBusyHandler)(void*); /* Function to call when busy */
// void *pBusyHandlerArg; /* Context argument for xBusyHandler */
// int aStat[4]; /* Total cache hits, misses, writes, spills */
// #ifdef SQLITE_TEST
// int nRead; /* Database pages read */
// #endif
void (*xReiniter)(DbPage *); /* Call this routine when reloading pages */
// int (*xGet)(Pager*,Pgno,DbPage**,int); /* Routine to fetch a patch */
// char *pTmpSpace; /* Pager.pageSize bytes of space for tmp use */
PCache *pPCache; /* Pointer to page cache object */
// Wal *pWal; /* Write-ahead log used by "journal_mode=wal" */
char *zWal; /* File name for write-ahead log */
};
// /*
// ** Indexes for use with Pager.aStat[]. The Pager.aStat[] array contains
// ** the values accessed by passing SQLITE_DBSTATUS_CACHE_HIT, CACHE_MISS
// ** or CACHE_WRITE to sqlite3_db_status().
// */
// #define PAGER_STAT_HIT 0
// #define PAGER_STAT_MISS 1
// #define PAGER_STAT_WRITE 2
// #define PAGER_STAT_SPILL 3
// /*
// ** The following global variables hold counters used for
// ** testing purposes only. These variables do not exist in
// ** a non-testing build. These variables are not thread-safe.
// */
// #ifdef SQLITE_TEST
// int sqlite3_pager_readdb_count = 0; /* Number of full pages read from DB */
// int sqlite3_pager_writedb_count = 0; /* Number of full pages written to DB */
// int sqlite3_pager_writej_count = 0; /* Number of pages written to journal */
// # define PAGER_INCR(v) v++
// #else
// # define PAGER_INCR(v)
// #endif
static const unsigned char aJournalMagic[] = {
0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd7,
};
// /*
// ** The size of the of each page record in the journal is given by
// ** the following macro.
// */
// #define JOURNAL_PG_SZ(pPager) ((pPager->pageSize) + 8)
// /*
// ** The journal header size for this pager. This is usually the same
// ** size as a single disk sector. See also setSectorSize().
// */
// #define JOURNAL_HDR_SZ(pPager) (pPager->sectorSize)
// /*
// ** The macro MEMDB is true if we are dealing with an in-memory database.
// ** We do this as a macro so that if the SQLITE_OMIT_MEMORYDB macro is set,
// ** the value of MEMDB will be a constant and the compiler will optimize
// ** out code that would never execute.
// */
// #ifdef SQLITE_OMIT_MEMORYDB
// # define MEMDB 0
// #else
// # define MEMDB pPager->memDb
// #endif
// /*
// ** The macro USEFETCH is true if we are allowed to use the xFetch and xUnfetch
// ** interfaces to access the database using memory-mapped I/O.
// */
// #if SQLITE_MAX_MMAP_SIZE>0
// # define USEFETCH(x) ((x)->bUseFetch)
// #else
// # define USEFETCH(x) 0
// #endif
// /*
// ** The argument to this macro is a file descriptor (type sqlite3_file*).
// ** Return 0 if it is not open, or non-zero (but not 1) if it is.
// **
// ** This is so that expressions can be written as:
// **
// ** if( isOpen(pPager->jfd) ){ ...
// **
// ** instead of
// **
// ** if( pPager->jfd->pMethods ){ ...
// */
// #define isOpen(pFd) ((pFd)->pMethods!=0)
// #ifdef SQLITE_DIRECT_OVERFLOW_READ
// /*
// ** Return true if page pgno can be read directly from the database file
// ** by the b-tree layer. This is the case if:
// **
// ** * the database file is open,
// ** * there are no dirty pages in the cache, and
// ** * the desired page is not currently in the wal file.
// */
// int sqlite3PagerDirectReadOk(Pager *pPager, Pgno pgno){
// if( pPager->fd->pMethods==0 ) return 0;
// if( sqlite3PCacheIsDirty(pPager->pPCache) ) return 0;
// #ifndef SQLITE_OMIT_WAL
// if( pPager->pWal ){
// u32 iRead = 0;
// int rc;
// rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iRead);
// return (rc==SQLITE_OK && iRead==0);
// }
// #endif
// return 1;
// }
// #endif
// #ifndef SQLITE_OMIT_WAL
// # define pagerUseWal(x) ((x)->pWal!=0)
// #else
// # define pagerUseWal(x) 0
// # define pagerRollbackWal(x) 0
// # define pagerWalFrames(v,w,x,y) 0
// # define pagerOpenWalIfPresent(z) SQLITE_OK
// # define pagerBeginReadTransaction(z) SQLITE_OK
// #endif
// #ifndef NDEBUG
// /*
// ** Usage:
// **
// ** assert( assert_pager_state(pPager) );
// **
// ** This function runs many asserts to try to find inconsistencies in
// ** the internal state of the Pager object.
// */
// static int assert_pager_state(Pager *p){
// Pager *pPager = p;
// /* State must be valid. */
// assert( p->eState==PAGER_OPEN
// || p->eState==PAGER_READER
// || p->eState==PAGER_WRITER_LOCKED
// || p->eState==PAGER_WRITER_CACHEMOD
// || p->eState==PAGER_WRITER_DBMOD
// || p->eState==PAGER_WRITER_FINISHED
// || p->eState==PAGER_ERROR
// );
// /* Regardless of the current state, a temp-file connection always behaves
// ** as if it has an exclusive lock on the database file. It never updates
// ** the change-counter field, so the changeCountDone flag is always set.
// */
// assert( p->tempFile==0 || p->eLock==EXCLUSIVE_LOCK );
// assert( p->tempFile==0 || pPager->changeCountDone );
// /* If the useJournal flag is clear, the journal-mode must be "OFF".
// ** And if the journal-mode is "OFF", the journal file must not be open.
// */
// assert( p->journalMode==PAGER_JOURNALMODE_OFF || p->useJournal );
// assert( p->journalMode!=PAGER_JOURNALMODE_OFF || !isOpen(p->jfd) );
// /* Check that MEMDB implies noSync. And an in-memory journal. Since
// ** this means an in-memory pager performs no IO at all, it cannot encounter
// ** either SQLITE_IOERR or SQLITE_FULL during rollback or while finalizing
// ** a journal file. (although the in-memory journal implementation may
// ** return SQLITE_IOERR_NOMEM while the journal file is being written). It
// ** is therefore not possible for an in-memory pager to enter the ERROR
// ** state.
// */
// if( MEMDB ){
// assert( !isOpen(p->fd) );
// assert( p->noSync );
// assert( p->journalMode==PAGER_JOURNALMODE_OFF
// || p->journalMode==PAGER_JOURNALMODE_MEMORY
// );
// assert( p->eState!=PAGER_ERROR && p->eState!=PAGER_OPEN );
// assert( pagerUseWal(p)==0 );
// }
// /* If changeCountDone is set, a RESERVED lock or greater must be held
// ** on the file.
// */
// assert( pPager->changeCountDone==0 || pPager->eLock>=RESERVED_LOCK );
// assert( p->eLock!=PENDING_LOCK );
// switch( p->eState ){
// case PAGER_OPEN:
// assert( !MEMDB );
// assert( pPager->errCode==SQLITE_OK );
// assert( sqlite3PcacheRefCount(pPager->pPCache)==0 || pPager->tempFile );
// break;
// case PAGER_READER:
// assert( pPager->errCode==SQLITE_OK );
// assert( p->eLock!=UNKNOWN_LOCK );
// assert( p->eLock>=SHARED_LOCK );
// break;
// case PAGER_WRITER_LOCKED:
// assert( p->eLock!=UNKNOWN_LOCK );
// assert( pPager->errCode==SQLITE_OK );
// if( !pagerUseWal(pPager) ){
// assert( p->eLock>=RESERVED_LOCK );
// }
// assert( pPager->dbSize==pPager->dbOrigSize );
// assert( pPager->dbOrigSize==pPager->dbFileSize );
// assert( pPager->dbOrigSize==pPager->dbHintSize );
// assert( pPager->setSuper==0 );
// break;
// case PAGER_WRITER_CACHEMOD:
// assert( p->eLock!=UNKNOWN_LOCK );
// assert( pPager->errCode==SQLITE_OK );
// if( !pagerUseWal(pPager) ){
// /* It is possible that if journal_mode=wal here that neither the
// ** journal file nor the WAL file are open. This happens during
// ** a rollback transaction that switches from journal_mode=off
// ** to journal_mode=wal.
// */
// assert( p->eLock>=RESERVED_LOCK );
// assert( isOpen(p->jfd)
// || p->journalMode==PAGER_JOURNALMODE_OFF
// || p->journalMode==PAGER_JOURNALMODE_WAL
// );
// }
// assert( pPager->dbOrigSize==pPager->dbFileSize );
// assert( pPager->dbOrigSize==pPager->dbHintSize );
// break;
// case PAGER_WRITER_DBMOD:
// assert( p->eLock==EXCLUSIVE_LOCK );
// assert( pPager->errCode==SQLITE_OK );
// assert( !pagerUseWal(pPager) );
// assert( p->eLock>=EXCLUSIVE_LOCK );
// assert( isOpen(p->jfd)
// || p->journalMode==PAGER_JOURNALMODE_OFF
// || p->journalMode==PAGER_JOURNALMODE_WAL
// || (sqlite3OsDeviceCharacteristics(p->fd)&SQLITE_IOCAP_BATCH_ATOMIC)
// );
// assert( pPager->dbOrigSize<=pPager->dbHintSize );
// break;
// case PAGER_WRITER_FINISHED:
// assert( p->eLock==EXCLUSIVE_LOCK );
// assert( pPager->errCode==SQLITE_OK );
// assert( !pagerUseWal(pPager) );
// assert( isOpen(p->jfd)
// || p->journalMode==PAGER_JOURNALMODE_OFF
// || p->journalMode==PAGER_JOURNALMODE_WAL
// || (sqlite3OsDeviceCharacteristics(p->fd)&SQLITE_IOCAP_BATCH_ATOMIC)
// );
// break;
// case PAGER_ERROR:
// /* There must be at least one outstanding reference to the pager if
// ** in ERROR state. Otherwise the pager should have already dropped
// ** back to OPEN state.
// */
// assert( pPager->errCode!=SQLITE_OK );
// assert( sqlite3PcacheRefCount(pPager->pPCache)>0 || pPager->tempFile );
// break;
// }
// return 1;
// }
// #endif /* ifndef NDEBUG */
// #ifdef SQLITE_DEBUG
// /*
// ** Return a pointer to a human readable string in a static buffer
// ** containing the state of the Pager object passed as an argument. This
// ** is intended to be used within debuggers. For example, as an alternative
// ** to "print *pPager" in gdb:
// **
// ** (gdb) printf "%s", print_pager_state(pPager)
// **
// ** This routine has external linkage in order to suppress compiler warnings
// ** about an unused function. It is enclosed within SQLITE_DEBUG and so does
// ** not appear in normal builds.
// */
// char *print_pager_state(Pager *p){
// static char zRet[1024];
// sqlite3_snprintf(1024, zRet,
// "Filename: %s\n"
// "State: %s errCode=%d\n"
// "Lock: %s\n"
// "Locking mode: locking_mode=%s\n"
// "Journal mode: journal_mode=%s\n"
// "Backing store: tempFile=%d memDb=%d useJournal=%d\n"
// "Journal: journalOff=%lld journalHdr=%lld\n"
// "Size: dbsize=%d dbOrigSize=%d dbFileSize=%d\n"
// , p->zFilename
// , p->eState==PAGER_OPEN ? "OPEN" :
// p->eState==PAGER_READER ? "READER" :
// p->eState==PAGER_WRITER_LOCKED ? "WRITER_LOCKED" :
// p->eState==PAGER_WRITER_CACHEMOD ? "WRITER_CACHEMOD" :
// p->eState==PAGER_WRITER_DBMOD ? "WRITER_DBMOD" :
// p->eState==PAGER_WRITER_FINISHED ? "WRITER_FINISHED" :
// p->eState==PAGER_ERROR ? "ERROR" : "?error?"
// , (int)p->errCode
// , p->eLock==NO_LOCK ? "NO_LOCK" :
// p->eLock==RESERVED_LOCK ? "RESERVED" :
// p->eLock==EXCLUSIVE_LOCK ? "EXCLUSIVE" :
// p->eLock==SHARED_LOCK ? "SHARED" :
// p->eLock==UNKNOWN_LOCK ? "UNKNOWN" : "?error?"
// , p->exclusiveMode ? "exclusive" : "normal"
// , p->journalMode==PAGER_JOURNALMODE_MEMORY ? "memory" :
// p->journalMode==PAGER_JOURNALMODE_OFF ? "off" :
// p->journalMode==PAGER_JOURNALMODE_DELETE ? "delete" :
// p->journalMode==PAGER_JOURNALMODE_PERSIST ? "persist" :
// p->journalMode==PAGER_JOURNALMODE_TRUNCATE ? "truncate" :
// p->journalMode==PAGER_JOURNALMODE_WAL ? "wal" : "?error?"
// , (int)p->tempFile, (int)p->memDb, (int)p->useJournal
// , p->journalOff, p->journalHdr
// , (int)p->dbSize, (int)p->dbOrigSize, (int)p->dbFileSize
// );
// return zRet;
// }
// #endif
// /* Forward references to the various page getters */
// static int getPageNormal(Pager*,Pgno,DbPage**,int);
// static int getPageError(Pager*,Pgno,DbPage**,int);
// #if SQLITE_MAX_MMAP_SIZE>0
// static int getPageMMap(Pager*,Pgno,DbPage**,int);
// #endif
// /*
// ** Set the Pager.xGet method for the appropriate routine used to fetch
// ** content from the pager.
// */
// static void setGetterMethod(Pager *pPager){
// if( pPager->errCode ){
// pPager->xGet = getPageError;
// #if SQLITE_MAX_MMAP_SIZE>0
// }else if( USEFETCH(pPager) ){
// pPager->xGet = getPageMMap;
// #endif /* SQLITE_MAX_MMAP_SIZE>0 */
// }else{
// pPager->xGet = getPageNormal;
// }
// }
// /*
// ** Return true if it is necessary to write page *pPg into the sub-journal.
// ** A page needs to be written into the sub-journal if there exists one
// ** or more open savepoints for which:
// **
// ** * The page-number is less than or equal to PagerSavepoint.nOrig, and
// ** * The bit corresponding to the page-number is not set in
// ** PagerSavepoint.pInSavepoint.
// */
// static int subjRequiresPage(PgHdr *pPg){
// Pager *pPager = pPg->pPager;
// PagerSavepoint *p;
// Pgno pgno = pPg->pgno;
// int i;
// for(i=0; i<pPager->nSavepoint; i++){
// p = &pPager->aSavepoint[i];
// if( p->nOrig>=pgno && 0==sqlite3BitvecTestNotNull(p->pInSavepoint, pgno) ){
// for(i=i+1; i<pPager->nSavepoint; i++){
// pPager->aSavepoint[i].bTruncateOnRelease = 0;
// }
// return 1;
// }
// }
// return 0;
// }
// #ifdef SQLITE_DEBUG
// /*
// ** Return true if the page is already in the journal file.
// */
// static int pageInJournal(Pager *pPager, PgHdr *pPg){
// return sqlite3BitvecTest(pPager->pInJournal, pPg->pgno);
// }
// #endif
// /*
// ** Read a 32-bit integer from the given file descriptor. Store the integer
// ** that is read in *pRes. Return SQLITE_OK if everything worked, or an
// ** error code is something goes wrong.
// **
// ** All values are stored on disk as big-endian.
// */
// static int read32bits(sqlite3_file *fd, i64 offset, u32 *pRes){
// unsigned char ac[4];
// int rc = sqlite3OsRead(fd, ac, sizeof(ac), offset);
// if( rc==SQLITE_OK ){
// *pRes = sqlite3Get4byte(ac);
// }
// return rc;
// }
// /*
// ** Write a 32-bit integer into a string buffer in big-endian byte order.
// */
// #define put32bits(A,B) sqlite3Put4byte((u8*)A,B)
// /*
// ** Write a 32-bit integer into the given file descriptor. Return SQLITE_OK
// ** on success or an error code is something goes wrong.
// */
// static int write32bits(sqlite3_file *fd, i64 offset, u32 val){
// char ac[4];
// put32bits(ac, val);
// return sqlite3OsWrite(fd, ac, 4, offset);
// }
// /*
// ** Unlock the database file to level eLock, which must be either NO_LOCK
// ** or SHARED_LOCK. Regardless of whether or not the call to xUnlock()
// ** succeeds, set the Pager.eLock variable to match the (attempted) new lock.
// **
// ** Except, if Pager.eLock is set to UNKNOWN_LOCK when this function is
// ** called, do not modify it. See the comment above the #define of
// ** UNKNOWN_LOCK for an explanation of this.
// */
// static int pagerUnlockDb(Pager *pPager, int eLock){
// int rc = SQLITE_OK;
// assert( !pPager->exclusiveMode || pPager->eLock==eLock );
// assert( eLock==NO_LOCK || eLock==SHARED_LOCK );
// assert( eLock!=NO_LOCK || pagerUseWal(pPager)==0 );
// if( isOpen(pPager->fd) ){
// assert( pPager->eLock>=eLock );
// rc = pPager->noLock ? SQLITE_OK : sqlite3OsUnlock(pPager->fd, eLock);
// if( pPager->eLock!=UNKNOWN_LOCK ){
// pPager->eLock = (u8)eLock;
// }
// IOTRACE(("UNLOCK %p %d\n", pPager, eLock))
// }
// pPager->changeCountDone = pPager->tempFile; /* ticket fb3b3024ea238d5c */
// return rc;
// }
// /*
// ** Lock the database file to level eLock, which must be either SHARED_LOCK,
// ** RESERVED_LOCK or EXCLUSIVE_LOCK. If the caller is successful, set the
// ** Pager.eLock variable to the new locking state.
// **
// ** Except, if Pager.eLock is set to UNKNOWN_LOCK when this function is
// ** called, do not modify it unless the new locking state is EXCLUSIVE_LOCK.
// ** See the comment above the #define of UNKNOWN_LOCK for an explanation
// ** of this.
// */
// static int pagerLockDb(Pager *pPager, int eLock){
// int rc = SQLITE_OK;
// assert( eLock==SHARED_LOCK || eLock==RESERVED_LOCK || eLock==EXCLUSIVE_LOCK );
// if( pPager->eLock<eLock || pPager->eLock==UNKNOWN_LOCK ){
// rc = pPager->noLock ? SQLITE_OK : sqlite3OsLock(pPager->fd, eLock);
// if( rc==SQLITE_OK && (pPager->eLock!=UNKNOWN_LOCK||eLock==EXCLUSIVE_LOCK) ){
// pPager->eLock = (u8)eLock;
// IOTRACE(("LOCK %p %d\n", pPager, eLock))
// }
// }
// return rc;
// }
// /*
// ** This function determines whether or not the atomic-write or
// ** atomic-batch-write optimizations can be used with this pager. The
// ** atomic-write optimization can be used if:
// **
// ** (a) the value returned by OsDeviceCharacteristics() indicates that
// ** a database page may be written atomically, and
// ** (b) the value returned by OsSectorSize() is less than or equal
// ** to the page size.
// **
// ** If it can be used, then the value returned is the size of the journal
// ** file when it contains rollback data for exactly one page.
// **
// ** The atomic-batch-write optimization can be used if OsDeviceCharacteristics()
// ** returns a value with the SQLITE_IOCAP_BATCH_ATOMIC bit set. -1 is
// ** returned in this case.
// **
// ** If neither optimization can be used, 0 is returned.
// */
// static int jrnlBufferSize(Pager *pPager){
// assert( !MEMDB );
// #if defined(SQLITE_ENABLE_ATOMIC_WRITE) \
// || defined(SQLITE_ENABLE_BATCH_ATOMIC_WRITE)
// int dc; /* Device characteristics */
// assert( isOpen(pPager->fd) );
// dc = sqlite3OsDeviceCharacteristics(pPager->fd);
// #else
// UNUSED_PARAMETER(pPager);
// #endif
// #ifdef SQLITE_ENABLE_BATCH_ATOMIC_WRITE
// if( pPager->dbSize>0 && (dc&SQLITE_IOCAP_BATCH_ATOMIC) ){
// return -1;
// }
// #endif
// #ifdef SQLITE_ENABLE_ATOMIC_WRITE
// {
// int nSector = pPager->sectorSize;
// int szPage = pPager->pageSize;
// assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
// assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
// if( 0==(dc&(SQLITE_IOCAP_ATOMIC|(szPage>>8)) || nSector>szPage) ){
// return 0;
// }
// }
// return JOURNAL_HDR_SZ(pPager) + JOURNAL_PG_SZ(pPager);
// #endif
// return 0;
// }
// /*
// ** If SQLITE_CHECK_PAGES is defined then we do some sanity checking
// ** on the cache using a hash function. This is used for testing
// ** and debugging only.
// */
// #ifdef SQLITE_CHECK_PAGES
// /*
// ** Return a 32-bit hash of the page data for pPage.
// */
// static u32 pager_datahash(int nByte, unsigned char *pData){
// u32 hash = 0;
// int i;
// for(i=0; i<nByte; i++){
// hash = (hash*1039) + pData[i];
// }
// return hash;
// }
// static u32 pager_pagehash(PgHdr *pPage){
// return pager_datahash(pPage->pPager->pageSize, (unsigned char *)pPage->pData);
// }
// static void pager_set_pagehash(PgHdr *pPage){
// pPage->pageHash = pager_pagehash(pPage);
// }
// /*
// ** The CHECK_PAGE macro takes a PgHdr* as an argument. If SQLITE_CHECK_PAGES
// ** is defined, and NDEBUG is not defined, an assert() statement checks
// ** that the page is either dirty or still matches the calculated page-hash.
// */
// #define CHECK_PAGE(x) checkPage(x)
// static void checkPage(PgHdr *pPg){
// Pager *pPager = pPg->pPager;
// assert( pPager->eState!=PAGER_ERROR );
// assert( (pPg->flags&PGHDR_DIRTY) || pPg->pageHash==pager_pagehash(pPg) );
// }
// #else
// #define pager_datahash(X,Y) 0
// #define pager_pagehash(X) 0
// #define pager_set_pagehash(X)
// #define CHECK_PAGE(x)
// #endif /* SQLITE_CHECK_PAGES */
// /*
// ** When this is called the journal file for pager pPager must be open.
// ** This function attempts to read a super-journal file name from the
// ** end of the file and, if successful, copies it into memory supplied
// ** by the caller. See comments above writeSuperJournal() for the format
// ** used to store a super-journal file name at the end of a journal file.
// **
// ** zSuper must point to a buffer of at least nSuper bytes allocated by
// ** the caller. This should be sqlite3_vfs.mxPathname+1 (to ensure there is
// ** enough space to write the super-journal name). If the super-journal
// ** name in the journal is longer than nSuper bytes (including a
// ** nul-terminator), then this is handled as if no super-journal name
// ** were present in the journal.
// **
// ** If a super-journal file name is present at the end of the journal
// ** file, then it is copied into the buffer pointed to by zSuper. A
// ** nul-terminator byte is appended to the buffer following the
// ** super-journal file name.
// **
// ** If it is determined that no super-journal file name is present
// ** zSuper[0] is set to 0 and SQLITE_OK returned.
// **
// ** If an error occurs while reading from the journal file, an SQLite
// ** error code is returned.
// */
// static int readSuperJournal(sqlite3_file *pJrnl, char *zSuper, u32 nSuper){
// int rc; /* Return code */
// u32 len; /* Length in bytes of super-journal name */
// i64 szJ; /* Total size in bytes of journal file pJrnl */
// u32 cksum; /* MJ checksum value read from journal */
// u32 u; /* Unsigned loop counter */
// unsigned char aMagic[8]; /* A buffer to hold the magic header */
// zSuper[0] = '\0';
// if( SQLITE_OK!=(rc = sqlite3OsFileSize(pJrnl, &szJ))
// || szJ<16
// || SQLITE_OK!=(rc = read32bits(pJrnl, szJ-16, &len))
// || len>=nSuper
// || len>szJ-16
// || len==0
// || SQLITE_OK!=(rc = read32bits(pJrnl, szJ-12, &cksum))
// || SQLITE_OK!=(rc = sqlite3OsRead(pJrnl, aMagic, 8, szJ-8))
// || memcmp(aMagic, aJournalMagic, 8)
// || SQLITE_OK!=(rc = sqlite3OsRead(pJrnl, zSuper, len, szJ-16-len))
// ){
// return rc;
// }
// /* See if the checksum matches the super-journal name */
// for(u=0; u<len; u++){
// cksum -= zSuper[u];
// }
// if( cksum ){
// /* If the checksum doesn't add up, then one or more of the disk sectors
// ** containing the super-journal filename is corrupted. This means
// ** definitely roll back, so just return SQLITE_OK and report a (nul)
// ** super-journal filename.
// */
// len = 0;
// }
// zSuper[len] = '\0';
// zSuper[len+1] = '\0';
// return SQLITE_OK;
// }
// /*
// ** Return the offset of the sector boundary at or immediately
// ** following the value in pPager->journalOff, assuming a sector
// ** size of pPager->sectorSize bytes.
// **
// ** i.e for a sector size of 512:
// **
// ** Pager.journalOff Return value
// ** ---------------------------------------
// ** 0 0
// ** 512 512
// ** 100 512
// ** 2000 2048
// **
// */
// static i64 journalHdrOffset(Pager *pPager){
// i64 offset = 0;
// i64 c = pPager->journalOff;
// if( c ){
// offset = ((c-1)/JOURNAL_HDR_SZ(pPager) + 1) * JOURNAL_HDR_SZ(pPager);
// }
// assert( offset%JOURNAL_HDR_SZ(pPager)==0 );
// assert( offset>=c );
// assert( (offset-c)<JOURNAL_HDR_SZ(pPager) );
// return offset;
// }
// /*
// ** The journal file must be open when this function is called.
// **
// ** This function is a no-op if the journal file has not been written to
// ** within the current transaction (i.e. if Pager.journalOff==0).
// **
// ** If doTruncate is non-zero or the Pager.journalSizeLimit variable is
// ** set to 0, then truncate the journal file to zero bytes in size. Otherwise,
// ** zero the 28-byte header at the start of the journal file. In either case,
// ** if the pager is not in no-sync mode, sync the journal file immediately
// ** after writing or truncating it.
// **
// ** If Pager.journalSizeLimit is set to a positive, non-zero value, and
// ** following the truncation or zeroing described above the size of the
// ** journal file in bytes is larger than this value, then truncate the
// ** journal file to Pager.journalSizeLimit bytes. The journal file does
// ** not need to be synced following this operation.
// **
// ** If an IO error occurs, abandon processing and return the IO error code.
// ** Otherwise, return SQLITE_OK.
// */
// static int zeroJournalHdr(Pager *pPager, int doTruncate){
// int rc = SQLITE_OK; /* Return code */
// assert( isOpen(pPager->jfd) );
// assert( !sqlite3JournalIsInMemory(pPager->jfd) );
// if( pPager->journalOff ){
// const i64 iLimit = pPager->journalSizeLimit; /* Local cache of jsl */
// IOTRACE(("JZEROHDR %p\n", pPager))
// if( doTruncate || iLimit==0 ){
// rc = sqlite3OsTruncate(pPager->jfd, 0);
// }else{
// static const char zeroHdr[28] = {0};
// rc = sqlite3OsWrite(pPager->jfd, zeroHdr, sizeof(zeroHdr), 0);
// }
// if( rc==SQLITE_OK && !pPager->noSync ){
// rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_DATAONLY|pPager->syncFlags);
// }
// /* At this point the transaction is committed but the write lock
// ** is still held on the file. If there is a size limit configured for
// ** the persistent journal and the journal file currently consumes more
// ** space than that limit allows for, truncate it now. There is no need
// ** to sync the file following this operation.
// */
// if( rc==SQLITE_OK && iLimit>0 ){
// i64 sz;
// rc = sqlite3OsFileSize(pPager->jfd, &sz);
// if( rc==SQLITE_OK && sz>iLimit ){
// rc = sqlite3OsTruncate(pPager->jfd, iLimit);
// }
// }
// }
// return rc;
// }
// /*
// ** The journal file must be open when this routine is called. A journal
// ** header (JOURNAL_HDR_SZ bytes) is written into the journal file at the
// ** current location.
// **
// ** The format for the journal header is as follows:
// ** - 8 bytes: Magic identifying journal format.
// ** - 4 bytes: Number of records in journal, or -1 no-sync mode is on.
// ** - 4 bytes: Random number used for page hash.
// ** - 4 bytes: Initial database page count.
// ** - 4 bytes: Sector size used by the process that wrote this journal.
// ** - 4 bytes: Database page size.
// **
// ** Followed by (JOURNAL_HDR_SZ - 28) bytes of unused space.
// */
// static int writeJournalHdr(Pager *pPager){
// int rc = SQLITE_OK; /* Return code */
// char *zHeader = pPager->pTmpSpace; /* Temporary space used to build header */
// u32 nHeader = (u32)pPager->pageSize;/* Size of buffer pointed to by zHeader */
// u32 nWrite; /* Bytes of header sector written */
// int ii; /* Loop counter */
// assert( isOpen(pPager->jfd) ); /* Journal file must be open. */
// if( nHeader>JOURNAL_HDR_SZ(pPager) ){
// nHeader = JOURNAL_HDR_SZ(pPager);
// }
// /* If there are active savepoints and any of them were created
// ** since the most recent journal header was written, update the
// ** PagerSavepoint.iHdrOffset fields now.
// */
// for(ii=0; ii<pPager->nSavepoint; ii++){
// if( pPager->aSavepoint[ii].iHdrOffset==0 ){
// pPager->aSavepoint[ii].iHdrOffset = pPager->journalOff;
// }
// }
// pPager->journalHdr = pPager->journalOff = journalHdrOffset(pPager);
// /*
// ** Write the nRec Field - the number of page records that follow this
// ** journal header. Normally, zero is written to this value at this time.
// ** After the records are added to the journal (and the journal synced,
// ** if in full-sync mode), the zero is overwritten with the true number
// ** of records (see syncJournal()).
// **
// ** A faster alternative is to write 0xFFFFFFFF to the nRec field. When
// ** reading the journal this value tells SQLite to assume that the
// ** rest of the journal file contains valid page records. This assumption
// ** is dangerous, as if a failure occurred whilst writing to the journal
// ** file it may contain some garbage data. There are two scenarios
// ** where this risk can be ignored:
// **
// ** * When the pager is in no-sync mode. Corruption can follow a
// ** power failure in this case anyway.
// **
// ** * When the SQLITE_IOCAP_SAFE_APPEND flag is set. This guarantees
// ** that garbage data is never appended to the journal file.
// */
// assert( isOpen(pPager->fd) || pPager->noSync );
// if( pPager->noSync || (pPager->journalMode==PAGER_JOURNALMODE_MEMORY)
// || (sqlite3OsDeviceCharacteristics(pPager->fd)&SQLITE_IOCAP_SAFE_APPEND)
// ){
// memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
// put32bits(&zHeader[sizeof(aJournalMagic)], 0xffffffff);
// }else{
// memset(zHeader, 0, sizeof(aJournalMagic)+4);
// }
// /* The random check-hash initializer */
// sqlite3_randomness(sizeof(pPager->cksumInit), &pPager->cksumInit);
// put32bits(&zHeader[sizeof(aJournalMagic)+4], pPager->cksumInit);
// /* The initial database size */
// put32bits(&zHeader[sizeof(aJournalMagic)+8], pPager->dbOrigSize);
// /* The assumed sector size for this process */
// put32bits(&zHeader[sizeof(aJournalMagic)+12], pPager->sectorSize);
// /* The page size */
// put32bits(&zHeader[sizeof(aJournalMagic)+16], pPager->pageSize);
// /* Initializing the tail of the buffer is not necessary. Everything
// ** works find if the following memset() is omitted. But initializing
// ** the memory prevents valgrind from complaining, so we are willing to
// ** take the performance hit.
// */
// memset(&zHeader[sizeof(aJournalMagic)+20], 0,
// nHeader-(sizeof(aJournalMagic)+20));
// /* In theory, it is only necessary to write the 28 bytes that the
// ** journal header consumes to the journal file here. Then increment the
// ** Pager.journalOff variable by JOURNAL_HDR_SZ so that the next
// ** record is written to the following sector (leaving a gap in the file
// ** that will be implicitly filled in by the OS).
// **
// ** However it has been discovered that on some systems this pattern can
// ** be significantly slower than contiguously writing data to the file,
// ** even if that means explicitly writing data to the block of
// ** (JOURNAL_HDR_SZ - 28) bytes that will not be used. So that is what
// ** is done.
// **
// ** The loop is required here in case the sector-size is larger than the
// ** database page size. Since the zHeader buffer is only Pager.pageSize
// ** bytes in size, more than one call to sqlite3OsWrite() may be required
// ** to populate the entire journal header sector.
// */
// for(nWrite=0; rc==SQLITE_OK&&nWrite<JOURNAL_HDR_SZ(pPager); nWrite+=nHeader){
// IOTRACE(("JHDR %p %lld %d\n", pPager, pPager->journalHdr, nHeader))
// rc = sqlite3OsWrite(pPager->jfd, zHeader, nHeader, pPager->journalOff);
// assert( pPager->journalHdr <= pPager->journalOff );
// pPager->journalOff += nHeader;
// }
// return rc;
// }
// /*
// ** The journal file must be open when this is called. A journal header file
// ** (JOURNAL_HDR_SZ bytes) is read from the current location in the journal
// ** file. The current location in the journal file is given by
// ** pPager->journalOff. See comments above function writeJournalHdr() for
// ** a description of the journal header format.
// **
// ** If the header is read successfully, *pNRec is set to the number of
// ** page records following this header and *pDbSize is set to the size of the
// ** database before the transaction began, in pages. Also, pPager->cksumInit
// ** is set to the value read from the journal header. SQLITE_OK is returned
// ** in this case.
// **
// ** If the journal header file appears to be corrupted, SQLITE_DONE is
// ** returned and *pNRec and *PDbSize are undefined. If JOURNAL_HDR_SZ bytes
// ** cannot be read from the journal file an error code is returned.
// */
// static int readJournalHdr(
// Pager *pPager, /* Pager object */
// int isHot,
// i64 journalSize, /* Size of the open journal file in bytes */
// u32 *pNRec, /* OUT: Value read from the nRec field */
// u32 *pDbSize /* OUT: Value of original database size field */
// ){
// int rc; /* Return code */
// unsigned char aMagic[8]; /* A buffer to hold the magic header */
// i64 iHdrOff; /* Offset of journal header being read */
// assert( isOpen(pPager->jfd) ); /* Journal file must be open. */
// /* Advance Pager.journalOff to the start of the next sector. If the
// ** journal file is too small for there to be a header stored at this
// ** point, return SQLITE_DONE.
// */
// pPager->journalOff = journalHdrOffset(pPager);
// if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){
// return SQLITE_DONE;
// }
// iHdrOff = pPager->journalOff;
// /* Read in the first 8 bytes of the journal header. If they do not match
// ** the magic string found at the start of each journal header, return
// ** SQLITE_DONE. If an IO error occurs, return an error code. Otherwise,
// ** proceed.
// */
// if( isHot || iHdrOff!=pPager->journalHdr ){
// rc = sqlite3OsRead(pPager->jfd, aMagic, sizeof(aMagic), iHdrOff);
// if( rc ){
// return rc;
// }
// if( memcmp(aMagic, aJournalMagic, sizeof(aMagic))!=0 ){
// return SQLITE_DONE;
// }
// }
// /* Read the first three 32-bit fields of the journal header: The nRec
// ** field, the checksum-initializer and the database size at the start
// ** of the transaction. Return an error code if anything goes wrong.
// */
// if( SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+8, pNRec))
// || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+12, &pPager->cksumInit))
// || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+16, pDbSize))
// ){
// return rc;
// }
// if( pPager->journalOff==0 ){
// u32 iPageSize; /* Page-size field of journal header */
// u32 iSectorSize; /* Sector-size field of journal header */
// /* Read the page-size and sector-size journal header fields. */
// if( SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+20, &iSectorSize))
// || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+24, &iPageSize))
// ){
// return rc;
// }
// /* Versions of SQLite prior to 3.5.8 set the page-size field of the
// ** journal header to zero. In this case, assume that the Pager.pageSize
// ** variable is already set to the correct page size.
// */
// if( iPageSize==0 ){
// iPageSize = pPager->pageSize;
// }
// /* Check that the values read from the page-size and sector-size fields
// ** are within range. To be 'in range', both values need to be a power
// ** of two greater than or equal to 512 or 32, and not greater than their
// ** respective compile time maximum limits.
// */
// if( iPageSize<512 || iSectorSize<32
// || iPageSize>SQLITE_MAX_PAGE_SIZE || iSectorSize>MAX_SECTOR_SIZE
// || ((iPageSize-1)&iPageSize)!=0 || ((iSectorSize-1)&iSectorSize)!=0
// ){
// /* If the either the page-size or sector-size in the journal-header is
// ** invalid, then the process that wrote the journal-header must have
// ** crashed before the header was synced. In this case stop reading
// ** the journal file here.
// */
// return SQLITE_DONE;
// }
// /* Update the page-size to match the value read from the journal.
// ** Use a testcase() macro to make sure that malloc failure within
// ** PagerSetPagesize() is tested.
// */
// rc = sqlite3PagerSetPagesize(pPager, &iPageSize, -1);
// testcase( rc!=SQLITE_OK );
// /* Update the assumed sector-size to match the value used by
// ** the process that created this journal. If this journal was
// ** created by a process other than this one, then this routine
// ** is being called from within pager_playback(). The local value
// ** of Pager.sectorSize is restored at the end of that routine.
// */
// pPager->sectorSize = iSectorSize;
// }
// pPager->journalOff += JOURNAL_HDR_SZ(pPager);
// return rc;
// }
// /*
// ** Write the supplied super-journal name into the journal file for pager
// ** pPager at the current location. The super-journal name must be the last
// ** thing written to a journal file. If the pager is in full-sync mode, the
// ** journal file descriptor is advanced to the next sector boundary before
// ** anything is written. The format is:
// **
// ** + 4 bytes: PAGER_MJ_PGNO.
// ** + N bytes: super-journal filename in utf-8.
// ** + 4 bytes: N (length of super-journal name in bytes, no nul-terminator).
// ** + 4 bytes: super-journal name checksum.
// ** + 8 bytes: aJournalMagic[].
// **
// ** The super-journal page checksum is the sum of the bytes in thesuper-journal
// ** name, where each byte is interpreted as a signed 8-bit integer.
// **
// ** If zSuper is a NULL pointer (occurs for a single database transaction),
// ** this call is a no-op.
// */
// static int writeSuperJournal(Pager *pPager, const char *zSuper){
// int rc; /* Return code */
// int nSuper; /* Length of string zSuper */
// i64 iHdrOff; /* Offset of header in journal file */
// i64 jrnlSize; /* Size of journal file on disk */
// u32 cksum = 0; /* Checksum of string zSuper */
// assert( pPager->setSuper==0 );
// assert( !pagerUseWal(pPager) );
// if( !zSuper
// || pPager->journalMode==PAGER_JOURNALMODE_MEMORY
// || !isOpen(pPager->jfd)
// ){
// return SQLITE_OK;
// }
// pPager->setSuper = 1;
// assert( pPager->journalHdr <= pPager->journalOff );
// /* Calculate the length in bytes and the checksum of zSuper */
// for(nSuper=0; zSuper[nSuper]; nSuper++){
// cksum += zSuper[nSuper];
// }
// /* If in full-sync mode, advance to the next disk sector before writing
// ** the super-journal name. This is in case the previous page written to
// ** the journal has already been synced.
// */
// if( pPager->fullSync ){
// pPager->journalOff = journalHdrOffset(pPager);
// }
// iHdrOff = pPager->journalOff;
// /* Write the super-journal data to the end of the journal file. If
// ** an error occurs, return the error code to the caller.
// */
// if( (0 != (rc = write32bits(pPager->jfd, iHdrOff, PAGER_MJ_PGNO(pPager))))
// || (0 != (rc = sqlite3OsWrite(pPager->jfd, zSuper, nSuper, iHdrOff+4)))
// || (0 != (rc = write32bits(pPager->jfd, iHdrOff+4+nSuper, nSuper)))
// || (0 != (rc = write32bits(pPager->jfd, iHdrOff+4+nSuper+4, cksum)))
// || (0 != (rc = sqlite3OsWrite(pPager->jfd, aJournalMagic, 8,
// iHdrOff+4+nSuper+8)))
// ){
// return rc;
// }
// pPager->journalOff += (nSuper+20);
// /* If the pager is in peristent-journal mode, then the physical
// ** journal-file may extend past the end of the super-journal name
// ** and 8 bytes of magic data just written to the file. This is
// ** dangerous because the code to rollback a hot-journal file
// ** will not be able to find the super-journal name to determine
// ** whether or not the journal is hot.
// **
// ** Easiest thing to do in this scenario is to truncate the journal
// ** file to the required size.
// */
// if( SQLITE_OK==(rc = sqlite3OsFileSize(pPager->jfd, &jrnlSize))
// && jrnlSize>pPager->journalOff
// ){
// rc = sqlite3OsTruncate(pPager->jfd, pPager->journalOff);
// }
// return rc;
// }
// /*
// ** Discard the entire contents of the in-memory page-cache.
// */
// static void pager_reset(Pager *pPager){
// pPager->iDataVersion++;
// sqlite3BackupRestart(pPager->pBackup);
// sqlite3PcacheClear(pPager->pPCache);
// }
// /*
// ** Return the pPager->iDataVersion value
// */
// u32 sqlite3PagerDataVersion(Pager *pPager){
// return pPager->iDataVersion;
// }
// /*
// ** Free all structures in the Pager.aSavepoint[] array and set both
// ** Pager.aSavepoint and Pager.nSavepoint to zero. Close the sub-journal
// ** if it is open and the pager is not in exclusive mode.
// */
// static void releaseAllSavepoints(Pager *pPager){
// int ii; /* Iterator for looping through Pager.aSavepoint */
// for(ii=0; ii<pPager->nSavepoint; ii++){
// sqlite3BitvecDestroy(pPager->aSavepoint[ii].pInSavepoint);
// }
// if( !pPager->exclusiveMode || sqlite3JournalIsInMemory(pPager->sjfd) ){
// sqlite3OsClose(pPager->sjfd);
// }
// sqlite3_free(pPager->aSavepoint);
// pPager->aSavepoint = 0;
// pPager->nSavepoint = 0;
// pPager->nSubRec = 0;
// }
// /*
// ** Set the bit number pgno in the PagerSavepoint.pInSavepoint
// ** bitvecs of all open savepoints. Return SQLITE_OK if successful
// ** or SQLITE_NOMEM if a malloc failure occurs.
// */
// static int addToSavepointBitvecs(Pager *pPager, Pgno pgno){
// int ii; /* Loop counter */
// int rc = SQLITE_OK; /* Result code */
// for(ii=0; ii<pPager->nSavepoint; ii++){
// PagerSavepoint *p = &pPager->aSavepoint[ii];
// if( pgno<=p->nOrig ){
// rc |= sqlite3BitvecSet(p->pInSavepoint, pgno);
// testcase( rc==SQLITE_NOMEM );
// assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
// }
// }
// return rc;
// }
// /*
// ** This function is a no-op if the pager is in exclusive mode and not
// ** in the ERROR state. Otherwise, it switches the pager to PAGER_OPEN
// ** state.
// **
// ** If the pager is not in exclusive-access mode, the database file is
// ** completely unlocked. If the file is unlocked and the file-system does
// ** not exhibit the UNDELETABLE_WHEN_OPEN property, the journal file is
// ** closed (if it is open).
// **
// ** If the pager is in ERROR state when this function is called, the
// ** contents of the pager cache are discarded before switching back to
// ** the OPEN state. Regardless of whether the pager is in exclusive-mode
// ** or not, any journal file left in the file-system will be treated
// ** as a hot-journal and rolled back the next time a read-transaction
// ** is opened (by this or by any other connection).
// */
// static void pager_unlock(Pager *pPager){
// assert( pPager->eState==PAGER_READER
// || pPager->eState==PAGER_OPEN
// || pPager->eState==PAGER_ERROR
// );
// sqlite3BitvecDestroy(pPager->pInJournal);
// pPager->pInJournal = 0;
// releaseAllSavepoints(pPager);
// if( pagerUseWal(pPager) ){
// assert( !isOpen(pPager->jfd) );
// sqlite3WalEndReadTransaction(pPager->pWal);
// pPager->eState = PAGER_OPEN;
// }else if( !pPager->exclusiveMode ){
// int rc; /* Error code returned by pagerUnlockDb() */
// int iDc = isOpen(pPager->fd)?sqlite3OsDeviceCharacteristics(pPager->fd):0;
// /* If the operating system support deletion of open files, then
// ** close the journal file when dropping the database lock. Otherwise
// ** another connection with journal_mode=delete might delete the file
// ** out from under us.
// */
// assert( (PAGER_JOURNALMODE_MEMORY & 5)!=1 );
// assert( (PAGER_JOURNALMODE_OFF & 5)!=1 );
// assert( (PAGER_JOURNALMODE_WAL & 5)!=1 );
// assert( (PAGER_JOURNALMODE_DELETE & 5)!=1 );
// assert( (PAGER_JOURNALMODE_TRUNCATE & 5)==1 );
// assert( (PAGER_JOURNALMODE_PERSIST & 5)==1 );
// if( 0==(iDc & SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN)
// || 1!=(pPager->journalMode & 5)
// ){
// sqlite3OsClose(pPager->jfd);
// }
// /* If the pager is in the ERROR state and the call to unlock the database
// ** file fails, set the current lock to UNKNOWN_LOCK. See the comment
// ** above the #define for UNKNOWN_LOCK for an explanation of why this
// ** is necessary.
// */
// rc = pagerUnlockDb(pPager, NO_LOCK);
// if( rc!=SQLITE_OK && pPager->eState==PAGER_ERROR ){
// pPager->eLock = UNKNOWN_LOCK;
// }
// /* The pager state may be changed from PAGER_ERROR to PAGER_OPEN here
// ** without clearing the error code. This is intentional - the error
// ** code is cleared and the cache reset in the block below.
// */
// assert( pPager->errCode || pPager->eState!=PAGER_ERROR );
// pPager->eState = PAGER_OPEN;
// }
// /* If Pager.errCode is set, the contents of the pager cache cannot be
// ** trusted. Now that there are no outstanding references to the pager,
// ** it can safely move back to PAGER_OPEN state. This happens in both
// ** normal and exclusive-locking mode.
// */
// assert( pPager->errCode==SQLITE_OK || !MEMDB );
// if( pPager->errCode ){
// if( pPager->tempFile==0 ){
// pager_reset(pPager);
// pPager->changeCountDone = 0;
// pPager->eState = PAGER_OPEN;
// }else{
// pPager->eState = (isOpen(pPager->jfd) ? PAGER_OPEN : PAGER_READER);
// }
// if( USEFETCH(pPager) ) sqlite3OsUnfetch(pPager->fd, 0, 0);
// pPager->errCode = SQLITE_OK;
// setGetterMethod(pPager);
// }
// pPager->journalOff = 0;
// pPager->journalHdr = 0;
// pPager->setSuper = 0;
// }
// /*
// ** This function is called whenever an IOERR or FULL error that requires
// ** the pager to transition into the ERROR state may ahve occurred.
// ** The first argument is a pointer to the pager structure, the second
// ** the error-code about to be returned by a pager API function. The
// ** value returned is a copy of the second argument to this function.
// **
// ** If the second argument is SQLITE_FULL, SQLITE_IOERR or one of the
// ** IOERR sub-codes, the pager enters the ERROR state and the error code
// ** is stored in Pager.errCode. While the pager remains in the ERROR state,
// ** all major API calls on the Pager will immediately return Pager.errCode.
// **
// ** The ERROR state indicates that the contents of the pager-cache
// ** cannot be trusted. This state can be cleared by completely discarding
// ** the contents of the pager-cache. If a transaction was active when
// ** the persistent error occurred, then the rollback journal may need
// ** to be replayed to restore the contents of the database file (as if
// ** it were a hot-journal).
// */
// static int pager_error(Pager *pPager, int rc){
// int rc2 = rc & 0xff;
// assert( rc==SQLITE_OK || !MEMDB );
// assert(
// pPager->errCode==SQLITE_FULL ||
// pPager->errCode==SQLITE_OK ||
// (pPager->errCode & 0xff)==SQLITE_IOERR
// );
// if( rc2==SQLITE_FULL || rc2==SQLITE_IOERR ){
// pPager->errCode = rc;
// pPager->eState = PAGER_ERROR;
// setGetterMethod(pPager);
// }
// return rc;
// }
// static int pager_truncate(Pager *pPager, Pgno nPage);
// /*
// ** The write transaction open on pPager is being committed (bCommit==1)
// ** or rolled back (bCommit==0).
// **
// ** Return TRUE if and only if all dirty pages should be flushed to disk.
// **
// ** Rules:
// **
// ** * For non-TEMP databases, always sync to disk. This is necessary
// ** for transactions to be durable.
// **
// ** * Sync TEMP database only on a COMMIT (not a ROLLBACK) when the backing
// ** file has been created already (via a spill on pagerStress()) and
// ** when the number of dirty pages in memory exceeds 25% of the total
// ** cache size.
// */
// static int pagerFlushOnCommit(Pager *pPager, int bCommit){
// if( pPager->tempFile==0 ) return 1;
// if( !bCommit ) return 0;
// if( !isOpen(pPager->fd) ) return 0;
// return (sqlite3PCachePercentDirty(pPager->pPCache)>=25);
// }
// /*
// ** This routine ends a transaction. A transaction is usually ended by
// ** either a COMMIT or a ROLLBACK operation. This routine may be called
// ** after rollback of a hot-journal, or if an error occurs while opening
// ** the journal file or writing the very first journal-header of a
// ** database transaction.
// **
// ** This routine is never called in PAGER_ERROR state. If it is called
// ** in PAGER_NONE or PAGER_SHARED state and the lock held is less
// ** exclusive than a RESERVED lock, it is a no-op.
// **
// ** Otherwise, any active savepoints are released.
// **
// ** If the journal file is open, then it is "finalized". Once a journal
// ** file has been finalized it is not possible to use it to roll back a
// ** transaction. Nor will it be considered to be a hot-journal by this
// ** or any other database connection. Exactly how a journal is finalized
// ** depends on whether or not the pager is running in exclusive mode and
// ** the current journal-mode (Pager.journalMode value), as follows:
// **
// ** journalMode==MEMORY
// ** Journal file descriptor is simply closed. This destroys an
// ** in-memory journal.
// **
// ** journalMode==TRUNCATE
// ** Journal file is truncated to zero bytes in size.
// **
// ** journalMode==PERSIST
// ** The first 28 bytes of the journal file are zeroed. This invalidates
// ** the first journal header in the file, and hence the entire journal
// ** file. An invalid journal file cannot be rolled back.
// **
// ** journalMode==DELETE
// ** The journal file is closed and deleted using sqlite3OsDelete().
// **
// ** If the pager is running in exclusive mode, this method of finalizing
// ** the journal file is never used. Instead, if the journalMode is
// ** DELETE and the pager is in exclusive mode, the method described under
// ** journalMode==PERSIST is used instead.
// **
// ** After the journal is finalized, the pager moves to PAGER_READER state.
// ** If running in non-exclusive rollback mode, the lock on the file is
// ** downgraded to a SHARED_LOCK.
// **
// ** SQLITE_OK is returned if no error occurs. If an error occurs during
// ** any of the IO operations to finalize the journal file or unlock the
// ** database then the IO error code is returned to the user. If the
// ** operation to finalize the journal file fails, then the code still
// ** tries to unlock the database file if not in exclusive mode. If the
// ** unlock operation fails as well, then the first error code related
// ** to the first error encountered (the journal finalization one) is
// ** returned.
// */
// static int pager_end_transaction(Pager *pPager, int hasSuper, int bCommit){
// int rc = SQLITE_OK; /* Error code from journal finalization operation */
// int rc2 = SQLITE_OK; /* Error code from db file unlock operation */
// /* Do nothing if the pager does not have an open write transaction
// ** or at least a RESERVED lock. This function may be called when there
// ** is no write-transaction active but a RESERVED or greater lock is
// ** held under two circumstances:
// **
// ** 1. After a successful hot-journal rollback, it is called with
// ** eState==PAGER_NONE and eLock==EXCLUSIVE_LOCK.
// **
// ** 2. If a connection with locking_mode=exclusive holding an EXCLUSIVE
// ** lock switches back to locking_mode=normal and then executes a
// ** read-transaction, this function is called with eState==PAGER_READER
// ** and eLock==EXCLUSIVE_LOCK when the read-transaction is closed.
// */
// assert( assert_pager_state(pPager) );
// assert( pPager->eState!=PAGER_ERROR );
// if( pPager->eState<PAGER_WRITER_LOCKED && pPager->eLock<RESERVED_LOCK ){
// return SQLITE_OK;
// }
// releaseAllSavepoints(pPager);
// assert( isOpen(pPager->jfd) || pPager->pInJournal==0
// || (sqlite3OsDeviceCharacteristics(pPager->fd)&SQLITE_IOCAP_BATCH_ATOMIC)
// );
// if( isOpen(pPager->jfd) ){
// assert( !pagerUseWal(pPager) );
// /* Finalize the journal file. */
// if( sqlite3JournalIsInMemory(pPager->jfd) ){
// /* assert( pPager->journalMode==PAGER_JOURNALMODE_MEMORY ); */
// sqlite3OsClose(pPager->jfd);
// }else if( pPager->journalMode==PAGER_JOURNALMODE_TRUNCATE ){
// if( pPager->journalOff==0 ){
// rc = SQLITE_OK;
// }else{
// rc = sqlite3OsTruncate(pPager->jfd, 0);
// if( rc==SQLITE_OK && pPager->fullSync ){
// /* Make sure the new file size is written into the inode right away.
// ** Otherwise the journal might resurrect following a power loss and
// ** cause the last transaction to roll back. See
// ** https://bugzilla.mozilla.org/show_bug.cgi?id=1072773
// */
// rc = sqlite3OsSync(pPager->jfd, pPager->syncFlags);
// }
// }
// pPager->journalOff = 0;
// }else if( pPager->journalMode==PAGER_JOURNALMODE_PERSIST
// || (pPager->exclusiveMode && pPager->journalMode!=PAGER_JOURNALMODE_WAL)
// ){
// rc = zeroJournalHdr(pPager, hasSuper||pPager->tempFile);
// pPager->journalOff = 0;
// }else{
// /* This branch may be executed with Pager.journalMode==MEMORY if
// ** a hot-journal was just rolled back. In this case the journal
// ** file should be closed and deleted. If this connection writes to
// ** the database file, it will do so using an in-memory journal.
// */
// int bDelete = !pPager->tempFile;
// assert( sqlite3JournalIsInMemory(pPager->jfd)==0 );
// assert( pPager->journalMode==PAGER_JOURNALMODE_DELETE
// || pPager->journalMode==PAGER_JOURNALMODE_MEMORY
// || pPager->journalMode==PAGER_JOURNALMODE_WAL
// );
// sqlite3OsClose(pPager->jfd);
// if( bDelete ){
// rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal, pPager->extraSync);
// }
// }
// }
// #ifdef SQLITE_CHECK_PAGES
// sqlite3PcacheIterateDirty(pPager->pPCache, pager_set_pagehash);
// if( pPager->dbSize==0 && sqlite3PcacheRefCount(pPager->pPCache)>0 ){
// PgHdr *p = sqlite3PagerLookup(pPager, 1);
// if( p ){
// p->pageHash = 0;
// sqlite3PagerUnrefNotNull(p);
// }
// }
// #endif
// sqlite3BitvecDestroy(pPager->pInJournal);
// pPager->pInJournal = 0;
// pPager->nRec = 0;
// if( rc==SQLITE_OK ){
// if( MEMDB || pagerFlushOnCommit(pPager, bCommit) ){
// sqlite3PcacheCleanAll(pPager->pPCache);
// }else{
// sqlite3PcacheClearWritable(pPager->pPCache);
// }
// sqlite3PcacheTruncate(pPager->pPCache, pPager->dbSize);
// }
// if( pagerUseWal(pPager) ){
// /* Drop the WAL write-lock, if any. Also, if the connection was in
// ** locking_mode=exclusive mode but is no longer, drop the EXCLUSIVE
// ** lock held on the database file.
// */
// rc2 = sqlite3WalEndWriteTransaction(pPager->pWal);
// assert( rc2==SQLITE_OK );
// }else if( rc==SQLITE_OK && bCommit && pPager->dbFileSize>pPager->dbSize ){
// /* This branch is taken when committing a transaction in rollback-journal
// ** mode if the database file on disk is larger than the database image.
// ** At this point the journal has been finalized and the transaction
// ** successfully committed, but the EXCLUSIVE lock is still held on the
// ** file. So it is safe to truncate the database file to its minimum
// ** required size. */
// assert( pPager->eLock==EXCLUSIVE_LOCK );
// rc = pager_truncate(pPager, pPager->dbSize);
// }
// if( rc==SQLITE_OK && bCommit ){
// rc = sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_COMMIT_PHASETWO, 0);
// if( rc==SQLITE_NOTFOUND ) rc = SQLITE_OK;
// }
// if( !pPager->exclusiveMode
// && (!pagerUseWal(pPager) || sqlite3WalExclusiveMode(pPager->pWal, 0))
// ){
// rc2 = pagerUnlockDb(pPager, SHARED_LOCK);
// }
// pPager->eState = PAGER_READER;
// pPager->setSuper = 0;
// return (rc==SQLITE_OK?rc2:rc);
// }
// /*
// ** Execute a rollback if a transaction is active and unlock the
// ** database file.
// **
// ** If the pager has already entered the ERROR state, do not attempt
// ** the rollback at this time. Instead, pager_unlock() is called. The
// ** call to pager_unlock() will discard all in-memory pages, unlock
// ** the database file and move the pager back to OPEN state. If this
// ** means that there is a hot-journal left in the file-system, the next
// ** connection to obtain a shared lock on the pager (which may be this one)
// ** will roll it back.
// **
// ** If the pager has not already entered the ERROR state, but an IO or
// ** malloc error occurs during a rollback, then this will itself cause
// ** the pager to enter the ERROR state. Which will be cleared by the
// ** call to pager_unlock(), as described above.
// */
// static void pagerUnlockAndRollback(Pager *pPager){
// if( pPager->eState!=PAGER_ERROR && pPager->eState!=PAGER_OPEN ){
// assert( assert_pager_state(pPager) );
// if( pPager->eState>=PAGER_WRITER_LOCKED ){
// sqlite3BeginBenignMalloc();
// sqlite3PagerRollback(pPager);
// sqlite3EndBenignMalloc();
// }else if( !pPager->exclusiveMode ){
// assert( pPager->eState==PAGER_READER );
// pager_end_transaction(pPager, 0, 0);
// }
// }
// pager_unlock(pPager);
// }
// /*
// ** Parameter aData must point to a buffer of pPager->pageSize bytes
// ** of data. Compute and return a checksum based ont the contents of the
// ** page of data and the current value of pPager->cksumInit.
// **
// ** This is not a real checksum. It is really just the sum of the
// ** random initial value (pPager->cksumInit) and every 200th byte
// ** of the page data, starting with byte offset (pPager->pageSize%200).
// ** Each byte is interpreted as an 8-bit unsigned integer.
// **
// ** Changing the formula used to compute this checksum results in an
// ** incompatible journal file format.
// **
// ** If journal corruption occurs due to a power failure, the most likely
// ** scenario is that one end or the other of the record will be changed.
// ** It is much less likely that the two ends of the journal record will be
// ** correct and the middle be corrupt. Thus, this "checksum" scheme,
// ** though fast and simple, catches the mostly likely kind of corruption.
// */
// static u32 pager_cksum(Pager *pPager, const u8 *aData){
// u32 cksum = pPager->cksumInit; /* Checksum value to return */
// int i = pPager->pageSize-200; /* Loop counter */
// while( i>0 ){
// cksum += aData[i];
// i -= 200;
// }
// return cksum;
// }
// /*
// ** Read a single page from either the journal file (if isMainJrnl==1) or
// ** from the sub-journal (if isMainJrnl==0) and playback that page.
// ** The page begins at offset *pOffset into the file. The *pOffset
// ** value is increased to the start of the next page in the journal.
// **
// ** The main rollback journal uses checksums - the statement journal does
// ** not.
// **
// ** If the page number of the page record read from the (sub-)journal file
// ** is greater than the current value of Pager.dbSize, then playback is
// ** skipped and SQLITE_OK is returned.
// **
// ** If pDone is not NULL, then it is a record of pages that have already
// ** been played back. If the page at *pOffset has already been played back
// ** (if the corresponding pDone bit is set) then skip the playback.
// ** Make sure the pDone bit corresponding to the *pOffset page is set
// ** prior to returning.
// **
// ** If the page record is successfully read from the (sub-)journal file
// ** and played back, then SQLITE_OK is returned. If an IO error occurs
// ** while reading the record from the (sub-)journal file or while writing
// ** to the database file, then the IO error code is returned. If data
// ** is successfully read from the (sub-)journal file but appears to be
// ** corrupted, SQLITE_DONE is returned. Data is considered corrupted in
// ** two circumstances:
// **
// ** * If the record page-number is illegal (0 or PAGER_MJ_PGNO), or
// ** * If the record is being rolled back from the main journal file
// ** and the checksum field does not match the record content.
// **
// ** Neither of these two scenarios are possible during a savepoint rollback.
// **
// ** If this is a savepoint rollback, then memory may have to be dynamically
// ** allocated by this function. If this is the case and an allocation fails,
// ** SQLITE_NOMEM is returned.
// */
// static int pager_playback_one_page(
// Pager *pPager, /* The pager being played back */
// i64 *pOffset, /* Offset of record to playback */
// Bitvec *pDone, /* Bitvec of pages already played back */
// int isMainJrnl, /* 1 -> main journal. 0 -> sub-journal. */
// int isSavepnt /* True for a savepoint rollback */
// ){
// int rc;
// PgHdr *pPg; /* An existing page in the cache */
// Pgno pgno; /* The page number of a page in journal */
// u32 cksum; /* Checksum used for sanity checking */
// char *aData; /* Temporary storage for the page */
// sqlite3_file *jfd; /* The file descriptor for the journal file */
// int isSynced; /* True if journal page is synced */
// assert( (isMainJrnl&~1)==0 ); /* isMainJrnl is 0 or 1 */
// assert( (isSavepnt&~1)==0 ); /* isSavepnt is 0 or 1 */
// assert( isMainJrnl || pDone ); /* pDone always used on sub-journals */
// assert( isSavepnt || pDone==0 ); /* pDone never used on non-savepoint */
// aData = pPager->pTmpSpace;
// assert( aData ); /* Temp storage must have already been allocated */
// assert( pagerUseWal(pPager)==0 || (!isMainJrnl && isSavepnt) );
// /* Either the state is greater than PAGER_WRITER_CACHEMOD (a transaction
// ** or savepoint rollback done at the request of the caller) or this is
// ** a hot-journal rollback. If it is a hot-journal rollback, the pager
// ** is in state OPEN and holds an EXCLUSIVE lock. Hot-journal rollback
// ** only reads from the main journal, not the sub-journal.
// */
// assert( pPager->eState>=PAGER_WRITER_CACHEMOD
// || (pPager->eState==PAGER_OPEN && pPager->eLock==EXCLUSIVE_LOCK)
// );
// assert( pPager->eState>=PAGER_WRITER_CACHEMOD || isMainJrnl );
// /* Read the page number and page data from the journal or sub-journal
// ** file. Return an error code to the caller if an IO error occurs.
// */
// jfd = isMainJrnl ? pPager->jfd : pPager->sjfd;
// rc = read32bits(jfd, *pOffset, &pgno);
// if( rc!=SQLITE_OK ) return rc;
// rc = sqlite3OsRead(jfd, (u8*)aData, pPager->pageSize, (*pOffset)+4);
// if( rc!=SQLITE_OK ) return rc;
// *pOffset += pPager->pageSize + 4 + isMainJrnl*4;
// /* Sanity checking on the page. This is more important that I originally
// ** thought. If a power failure occurs while the journal is being written,
// ** it could cause invalid data to be written into the journal. We need to
// ** detect this invalid data (with high probability) and ignore it.
// */
// if( pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){
// assert( !isSavepnt );
// return SQLITE_DONE;
// }
// if( pgno>(Pgno)pPager->dbSize || sqlite3BitvecTest(pDone, pgno) ){
// return SQLITE_OK;
// }
// if( isMainJrnl ){
// rc = read32bits(jfd, (*pOffset)-4, &cksum);
// if( rc ) return rc;
// if( !isSavepnt && pager_cksum(pPager, (u8*)aData)!=cksum ){
// return SQLITE_DONE;
// }
// }
// /* If this page has already been played back before during the current
// ** rollback, then don't bother to play it back again.
// */
// if( pDone && (rc = sqlite3BitvecSet(pDone, pgno))!=SQLITE_OK ){
// return rc;
// }
// /* When playing back page 1, restore the nReserve setting
// */
// if( pgno==1 && pPager->nReserve!=((u8*)aData)[20] ){
// pPager->nReserve = ((u8*)aData)[20];
// }
// /* If the pager is in CACHEMOD state, then there must be a copy of this
// ** page in the pager cache. In this case just update the pager cache,
// ** not the database file. The page is left marked dirty in this case.
// **
// ** An exception to the above rule: If the database is in no-sync mode
// ** and a page is moved during an incremental vacuum then the page may
// ** not be in the pager cache. Later: if a malloc() or IO error occurs
// ** during a Movepage() call, then the page may not be in the cache
// ** either. So the condition described in the above paragraph is not
// ** assert()able.
// **
// ** If in WRITER_DBMOD, WRITER_FINISHED or OPEN state, then we update the
// ** pager cache if it exists and the main file. The page is then marked
// ** not dirty. Since this code is only executed in PAGER_OPEN state for
// ** a hot-journal rollback, it is guaranteed that the page-cache is empty
// ** if the pager is in OPEN state.
// **
// ** Ticket #1171: The statement journal might contain page content that is
// ** different from the page content at the start of the transaction.
// ** This occurs when a page is changed prior to the start of a statement
// ** then changed again within the statement. When rolling back such a
// ** statement we must not write to the original database unless we know
// ** for certain that original page contents are synced into the main rollback
// ** journal. Otherwise, a power loss might leave modified data in the
// ** database file without an entry in the rollback journal that can
// ** restore the database to its original form. Two conditions must be
// ** met before writing to the database files. (1) the database must be
// ** locked. (2) we know that the original page content is fully synced
// ** in the main journal either because the page is not in cache or else
// ** the page is marked as needSync==0.
// **
// ** 2008-04-14: When attempting to vacuum a corrupt database file, it
// ** is possible to fail a statement on a database that does not yet exist.
// ** Do not attempt to write if database file has never been opened.
// */
// if( pagerUseWal(pPager) ){
// pPg = 0;
// }else{
// pPg = sqlite3PagerLookup(pPager, pgno);
// }
// assert( pPg || !MEMDB );
// assert( pPager->eState!=PAGER_OPEN || pPg==0 || pPager->tempFile );
// PAGERTRACE(("PLAYBACK %d page %d hash(%08x) %s\n",
// PAGERID(pPager), pgno, pager_datahash(pPager->pageSize, (u8*)aData),
// (isMainJrnl?"main-journal":"sub-journal")
// ));
// if( isMainJrnl ){
// isSynced = pPager->noSync || (*pOffset <= pPager->journalHdr);
// }else{
// isSynced = (pPg==0 || 0==(pPg->flags & PGHDR_NEED_SYNC));
// }
// if( isOpen(pPager->fd)
// && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
// && isSynced
// ){
// i64 ofst = (pgno-1)*(i64)pPager->pageSize;
// testcase( !isSavepnt && pPg!=0 && (pPg->flags&PGHDR_NEED_SYNC)!=0 );
// assert( !pagerUseWal(pPager) );
// /* Write the data read from the journal back into the database file.
// ** This is usually safe even for an encrypted database - as the data
// ** was encrypted before it was written to the journal file. The exception
// ** is if the data was just read from an in-memory sub-journal. In that
// ** case it must be encrypted here before it is copied into the database
// ** file. */
// rc = sqlite3OsWrite(pPager->fd, (u8 *)aData, pPager->pageSize, ofst);
// if( pgno>pPager->dbFileSize ){
// pPager->dbFileSize = pgno;
// }
// if( pPager->pBackup ){
// sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)aData);
// }
// }else if( !isMainJrnl && pPg==0 ){
// /* If this is a rollback of a savepoint and data was not written to
// ** the database and the page is not in-memory, there is a potential
// ** problem. When the page is next fetched by the b-tree layer, it
// ** will be read from the database file, which may or may not be
// ** current.
// **
// ** There are a couple of different ways this can happen. All are quite
// ** obscure. When running in synchronous mode, this can only happen
// ** if the page is on the free-list at the start of the transaction, then
// ** populated, then moved using sqlite3PagerMovepage().
// **
// ** The solution is to add an in-memory page to the cache containing
// ** the data just read from the sub-journal. Mark the page as dirty
// ** and if the pager requires a journal-sync, then mark the page as
// ** requiring a journal-sync before it is written.
// */
// assert( isSavepnt );
// assert( (pPager->doNotSpill & SPILLFLAG_ROLLBACK)==0 );
// pPager->doNotSpill |= SPILLFLAG_ROLLBACK;
// rc = sqlite3PagerGet(pPager, pgno, &pPg, 1);
// assert( (pPager->doNotSpill & SPILLFLAG_ROLLBACK)!=0 );
// pPager->doNotSpill &= ~SPILLFLAG_ROLLBACK;
// if( rc!=SQLITE_OK ) return rc;
// sqlite3PcacheMakeDirty(pPg);
// }
// if( pPg ){
// /* No page should ever be explicitly rolled back that is in use, except
// ** for page 1 which is held in use in order to keep the lock on the
// ** database active. However such a page may be rolled back as a result
// ** of an internal error resulting in an automatic call to
// ** sqlite3PagerRollback().
// */
// void *pData;
// pData = pPg->pData;
// memcpy(pData, (u8*)aData, pPager->pageSize);
// pPager->xReiniter(pPg);
// /* It used to be that sqlite3PcacheMakeClean(pPg) was called here. But
// ** that call was dangerous and had no detectable benefit since the cache
// ** is normally cleaned by sqlite3PcacheCleanAll() after rollback and so
// ** has been removed. */
// pager_set_pagehash(pPg);
// /* If this was page 1, then restore the value of Pager.dbFileVers.
// ** Do this before any decoding. */
// if( pgno==1 ){
// memcpy(&pPager->dbFileVers, &((u8*)pData)[24],sizeof(pPager->dbFileVers));
// }
// sqlite3PcacheRelease(pPg);
// }
// return rc;
// }
// /*
// ** Parameter zSuper is the name of a super-journal file. A single journal
// ** file that referred to the super-journal file has just been rolled back.
// ** This routine checks if it is possible to delete the super-journal file,
// ** and does so if it is.
// **
// ** Argument zSuper may point to Pager.pTmpSpace. So that buffer is not
// ** available for use within this function.
// **
// ** When a super-journal file is created, it is populated with the names
// ** of all of its child journals, one after another, formatted as utf-8
// ** encoded text. The end of each child journal file is marked with a
// ** nul-terminator byte (0x00). i.e. the entire contents of a super-journal
// ** file for a transaction involving two databases might be:
// **
// ** "/home/bill/a.db-journal\x00/home/bill/b.db-journal\x00"
// **
// ** A super-journal file may only be deleted once all of its child
// ** journals have been rolled back.
// **
// ** This function reads the contents of the super-journal file into
// ** memory and loops through each of the child journal names. For
// ** each child journal, it checks if:
// **
// ** * if the child journal exists, and if so
// ** * if the child journal contains a reference to super-journal
// ** file zSuper
// **
// ** If a child journal can be found that matches both of the criteria
// ** above, this function returns without doing anything. Otherwise, if
// ** no such child journal can be found, file zSuper is deleted from
// ** the file-system using sqlite3OsDelete().
// **
// ** If an IO error within this function, an error code is returned. This
// ** function allocates memory by calling sqlite3Malloc(). If an allocation
// ** fails, SQLITE_NOMEM is returned. Otherwise, if no IO or malloc errors
// ** occur, SQLITE_OK is returned.
// **
// ** TODO: This function allocates a single block of memory to load
// ** the entire contents of the super-journal file. This could be
// ** a couple of kilobytes or so - potentially larger than the page
// ** size.
// */
// static int pager_delsuper(Pager *pPager, const char *zSuper){
// sqlite3_vfs *pVfs = pPager->pVfs;
// int rc; /* Return code */
// sqlite3_file *pSuper; /* Malloc'd super-journal file descriptor */
// sqlite3_file *pJournal; /* Malloc'd child-journal file descriptor */
// char *zSuperJournal = 0; /* Contents of super-journal file */
// i64 nSuperJournal; /* Size of super-journal file */
// char *zJournal; /* Pointer to one journal within MJ file */
// char *zSuperPtr; /* Space to hold super-journal filename */
// char *zFree = 0; /* Free this buffer */
// int nSuperPtr; /* Amount of space allocated to zSuperPtr[] */
// /* Allocate space for both the pJournal and pSuper file descriptors.
// ** If successful, open the super-journal file for reading.
// */
// pSuper = (sqlite3_file *)sqlite3MallocZero(pVfs->szOsFile * 2);
// if( !pSuper ){
// rc = SQLITE_NOMEM;
// pJournal = 0;
// }else{
// const int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_SUPER_JOURNAL);
// rc = sqlite3OsOpen(pVfs, zSuper, pSuper, flags, 0);
// pJournal = (sqlite3_file *)(((u8 *)pSuper) + pVfs->szOsFile);
// }
// if( rc!=SQLITE_OK ) goto delsuper_out;
// /* Load the entire super-journal file into space obtained from
// ** sqlite3_malloc() and pointed to by zSuperJournal. Also obtain
// ** sufficient space (in zSuperPtr) to hold the names of super-journal
// ** files extracted from regular rollback-journals.
// */
// rc = sqlite3OsFileSize(pSuper, &nSuperJournal);
// if( rc!=SQLITE_OK ) goto delsuper_out;
// nSuperPtr = pVfs->mxPathname+1;
// zFree = sqlite3Malloc(4 + nSuperJournal + nSuperPtr + 2);
// if( !zFree ){
// rc = SQLITE_NOMEM;
// goto delsuper_out;
// }
// zFree[0] = zFree[1] = zFree[2] = zFree[3] = 0;
// zSuperJournal = &zFree[4];
// zSuperPtr = &zSuperJournal[nSuperJournal+2];
// rc = sqlite3OsRead(pSuper, zSuperJournal, (int)nSuperJournal, 0);
// if( rc!=SQLITE_OK ) goto delsuper_out;
// zSuperJournal[nSuperJournal] = 0;
// zSuperJournal[nSuperJournal+1] = 0;
// zJournal = zSuperJournal;
// while( (zJournal-zSuperJournal)<nSuperJournal ){
// int exists;
// rc = sqlite3OsAccess(pVfs, zJournal, SQLITE_ACCESS_EXISTS, &exists);
// if( rc!=SQLITE_OK ){
// goto delsuper_out;
// }
// if( exists ){
// /* One of the journals pointed to by the super-journal exists.
// ** Open it and check if it points at the super-journal. If
// ** so, return without deleting the super-journal file.
// ** NB: zJournal is really a MAIN_JOURNAL. But call it a
// ** SUPER_JOURNAL here so that the VFS will not send the zJournal
// ** name into sqlite3_database_file_object().
// */
// int c;
// int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_SUPER_JOURNAL);
// rc = sqlite3OsOpen(pVfs, zJournal, pJournal, flags, 0);
// if( rc!=SQLITE_OK ){
// goto delsuper_out;
// }
// rc = readSuperJournal(pJournal, zSuperPtr, nSuperPtr);
// sqlite3OsClose(pJournal);
// if( rc!=SQLITE_OK ){
// goto delsuper_out;
// }
// c = zSuperPtr[0]!=0 && strcmp(zSuperPtr, zSuper)==0;
// if( c ){
// /* We have a match. Do not delete the super-journal file. */
// goto delsuper_out;
// }
// }
// zJournal += (sqlite3Strlen30(zJournal)+1);
// }
// sqlite3OsClose(pSuper);
// rc = sqlite3OsDelete(pVfs, zSuper, 0);
// delsuper_out:
// sqlite3_free(zFree);
// if( pSuper ){
// sqlite3OsClose(pSuper);
// assert( !isOpen(pJournal) );
// sqlite3_free(pSuper);
// }
// return rc;
// }
// /*
// ** This function is used to change the actual size of the database
// ** file in the file-system. This only happens when committing a transaction,
// ** or rolling back a transaction (including rolling back a hot-journal).
// **
// ** If the main database file is not open, or the pager is not in either
// ** DBMOD or OPEN state, this function is a no-op. Otherwise, the size
// ** of the file is changed to nPage pages (nPage*pPager->pageSize bytes).
// ** If the file on disk is currently larger than nPage pages, then use the VFS
// ** xTruncate() method to truncate it.
// **
// ** Or, it might be the case that the file on disk is smaller than
// ** nPage pages. Some operating system implementations can get confused if
// ** you try to truncate a file to some size that is larger than it
// ** currently is, so detect this case and write a single zero byte to
// ** the end of the new file instead.
// **
// ** If successful, return SQLITE_OK. If an IO error occurs while modifying
// ** the database file, return the error code to the caller.
// */
// static int pager_truncate(Pager *pPager, Pgno nPage){
// int rc = SQLITE_OK;
// assert( pPager->eState!=PAGER_ERROR );
// assert( pPager->eState!=PAGER_READER );
// if( isOpen(pPager->fd)
// && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
// ){
// i64 currentSize, newSize;
// int szPage = pPager->pageSize;
// assert( pPager->eLock==EXCLUSIVE_LOCK );
// /* TODO: Is it safe to use Pager.dbFileSize here? */
// rc = sqlite3OsFileSize(pPager->fd, &currentSize);
// newSize = szPage*(i64)nPage;
// if( rc==SQLITE_OK && currentSize!=newSize ){
// if( currentSize>newSize ){
// rc = sqlite3OsTruncate(pPager->fd, newSize);
// }else if( (currentSize+szPage)<=newSize ){
// char *pTmp = pPager->pTmpSpace;
// memset(pTmp, 0, szPage);
// testcase( (newSize-szPage) == currentSize );
// testcase( (newSize-szPage) > currentSize );
// rc = sqlite3OsWrite(pPager->fd, pTmp, szPage, newSize-szPage);
// }
// if( rc==SQLITE_OK ){
// pPager->dbFileSize = nPage;
// }
// }
// }
// return rc;
// }
// /*
// ** Return a sanitized version of the sector-size of OS file pFile. The
// ** return value is guaranteed to lie between 32 and MAX_SECTOR_SIZE.
// */
// int sqlite3SectorSize(sqlite3_file *pFile){
// int iRet = sqlite3OsSectorSize(pFile);
// if( iRet<32 ){
// iRet = 512;
// }else if( iRet>MAX_SECTOR_SIZE ){
// assert( MAX_SECTOR_SIZE>=512 );
// iRet = MAX_SECTOR_SIZE;
// }
// return iRet;
// }
// /*
// ** Set the value of the Pager.sectorSize variable for the given
// ** pager based on the value returned by the xSectorSize method
// ** of the open database file. The sector size will be used
// ** to determine the size and alignment of journal header and
// ** super-journal pointers within created journal files.
// **
// ** For temporary files the effective sector size is always 512 bytes.
// **
// ** Otherwise, for non-temporary files, the effective sector size is
// ** the value returned by the xSectorSize() method rounded up to 32 if
// ** it is less than 32, or rounded down to MAX_SECTOR_SIZE if it
// ** is greater than MAX_SECTOR_SIZE.
// **
// ** If the file has the SQLITE_IOCAP_POWERSAFE_OVERWRITE property, then set
// ** the effective sector size to its minimum value (512). The purpose of
// ** pPager->sectorSize is to define the "blast radius" of bytes that
// ** might change if a crash occurs while writing to a single byte in
// ** that range. But with POWERSAFE_OVERWRITE, the blast radius is zero
// ** (that is what POWERSAFE_OVERWRITE means), so we minimize the sector
// ** size. For backwards compatibility of the rollback journal file format,
// ** we cannot reduce the effective sector size below 512.
// */
// static void setSectorSize(Pager *pPager){
// assert( isOpen(pPager->fd) || pPager->tempFile );
// if( pPager->tempFile
// || (sqlite3OsDeviceCharacteristics(pPager->fd) &
// SQLITE_IOCAP_POWERSAFE_OVERWRITE)!=0
// ){
// /* Sector size doesn't matter for temporary files. Also, the file
// ** may not have been opened yet, in which case the OsSectorSize()
// ** call will segfault. */
// pPager->sectorSize = 512;
// }else{
// pPager->sectorSize = sqlite3SectorSize(pPager->fd);
// }
// }
// /*
// ** Playback the journal and thus restore the database file to
// ** the state it was in before we started making changes.
// **
// ** The journal file format is as follows:
// **
// ** (1) 8 byte prefix. A copy of aJournalMagic[].
// ** (2) 4 byte big-endian integer which is the number of valid page records
// ** in the journal. If this value is 0xffffffff, then compute the
// ** number of page records from the journal size.
// ** (3) 4 byte big-endian integer which is the initial value for the
// ** sanity checksum.
// ** (4) 4 byte integer which is the number of pages to truncate the
// ** database to during a rollback.
// ** (5) 4 byte big-endian integer which is the sector size. The header
// ** is this many bytes in size.
// ** (6) 4 byte big-endian integer which is the page size.
// ** (7) zero padding out to the next sector size.
// ** (8) Zero or more pages instances, each as follows:
// ** + 4 byte page number.
// ** + pPager->pageSize bytes of data.
// ** + 4 byte checksum
// **
// ** When we speak of the journal header, we mean the first 7 items above.
// ** Each entry in the journal is an instance of the 8th item.
// **
// ** Call the value from the second bullet "nRec". nRec is the number of
// ** valid page entries in the journal. In most cases, you can compute the
// ** value of nRec from the size of the journal file. But if a power
// ** failure occurred while the journal was being written, it could be the
// ** case that the size of the journal file had already been increased but
// ** the extra entries had not yet made it safely to disk. In such a case,
// ** the value of nRec computed from the file size would be too large. For
// ** that reason, we always use the nRec value in the header.
// **
// ** If the nRec value is 0xffffffff it means that nRec should be computed
// ** from the file size. This value is used when the user selects the
// ** no-sync option for the journal. A power failure could lead to corruption
// ** in this case. But for things like temporary table (which will be
// ** deleted when the power is restored) we don't care.
// **
// ** If the file opened as the journal file is not a well-formed
// ** journal file then all pages up to the first corrupted page are rolled
// ** back (or no pages if the journal header is corrupted). The journal file
// ** is then deleted and SQLITE_OK returned, just as if no corruption had
// ** been encountered.
// **
// ** If an I/O or malloc() error occurs, the journal-file is not deleted
// ** and an error code is returned.
// **
// ** The isHot parameter indicates that we are trying to rollback a journal
// ** that might be a hot journal. Or, it could be that the journal is
// ** preserved because of JOURNALMODE_PERSIST or JOURNALMODE_TRUNCATE.
// ** If the journal really is hot, reset the pager cache prior rolling
// ** back any content. If the journal is merely persistent, no reset is
// ** needed.
// */
// static int pager_playback(Pager *pPager, int isHot){
// sqlite3_vfs *pVfs = pPager->pVfs;
// i64 szJ; /* Size of the journal file in bytes */
// u32 nRec; /* Number of Records in the journal */
// u32 u; /* Unsigned loop counter */
// Pgno mxPg = 0; /* Size of the original file in pages */
// int rc; /* Result code of a subroutine */
// int res = 1; /* Value returned by sqlite3OsAccess() */
// char *zSuper = 0; /* Name of super-journal file if any */
// int needPagerReset; /* True to reset page prior to first page rollback */
// int nPlayback = 0; /* Total number of pages restored from journal */
// u32 savedPageSize = pPager->pageSize;
// /* Figure out how many records are in the journal. Abort early if
// ** the journal is empty.
// */
// assert( isOpen(pPager->jfd) );
// rc = sqlite3OsFileSize(pPager->jfd, &szJ);
// if( rc!=SQLITE_OK ){
// goto end_playback;
// }
// /* Read the super-journal name from the journal, if it is present.
// ** If a super-journal file name is specified, but the file is not
// ** present on disk, then the journal is not hot and does not need to be
// ** played back.
// **
// ** TODO: Technically the following is an error because it assumes that
// ** buffer Pager.pTmpSpace is (mxPathname+1) bytes or larger. i.e. that
// ** (pPager->pageSize >= pPager->pVfs->mxPathname+1). Using os_unix.c,
// ** mxPathname is 512, which is the same as the minimum allowable value
// ** for pageSize.
// */
// zSuper = pPager->pTmpSpace;
// rc = readSuperJournal(pPager->jfd, zSuper, pPager->pVfs->mxPathname+1);
// if( rc==SQLITE_OK && zSuper[0] ){
// rc = sqlite3OsAccess(pVfs, zSuper, SQLITE_ACCESS_EXISTS, &res);
// }
// zSuper = 0;
// if( rc!=SQLITE_OK || !res ){
// goto end_playback;
// }
// pPager->journalOff = 0;
// needPagerReset = isHot;
// /* This loop terminates either when a readJournalHdr() or
// ** pager_playback_one_page() call returns SQLITE_DONE or an IO error
// ** occurs.
// */
// while( 1 ){
// /* Read the next journal header from the journal file. If there are
// ** not enough bytes left in the journal file for a complete header, or
// ** it is corrupted, then a process must have failed while writing it.
// ** This indicates nothing more needs to be rolled back.
// */
// rc = readJournalHdr(pPager, isHot, szJ, &nRec, &mxPg);
// if( rc!=SQLITE_OK ){
// if( rc==SQLITE_DONE ){
// rc = SQLITE_OK;
// }
// goto end_playback;
// }
// /* If nRec is 0xffffffff, then this journal was created by a process
// ** working in no-sync mode. This means that the rest of the journal
// ** file consists of pages, there are no more journal headers. Compute
// ** the value of nRec based on this assumption.
// */
// if( nRec==0xffffffff ){
// assert( pPager->journalOff==JOURNAL_HDR_SZ(pPager) );
// nRec = (int)((szJ - JOURNAL_HDR_SZ(pPager))/JOURNAL_PG_SZ(pPager));
// }
// /* If nRec is 0 and this rollback is of a transaction created by this
// ** process and if this is the final header in the journal, then it means
// ** that this part of the journal was being filled but has not yet been
// ** synced to disk. Compute the number of pages based on the remaining
// ** size of the file.
// **
// ** The third term of the test was added to fix ticket #2565.
// ** When rolling back a hot journal, nRec==0 always means that the next
// ** chunk of the journal contains zero pages to be rolled back. But
// ** when doing a ROLLBACK and the nRec==0 chunk is the last chunk in
// ** the journal, it means that the journal might contain additional
// ** pages that need to be rolled back and that the number of pages
// ** should be computed based on the journal file size.
// */
// if( nRec==0 && !isHot &&
// pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff ){
// nRec = (int)((szJ - pPager->journalOff) / JOURNAL_PG_SZ(pPager));
// }
// /* If this is the first header read from the journal, truncate the
// ** database file back to its original size.
// */
// if( pPager->journalOff==JOURNAL_HDR_SZ(pPager) ){
// rc = pager_truncate(pPager, mxPg);
// if( rc!=SQLITE_OK ){
// goto end_playback;
// }
// pPager->dbSize = mxPg;
// }
// /* Copy original pages out of the journal and back into the
// ** database file and/or page cache.
// */
// for(u=0; u<nRec; u++){
// if( needPagerReset ){
// pager_reset(pPager);
// needPagerReset = 0;
// }
// rc = pager_playback_one_page(pPager,&pPager->journalOff,0,1,0);
// if( rc==SQLITE_OK ){
// nPlayback++;
// }else{
// if( rc==SQLITE_DONE ){
// pPager->journalOff = szJ;
// break;
// }else if( rc==SQLITE_IOERR_SHORT_READ ){
// /* If the journal has been truncated, simply stop reading and
// ** processing the journal. This might happen if the journal was
// ** not completely written and synced prior to a crash. In that
// ** case, the database should have never been written in the
// ** first place so it is OK to simply abandon the rollback. */
// rc = SQLITE_OK;
// goto end_playback;
// }else{
// /* If we are unable to rollback, quit and return the error
// ** code. This will cause the pager to enter the error state
// ** so that no further harm will be done. Perhaps the next
// ** process to come along will be able to rollback the database.
// */
// goto end_playback;
// }
// }
// }
// }
// /*NOTREACHED*/
// assert( 0 );
// end_playback:
// if( rc==SQLITE_OK ){
// rc = sqlite3PagerSetPagesize(pPager, &savedPageSize, -1);
// }
// /* Following a rollback, the database file should be back in its original
// ** state prior to the start of the transaction, so invoke the
// ** SQLITE_FCNTL_DB_UNCHANGED file-control method to disable the
// ** assertion that the transaction counter was modified.
// */
// #ifdef SQLITE_DEBUG
// sqlite3OsFileControlHint(pPager->fd,SQLITE_FCNTL_DB_UNCHANGED,0);
// #endif
// /* If this playback is happening automatically as a result of an IO or
// ** malloc error that occurred after the change-counter was updated but
// ** before the transaction was committed, then the change-counter
// ** modification may just have been reverted. If this happens in exclusive
// ** mode, then subsequent transactions performed by the connection will not
// ** update the change-counter at all. This may lead to cache inconsistency
// ** problems for other processes at some point in the future. So, just
// ** in case this has happened, clear the changeCountDone flag now.
// */
// pPager->changeCountDone = pPager->tempFile;
// if( rc==SQLITE_OK ){
// /* Leave 4 bytes of space before the super-journal filename in memory.
// ** This is because it may end up being passed to sqlite3OsOpen(), in
// ** which case it requires 4 0x00 bytes in memory immediately before
// ** the filename. */
// zSuper = &pPager->pTmpSpace[4];
// rc = readSuperJournal(pPager->jfd, zSuper, pPager->pVfs->mxPathname+1);
// testcase( rc!=SQLITE_OK );
// }
// if( rc==SQLITE_OK
// && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
// ){
// rc = sqlite3PagerSync(pPager, 0);
// }
// if( rc==SQLITE_OK ){
// rc = pager_end_transaction(pPager, zSuper[0]!='\0', 0);
// testcase( rc!=SQLITE_OK );
// }
// if( rc==SQLITE_OK && zSuper[0] && res ){
// /* If there was a super-journal and this routine will return success,
// ** see if it is possible to delete the super-journal.
// */
// assert( zSuper==&pPager->pTmpSpace[4] );
// memset(&zSuper[-4], 0, 4);
// rc = pager_delsuper(pPager, zSuper);
// testcase( rc!=SQLITE_OK );
// }
// if( isHot && nPlayback ){
// sqlite3_log(SQLITE_NOTICE_RECOVER_ROLLBACK, "recovered %d pages from %s",
// nPlayback, pPager->zJournal);
// }
// /* The Pager.sectorSize variable may have been updated while rolling
// ** back a journal created by a process with a different sector size
// ** value. Reset it to the correct value for this process.
// */
// setSectorSize(pPager);
// return rc;
// }
// /*
// ** Read the content for page pPg out of the database file (or out of
// ** the WAL if that is where the most recent copy if found) into
// ** pPg->pData. A shared lock or greater must be held on the database
// ** file before this function is called.
// **
// ** If page 1 is read, then the value of Pager.dbFileVers[] is set to
// ** the value read from the database file.
// **
// ** If an IO error occurs, then the IO error is returned to the caller.
// ** Otherwise, SQLITE_OK is returned.
// */
// static int readDbPage(PgHdr *pPg){
// Pager *pPager = pPg->pPager; /* Pager object associated with page pPg */
// int rc = SQLITE_OK; /* Return code */
// #ifndef SQLITE_OMIT_WAL
// u32 iFrame = 0; /* Frame of WAL containing pgno */
// assert( pPager->eState>=PAGER_READER && !MEMDB );
// assert( isOpen(pPager->fd) );
// if( pagerUseWal(pPager) ){
// rc = sqlite3WalFindFrame(pPager->pWal, pPg->pgno, &iFrame);
// if( rc ) return rc;
// }
// if( iFrame ){
// rc = sqlite3WalReadFrame(pPager->pWal, iFrame,pPager->pageSize,pPg->pData);
// }else
// #endif
// {
// i64 iOffset = (pPg->pgno-1)*(i64)pPager->pageSize;
// rc = sqlite3OsRead(pPager->fd, pPg->pData, pPager->pageSize, iOffset);
// if( rc==SQLITE_IOERR_SHORT_READ ){
// rc = SQLITE_OK;
// }
// }
// if( pPg->pgno==1 ){
// if( rc ){
// /* If the read is unsuccessful, set the dbFileVers[] to something
// ** that will never be a valid file version. dbFileVers[] is a copy
// ** of bytes 24..39 of the database. Bytes 28..31 should always be
// ** zero or the size of the database in page. Bytes 32..35 and 35..39
// ** should be page numbers which are never 0xffffffff. So filling
// ** pPager->dbFileVers[] with all 0xff bytes should suffice.
// **
// ** For an encrypted database, the situation is more complex: bytes
// ** 24..39 of the database are white noise. But the probability of
// ** white noise equaling 16 bytes of 0xff is vanishingly small so
// ** we should still be ok.
// */
// memset(pPager->dbFileVers, 0xff, sizeof(pPager->dbFileVers));
// }else{
// u8 *dbFileVers = &((u8*)pPg->pData)[24];
// memcpy(&pPager->dbFileVers, dbFileVers, sizeof(pPager->dbFileVers));
// }
// }
// PAGER_INCR(sqlite3_pager_readdb_count);
// PAGER_INCR(pPager->nRead);
// IOTRACE(("PGIN %p %d\n", pPager, pPg->pgno));
// PAGERTRACE(("FETCH %d page %d hash(%08x)\n",
// PAGERID(pPager), pPg->pgno, pager_pagehash(pPg)));
// return rc;
// }
// /*
// ** Update the value of the change-counter at offsets 24 and 92 in
// ** the header and the sqlite version number at offset 96.
// **
// ** This is an unconditional update. See also the pager_incr_changecounter()
// ** routine which only updates the change-counter if the update is actually
// ** needed, as determined by the pPager->changeCountDone state variable.
// */
// static void pager_write_changecounter(PgHdr *pPg){
// u32 change_counter;
// if( NEVER(pPg==0) ) return;
// /* Increment the value just read and write it back to byte 24. */
// change_counter = sqlite3Get4byte((u8*)pPg->pPager->dbFileVers)+1;
// put32bits(((char*)pPg->pData)+24, change_counter);
// /* Also store the SQLite version number in bytes 96..99 and in
// ** bytes 92..95 store the change counter for which the version number
// ** is valid. */
// put32bits(((char*)pPg->pData)+92, change_counter);
// put32bits(((char*)pPg->pData)+96, SQLITE_VERSION_NUMBER);
// }
// #ifndef SQLITE_OMIT_WAL
// /*
// ** This function is invoked once for each page that has already been
// ** written into the log file when a WAL transaction is rolled back.
// ** Parameter iPg is the page number of said page. The pCtx argument
// ** is actually a pointer to the Pager structure.
// **
// ** If page iPg is present in the cache, and has no outstanding references,
// ** it is discarded. Otherwise, if there are one or more outstanding
// ** references, the page content is reloaded from the database. If the
// ** attempt to reload content from the database is required and fails,
// ** return an SQLite error code. Otherwise, SQLITE_OK.
// */
// static int pagerUndoCallback(void *pCtx, Pgno iPg){
// int rc = SQLITE_OK;
// Pager *pPager = (Pager *)pCtx;
// PgHdr *pPg;
// assert( pagerUseWal(pPager) );
// pPg = sqlite3PagerLookup(pPager, iPg);
// if( pPg ){
// if( sqlite3PcachePageRefcount(pPg)==1 ){
// sqlite3PcacheDrop(pPg);
// }else{
// rc = readDbPage(pPg);
// if( rc==SQLITE_OK ){
// pPager->xReiniter(pPg);
// }
// sqlite3PagerUnrefNotNull(pPg);
// }
// }
// /* Normally, if a transaction is rolled back, any backup processes are
// ** updated as data is copied out of the rollback journal and into the
// ** database. This is not generally possible with a WAL database, as
// ** rollback involves simply truncating the log file. Therefore, if one
// ** or more frames have already been written to the log (and therefore
// ** also copied into the backup databases) as part of this transaction,
// ** the backups must be restarted.
// */
// sqlite3BackupRestart(pPager->pBackup);
// return rc;
// }
// /*
// ** This function is called to rollback a transaction on a WAL database.
// */
// static int pagerRollbackWal(Pager *pPager){
// int rc; /* Return Code */
// PgHdr *pList; /* List of dirty pages to revert */
// /* For all pages in the cache that are currently dirty or have already
// ** been written (but not committed) to the log file, do one of the
// ** following:
// **
// ** + Discard the cached page (if refcount==0), or
// ** + Reload page content from the database (if refcount>0).
// */
// pPager->dbSize = pPager->dbOrigSize;
// rc = sqlite3WalUndo(pPager->pWal, pagerUndoCallback, (void *)pPager);
// pList = sqlite3PcacheDirtyList(pPager->pPCache);
// while( pList && rc==SQLITE_OK ){
// PgHdr *pNext = pList->pDirty;
// rc = pagerUndoCallback((void *)pPager, pList->pgno);
// pList = pNext;
// }
// return rc;
// }
// /*
// ** This function is a wrapper around sqlite3WalFrames(). As well as logging
// ** the contents of the list of pages headed by pList (connected by pDirty),
// ** this function notifies any active backup processes that the pages have
// ** changed.
// **
// ** The list of pages passed into this routine is always sorted by page number.
// ** Hence, if page 1 appears anywhere on the list, it will be the first page.
// */
// static int pagerWalFrames(
// Pager *pPager, /* Pager object */
// PgHdr *pList, /* List of frames to log */
// Pgno nTruncate, /* Database size after this commit */
// int isCommit /* True if this is a commit */
// ){
// int rc; /* Return code */
// int nList; /* Number of pages in pList */
// PgHdr *p; /* For looping over pages */
// assert( pPager->pWal );
// assert( pList );
// #ifdef SQLITE_DEBUG
// /* Verify that the page list is in accending order */
// for(p=pList; p && p->pDirty; p=p->pDirty){
// assert( p->pgno < p->pDirty->pgno );
// }
// #endif
// assert( pList->pDirty==0 || isCommit );
// if( isCommit ){
// /* If a WAL transaction is being committed, there is no point in writing
// ** any pages with page numbers greater than nTruncate into the WAL file.
// ** They will never be read by any client. So remove them from the pDirty
// ** list here. */
// PgHdr **ppNext = &pList;
// nList = 0;
// for(p=pList; (*ppNext = p)!=0; p=p->pDirty){
// if( p->pgno<=nTruncate ){
// ppNext = &p->pDirty;
// nList++;
// }
// }
// assert( pList );
// }else{
// nList = 1;
// }
// pPager->aStat[PAGER_STAT_WRITE] += nList;
// if( pList->pgno==1 ) pager_write_changecounter(pList);
// rc = sqlite3WalFrames(pPager->pWal,
// pPager->pageSize, pList, nTruncate, isCommit, pPager->walSyncFlags
// );
// if( rc==SQLITE_OK && pPager->pBackup ){
// for(p=pList; p; p=p->pDirty){
// sqlite3BackupUpdate(pPager->pBackup, p->pgno, (u8 *)p->pData);
// }
// }
// #ifdef SQLITE_CHECK_PAGES
// pList = sqlite3PcacheDirtyList(pPager->pPCache);
// for(p=pList; p; p=p->pDirty){
// pager_set_pagehash(p);
// }
// #endif
// return rc;
// }
// /*
// ** Begin a read transaction on the WAL.
// **
// ** This routine used to be called "pagerOpenSnapshot()" because it essentially
// ** makes a snapshot of the database at the current point in time and preserves
// ** that snapshot for use by the reader in spite of concurrently changes by
// ** other writers or checkpointers.
// */
// static int pagerBeginReadTransaction(Pager *pPager){
// int rc; /* Return code */
// int changed = 0; /* True if cache must be reset */
// assert( pagerUseWal(pPager) );
// assert( pPager->eState==PAGER_OPEN || pPager->eState==PAGER_READER );
// /* sqlite3WalEndReadTransaction() was not called for the previous
// ** transaction in locking_mode=EXCLUSIVE. So call it now. If we
// ** are in locking_mode=NORMAL and EndRead() was previously called,
// ** the duplicate call is harmless.
// */
// sqlite3WalEndReadTransaction(pPager->pWal);
// rc = sqlite3WalBeginReadTransaction(pPager->pWal, &changed);
// if( rc!=SQLITE_OK || changed ){
// pager_reset(pPager);
// if( USEFETCH(pPager) ) sqlite3OsUnfetch(pPager->fd, 0, 0);
// }
// return rc;
// }
// #endif
// /*
// ** This function is called as part of the transition from PAGER_OPEN
// ** to PAGER_READER state to determine the size of the database file
// ** in pages (assuming the page size currently stored in Pager.pageSize).
// **
// ** If no error occurs, SQLITE_OK is returned and the size of the database
// ** in pages is stored in *pnPage. Otherwise, an error code (perhaps
// ** SQLITE_IOERR_FSTAT) is returned and *pnPage is left unmodified.
// */
// static int pagerPagecount(Pager *pPager, Pgno *pnPage){
// Pgno nPage; /* Value to return via *pnPage */
// /* Query the WAL sub-system for the database size. The WalDbsize()
// ** function returns zero if the WAL is not open (i.e. Pager.pWal==0), or
// ** if the database size is not available. The database size is not
// ** available from the WAL sub-system if the log file is empty or
// ** contains no valid committed transactions.
// */
// assert( pPager->eState==PAGER_OPEN );
// assert( pPager->eLock>=SHARED_LOCK );
// assert( isOpen(pPager->fd) );
// assert( pPager->tempFile==0 );
// nPage = sqlite3WalDbsize(pPager->pWal);
// /* If the number of pages in the database is not available from the
// ** WAL sub-system, determine the page count based on the size of
// ** the database file. If the size of the database file is not an
// ** integer multiple of the page-size, round up the result.
// */
// if( nPage==0 && ALWAYS(isOpen(pPager->fd)) ){
// i64 n = 0; /* Size of db file in bytes */
// int rc = sqlite3OsFileSize(pPager->fd, &n);
// if( rc!=SQLITE_OK ){
// return rc;
// }
// nPage = (Pgno)((n+pPager->pageSize-1) / pPager->pageSize);
// }
// /* If the current number of pages in the file is greater than the
// ** configured maximum pager number, increase the allowed limit so
// ** that the file can be read.
// */
// if( nPage>pPager->mxPgno ){
// pPager->mxPgno = (Pgno)nPage;
// }
// *pnPage = nPage;
// return SQLITE_OK;
// }
// #ifndef SQLITE_OMIT_WAL
// /*
// ** Check if the *-wal file that corresponds to the database opened by pPager
// ** exists if the database is not empy, or verify that the *-wal file does
// ** not exist (by deleting it) if the database file is empty.
// **
// ** If the database is not empty and the *-wal file exists, open the pager
// ** in WAL mode. If the database is empty or if no *-wal file exists and
// ** if no error occurs, make sure Pager.journalMode is not set to
// ** PAGER_JOURNALMODE_WAL.
// **
// ** Return SQLITE_OK or an error code.
// **
// ** The caller must hold a SHARED lock on the database file to call this
// ** function. Because an EXCLUSIVE lock on the db file is required to delete
// ** a WAL on a none-empty database, this ensures there is no race condition
// ** between the xAccess() below and an xDelete() being executed by some
// ** other connection.
// */
// static int pagerOpenWalIfPresent(Pager *pPager){
// int rc = SQLITE_OK;
// assert( pPager->eState==PAGER_OPEN );
// assert( pPager->eLock>=SHARED_LOCK );
// if( !pPager->tempFile ){
// int isWal; /* True if WAL file exists */
// rc = sqlite3OsAccess(
// pPager->pVfs, pPager->zWal, SQLITE_ACCESS_EXISTS, &isWal
// );
// if( rc==SQLITE_OK ){
// if( isWal ){
// Pgno nPage; /* Size of the database file */
// rc = pagerPagecount(pPager, &nPage);
// if( rc ) return rc;
// if( nPage==0 ){
// rc = sqlite3OsDelete(pPager->pVfs, pPager->zWal, 0);
// }else{
// testcase( sqlite3PcachePagecount(pPager->pPCache)==0 );
// rc = sqlite3PagerOpenWal(pPager, 0);
// }
// }else if( pPager->journalMode==PAGER_JOURNALMODE_WAL ){
// pPager->journalMode = PAGER_JOURNALMODE_DELETE;
// }
// }
// }
// return rc;
// }
// #endif
// /*
// ** Playback savepoint pSavepoint. Or, if pSavepoint==NULL, then playback
// ** the entire super-journal file. The case pSavepoint==NULL occurs when
// ** a ROLLBACK TO command is invoked on a SAVEPOINT that is a transaction
// ** savepoint.
// **
// ** When pSavepoint is not NULL (meaning a non-transaction savepoint is
// ** being rolled back), then the rollback consists of up to three stages,
// ** performed in the order specified:
// **
// ** * Pages are played back from the main journal starting at byte
// ** offset PagerSavepoint.iOffset and continuing to
// ** PagerSavepoint.iHdrOffset, or to the end of the main journal
// ** file if PagerSavepoint.iHdrOffset is zero.
// **
// ** * If PagerSavepoint.iHdrOffset is not zero, then pages are played
// ** back starting from the journal header immediately following
// ** PagerSavepoint.iHdrOffset to the end of the main journal file.
// **
// ** * Pages are then played back from the sub-journal file, starting
// ** with the PagerSavepoint.iSubRec and continuing to the end of
// ** the journal file.
// **
// ** Throughout the rollback process, each time a page is rolled back, the
// ** corresponding bit is set in a bitvec structure (variable pDone in the
// ** implementation below). This is used to ensure that a page is only
// ** rolled back the first time it is encountered in either journal.
// **
// ** If pSavepoint is NULL, then pages are only played back from the main
// ** journal file. There is no need for a bitvec in this case.
// **
// ** In either case, before playback commences the Pager.dbSize variable
// ** is reset to the value that it held at the start of the savepoint
// ** (or transaction). No page with a page-number greater than this value
// ** is played back. If one is encountered it is simply skipped.
// */
// static int pagerPlaybackSavepoint(Pager *pPager, PagerSavepoint *pSavepoint){
// i64 szJ; /* Effective size of the main journal */
// i64 iHdrOff; /* End of first segment of main-journal records */
// int rc = SQLITE_OK; /* Return code */
// Bitvec *pDone = 0; /* Bitvec to ensure pages played back only once */
// assert( pPager->eState!=PAGER_ERROR );
// assert( pPager->eState>=PAGER_WRITER_LOCKED );
// /* Allocate a bitvec to use to store the set of pages rolled back */
// if( pSavepoint ){
// pDone = sqlite3BitvecCreate(pSavepoint->nOrig);
// if( !pDone ){
// return SQLITE_NOMEM;
// }
// }
// /* Set the database size back to the value it was before the savepoint
// ** being reverted was opened.
// */
// pPager->dbSize = pSavepoint ? pSavepoint->nOrig : pPager->dbOrigSize;
// pPager->changeCountDone = pPager->tempFile;
// if( !pSavepoint && pagerUseWal(pPager) ){
// return pagerRollbackWal(pPager);
// }
// /* Use pPager->journalOff as the effective size of the main rollback
// ** journal. The actual file might be larger than this in
// ** PAGER_JOURNALMODE_TRUNCATE or PAGER_JOURNALMODE_PERSIST. But anything
// ** past pPager->journalOff is off-limits to us.
// */
// szJ = pPager->journalOff;
// assert( pagerUseWal(pPager)==0 || szJ==0 );
// /* Begin by rolling back records from the main journal starting at
// ** PagerSavepoint.iOffset and continuing to the next journal header.
// ** There might be records in the main journal that have a page number
// ** greater than the current database size (pPager->dbSize) but those
// ** will be skipped automatically. Pages are added to pDone as they
// ** are played back.
// */
// if( pSavepoint && !pagerUseWal(pPager) ){
// iHdrOff = pSavepoint->iHdrOffset ? pSavepoint->iHdrOffset : szJ;
// pPager->journalOff = pSavepoint->iOffset;
// while( rc==SQLITE_OK && pPager->journalOff<iHdrOff ){
// rc = pager_playback_one_page(pPager, &pPager->journalOff, pDone, 1, 1);
// }
// assert( rc!=SQLITE_DONE );
// }else{
// pPager->journalOff = 0;
// }
// /* Continue rolling back records out of the main journal starting at
// ** the first journal header seen and continuing until the effective end
// ** of the main journal file. Continue to skip out-of-range pages and
// ** continue adding pages rolled back to pDone.
// */
// while( rc==SQLITE_OK && pPager->journalOff<szJ ){
// u32 ii; /* Loop counter */
// u32 nJRec = 0; /* Number of Journal Records */
// u32 dummy;
// rc = readJournalHdr(pPager, 0, szJ, &nJRec, &dummy);
// assert( rc!=SQLITE_DONE );
// /*
// ** The "pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff"
// ** test is related to ticket #2565. See the discussion in the
// ** pager_playback() function for additional information.
// */
// if( nJRec==0
// && pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff
// ){
// nJRec = (u32)((szJ - pPager->journalOff)/JOURNAL_PG_SZ(pPager));
// }
// for(ii=0; rc==SQLITE_OK && ii<nJRec && pPager->journalOff<szJ; ii++){
// rc = pager_playback_one_page(pPager, &pPager->journalOff, pDone, 1, 1);
// }
// assert( rc!=SQLITE_DONE );
// }
// assert( rc!=SQLITE_OK || pPager->journalOff>=szJ );
// /* Finally, rollback pages from the sub-journal. Page that were
// ** previously rolled back out of the main journal (and are hence in pDone)
// ** will be skipped. Out-of-range pages are also skipped.
// */
// if( pSavepoint ){
// u32 ii; /* Loop counter */
// i64 offset = (i64)pSavepoint->iSubRec*(4+pPager->pageSize);
// if( pagerUseWal(pPager) ){
// rc = sqlite3WalSavepointUndo(pPager->pWal, pSavepoint->aWalData);
// }
// for(ii=pSavepoint->iSubRec; rc==SQLITE_OK && ii<pPager->nSubRec; ii++){
// assert( offset==(i64)ii*(4+pPager->pageSize) );
// rc = pager_playback_one_page(pPager, &offset, pDone, 0, 1);
// }
// assert( rc!=SQLITE_DONE );
// }
// sqlite3BitvecDestroy(pDone);
// if( rc==SQLITE_OK ){
// pPager->journalOff = szJ;
// }
// return rc;
// }
// /*
// ** Change the maximum number of in-memory pages that are allowed
// ** before attempting to recycle clean and unused pages.
// */
// void sqlite3PagerSetCachesize(Pager *pPager, int mxPage){
// sqlite3PcacheSetCachesize(pPager->pPCache, mxPage);
// }
// /*
// ** Change the maximum number of in-memory pages that are allowed
// ** before attempting to spill pages to journal.
// */
// int sqlite3PagerSetSpillsize(Pager *pPager, int mxPage){
// return sqlite3PcacheSetSpillsize(pPager->pPCache, mxPage);
// }
// /*
// ** Invoke SQLITE_FCNTL_MMAP_SIZE based on the current value of szMmap.
// */
// static void pagerFixMaplimit(Pager *pPager){
// #if SQLITE_MAX_MMAP_SIZE>0
// sqlite3_file *fd = pPager->fd;
// if( isOpen(fd) && fd->pMethods->iVersion>=3 ){
// sqlite3_int64 sz;
// sz = pPager->szMmap;
// pPager->bUseFetch = (sz>0);
// setGetterMethod(pPager);
// sqlite3OsFileControlHint(pPager->fd, SQLITE_FCNTL_MMAP_SIZE, &sz);
// }
// #endif
// }
// /*
// ** Change the maximum size of any memory mapping made of the database file.
// */
// void sqlite3PagerSetMmapLimit(Pager *pPager, sqlite3_int64 szMmap){
// pPager->szMmap = szMmap;
// pagerFixMaplimit(pPager);
// }
// /*
// ** Free as much memory as possible from the pager.
// */
// void sqlite3PagerShrink(Pager *pPager){
// sqlite3PcacheShrink(pPager->pPCache);
// }
// /*
// ** Adjust settings of the pager to those specified in the pgFlags parameter.
// **
// ** The "level" in pgFlags & PAGER_SYNCHRONOUS_MASK sets the robustness
// ** of the database to damage due to OS crashes or power failures by
// ** changing the number of syncs()s when writing the journals.
// ** There are four levels:
// **
// ** OFF sqlite3OsSync() is never called. This is the default
// ** for temporary and transient files.
// **
// ** NORMAL The journal is synced once before writes begin on the
// ** database. This is normally adequate protection, but
// ** it is theoretically possible, though very unlikely,
// ** that an inopertune power failure could leave the journal
// ** in a state which would cause damage to the database
// ** when it is rolled back.
// **
// ** FULL The journal is synced twice before writes begin on the
// ** database (with some additional information - the nRec field
// ** of the journal header - being written in between the two
// ** syncs). If we assume that writing a
// ** single disk sector is atomic, then this mode provides
// ** assurance that the journal will not be corrupted to the
// ** point of causing damage to the database during rollback.
// **
// ** EXTRA This is like FULL except that is also syncs the directory
// ** that contains the rollback journal after the rollback
// ** journal is unlinked.
// **
// ** The above is for a rollback-journal mode. For WAL mode, OFF continues
// ** to mean that no syncs ever occur. NORMAL means that the WAL is synced
// ** prior to the start of checkpoint and that the database file is synced
// ** at the conclusion of the checkpoint if the entire content of the WAL
// ** was written back into the database. But no sync operations occur for
// ** an ordinary commit in NORMAL mode with WAL. FULL means that the WAL
// ** file is synced following each commit operation, in addition to the
// ** syncs associated with NORMAL. There is no difference between FULL
// ** and EXTRA for WAL mode.
// **
// ** Do not confuse synchronous=FULL with SQLITE_SYNC_FULL. The
// ** SQLITE_SYNC_FULL macro means to use the MacOSX-style full-fsync
// ** using fcntl(F_FULLFSYNC). SQLITE_SYNC_NORMAL means to do an
// ** ordinary fsync() call. There is no difference between SQLITE_SYNC_FULL
// ** and SQLITE_SYNC_NORMAL on platforms other than MacOSX. But the
// ** synchronous=FULL versus synchronous=NORMAL setting determines when
// ** the xSync primitive is called and is relevant to all platforms.
// **
// ** Numeric values associated with these states are OFF==1, NORMAL=2,
// ** and FULL=3.
// */
// #ifndef SQLITE_OMIT_PAGER_PRAGMAS
// void sqlite3PagerSetFlags(
// Pager *pPager, /* The pager to set safety level for */
// unsigned pgFlags /* Various flags */
// ){
// unsigned level = pgFlags & PAGER_SYNCHRONOUS_MASK;
// if( pPager->tempFile ){
// pPager->noSync = 1;
// pPager->fullSync = 0;
// pPager->extraSync = 0;
// }else{
// pPager->noSync = level==PAGER_SYNCHRONOUS_OFF ?1:0;
// pPager->fullSync = level>=PAGER_SYNCHRONOUS_FULL ?1:0;
// pPager->extraSync = level==PAGER_SYNCHRONOUS_EXTRA ?1:0;
// }
// if( pPager->noSync ){
// pPager->syncFlags = 0;
// }else if( pgFlags & PAGER_FULLFSYNC ){
// pPager->syncFlags = SQLITE_SYNC_FULL;
// }else{
// pPager->syncFlags = SQLITE_SYNC_NORMAL;
// }
// pPager->walSyncFlags = (pPager->syncFlags<<2);
// if( pPager->fullSync ){
// pPager->walSyncFlags |= pPager->syncFlags;
// }
// if( (pgFlags & PAGER_CKPT_FULLFSYNC) && !pPager->noSync ){
// pPager->walSyncFlags |= (SQLITE_SYNC_FULL<<2);
// }
// if( pgFlags & PAGER_CACHESPILL ){
// pPager->doNotSpill &= ~SPILLFLAG_OFF;
// }else{
// pPager->doNotSpill |= SPILLFLAG_OFF;
// }
// }
// #endif
// /*
// ** The following global variable is incremented whenever the library
// ** attempts to open a temporary file. This information is used for
// ** testing and analysis only.
// */
// #ifdef SQLITE_TEST
// int sqlite3_opentemp_count = 0;
// #endif
// /*
// ** Open a temporary file.
// **
// ** Write the file descriptor into *pFile. Return SQLITE_OK on success
// ** or some other error code if we fail. The OS will automatically
// ** delete the temporary file when it is closed.
// **
// ** The flags passed to the VFS layer xOpen() call are those specified
// ** by parameter vfsFlags ORed with the following:
// **
// ** SQLITE_OPEN_READWRITE
// ** SQLITE_OPEN_CREATE
// ** SQLITE_OPEN_EXCLUSIVE
// ** SQLITE_OPEN_DELETEONCLOSE
// */
// static int pagerOpentemp(
// Pager *pPager, /* The pager object */
// sqlite3_file *pFile, /* Write the file descriptor here */
// int vfsFlags /* Flags passed through to the VFS */
// ){
// int rc; /* Return code */
// #ifdef SQLITE_TEST
// sqlite3_opentemp_count++; /* Used for testing and analysis only */
// #endif
// vfsFlags |= SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE |
// SQLITE_OPEN_EXCLUSIVE | SQLITE_OPEN_DELETEONCLOSE;
// rc = sqlite3OsOpen(pPager->pVfs, 0, pFile, vfsFlags, 0);
// assert( rc!=SQLITE_OK || isOpen(pFile) );
// return rc;
// }
// /*
// ** Set the busy handler function.
// **
// ** The pager invokes the busy-handler if sqlite3OsLock() returns
// ** SQLITE_BUSY when trying to upgrade from no-lock to a SHARED lock,
// ** or when trying to upgrade from a RESERVED lock to an EXCLUSIVE
// ** lock. It does *not* invoke the busy handler when upgrading from
// ** SHARED to RESERVED, or when upgrading from SHARED to EXCLUSIVE
// ** (which occurs during hot-journal rollback). Summary:
// **
// ** Transition | Invokes xBusyHandler
// ** --------------------------------------------------------
// ** NO_LOCK -> SHARED_LOCK | Yes
// ** SHARED_LOCK -> RESERVED_LOCK | No
// ** SHARED_LOCK -> EXCLUSIVE_LOCK | No
// ** RESERVED_LOCK -> EXCLUSIVE_LOCK | Yes
// **
// ** If the busy-handler callback returns non-zero, the lock is
// ** retried. If it returns zero, then the SQLITE_BUSY error is
// ** returned to the caller of the pager API function.
// */
// void sqlite3PagerSetBusyHandler(
// Pager *pPager, /* Pager object */
// int (*xBusyHandler)(void *), /* Pointer to busy-handler function */
// void *pBusyHandlerArg /* Argument to pass to xBusyHandler */
// ){
// void **ap;
// pPager->xBusyHandler = xBusyHandler;
// pPager->pBusyHandlerArg = pBusyHandlerArg;
// ap = (void **)&pPager->xBusyHandler;
// assert( ((int(*)(void *))(ap[0]))==xBusyHandler );
// assert( ap[1]==pBusyHandlerArg );
// sqlite3OsFileControlHint(pPager->fd, SQLITE_FCNTL_BUSYHANDLER, (void *)ap);
// }
int sqlite3PagerSetPagesize(Pager *pPager, u32 *pPageSize, int nReserve) {
// int rc = SQLITE_OK;
// /* It is not possible to do a full assert_pager_state() here, as this
// ** function may be called from within PagerOpen(), before the state
// ** of the Pager object is internally consistent.
// **
// ** At one point this function returned an error if the pager was in
// ** PAGER_ERROR state. But since PAGER_ERROR state guarantees that
// ** there is at least one outstanding page reference, this function
// ** is a no-op for that case anyhow.
// */
// u32 pageSize = *pPageSize;
// assert( pageSize==0 || (pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE) );
// if( (pPager->memDb==0 || pPager->dbSize==0)
// && sqlite3PcacheRefCount(pPager->pPCache)==0
// && pageSize && pageSize!=(u32)pPager->pageSize
// ){
// char *pNew = NULL; /* New temp space */
// i64 nByte = 0;
// if( pPager->eState>PAGER_OPEN && isOpen(pPager->fd) ){
// rc = sqlite3OsFileSize(pPager->fd, &nByte);
// }
// if( rc==SQLITE_OK ){
// /* 8 bytes of zeroed overrun space is sufficient so that the b-tree
// * cell header parser will never run off the end of the allocation */
// pNew = (char *)sqlite3PageMalloc(pageSize+8);
// if( !pNew ){
// rc = SQLITE_NOMEM;
// }else{
// memset(pNew+pageSize, 0, 8);
// }
// }
// if( rc==SQLITE_OK ){
// pager_reset(pPager);
// rc = sqlite3PcacheSetPageSize(pPager->pPCache, pageSize);
// }
// if( rc==SQLITE_OK ){
// sqlite3PageFree(pPager->pTmpSpace);
// pPager->pTmpSpace = pNew;
// pPager->dbSize = (Pgno)((nByte+pageSize-1)/pageSize);
// pPager->pageSize = pageSize;
// }else{
// sqlite3PageFree(pNew);
// }
// }
// *pPageSize = pPager->pageSize;
// if( rc==SQLITE_OK ){
// if( nReserve<0 ) nReserve = pPager->nReserve;
// assert( nReserve>=0 && nReserve<1000 );
// pPager->nReserve = (i16)nReserve;
// pagerFixMaplimit(pPager);
// }
// return rc;
}
// /*
// ** Return a pointer to the "temporary page" buffer held internally
// ** by the pager. This is a buffer that is big enough to hold the
// ** entire content of a database page. This buffer is used internally
// ** during rollback and will be overwritten whenever a rollback
// ** occurs. But other modules are free to use it too, as long as
// ** no rollbacks are happening.
// */
// void *sqlite3PagerTempSpace(Pager *pPager){
// return pPager->pTmpSpace;
// }
// /*
// ** Attempt to set the maximum database page count if mxPage is positive.
// ** Make no changes if mxPage is zero or negative. And never reduce the
// ** maximum page count below the current size of the database.
// **
// ** Regardless of mxPage, return the current maximum page count.
// */
// Pgno sqlite3PagerMaxPageCount(Pager *pPager, Pgno mxPage){
// if( mxPage>0 ){
// pPager->mxPgno = mxPage;
// }
// assert( pPager->eState!=PAGER_OPEN ); /* Called only by OP_MaxPgcnt */
// /* assert( pPager->mxPgno>=pPager->dbSize ); */
// /* OP_MaxPgcnt ensures that the parameter passed to this function is not
// ** less than the total number of valid pages in the database. But this
// ** may be less than Pager.dbSize, and so the assert() above is not valid */
// return pPager->mxPgno;
// }
// /*
// ** The following set of routines are used to disable the simulated
// ** I/O error mechanism. These routines are used to avoid simulated
// ** errors in places where we do not care about errors.
// **
// ** Unless -DSQLITE_TEST=1 is used, these routines are all no-ops
// ** and generate no code.
// */
// #ifdef SQLITE_TEST
// extern int sqlite3_io_error_pending;
// extern int sqlite3_io_error_hit;
// static int saved_cnt;
// void disable_simulated_io_errors(void){
// saved_cnt = sqlite3_io_error_pending;
// sqlite3_io_error_pending = -1;
// }
// void enable_simulated_io_errors(void){
// sqlite3_io_error_pending = saved_cnt;
// }
// #else
// # define disable_simulated_io_errors()
// # define enable_simulated_io_errors()
// #endif
// /*
// ** Read the first N bytes from the beginning of the file into memory
// ** that pDest points to.
// **
// ** If the pager was opened on a transient file (zFilename==""), or
// ** opened on a file less than N bytes in size, the output buffer is
// ** zeroed and SQLITE_OK returned. The rationale for this is that this
// ** function is used to read database headers, and a new transient or
// ** zero sized database has a header than consists entirely of zeroes.
// **
// ** If any IO error apart from SQLITE_IOERR_SHORT_READ is encountered,
// ** the error code is returned to the caller and the contents of the
// ** output buffer undefined.
// */
// int sqlite3PagerReadFileheader(Pager *pPager, int N, unsigned char *pDest){
// int rc = SQLITE_OK;
// memset(pDest, 0, N);
// assert( isOpen(pPager->fd) || pPager->tempFile );
// /* This routine is only called by btree immediately after creating
// ** the Pager object. There has not been an opportunity to transition
// ** to WAL mode yet.
// */
// assert( !pagerUseWal(pPager) );
// if( isOpen(pPager->fd) ){
// IOTRACE(("DBHDR %p 0 %d\n", pPager, N))
// rc = sqlite3OsRead(pPager->fd, pDest, N, 0);
// if( rc==SQLITE_IOERR_SHORT_READ ){
// rc = SQLITE_OK;
// }
// }
// return rc;
// }
// /*
// ** This function may only be called when a read-transaction is open on
// ** the pager. It returns the total number of pages in the database.
// **
// ** However, if the file is between 1 and <page-size> bytes in size, then
// ** this is considered a 1 page file.
// */
// void sqlite3PagerPagecount(Pager *pPager, int *pnPage){
// assert( pPager->eState>=PAGER_READER );
// assert( pPager->eState!=PAGER_WRITER_FINISHED );
// *pnPage = (int)pPager->dbSize;
// }
// /*
// ** Try to obtain a lock of type locktype on the database file. If
// ** a similar or greater lock is already held, this function is a no-op
// ** (returning SQLITE_OK immediately).
// **
// ** Otherwise, attempt to obtain the lock using sqlite3OsLock(). Invoke
// ** the busy callback if the lock is currently not available. Repeat
// ** until the busy callback returns false or until the attempt to
// ** obtain the lock succeeds.
// **
// ** Return SQLITE_OK on success and an error code if we cannot obtain
// ** the lock. If the lock is obtained successfully, set the Pager.state
// ** variable to locktype before returning.
// */
// static int pager_wait_on_lock(Pager *pPager, int locktype){
// int rc; /* Return code */
// /* Check that this is either a no-op (because the requested lock is
// ** already held), or one of the transitions that the busy-handler
// ** may be invoked during, according to the comment above
// ** sqlite3PagerSetBusyhandler().
// */
// assert( (pPager->eLock>=locktype)
// || (pPager->eLock==NO_LOCK && locktype==SHARED_LOCK)
// || (pPager->eLock==RESERVED_LOCK && locktype==EXCLUSIVE_LOCK)
// );
// do {
// rc = pagerLockDb(pPager, locktype);
// }while( rc==SQLITE_BUSY && pPager->xBusyHandler(pPager->pBusyHandlerArg) );
// return rc;
// }
// /*
// ** Function assertTruncateConstraint(pPager) checks that one of the
// ** following is true for all dirty pages currently in the page-cache:
// **
// ** a) The page number is less than or equal to the size of the
// ** current database image, in pages, OR
// **
// ** b) if the page content were written at this time, it would not
// ** be necessary to write the current content out to the sub-journal
// ** (as determined by function subjRequiresPage()).
// **
// ** If the condition asserted by this function were not true, and the
// ** dirty page were to be discarded from the cache via the pagerStress()
// ** routine, pagerStress() would not write the current page content to
// ** the database file. If a savepoint transaction were rolled back after
// ** this happened, the correct behavior would be to restore the current
// ** content of the page. However, since this content is not present in either
// ** the database file or the portion of the rollback journal and
// ** sub-journal rolled back the content could not be restored and the
// ** database image would become corrupt. It is therefore fortunate that
// ** this circumstance cannot arise.
// */
// #if defined(SQLITE_DEBUG)
// static void assertTruncateConstraintCb(PgHdr *pPg){
// assert( pPg->flags&PGHDR_DIRTY );
// assert( !subjRequiresPage(pPg) || pPg->pgno<=pPg->pPager->dbSize );
// }
// static void assertTruncateConstraint(Pager *pPager){
// sqlite3PcacheIterateDirty(pPager->pPCache, assertTruncateConstraintCb);
// }
// #else
// # define assertTruncateConstraint(pPager)
// #endif
// /*
// ** Truncate the in-memory database file image to nPage pages. This
// ** function does not actually modify the database file on disk. It
// ** just sets the internal state of the pager object so that the
// ** truncation will be done when the current transaction is committed.
// **
// ** This function is only called right before committing a transaction.
// ** Once this function has been called, the transaction must either be
// ** rolled back or committed. It is not safe to call this function and
// ** then continue writing to the database.
// */
// void sqlite3PagerTruncateImage(Pager *pPager, Pgno nPage){
// assert( pPager->dbSize>=nPage || CORRUPT_DB );
// testcase( pPager->dbSize<nPage );
// assert( pPager->eState>=PAGER_WRITER_CACHEMOD );
// pPager->dbSize = nPage;
// /* At one point the code here called assertTruncateConstraint() to
// ** ensure that all pages being truncated away by this operation are,
// ** if one or more savepoints are open, present in the savepoint
// ** journal so that they can be restored if the savepoint is rolled
// ** back. This is no longer necessary as this function is now only
// ** called right before committing a transaction. So although the
// ** Pager object may still have open savepoints (Pager.nSavepoint!=0),
// ** they cannot be rolled back. So the assertTruncateConstraint() call
// ** is no longer correct. */
// }
// /*
// ** This function is called before attempting a hot-journal rollback. It
// ** syncs the journal file to disk, then sets pPager->journalHdr to the
// ** size of the journal file so that the pager_playback() routine knows
// ** that the entire journal file has been synced.
// **
// ** Syncing a hot-journal to disk before attempting to roll it back ensures
// ** that if a power-failure occurs during the rollback, the process that
// ** attempts rollback following system recovery sees the same journal
// ** content as this process.
// **
// ** If everything goes as planned, SQLITE_OK is returned. Otherwise,
// ** an SQLite error code.
// */
// static int pagerSyncHotJournal(Pager *pPager){
// int rc = SQLITE_OK;
// if( !pPager->noSync ){
// rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_NORMAL);
// }
// if( rc==SQLITE_OK ){
// rc = sqlite3OsFileSize(pPager->jfd, &pPager->journalHdr);
// }
// return rc;
// }
// #if SQLITE_MAX_MMAP_SIZE>0
// /*
// ** Obtain a reference to a memory mapped page object for page number pgno.
// ** The new object will use the pointer pData, obtained from xFetch().
// ** If successful, set *ppPage to point to the new page reference
// ** and return SQLITE_OK. Otherwise, return an SQLite error code and set
// ** *ppPage to zero.
// **
// ** Page references obtained by calling this function should be released
// ** by calling pagerReleaseMapPage().
// */
// static int pagerAcquireMapPage(
// Pager *pPager, /* Pager object */
// Pgno pgno, /* Page number */
// void *pData, /* xFetch()'d data for this page */
// PgHdr **ppPage /* OUT: Acquired page object */
// ){
// PgHdr *p; /* Memory mapped page to return */
// if( pPager->pMmapFreelist ){
// *ppPage = p = pPager->pMmapFreelist;
// pPager->pMmapFreelist = p->pDirty;
// p->pDirty = 0;
// assert( pPager->nExtra>=8 );
// memset(p->pExtra, 0, 8);
// }else{
// *ppPage = p = (PgHdr *)sqlite3MallocZero(sizeof(PgHdr) + pPager->nExtra);
// if( p==0 ){
// sqlite3OsUnfetch(pPager->fd, (i64)(pgno-1) * pPager->pageSize, pData);
// return SQLITE_NOMEM;
// }
// p->pExtra = (void *)&p[1];
// p->flags = PGHDR_MMAP;
// p->nRef = 1;
// p->pPager = pPager;
// }
// assert( p->pExtra==(void *)&p[1] );
// assert( p->pPage==0 );
// assert( p->flags==PGHDR_MMAP );
// assert( p->pPager==pPager );
// assert( p->nRef==1 );
// p->pgno = pgno;
// p->pData = pData;
// pPager->nMmapOut++;
// return SQLITE_OK;
// }
// #endif
// /*
// ** Release a reference to page pPg. pPg must have been returned by an
// ** earlier call to pagerAcquireMapPage().
// */
// static void pagerReleaseMapPage(PgHdr *pPg){
// Pager *pPager = pPg->pPager;
// pPager->nMmapOut--;
// pPg->pDirty = pPager->pMmapFreelist;
// pPager->pMmapFreelist = pPg;
// assert( pPager->fd->pMethods->iVersion>=3 );
// sqlite3OsUnfetch(pPager->fd, (i64)(pPg->pgno-1)*pPager->pageSize, pPg->pData);
// }
// /*
// ** Free all PgHdr objects stored in the Pager.pMmapFreelist list.
// */
// static void pagerFreeMapHdrs(Pager *pPager){
// PgHdr *p;
// PgHdr *pNext;
// for(p=pPager->pMmapFreelist; p; p=pNext){
// pNext = p->pDirty;
// sqlite3_free(p);
// }
// }
// /* Verify that the database file has not be deleted or renamed out from
// ** under the pager. Return SQLITE_OK if the database is still where it ought
// ** to be on disk. Return non-zero (SQLITE_READONLY_DBMOVED or some other error
// ** code from sqlite3OsAccess()) if the database has gone missing.
// */
// static int databaseIsUnmoved(Pager *pPager){
// int bHasMoved = 0;
// int rc;
// if( pPager->tempFile ) return SQLITE_OK;
// if( pPager->dbSize==0 ) return SQLITE_OK;
// assert( pPager->zFilename && pPager->zFilename[0] );
// rc = sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_HAS_MOVED, &bHasMoved);
// if( rc==SQLITE_NOTFOUND ){
// /* If the HAS_MOVED file-control is unimplemented, assume that the file
// ** has not been moved. That is the historical behavior of SQLite: prior to
// ** version 3.8.3, it never checked */
// rc = SQLITE_OK;
// }else if( rc==SQLITE_OK && bHasMoved ){
// rc = SQLITE_READONLY_DBMOVED;
// }
// return rc;
// }
/*
** Shutdown the page cache. Free all memory and close all files.
**
** If a transaction was in progress when this routine is called, that
** transaction is rolled back. All outstanding pages are invalidated
** and their memory is freed. Any attempt to use a page associated
** with this page cache after this function returns will likely
** result in a coredump.
**
** This function always succeeds. If a transaction is active an attempt
** is made to roll it back. If an error occurs during the rollback
** a hot journal may be left in the filesystem but no error is returned
** to the caller.
*/
int sqlite3PagerClose(Pager *pPager, sqlite3 *db) {
// u8 *pTmp = (u8*)pPager->pTmpSpace;
// assert( db || pagerUseWal(pPager)==0 );
// assert( assert_pager_state(pPager) );
// disable_simulated_io_errors();
// sqlite3BeginBenignMalloc();
// pagerFreeMapHdrs(pPager);
// /* pPager->errCode = 0; */
// pPager->exclusiveMode = 0;
// #ifndef SQLITE_OMIT_WAL
// {
// u8 *a = 0;
// assert( db || pPager->pWal==0 );
// if( db && 0==(db->flags & SQLITE_NoCkptOnClose)
// && SQLITE_OK==databaseIsUnmoved(pPager)
// ){
// a = pTmp;
// }
// sqlite3WalClose(pPager->pWal, db, pPager->walSyncFlags, pPager->pageSize,a);
// pPager->pWal = 0;
// }
// #endif
// pager_reset(pPager);
// if( MEMDB ){
// pager_unlock(pPager);
// }else{
// /* If it is open, sync the journal file before calling UnlockAndRollback.
// ** If this is not done, then an unsynced portion of the open journal
// ** file may be played back into the database. If a power failure occurs
// ** while this is happening, the database could become corrupt.
// **
// ** If an error occurs while trying to sync the journal, shift the pager
// ** into the ERROR state. This causes UnlockAndRollback to unlock the
// ** database and close the journal file without attempting to roll it
// ** back or finalize it. The next database user will have to do hot-journal
// ** rollback before accessing the database file.
// */
// if( isOpen(pPager->jfd) ){
// pager_error(pPager, pagerSyncHotJournal(pPager));
// }
// pagerUnlockAndRollback(pPager);
// }
// sqlite3EndBenignMalloc();
// enable_simulated_io_errors();
// PAGERTRACE(("CLOSE %d\n", PAGERID(pPager)));
// IOTRACE(("CLOSE %p\n", pPager))
// sqlite3OsClose(pPager->jfd);
// sqlite3OsClose(pPager->fd);
// sqlite3PageFree(pTmp);
// sqlite3PcacheClose(pPager->pPCache);
// assert( !pPager->aSavepoint && !pPager->pInJournal );
// assert( !isOpen(pPager->jfd) && !isOpen(pPager->sjfd) );
// sqlite3_free(pPager);
return SQLITE_OK;
}
// #if !defined(NDEBUG) || defined(SQLITE_TEST)
// /*
// ** Return the page number for page pPg.
// */
// Pgno sqlite3PagerPagenumber(DbPage *pPg){
// return pPg->pgno;
// }
// #endif
// /*
// ** Increment the reference count for page pPg.
// */
// void sqlite3PagerRef(DbPage *pPg){
// sqlite3PcacheRef(pPg);
// }
// /*
// ** Sync the journal. In other words, make sure all the pages that have
// ** been written to the journal have actually reached the surface of the
// ** disk and can be restored in the event of a hot-journal rollback.
// **
// ** If the Pager.noSync flag is set, then this function is a no-op.
// ** Otherwise, the actions required depend on the journal-mode and the
// ** device characteristics of the file-system, as follows:
// **
// ** * If the journal file is an in-memory journal file, no action need
// ** be taken.
// **
// ** * Otherwise, if the device does not support the SAFE_APPEND property,
// ** then the nRec field of the most recently written journal header
// ** is updated to contain the number of journal records that have
// ** been written following it. If the pager is operating in full-sync
// ** mode, then the journal file is synced before this field is updated.
// **
// ** * If the device does not support the SEQUENTIAL property, then
// ** journal file is synced.
// **
// ** Or, in pseudo-code:
// **
// ** if( NOT <in-memory journal> ){
// ** if( NOT SAFE_APPEND ){
// ** if( <full-sync mode> ) xSync(<journal file>);
// ** <update nRec field>
// ** }
// ** if( NOT SEQUENTIAL ) xSync(<journal file>);
// ** }
// **
// ** If successful, this routine clears the PGHDR_NEED_SYNC flag of every
// ** page currently held in memory before returning SQLITE_OK. If an IO
// ** error is encountered, then the IO error code is returned to the caller.
// */
// static int syncJournal(Pager *pPager, int newHdr){
// int rc; /* Return code */
// assert( pPager->eState==PAGER_WRITER_CACHEMOD
// || pPager->eState==PAGER_WRITER_DBMOD
// );
// assert( assert_pager_state(pPager) );
// assert( !pagerUseWal(pPager) );
// rc = sqlite3PagerExclusiveLock(pPager);
// if( rc!=SQLITE_OK ) return rc;
// if( !pPager->noSync ){
// assert( !pPager->tempFile );
// if( isOpen(pPager->jfd) && pPager->journalMode!=PAGER_JOURNALMODE_MEMORY ){
// const int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
// assert( isOpen(pPager->jfd) );
// if( 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
// /* This block deals with an obscure problem. If the last connection
// ** that wrote to this database was operating in persistent-journal
// ** mode, then the journal file may at this point actually be larger
// ** than Pager.journalOff bytes. If the next thing in the journal
// ** file happens to be a journal-header (written as part of the
// ** previous connection's transaction), and a crash or power-failure
// ** occurs after nRec is updated but before this connection writes
// ** anything else to the journal file (or commits/rolls back its
// ** transaction), then SQLite may become confused when doing the
// ** hot-journal rollback following recovery. It may roll back all
// ** of this connections data, then proceed to rolling back the old,
// ** out-of-date data that follows it. Database corruption.
// **
// ** To work around this, if the journal file does appear to contain
// ** a valid header following Pager.journalOff, then write a 0x00
// ** byte to the start of it to prevent it from being recognized.
// **
// ** Variable iNextHdrOffset is set to the offset at which this
// ** problematic header will occur, if it exists. aMagic is used
// ** as a temporary buffer to inspect the first couple of bytes of
// ** the potential journal header.
// */
// i64 iNextHdrOffset;
// u8 aMagic[8];
// u8 zHeader[sizeof(aJournalMagic)+4];
// memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
// put32bits(&zHeader[sizeof(aJournalMagic)], pPager->nRec);
// iNextHdrOffset = journalHdrOffset(pPager);
// rc = sqlite3OsRead(pPager->jfd, aMagic, 8, iNextHdrOffset);
// if( rc==SQLITE_OK && 0==memcmp(aMagic, aJournalMagic, 8) ){
// static const u8 zerobyte = 0;
// rc = sqlite3OsWrite(pPager->jfd, &zerobyte, 1, iNextHdrOffset);
// }
// if( rc!=SQLITE_OK && rc!=SQLITE_IOERR_SHORT_READ ){
// return rc;
// }
// /* Write the nRec value into the journal file header. If in
// ** full-synchronous mode, sync the journal first. This ensures that
// ** all data has really hit the disk before nRec is updated to mark
// ** it as a candidate for rollback.
// **
// ** This is not required if the persistent media supports the
// ** SAFE_APPEND property. Because in this case it is not possible
// ** for garbage data to be appended to the file, the nRec field
// ** is populated with 0xFFFFFFFF when the journal header is written
// ** and never needs to be updated.
// */
// if( pPager->fullSync && 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){
// PAGERTRACE(("SYNC journal of %d\n", PAGERID(pPager)));
// IOTRACE(("JSYNC %p\n", pPager))
// rc = sqlite3OsSync(pPager->jfd, pPager->syncFlags);
// if( rc!=SQLITE_OK ) return rc;
// }
// IOTRACE(("JHDR %p %lld\n", pPager, pPager->journalHdr));
// rc = sqlite3OsWrite(
// pPager->jfd, zHeader, sizeof(zHeader), pPager->journalHdr
// );
// if( rc!=SQLITE_OK ) return rc;
// }
// if( 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){
// PAGERTRACE(("SYNC journal of %d\n", PAGERID(pPager)));
// IOTRACE(("JSYNC %p\n", pPager))
// rc = sqlite3OsSync(pPager->jfd, pPager->syncFlags|
// (pPager->syncFlags==SQLITE_SYNC_FULL?SQLITE_SYNC_DATAONLY:0)
// );
// if( rc!=SQLITE_OK ) return rc;
// }
// pPager->journalHdr = pPager->journalOff;
// if( newHdr && 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
// pPager->nRec = 0;
// rc = writeJournalHdr(pPager);
// if( rc!=SQLITE_OK ) return rc;
// }
// }else{
// pPager->journalHdr = pPager->journalOff;
// }
// }
// /* Unless the pager is in noSync mode, the journal file was just
// ** successfully synced. Either way, clear the PGHDR_NEED_SYNC flag on
// ** all pages.
// */
// sqlite3PcacheClearSyncFlags(pPager->pPCache);
// pPager->eState = PAGER_WRITER_DBMOD;
// assert( assert_pager_state(pPager) );
// return SQLITE_OK;
// }
// /*
// ** The argument is the first in a linked list of dirty pages connected
// ** by the PgHdr.pDirty pointer. This function writes each one of the
// ** in-memory pages in the list to the database file. The argument may
// ** be NULL, representing an empty list. In this case this function is
// ** a no-op.
// **
// ** The pager must hold at least a RESERVED lock when this function
// ** is called. Before writing anything to the database file, this lock
// ** is upgraded to an EXCLUSIVE lock. If the lock cannot be obtained,
// ** SQLITE_BUSY is returned and no data is written to the database file.
// **
// ** If the pager is a temp-file pager and the actual file-system file
// ** is not yet open, it is created and opened before any data is
// ** written out.
// **
// ** Once the lock has been upgraded and, if necessary, the file opened,
// ** the pages are written out to the database file in list order. Writing
// ** a page is skipped if it meets either of the following criteria:
// **
// ** * The page number is greater than Pager.dbSize, or
// ** * The PGHDR_DONT_WRITE flag is set on the page.
// **
// ** If writing out a page causes the database file to grow, Pager.dbFileSize
// ** is updated accordingly. If page 1 is written out, then the value cached
// ** in Pager.dbFileVers[] is updated to match the new value stored in
// ** the database file.
// **
// ** If everything is successful, SQLITE_OK is returned. If an IO error
// ** occurs, an IO error code is returned. Or, if the EXCLUSIVE lock cannot
// ** be obtained, SQLITE_BUSY is returned.
// */
// static int pager_write_pagelist(Pager *pPager, PgHdr *pList){
// int rc = SQLITE_OK; /* Return code */
// /* This function is only called for rollback pagers in WRITER_DBMOD state. */
// assert( !pagerUseWal(pPager) );
// assert( pPager->tempFile || pPager->eState==PAGER_WRITER_DBMOD );
// assert( pPager->eLock==EXCLUSIVE_LOCK );
// assert( isOpen(pPager->fd) || pList->pDirty==0 );
// /* If the file is a temp-file has not yet been opened, open it now. It
// ** is not possible for rc to be other than SQLITE_OK if this branch
// ** is taken, as pager_wait_on_lock() is a no-op for temp-files.
// */
// if( !isOpen(pPager->fd) ){
// assert( pPager->tempFile && rc==SQLITE_OK );
// rc = pagerOpentemp(pPager, pPager->fd, pPager->vfsFlags);
// }
// /* Before the first write, give the VFS a hint of what the final
// ** file size will be.
// */
// assert( rc!=SQLITE_OK || isOpen(pPager->fd) );
// if( rc==SQLITE_OK
// && pPager->dbHintSize<pPager->dbSize
// && (pList->pDirty || pList->pgno>pPager->dbHintSize)
// ){
// sqlite3_int64 szFile = pPager->pageSize * (sqlite3_int64)pPager->dbSize;
// sqlite3OsFileControlHint(pPager->fd, SQLITE_FCNTL_SIZE_HINT, &szFile);
// pPager->dbHintSize = pPager->dbSize;
// }
// while( rc==SQLITE_OK && pList ){
// Pgno pgno = pList->pgno;
// /* If there are dirty pages in the page cache with page numbers greater
// ** than Pager.dbSize, this means sqlite3PagerTruncateImage() was called to
// ** make the file smaller (presumably by auto-vacuum code). Do not write
// ** any such pages to the file.
// **
// ** Also, do not write out any page that has the PGHDR_DONT_WRITE flag
// ** set (set by sqlite3PagerDontWrite()).
// */
// if( pgno<=pPager->dbSize && 0==(pList->flags&PGHDR_DONT_WRITE) ){
// i64 offset = (pgno-1)*(i64)pPager->pageSize; /* Offset to write */
// char *pData; /* Data to write */
// assert( (pList->flags&PGHDR_NEED_SYNC)==0 );
// if( pList->pgno==1 ) pager_write_changecounter(pList);
// pData = pList->pData;
// /* Write out the page data. */
// rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize, offset);
// /* If page 1 was just written, update Pager.dbFileVers to match
// ** the value now stored in the database file. If writing this
// ** page caused the database file to grow, update dbFileSize.
// */
// if( pgno==1 ){
// memcpy(&pPager->dbFileVers, &pData[24], sizeof(pPager->dbFileVers));
// }
// if( pgno>pPager->dbFileSize ){
// pPager->dbFileSize = pgno;
// }
// pPager->aStat[PAGER_STAT_WRITE]++;
// /* Update any backup objects copying the contents of this pager. */
// sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)pList->pData);
// PAGERTRACE(("STORE %d page %d hash(%08x)\n",
// PAGERID(pPager), pgno, pager_pagehash(pList)));
// IOTRACE(("PGOUT %p %d\n", pPager, pgno));
// PAGER_INCR(sqlite3_pager_writedb_count);
// }else{
// PAGERTRACE(("NOSTORE %d page %d\n", PAGERID(pPager), pgno));
// }
// pager_set_pagehash(pList);
// pList = pList->pDirty;
// }
// return rc;
// }
// /*
// ** Ensure that the sub-journal file is open. If it is already open, this
// ** function is a no-op.
// **
// ** SQLITE_OK is returned if everything goes according to plan. An
// ** SQLITE_IOERR_XXX error code is returned if a call to sqlite3OsOpen()
// ** fails.
// */
// static int openSubJournal(Pager *pPager){
// int rc = SQLITE_OK;
// if( !isOpen(pPager->sjfd) ){
// const int flags = SQLITE_OPEN_SUBJOURNAL | SQLITE_OPEN_READWRITE
// | SQLITE_OPEN_CREATE | SQLITE_OPEN_EXCLUSIVE
// | SQLITE_OPEN_DELETEONCLOSE;
// int nStmtSpill = sqlite3Config.nStmtSpill;
// if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY || pPager->subjInMemory ){
// nStmtSpill = -1;
// }
// rc = sqlite3JournalOpen(pPager->pVfs, 0, pPager->sjfd, flags, nStmtSpill);
// }
// return rc;
// }
// /*
// ** Append a record of the current state of page pPg to the sub-journal.
// **
// ** If successful, set the bit corresponding to pPg->pgno in the bitvecs
// ** for all open savepoints before returning.
// **
// ** This function returns SQLITE_OK if everything is successful, an IO
// ** error code if the attempt to write to the sub-journal fails, or
// ** SQLITE_NOMEM if a malloc fails while setting a bit in a savepoint
// ** bitvec.
// */
// static int subjournalPage(PgHdr *pPg){
// int rc = SQLITE_OK;
// Pager *pPager = pPg->pPager;
// if( pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
// /* Open the sub-journal, if it has not already been opened */
// assert( pPager->useJournal );
// assert( isOpen(pPager->jfd) || pagerUseWal(pPager) );
// assert( isOpen(pPager->sjfd) || pPager->nSubRec==0 );
// assert( pagerUseWal(pPager)
// || pageInJournal(pPager, pPg)
// || pPg->pgno>pPager->dbOrigSize
// );
// rc = openSubJournal(pPager);
// /* If the sub-journal was opened successfully (or was already open),
// ** write the journal record into the file. */
// if( rc==SQLITE_OK ){
// void *pData = pPg->pData;
// i64 offset = (i64)pPager->nSubRec*(4+pPager->pageSize);
// char *pData2;
// pData2 = pData;
// PAGERTRACE(("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno));
// rc = write32bits(pPager->sjfd, offset, pPg->pgno);
// if( rc==SQLITE_OK ){
// rc = sqlite3OsWrite(pPager->sjfd, pData2, pPager->pageSize, offset+4);
// }
// }
// }
// if( rc==SQLITE_OK ){
// pPager->nSubRec++;
// assert( pPager->nSavepoint>0 );
// rc = addToSavepointBitvecs(pPager, pPg->pgno);
// }
// return rc;
// }
// static int subjournalPageIfRequired(PgHdr *pPg){
// if( subjRequiresPage(pPg) ){
// return subjournalPage(pPg);
// }else{
// return SQLITE_OK;
// }
// }
// /*
// ** This function is called by the pcache layer when it has reached some
// ** soft memory limit. The first argument is a pointer to a Pager object
// ** (cast as a void*). The pager is always 'purgeable' (not an in-memory
// ** database). The second argument is a reference to a page that is
// ** currently dirty but has no outstanding references. The page
// ** is always associated with the Pager object passed as the first
// ** argument.
// **
// ** The job of this function is to make pPg clean by writing its contents
// ** out to the database file, if possible. This may involve syncing the
// ** journal file.
// **
// ** If successful, sqlite3PcacheMakeClean() is called on the page and
// ** SQLITE_OK returned. If an IO error occurs while trying to make the
// ** page clean, the IO error code is returned. If the page cannot be
// ** made clean for some other reason, but no error occurs, then SQLITE_OK
// ** is returned by sqlite3PcacheMakeClean() is not called.
// */
// static int pagerStress(void *p, PgHdr *pPg){
// Pager *pPager = (Pager *)p;
// int rc = SQLITE_OK;
// assert( pPg->pPager==pPager );
// assert( pPg->flags&PGHDR_DIRTY );
// /* The doNotSpill NOSYNC bit is set during times when doing a sync of
// ** journal (and adding a new header) is not allowed. This occurs
// ** during calls to sqlite3PagerWrite() while trying to journal multiple
// ** pages belonging to the same sector.
// **
// ** The doNotSpill ROLLBACK and OFF bits inhibits all cache spilling
// ** regardless of whether or not a sync is required. This is set during
// ** a rollback or by user request, respectively.
// **
// ** Spilling is also prohibited when in an error state since that could
// ** lead to database corruption. In the current implementation it
// ** is impossible for sqlite3PcacheFetch() to be called with createFlag==3
// ** while in the error state, hence it is impossible for this routine to
// ** be called in the error state. Nevertheless, we include a NEVER()
// ** test for the error state as a safeguard against future changes.
// */
// if( NEVER(pPager->errCode) ) return SQLITE_OK;
// testcase( pPager->doNotSpill & SPILLFLAG_ROLLBACK );
// testcase( pPager->doNotSpill & SPILLFLAG_OFF );
// testcase( pPager->doNotSpill & SPILLFLAG_NOSYNC );
// if( pPager->doNotSpill
// && ((pPager->doNotSpill & (SPILLFLAG_ROLLBACK|SPILLFLAG_OFF))!=0
// || (pPg->flags & PGHDR_NEED_SYNC)!=0)
// ){
// return SQLITE_OK;
// }
// pPager->aStat[PAGER_STAT_SPILL]++;
// pPg->pDirty = 0;
// if( pagerUseWal(pPager) ){
// /* Write a single frame for this page to the log. */
// rc = subjournalPageIfRequired(pPg);
// if( rc==SQLITE_OK ){
// rc = pagerWalFrames(pPager, pPg, 0, 0);
// }
// }else{
// #ifdef SQLITE_ENABLE_BATCH_ATOMIC_WRITE
// if( pPager->tempFile==0 ){
// rc = sqlite3JournalCreate(pPager->jfd);
// if( rc!=SQLITE_OK ) return pager_error(pPager, rc);
// }
// #endif
// /* Sync the journal file if required. */
// if( pPg->flags&PGHDR_NEED_SYNC
// || pPager->eState==PAGER_WRITER_CACHEMOD
// ){
// rc = syncJournal(pPager, 1);
// }
// /* Write the contents of the page out to the database file. */
// if( rc==SQLITE_OK ){
// assert( (pPg->flags&PGHDR_NEED_SYNC)==0 );
// rc = pager_write_pagelist(pPager, pPg);
// }
// }
// /* Mark the page as clean. */
// if( rc==SQLITE_OK ){
// PAGERTRACE(("STRESS %d page %d\n", PAGERID(pPager), pPg->pgno));
// sqlite3PcacheMakeClean(pPg);
// }
// return pager_error(pPager, rc);
// }
// /*
// ** Flush all unreferenced dirty pages to disk.
// */
// int sqlite3PagerFlush(Pager *pPager){
// int rc = pPager->errCode;
// if( !MEMDB ){
// PgHdr *pList = sqlite3PcacheDirtyList(pPager->pPCache);
// assert( assert_pager_state(pPager) );
// while( rc==SQLITE_OK && pList ){
// PgHdr *pNext = pList->pDirty;
// if( pList->nRef==0 ){
// rc = pagerStress((void*)pPager, pList);
// }
// pList = pNext;
// }
// }
// return rc;
// }
int sqlite3PagerOpen(Pager **ppPager, const char *zFilename, int nExtra, int flags, int vfsFlags,
void (*xReinit)(DbPage *)) {
u8 * pPtr;
Pager * pPager = 0; /* Pager object to allocate and return */
int rc = SQLITE_OK; /* Return code */
int tempFile = 0; /* True for temp files (incl. in-memory files) */
int memDb = 0; /* True if this is an in-memory file */
int memJM = 0; /* Memory journal mode */
int readOnly = 0; /* True if this is a read-only file */
int journalFileSize; /* Bytes to allocate for each journal fd */
int nPathname = 120; /* Number of bytes in zPathname */
int useJournal = (flags & PAGER_OMIT_JOURNAL) == 0; /* False to omit journal */
int pcacheSize = sqlite3PcacheSize(); /* Bytes to allocate for PCache */
u32 szPageDflt = SQLITE_DEFAULT_PAGE_SIZE; /* Default page size */
const char *zUri = 0; /* URI args to copy */
int nUriByte = 1; /* Number of bytes of URI args at *zUri */
int nUri = 0; /* Number of URI parameters */
int tsize;
journalFileSize = 120;
/* Set the output variable to NULL in case an error occurs. */
*ppPager = 0;
tsize = ROUND8(sizeof(*pPager)) /* Pager */
+ ROUND8(pcacheSize) /* PCache */
+ sizeof(pPager) /* Self contained pager pointer */
+ 4 /* Database prefix (4 Bytes) */
+ nPathname + 1 /* Database file name */
+ nPathname + 8 + 1 /* Journal file name */
+ nPathname + 4 + 1 /* WAL file name */
+ 3; /* 3 bytes of terminalter */
pPtr = (u8 *)calloc(1, tsize);
if (!pPtr) {
return SQLITE_NOMEM;
}
pPager = (Pager *)pPtr;
pPtr += ROUND8(sizeof(*pPager));
pPager->pPCache = (PCache *)pPtr;
pPtr += ROUND8(pcacheSize);
memcpy(pPtr, &pPager, sizeof(pPager));
pPtr += sizeof(pPager);
pPtr += 4;
pPager->zFilename = (char *)pPtr;
memcpy(pPtr, zFilename, strlen(zFilename));
pPtr += (nPathname + 1);
pPager->zJournal = (char *)pPtr;
memcpy(pPtr, zFilename, strlen(zFilename));
pPtr += nPathname;
memcpy(pPtr, "-journal", 8);
pPtr += 8 + 1;
pPager->zWal = (char *)pPtr;
memcpy(pPtr, zFilename, nPathname);
pPtr += nPathname;
memcpy(pPtr, "-wal", 4);
pPtr += 4 + 1;
pPager->vfsFlags = vfsFlags;
/* Open the pager file.
*/
int fout = 0; /* VFS flags returned by xOpen() */
pPager->fd = open(zFilename, O_RDWR | O_CREAT, 0755);
if (pPager->fd < 0) {
return -1;
}
readOnly = 0;
/* If the file was successfully opened for read/write access,
** choose a default page size in case we have to create the
** database file. The default page size is the maximum of:
**
** + SQLITE_DEFAULT_PAGE_SIZE,
** + The value returned by sqlite3OsSectorSize()
** + The largest page size that can be written atomically.
*/
// if (rc == SQLITE_OK) {
// int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
// if (!readOnly) {
// setSectorSize(pPager);
// if (szPageDflt < pPager->sectorSize) {
// if (pPager->sectorSize > SQLITE_MAX_DEFAULT_PAGE_SIZE) {
// szPageDflt = SQLITE_MAX_DEFAULT_PAGE_SIZE;
// } else {
// szPageDflt = (u32)pPager->sectorSize;
// }
// }
// }
// pPager->noLock = sqlite3_uri_boolean(pPager->zFilename, "nolock", 0);
// if ((iDc & SQLITE_IOCAP_IMMUTABLE) != 0 || sqlite3_uri_boolean(pPager->zFilename, "immutable", 0)) {
// vfsFlags |= SQLITE_OPEN_READONLY;
// goto act_like_temp_file;
// }
// }
// /* The following call to PagerSetPagesize() serves to set the value of
// ** Pager.pageSize and to allocate the Pager.pTmpSpace buffer.
// */
// if (rc == SQLITE_OK) {
// assert(pPager->memDb == 0);
// rc = sqlite3PagerSetPagesize(pPager, &szPageDflt, -1);
// testcase(rc != SQLITE_OK);
// }
// /* Initialize the PCache object. */
// if (rc == SQLITE_OK) {
// nExtra = ROUND8(nExtra);
// assert(nExtra >= 8 && nExtra < 1000);
// rc = sqlite3PcacheOpen(szPageDflt, nExtra, !memDb, !memDb ? pagerStress : 0, (void *)pPager, pPager->pPCache);
// }
// /* If an error occurred above, free the Pager structure and close the file.
// */
// if (rc != SQLITE_OK) {
// sqlite3OsClose(pPager->fd);
// sqlite3PageFree(pPager->pTmpSpace);
// sqlite3_free(pPager);
// return rc;
// }
// PAGERTRACE(("OPEN %d %s\n", FILEHANDLEID(pPager->fd), pPager->zFilename));
// IOTRACE(("OPEN %p %s\n", pPager, pPager->zFilename))
// pPager->useJournal = (u8)useJournal;
// pPager->mxPgno = SQLITE_MAX_PAGE_COUNT;
// pPager->tempFile = (u8)tempFile;
// assert(tempFile == PAGER_LOCKINGMODE_NORMAL || tempFile == PAGER_LOCKINGMODE_EXCLUSIVE);
// assert(PAGER_LOCKINGMODE_EXCLUSIVE == 1);
// pPager->exclusiveMode = (u8)tempFile;
// pPager->changeCountDone = pPager->tempFile;
// pPager->memDb = (u8)memDb;
// pPager->readOnly = (u8)readOnly;
// assert(useJournal || pPager->tempFile);
// pPager->noSync = pPager->tempFile;
// if (pPager->noSync) {
// assert(pPager->fullSync == 0);
// assert(pPager->extraSync == 0);
// assert(pPager->syncFlags == 0);
// assert(pPager->walSyncFlags == 0);
// } else {
// pPager->fullSync = 1;
// pPager->extraSync = 0;
// pPager->syncFlags = SQLITE_SYNC_NORMAL;
// pPager->walSyncFlags = SQLITE_SYNC_NORMAL | (SQLITE_SYNC_NORMAL << 2);
// }
// pPager->nExtra = (u16)nExtra;
// pPager->journalSizeLimit = SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT;
// assert(isOpen(pPager->fd) || tempFile);
// setSectorSize(pPager);
// if (!useJournal) {
// pPager->journalMode = PAGER_JOURNALMODE_OFF;
// } else if (memDb || memJM) {
// pPager->journalMode = PAGER_JOURNALMODE_MEMORY;
// }
// pPager->xReiniter = xReinit;
// setGetterMethod(pPager);
*ppPager = pPager;
return SQLITE_OK;
}
// /*
// ** Return the sqlite3_file for the main database given the name
// ** of the corresonding WAL or Journal name as passed into
// ** xOpen.
// */
// sqlite3_file *sqlite3_database_file_object(const char *zName){
// Pager *pPager;
// while( zName[-1]!=0 || zName[-2]!=0 || zName[-3]!=0 || zName[-4]!=0 ){
// zName--;
// }
// pPager = *(Pager**)(zName - 4 - sizeof(Pager*));
// return pPager->fd;
// }
// /*
// ** This function is called after transitioning from PAGER_UNLOCK to
// ** PAGER_SHARED state. It tests if there is a hot journal present in
// ** the file-system for the given pager. A hot journal is one that
// ** needs to be played back. According to this function, a hot-journal
// ** file exists if the following criteria are met:
// **
// ** * The journal file exists in the file system, and
// ** * No process holds a RESERVED or greater lock on the database file, and
// ** * The database file itself is greater than 0 bytes in size, and
// ** * The first byte of the journal file exists and is not 0x00.
// **
// ** If the current size of the database file is 0 but a journal file
// ** exists, that is probably an old journal left over from a prior
// ** database with the same name. In this case the journal file is
// ** just deleted using OsDelete, *pExists is set to 0 and SQLITE_OK
// ** is returned.
// **
// ** This routine does not check if there is a super-journal filename
// ** at the end of the file. If there is, and that super-journal file
// ** does not exist, then the journal file is not really hot. In this
// ** case this routine will return a false-positive. The pager_playback()
// ** routine will discover that the journal file is not really hot and
// ** will not roll it back.
// **
// ** If a hot-journal file is found to exist, *pExists is set to 1 and
// ** SQLITE_OK returned. If no hot-journal file is present, *pExists is
// ** set to 0 and SQLITE_OK returned. If an IO error occurs while trying
// ** to determine whether or not a hot-journal file exists, the IO error
// ** code is returned and the value of *pExists is undefined.
// */
// static int hasHotJournal(Pager *pPager, int *pExists){
// sqlite3_vfs * const pVfs = pPager->pVfs;
// int rc = SQLITE_OK; /* Return code */
// int exists = 1; /* True if a journal file is present */
// int jrnlOpen = !!isOpen(pPager->jfd);
// assert( pPager->useJournal );
// assert( isOpen(pPager->fd) );
// assert( pPager->eState==PAGER_OPEN );
// assert( jrnlOpen==0 || ( sqlite3OsDeviceCharacteristics(pPager->jfd) &
// SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
// ));
// *pExists = 0;
// if( !jrnlOpen ){
// rc = sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &exists);
// }
// if( rc==SQLITE_OK && exists ){
// int locked = 0; /* True if some process holds a RESERVED lock */
// /* Race condition here: Another process might have been holding the
// ** the RESERVED lock and have a journal open at the sqlite3OsAccess()
// ** call above, but then delete the journal and drop the lock before
// ** we get to the following sqlite3OsCheckReservedLock() call. If that
// ** is the case, this routine might think there is a hot journal when
// ** in fact there is none. This results in a false-positive which will
// ** be dealt with by the playback routine. Ticket #3883.
// */
// rc = sqlite3OsCheckReservedLock(pPager->fd, &locked);
// if( rc==SQLITE_OK && !locked ){
// Pgno nPage; /* Number of pages in database file */
// assert( pPager->tempFile==0 );
// rc = pagerPagecount(pPager, &nPage);
// if( rc==SQLITE_OK ){
// /* If the database is zero pages in size, that means that either (1) the
// ** journal is a remnant from a prior database with the same name where
// ** the database file but not the journal was deleted, or (2) the initial
// ** transaction that populates a new database is being rolled back.
// ** In either case, the journal file can be deleted. However, take care
// ** not to delete the journal file if it is already open due to
// ** journal_mode=PERSIST.
// */
// if( nPage==0 && !jrnlOpen ){
// sqlite3BeginBenignMalloc();
// if( pagerLockDb(pPager, RESERVED_LOCK)==SQLITE_OK ){
// sqlite3OsDelete(pVfs, pPager->zJournal, 0);
// if( !pPager->exclusiveMode ) pagerUnlockDb(pPager, SHARED_LOCK);
// }
// sqlite3EndBenignMalloc();
// }else{
// /* The journal file exists and no other connection has a reserved
// ** or greater lock on the database file. Now check that there is
// ** at least one non-zero bytes at the start of the journal file.
// ** If there is, then we consider this journal to be hot. If not,
// ** it can be ignored.
// */
// if( !jrnlOpen ){
// int f = SQLITE_OPEN_READONLY|SQLITE_OPEN_MAIN_JOURNAL;
// rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &f);
// }
// if( rc==SQLITE_OK ){
// u8 first = 0;
// rc = sqlite3OsRead(pPager->jfd, (void *)&first, 1, 0);
// if( rc==SQLITE_IOERR_SHORT_READ ){
// rc = SQLITE_OK;
// }
// if( !jrnlOpen ){
// sqlite3OsClose(pPager->jfd);
// }
// *pExists = (first!=0);
// }else if( rc==SQLITE_CANTOPEN ){
// /* If we cannot open the rollback journal file in order to see if
// ** it has a zero header, that might be due to an I/O error, or
// ** it might be due to the race condition described above and in
// ** ticket #3883. Either way, assume that the journal is hot.
// ** This might be a false positive. But if it is, then the
// ** automatic journal playback and recovery mechanism will deal
// ** with it under an EXCLUSIVE lock where we do not need to
// ** worry so much with race conditions.
// */
// *pExists = 1;
// rc = SQLITE_OK;
// }
// }
// }
// }
// }
// return rc;
// }
// /*
// ** This function is called to obtain a shared lock on the database file.
// ** It is illegal to call sqlite3PagerGet() until after this function
// ** has been successfully called. If a shared-lock is already held when
// ** this function is called, it is a no-op.
// **
// ** The following operations are also performed by this function.
// **
// ** 1) If the pager is currently in PAGER_OPEN state (no lock held
// ** on the database file), then an attempt is made to obtain a
// ** SHARED lock on the database file. Immediately after obtaining
// ** the SHARED lock, the file-system is checked for a hot-journal,
// ** which is played back if present. Following any hot-journal
// ** rollback, the contents of the cache are validated by checking
// ** the 'change-counter' field of the database file header and
// ** discarded if they are found to be invalid.
// **
// ** 2) If the pager is running in exclusive-mode, and there are currently
// ** no outstanding references to any pages, and is in the error state,
// ** then an attempt is made to clear the error state by discarding
// ** the contents of the page cache and rolling back any open journal
// ** file.
// **
// ** If everything is successful, SQLITE_OK is returned. If an IO error
// ** occurs while locking the database, checking for a hot-journal file or
// ** rolling back a journal file, the IO error code is returned.
// */
// int sqlite3PagerSharedLock(Pager *pPager){
// int rc = SQLITE_OK; /* Return code */
// /* This routine is only called from b-tree and only when there are no
// ** outstanding pages. This implies that the pager state should either
// ** be OPEN or READER. READER is only possible if the pager is or was in
// ** exclusive access mode. */
// assert( sqlite3PcacheRefCount(pPager->pPCache)==0 );
// assert( assert_pager_state(pPager) );
// assert( pPager->eState==PAGER_OPEN || pPager->eState==PAGER_READER );
// assert( pPager->errCode==SQLITE_OK );
// if( !pagerUseWal(pPager) && pPager->eState==PAGER_OPEN ){
// int bHotJournal = 1; /* True if there exists a hot journal-file */
// assert( !MEMDB );
// assert( pPager->tempFile==0 || pPager->eLock==EXCLUSIVE_LOCK );
// rc = pager_wait_on_lock(pPager, SHARED_LOCK);
// if( rc!=SQLITE_OK ){
// assert( pPager->eLock==NO_LOCK || pPager->eLock==UNKNOWN_LOCK );
// goto failed;
// }
// /* If a journal file exists, and there is no RESERVED lock on the
// ** database file, then it either needs to be played back or deleted.
// */
// if( pPager->eLock<=SHARED_LOCK ){
// rc = hasHotJournal(pPager, &bHotJournal);
// }
// if( rc!=SQLITE_OK ){
// goto failed;
// }
// if( bHotJournal ){
// if( pPager->readOnly ){
// rc = SQLITE_READONLY_ROLLBACK;
// goto failed;
// }
// /* Get an EXCLUSIVE lock on the database file. At this point it is
// ** important that a RESERVED lock is not obtained on the way to the
// ** EXCLUSIVE lock. If it were, another process might open the
// ** database file, detect the RESERVED lock, and conclude that the
// ** database is safe to read while this process is still rolling the
// ** hot-journal back.
// **
// ** Because the intermediate RESERVED lock is not requested, any
// ** other process attempting to access the database file will get to
// ** this point in the code and fail to obtain its own EXCLUSIVE lock
// ** on the database file.
// **
// ** Unless the pager is in locking_mode=exclusive mode, the lock is
// ** downgraded to SHARED_LOCK before this function returns.
// */
// rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
// if( rc!=SQLITE_OK ){
// goto failed;
// }
// /* If it is not already open and the file exists on disk, open the
// ** journal for read/write access. Write access is required because
// ** in exclusive-access mode the file descriptor will be kept open
// ** and possibly used for a transaction later on. Also, write-access
// ** is usually required to finalize the journal in journal_mode=persist
// ** mode (and also for journal_mode=truncate on some systems).
// **
// ** If the journal does not exist, it usually means that some
// ** other connection managed to get in and roll it back before
// ** this connection obtained the exclusive lock above. Or, it
// ** may mean that the pager was in the error-state when this
// ** function was called and the journal file does not exist.
// */
// if( !isOpen(pPager->jfd) ){
// sqlite3_vfs * const pVfs = pPager->pVfs;
// int bExists; /* True if journal file exists */
// rc = sqlite3OsAccess(
// pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &bExists);
// if( rc==SQLITE_OK && bExists ){
// int fout = 0;
// int f = SQLITE_OPEN_READWRITE|SQLITE_OPEN_MAIN_JOURNAL;
// assert( !pPager->tempFile );
// rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &fout);
// assert( rc!=SQLITE_OK || isOpen(pPager->jfd) );
// if( rc==SQLITE_OK && fout&SQLITE_OPEN_READONLY ){
// rc = SQLITE_CANTOPEN_BKPT;
// sqlite3OsClose(pPager->jfd);
// }
// }
// }
// /* Playback and delete the journal. Drop the database write
// ** lock and reacquire the read lock. Purge the cache before
// ** playing back the hot-journal so that we don't end up with
// ** an inconsistent cache. Sync the hot journal before playing
// ** it back since the process that crashed and left the hot journal
// ** probably did not sync it and we are required to always sync
// ** the journal before playing it back.
// */
// if( isOpen(pPager->jfd) ){
// assert( rc==SQLITE_OK );
// rc = pagerSyncHotJournal(pPager);
// if( rc==SQLITE_OK ){
// rc = pager_playback(pPager, !pPager->tempFile);
// pPager->eState = PAGER_OPEN;
// }
// }else if( !pPager->exclusiveMode ){
// pagerUnlockDb(pPager, SHARED_LOCK);
// }
// if( rc!=SQLITE_OK ){
// /* This branch is taken if an error occurs while trying to open
// ** or roll back a hot-journal while holding an EXCLUSIVE lock. The
// ** pager_unlock() routine will be called before returning to unlock
// ** the file. If the unlock attempt fails, then Pager.eLock must be
// ** set to UNKNOWN_LOCK (see the comment above the #define for
// ** UNKNOWN_LOCK above for an explanation).
// **
// ** In order to get pager_unlock() to do this, set Pager.eState to
// ** PAGER_ERROR now. This is not actually counted as a transition
// ** to ERROR state in the state diagram at the top of this file,
// ** since we know that the same call to pager_unlock() will very
// ** shortly transition the pager object to the OPEN state. Calling
// ** assert_pager_state() would fail now, as it should not be possible
// ** to be in ERROR state when there are zero outstanding page
// ** references.
// */
// pager_error(pPager, rc);
// goto failed;
// }
// assert( pPager->eState==PAGER_OPEN );
// assert( (pPager->eLock==SHARED_LOCK)
// || (pPager->exclusiveMode && pPager->eLock>SHARED_LOCK)
// );
// }
// if( !pPager->tempFile && pPager->hasHeldSharedLock ){
// /* The shared-lock has just been acquired then check to
// ** see if the database has been modified. If the database has changed,
// ** flush the cache. The hasHeldSharedLock flag prevents this from
// ** occurring on the very first access to a file, in order to save a
// ** single unnecessary sqlite3OsRead() call at the start-up.
// **
// ** Database changes are detected by looking at 15 bytes beginning
// ** at offset 24 into the file. The first 4 of these 16 bytes are
// ** a 32-bit counter that is incremented with each change. The
// ** other bytes change randomly with each file change when
// ** a codec is in use.
// **
// ** There is a vanishingly small chance that a change will not be
// ** detected. The chance of an undetected change is so small that
// ** it can be neglected.
// */
// char dbFileVers[sizeof(pPager->dbFileVers)];
// IOTRACE(("CKVERS %p %d\n", pPager, sizeof(dbFileVers)));
// rc = sqlite3OsRead(pPager->fd, &dbFileVers, sizeof(dbFileVers), 24);
// if( rc!=SQLITE_OK ){
// if( rc!=SQLITE_IOERR_SHORT_READ ){
// goto failed;
// }
// memset(dbFileVers, 0, sizeof(dbFileVers));
// }
// if( memcmp(pPager->dbFileVers, dbFileVers, sizeof(dbFileVers))!=0 ){
// pager_reset(pPager);
// /* Unmap the database file. It is possible that external processes
// ** may have truncated the database file and then extended it back
// ** to its original size while this process was not holding a lock.
// ** In this case there may exist a Pager.pMap mapping that appears
// ** to be the right size but is not actually valid. Avoid this
// ** possibility by unmapping the db here. */
// if( USEFETCH(pPager) ){
// sqlite3OsUnfetch(pPager->fd, 0, 0);
// }
// }
// }
// /* If there is a WAL file in the file-system, open this database in WAL
// ** mode. Otherwise, the following function call is a no-op.
// */
// rc = pagerOpenWalIfPresent(pPager);
// #ifndef SQLITE_OMIT_WAL
// assert( pPager->pWal==0 || rc==SQLITE_OK );
// #endif
// }
// if( pagerUseWal(pPager) ){
// assert( rc==SQLITE_OK );
// rc = pagerBeginReadTransaction(pPager);
// }
// if( pPager->tempFile==0 && pPager->eState==PAGER_OPEN && rc==SQLITE_OK ){
// rc = pagerPagecount(pPager, &pPager->dbSize);
// }
// failed:
// if( rc!=SQLITE_OK ){
// assert( !MEMDB );
// pager_unlock(pPager);
// assert( pPager->eState==PAGER_OPEN );
// }else{
// pPager->eState = PAGER_READER;
// pPager->hasHeldSharedLock = 1;
// }
// return rc;
// }
// /*
// ** If the reference count has reached zero, rollback any active
// ** transaction and unlock the pager.
// **
// ** Except, in locking_mode=EXCLUSIVE when there is nothing to in
// ** the rollback journal, the unlock is not performed and there is
// ** nothing to rollback, so this routine is a no-op.
// */
// static void pagerUnlockIfUnused(Pager *pPager){
// if( sqlite3PcacheRefCount(pPager->pPCache)==0 ){
// assert( pPager->nMmapOut==0 ); /* because page1 is never memory mapped */
// pagerUnlockAndRollback(pPager);
// }
// }
// /*
// ** The page getter methods each try to acquire a reference to a
// ** page with page number pgno. If the requested reference is
// ** successfully obtained, it is copied to *ppPage and SQLITE_OK returned.
// **
// ** There are different implementations of the getter method depending
// ** on the current state of the pager.
// **
// ** getPageNormal() -- The normal getter
// ** getPageError() -- Used if the pager is in an error state
// ** getPageMmap() -- Used if memory-mapped I/O is enabled
// **
// ** If the requested page is already in the cache, it is returned.
// ** Otherwise, a new page object is allocated and populated with data
// ** read from the database file. In some cases, the pcache module may
// ** choose not to allocate a new page object and may reuse an existing
// ** object with no outstanding references.
// **
// ** The extra data appended to a page is always initialized to zeros the
// ** first time a page is loaded into memory. If the page requested is
// ** already in the cache when this function is called, then the extra
// ** data is left as it was when the page object was last used.
// **
// ** If the database image is smaller than the requested page or if
// ** the flags parameter contains the PAGER_GET_NOCONTENT bit and the
// ** requested page is not already stored in the cache, then no
// ** actual disk read occurs. In this case the memory image of the
// ** page is initialized to all zeros.
// **
// ** If PAGER_GET_NOCONTENT is true, it means that we do not care about
// ** the contents of the page. This occurs in two scenarios:
// **
// ** a) When reading a free-list leaf page from the database, and
// **
// ** b) When a savepoint is being rolled back and we need to load
// ** a new page into the cache to be filled with the data read
// ** from the savepoint journal.
// **
// ** If PAGER_GET_NOCONTENT is true, then the data returned is zeroed instead
// ** of being read from the database. Additionally, the bits corresponding
// ** to pgno in Pager.pInJournal (bitvec of pages already written to the
// ** journal file) and the PagerSavepoint.pInSavepoint bitvecs of any open
// ** savepoints are set. This means if the page is made writable at any
// ** point in the future, using a call to sqlite3PagerWrite(), its contents
// ** will not be journaled. This saves IO.
// **
// ** The acquisition might fail for several reasons. In all cases,
// ** an appropriate error code is returned and *ppPage is set to NULL.
// **
// ** See also sqlite3PagerLookup(). Both this routine and Lookup() attempt
// ** to find a page in the in-memory cache first. If the page is not already
// ** in memory, this routine goes to disk to read it in whereas Lookup()
// ** just returns 0. This routine acquires a read-lock the first time it
// ** has to go to disk, and could also playback an old journal if necessary.
// ** Since Lookup() never goes to disk, it never has to deal with locks
// ** or journal files.
// */
// static int getPageNormal(
// Pager *pPager, /* The pager open on the database file */
// Pgno pgno, /* Page number to fetch */
// DbPage **ppPage, /* Write a pointer to the page here */
// int flags /* PAGER_GET_XXX flags */
// ){
// int rc = SQLITE_OK;
// PgHdr *pPg;
// u8 noContent; /* True if PAGER_GET_NOCONTENT is set */
// sqlite3_pcache_page *pBase;
// assert( pPager->errCode==SQLITE_OK );
// assert( pPager->eState>=PAGER_READER );
// assert( assert_pager_state(pPager) );
// assert( pPager->hasHeldSharedLock==1 );
// if( pgno==0 ) return SQLITE_CORRUPT_BKPT;
// pBase = sqlite3PcacheFetch(pPager->pPCache, pgno, 3);
// if( pBase==0 ){
// pPg = 0;
// rc = sqlite3PcacheFetchStress(pPager->pPCache, pgno, &pBase);
// if( rc!=SQLITE_OK ) goto pager_acquire_err;
// if( pBase==0 ){
// rc = SQLITE_NOMEM;
// goto pager_acquire_err;
// }
// }
// pPg = *ppPage = sqlite3PcacheFetchFinish(pPager->pPCache, pgno, pBase);
// assert( pPg==(*ppPage) );
// assert( pPg->pgno==pgno );
// assert( pPg->pPager==pPager || pPg->pPager==0 );
// noContent = (flags & PAGER_GET_NOCONTENT)!=0;
// if( pPg->pPager && !noContent ){
// /* In this case the pcache already contains an initialized copy of
// ** the page. Return without further ado. */
// assert( pgno!=PAGER_MJ_PGNO(pPager) );
// pPager->aStat[PAGER_STAT_HIT]++;
// return SQLITE_OK;
// }else{
// /* The pager cache has created a new page. Its content needs to
// ** be initialized. But first some error checks:
// **
// ** (*) obsolete. Was: maximum page number is 2^31
// ** (2) Never try to fetch the locking page
// */
// if( pgno==PAGER_MJ_PGNO(pPager) ){
// rc = SQLITE_CORRUPT_BKPT;
// goto pager_acquire_err;
// }
// pPg->pPager = pPager;
// assert( !isOpen(pPager->fd) || !MEMDB );
// if( !isOpen(pPager->fd) || pPager->dbSize<pgno || noContent ){
// if( pgno>pPager->mxPgno ){
// rc = SQLITE_FULL;
// goto pager_acquire_err;
// }
// if( noContent ){
// /* Failure to set the bits in the InJournal bit-vectors is benign.
// ** It merely means that we might do some extra work to journal a
// ** page that does not need to be journaled. Nevertheless, be sure
// ** to test the case where a malloc error occurs while trying to set
// ** a bit in a bit vector.
// */
// sqlite3BeginBenignMalloc();
// if( pgno<=pPager->dbOrigSize ){
// TESTONLY( rc = ) sqlite3BitvecSet(pPager->pInJournal, pgno);
// testcase( rc==SQLITE_NOMEM );
// }
// TESTONLY( rc = ) addToSavepointBitvecs(pPager, pgno);
// testcase( rc==SQLITE_NOMEM );
// sqlite3EndBenignMalloc();
// }
// memset(pPg->pData, 0, pPager->pageSize);
// IOTRACE(("ZERO %p %d\n", pPager, pgno));
// }else{
// assert( pPg->pPager==pPager );
// pPager->aStat[PAGER_STAT_MISS]++;
// rc = readDbPage(pPg);
// if( rc!=SQLITE_OK ){
// goto pager_acquire_err;
// }
// }
// pager_set_pagehash(pPg);
// }
// return SQLITE_OK;
// pager_acquire_err:
// assert( rc!=SQLITE_OK );
// if( pPg ){
// sqlite3PcacheDrop(pPg);
// }
// pagerUnlockIfUnused(pPager);
// *ppPage = 0;
// return rc;
// }
// #if SQLITE_MAX_MMAP_SIZE>0
// /* The page getter for when memory-mapped I/O is enabled */
// static int getPageMMap(
// Pager *pPager, /* The pager open on the database file */
// Pgno pgno, /* Page number to fetch */
// DbPage **ppPage, /* Write a pointer to the page here */
// int flags /* PAGER_GET_XXX flags */
// ){
// int rc = SQLITE_OK;
// PgHdr *pPg = 0;
// u32 iFrame = 0; /* Frame to read from WAL file */
// /* It is acceptable to use a read-only (mmap) page for any page except
// ** page 1 if there is no write-transaction open or the ACQUIRE_READONLY
// ** flag was specified by the caller. And so long as the db is not a
// ** temporary or in-memory database. */
// const int bMmapOk = (pgno>1
// && (pPager->eState==PAGER_READER || (flags & PAGER_GET_READONLY))
// );
// assert( USEFETCH(pPager) );
// /* Optimization note: Adding the "pgno<=1" term before "pgno==0" here
// ** allows the compiler optimizer to reuse the results of the "pgno>1"
// ** test in the previous statement, and avoid testing pgno==0 in the
// ** common case where pgno is large. */
// if( pgno<=1 && pgno==0 ){
// return SQLITE_CORRUPT_BKPT;
// }
// assert( pPager->eState>=PAGER_READER );
// assert( assert_pager_state(pPager) );
// assert( pPager->hasHeldSharedLock==1 );
// assert( pPager->errCode==SQLITE_OK );
// if( bMmapOk && pagerUseWal(pPager) ){
// rc = sqlite3WalFindFrame(pPager->pWal, pgno, &iFrame);
// if( rc!=SQLITE_OK ){
// *ppPage = 0;
// return rc;
// }
// }
// if( bMmapOk && iFrame==0 ){
// void *pData = 0;
// rc = sqlite3OsFetch(pPager->fd,
// (i64)(pgno-1) * pPager->pageSize, pPager->pageSize, &pData
// );
// if( rc==SQLITE_OK && pData ){
// if( pPager->eState>PAGER_READER || pPager->tempFile ){
// pPg = sqlite3PagerLookup(pPager, pgno);
// }
// if( pPg==0 ){
// rc = pagerAcquireMapPage(pPager, pgno, pData, &pPg);
// }else{
// sqlite3OsUnfetch(pPager->fd, (i64)(pgno-1)*pPager->pageSize, pData);
// }
// if( pPg ){
// assert( rc==SQLITE_OK );
// *ppPage = pPg;
// return SQLITE_OK;
// }
// }
// if( rc!=SQLITE_OK ){
// *ppPage = 0;
// return rc;
// }
// }
// return getPageNormal(pPager, pgno, ppPage, flags);
// }
// #endif /* SQLITE_MAX_MMAP_SIZE>0 */
// /* The page getter method for when the pager is an error state */
// static int getPageError(
// Pager *pPager, /* The pager open on the database file */
// Pgno pgno, /* Page number to fetch */
// DbPage **ppPage, /* Write a pointer to the page here */
// int flags /* PAGER_GET_XXX flags */
// ){
// UNUSED_PARAMETER(pgno);
// UNUSED_PARAMETER(flags);
// assert( pPager->errCode!=SQLITE_OK );
// *ppPage = 0;
// return pPager->errCode;
// }
// /* Dispatch all page fetch requests to the appropriate getter method.
// */
// int sqlite3PagerGet(
// Pager *pPager, /* The pager open on the database file */
// Pgno pgno, /* Page number to fetch */
// DbPage **ppPage, /* Write a pointer to the page here */
// int flags /* PAGER_GET_XXX flags */
// ){
// return pPager->xGet(pPager, pgno, ppPage, flags);
// }
// /*
// ** Acquire a page if it is already in the in-memory cache. Do
// ** not read the page from disk. Return a pointer to the page,
// ** or 0 if the page is not in cache.
// **
// ** See also sqlite3PagerGet(). The difference between this routine
// ** and sqlite3PagerGet() is that _get() will go to the disk and read
// ** in the page if the page is not already in cache. This routine
// ** returns NULL if the page is not in cache or if a disk I/O error
// ** has ever happened.
// */
// DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno){
// sqlite3_pcache_page *pPage;
// assert( pPager!=0 );
// assert( pgno!=0 );
// assert( pPager->pPCache!=0 );
// pPage = sqlite3PcacheFetch(pPager->pPCache, pgno, 0);
// assert( pPage==0 || pPager->hasHeldSharedLock );
// if( pPage==0 ) return 0;
// return sqlite3PcacheFetchFinish(pPager->pPCache, pgno, pPage);
// }
// /*
// ** Release a page reference.
// **
// ** The sqlite3PagerUnref() and sqlite3PagerUnrefNotNull() may only be
// ** used if we know that the page being released is not the last page.
// ** The btree layer always holds page1 open until the end, so these first
// ** to routines can be used to release any page other than BtShared.pPage1.
// **
// ** Use sqlite3PagerUnrefPageOne() to release page1. This latter routine
// ** checks the total number of outstanding pages and if the number of
// ** pages reaches zero it drops the database lock.
// */
// void sqlite3PagerUnrefNotNull(DbPage *pPg){
// TESTONLY( Pager *pPager = pPg->pPager; )
// assert( pPg!=0 );
// if( pPg->flags & PGHDR_MMAP ){
// assert( pPg->pgno!=1 ); /* Page1 is never memory mapped */
// pagerReleaseMapPage(pPg);
// }else{
// sqlite3PcacheRelease(pPg);
// }
// /* Do not use this routine to release the last reference to page1 */
// assert( sqlite3PcacheRefCount(pPager->pPCache)>0 );
// }
// void sqlite3PagerUnref(DbPage *pPg){
// if( pPg ) sqlite3PagerUnrefNotNull(pPg);
// }
// void sqlite3PagerUnrefPageOne(DbPage *pPg){
// Pager *pPager;
// assert( pPg!=0 );
// assert( pPg->pgno==1 );
// assert( (pPg->flags & PGHDR_MMAP)==0 ); /* Page1 is never memory mapped */
// pPager = pPg->pPager;
// sqlite3PcacheRelease(pPg);
// pagerUnlockIfUnused(pPager);
// }
// /*
// ** This function is called at the start of every write transaction.
// ** There must already be a RESERVED or EXCLUSIVE lock on the database
// ** file when this routine is called.
// **
// ** Open the journal file for pager pPager and write a journal header
// ** to the start of it. If there are active savepoints, open the sub-journal
// ** as well. This function is only used when the journal file is being
// ** opened to write a rollback log for a transaction. It is not used
// ** when opening a hot journal file to roll it back.
// **
// ** If the journal file is already open (as it may be in exclusive mode),
// ** then this function just writes a journal header to the start of the
// ** already open file.
// **
// ** Whether or not the journal file is opened by this function, the
// ** Pager.pInJournal bitvec structure is allocated.
// **
// ** Return SQLITE_OK if everything is successful. Otherwise, return
// ** SQLITE_NOMEM if the attempt to allocate Pager.pInJournal fails, or
// ** an IO error code if opening or writing the journal file fails.
// */
// static int pager_open_journal(Pager *pPager){
// int rc = SQLITE_OK; /* Return code */
// sqlite3_vfs * const pVfs = pPager->pVfs; /* Local cache of vfs pointer */
// assert( pPager->eState==PAGER_WRITER_LOCKED );
// assert( assert_pager_state(pPager) );
// assert( pPager->pInJournal==0 );
// /* If already in the error state, this function is a no-op. But on
// ** the other hand, this routine is never called if we are already in
// ** an error state. */
// if( NEVER(pPager->errCode) ) return pPager->errCode;
// if( !pagerUseWal(pPager) && pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
// pPager->pInJournal = sqlite3BitvecCreate(pPager->dbSize);
// if( pPager->pInJournal==0 ){
// return SQLITE_NOMEM;
// }
// /* Open the journal file if it is not already open. */
// if( !isOpen(pPager->jfd) ){
// if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY ){
// sqlite3MemJournalOpen(pPager->jfd);
// }else{
// int flags = SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE;
// int nSpill;
// if( pPager->tempFile ){
// flags |= (SQLITE_OPEN_DELETEONCLOSE|SQLITE_OPEN_TEMP_JOURNAL);
// nSpill = sqlite3Config.nStmtSpill;
// }else{
// flags |= SQLITE_OPEN_MAIN_JOURNAL;
// nSpill = jrnlBufferSize(pPager);
// }
// /* Verify that the database still has the same name as it did when
// ** it was originally opened. */
// rc = databaseIsUnmoved(pPager);
// if( rc==SQLITE_OK ){
// rc = sqlite3JournalOpen (
// pVfs, pPager->zJournal, pPager->jfd, flags, nSpill
// );
// }
// }
// assert( rc!=SQLITE_OK || isOpen(pPager->jfd) );
// }
// /* Write the first journal header to the journal file and open
// ** the sub-journal if necessary.
// */
// if( rc==SQLITE_OK ){
// /* TODO: Check if all of these are really required. */
// pPager->nRec = 0;
// pPager->journalOff = 0;
// pPager->setSuper = 0;
// pPager->journalHdr = 0;
// rc = writeJournalHdr(pPager);
// }
// }
// if( rc!=SQLITE_OK ){
// sqlite3BitvecDestroy(pPager->pInJournal);
// pPager->pInJournal = 0;
// }else{
// assert( pPager->eState==PAGER_WRITER_LOCKED );
// pPager->eState = PAGER_WRITER_CACHEMOD;
// }
// return rc;
// }
// /*
// ** Begin a write-transaction on the specified pager object. If a
// ** write-transaction has already been opened, this function is a no-op.
// **
// ** If the exFlag argument is false, then acquire at least a RESERVED
// ** lock on the database file. If exFlag is true, then acquire at least
// ** an EXCLUSIVE lock. If such a lock is already held, no locking
// ** functions need be called.
// **
// ** If the subjInMemory argument is non-zero, then any sub-journal opened
// ** within this transaction will be opened as an in-memory file. This
// ** has no effect if the sub-journal is already opened (as it may be when
// ** running in exclusive mode) or if the transaction does not require a
// ** sub-journal. If the subjInMemory argument is zero, then any required
// ** sub-journal is implemented in-memory if pPager is an in-memory database,
// ** or using a temporary file otherwise.
// */
// int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
// int rc = SQLITE_OK;
// if( pPager->errCode ) return pPager->errCode;
// assert( pPager->eState>=PAGER_READER && pPager->eState<PAGER_ERROR );
// pPager->subjInMemory = (u8)subjInMemory;
// if( pPager->eState==PAGER_READER ){
// assert( pPager->pInJournal==0 );
// if( pagerUseWal(pPager) ){
// /* If the pager is configured to use locking_mode=exclusive, and an
// ** exclusive lock on the database is not already held, obtain it now.
// */
// if( pPager->exclusiveMode && sqlite3WalExclusiveMode(pPager->pWal, -1) ){
// rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
// if( rc!=SQLITE_OK ){
// return rc;
// }
// (void)sqlite3WalExclusiveMode(pPager->pWal, 1);
// }
// /* Grab the write lock on the log file. If successful, upgrade to
// ** PAGER_RESERVED state. Otherwise, return an error code to the caller.
// ** The busy-handler is not invoked if another connection already
// ** holds the write-lock. If possible, the upper layer will call it.
// */
// rc = sqlite3WalBeginWriteTransaction(pPager->pWal);
// }else{
// /* Obtain a RESERVED lock on the database file. If the exFlag parameter
// ** is true, then immediately upgrade this to an EXCLUSIVE lock. The
// ** busy-handler callback can be used when upgrading to the EXCLUSIVE
// ** lock, but not when obtaining the RESERVED lock.
// */
// rc = pagerLockDb(pPager, RESERVED_LOCK);
// if( rc==SQLITE_OK && exFlag ){
// rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
// }
// }
// if( rc==SQLITE_OK ){
// /* Change to WRITER_LOCKED state.
// **
// ** WAL mode sets Pager.eState to PAGER_WRITER_LOCKED or CACHEMOD
// ** when it has an open transaction, but never to DBMOD or FINISHED.
// ** This is because in those states the code to roll back savepoint
// ** transactions may copy data from the sub-journal into the database
// ** file as well as into the page cache. Which would be incorrect in
// ** WAL mode.
// */
// pPager->eState = PAGER_WRITER_LOCKED;
// pPager->dbHintSize = pPager->dbSize;
// pPager->dbFileSize = pPager->dbSize;
// pPager->dbOrigSize = pPager->dbSize;
// pPager->journalOff = 0;
// }
// assert( rc==SQLITE_OK || pPager->eState==PAGER_READER );
// assert( rc!=SQLITE_OK || pPager->eState==PAGER_WRITER_LOCKED );
// assert( assert_pager_state(pPager) );
// }
// PAGERTRACE(("TRANSACTION %d\n", PAGERID(pPager)));
// return rc;
// }
// /*
// ** Write page pPg onto the end of the rollback journal.
// */
// static SQLITE_NOINLINE int pagerAddPageToRollbackJournal(PgHdr *pPg){
// Pager *pPager = pPg->pPager;
// int rc;
// u32 cksum;
// char *pData2;
// i64 iOff = pPager->journalOff;
// /* We should never write to the journal file the page that
// ** contains the database locks. The following assert verifies
// ** that we do not. */
// assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );
// assert( pPager->journalHdr<=pPager->journalOff );
// pData2 = pPg->pData;
// cksum = pager_cksum(pPager, (u8*)pData2);
// /* Even if an IO or diskfull error occurs while journalling the
// ** page in the block above, set the need-sync flag for the page.
// ** Otherwise, when the transaction is rolled back, the logic in
// ** playback_one_page() will think that the page needs to be restored
// ** in the database file. And if an IO error occurs while doing so,
// ** then corruption may follow.
// */
// pPg->flags |= PGHDR_NEED_SYNC;
// rc = write32bits(pPager->jfd, iOff, pPg->pgno);
// if( rc!=SQLITE_OK ) return rc;
// rc = sqlite3OsWrite(pPager->jfd, pData2, pPager->pageSize, iOff+4);
// if( rc!=SQLITE_OK ) return rc;
// rc = write32bits(pPager->jfd, iOff+pPager->pageSize+4, cksum);
// if( rc!=SQLITE_OK ) return rc;
// IOTRACE(("JOUT %p %d %lld %d\n", pPager, pPg->pgno,
// pPager->journalOff, pPager->pageSize));
// PAGER_INCR(sqlite3_pager_writej_count);
// PAGERTRACE(("JOURNAL %d page %d needSync=%d hash(%08x)\n",
// PAGERID(pPager), pPg->pgno,
// ((pPg->flags&PGHDR_NEED_SYNC)?1:0), pager_pagehash(pPg)));
// pPager->journalOff += 8 + pPager->pageSize;
// pPager->nRec++;
// assert( pPager->pInJournal!=0 );
// rc = sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);
// testcase( rc==SQLITE_NOMEM );
// assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
// rc |= addToSavepointBitvecs(pPager, pPg->pgno);
// assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
// return rc;
// }
// /*
// ** Mark a single data page as writeable. The page is written into the
// ** main journal or sub-journal as required. If the page is written into
// ** one of the journals, the corresponding bit is set in the
// ** Pager.pInJournal bitvec and the PagerSavepoint.pInSavepoint bitvecs
// ** of any open savepoints as appropriate.
// */
// static int pager_write(PgHdr *pPg){
// Pager *pPager = pPg->pPager;
// int rc = SQLITE_OK;
// /* This routine is not called unless a write-transaction has already
// ** been started. The journal file may or may not be open at this point.
// ** It is never called in the ERROR state.
// */
// assert( pPager->eState==PAGER_WRITER_LOCKED
// || pPager->eState==PAGER_WRITER_CACHEMOD
// || pPager->eState==PAGER_WRITER_DBMOD
// );
// assert( assert_pager_state(pPager) );
// assert( pPager->errCode==0 );
// assert( pPager->readOnly==0 );
// CHECK_PAGE(pPg);
// /* The journal file needs to be opened. Higher level routines have already
// ** obtained the necessary locks to begin the write-transaction, but the
// ** rollback journal might not yet be open. Open it now if this is the case.
// **
// ** This is done before calling sqlite3PcacheMakeDirty() on the page.
// ** Otherwise, if it were done after calling sqlite3PcacheMakeDirty(), then
// ** an error might occur and the pager would end up in WRITER_LOCKED state
// ** with pages marked as dirty in the cache.
// */
// if( pPager->eState==PAGER_WRITER_LOCKED ){
// rc = pager_open_journal(pPager);
// if( rc!=SQLITE_OK ) return rc;
// }
// assert( pPager->eState>=PAGER_WRITER_CACHEMOD );
// assert( assert_pager_state(pPager) );
// /* Mark the page that is about to be modified as dirty. */
// sqlite3PcacheMakeDirty(pPg);
// /* If a rollback journal is in use, them make sure the page that is about
// ** to change is in the rollback journal, or if the page is a new page off
// ** then end of the file, make sure it is marked as PGHDR_NEED_SYNC.
// */
// assert( (pPager->pInJournal!=0) == isOpen(pPager->jfd) );
// if( pPager->pInJournal!=0
// && sqlite3BitvecTestNotNull(pPager->pInJournal, pPg->pgno)==0
// ){
// assert( pagerUseWal(pPager)==0 );
// if( pPg->pgno<=pPager->dbOrigSize ){
// rc = pagerAddPageToRollbackJournal(pPg);
// if( rc!=SQLITE_OK ){
// return rc;
// }
// }else{
// if( pPager->eState!=PAGER_WRITER_DBMOD ){
// pPg->flags |= PGHDR_NEED_SYNC;
// }
// PAGERTRACE(("APPEND %d page %d needSync=%d\n",
// PAGERID(pPager), pPg->pgno,
// ((pPg->flags&PGHDR_NEED_SYNC)?1:0)));
// }
// }
// /* The PGHDR_DIRTY bit is set above when the page was added to the dirty-list
// ** and before writing the page into the rollback journal. Wait until now,
// ** after the page has been successfully journalled, before setting the
// ** PGHDR_WRITEABLE bit that indicates that the page can be safely modified.
// */
// pPg->flags |= PGHDR_WRITEABLE;
// /* If the statement journal is open and the page is not in it,
// ** then write the page into the statement journal.
// */
// if( pPager->nSavepoint>0 ){
// rc = subjournalPageIfRequired(pPg);
// }
// /* Update the database size and return. */
// if( pPager->dbSize<pPg->pgno ){
// pPager->dbSize = pPg->pgno;
// }
// return rc;
// }
// /*
// ** This is a variant of sqlite3PagerWrite() that runs when the sector size
// ** is larger than the page size. SQLite makes the (reasonable) assumption that
// ** all bytes of a sector are written together by hardware. Hence, all bytes of
// ** a sector need to be journalled in case of a power loss in the middle of
// ** a write.
// **
// ** Usually, the sector size is less than or equal to the page size, in which
// ** case pages can be individually written. This routine only runs in the
// ** exceptional case where the page size is smaller than the sector size.
// */
// static SQLITE_NOINLINE int pagerWriteLargeSector(PgHdr *pPg){
// int rc = SQLITE_OK; /* Return code */
// Pgno nPageCount; /* Total number of pages in database file */
// Pgno pg1; /* First page of the sector pPg is located on. */
// int nPage = 0; /* Number of pages starting at pg1 to journal */
// int ii; /* Loop counter */
// int needSync = 0; /* True if any page has PGHDR_NEED_SYNC */
// Pager *pPager = pPg->pPager; /* The pager that owns pPg */
// Pgno nPagePerSector = (pPager->sectorSize/pPager->pageSize);
// /* Set the doNotSpill NOSYNC bit to 1. This is because we cannot allow
// ** a journal header to be written between the pages journaled by
// ** this function.
// */
// assert( !MEMDB );
// assert( (pPager->doNotSpill & SPILLFLAG_NOSYNC)==0 );
// pPager->doNotSpill |= SPILLFLAG_NOSYNC;
// /* This trick assumes that both the page-size and sector-size are
// ** an integer power of 2. It sets variable pg1 to the identifier
// ** of the first page of the sector pPg is located on.
// */
// pg1 = ((pPg->pgno-1) & ~(nPagePerSector-1)) + 1;
// nPageCount = pPager->dbSize;
// if( pPg->pgno>nPageCount ){
// nPage = (pPg->pgno - pg1)+1;
// }else if( (pg1+nPagePerSector-1)>nPageCount ){
// nPage = nPageCount+1-pg1;
// }else{
// nPage = nPagePerSector;
// }
// assert(nPage>0);
// assert(pg1<=pPg->pgno);
// assert((pg1+nPage)>pPg->pgno);
// for(ii=0; ii<nPage && rc==SQLITE_OK; ii++){
// Pgno pg = pg1+ii;
// PgHdr *pPage;
// if( pg==pPg->pgno || !sqlite3BitvecTest(pPager->pInJournal, pg) ){
// if( pg!=PAGER_MJ_PGNO(pPager) ){
// rc = sqlite3PagerGet(pPager, pg, &pPage, 0);
// if( rc==SQLITE_OK ){
// rc = pager_write(pPage);
// if( pPage->flags&PGHDR_NEED_SYNC ){
// needSync = 1;
// }
// sqlite3PagerUnrefNotNull(pPage);
// }
// }
// }else if( (pPage = sqlite3PagerLookup(pPager, pg))!=0 ){
// if( pPage->flags&PGHDR_NEED_SYNC ){
// needSync = 1;
// }
// sqlite3PagerUnrefNotNull(pPage);
// }
// }
// /* If the PGHDR_NEED_SYNC flag is set for any of the nPage pages
// ** starting at pg1, then it needs to be set for all of them. Because
// ** writing to any of these nPage pages may damage the others, the
// ** journal file must contain sync()ed copies of all of them
// ** before any of them can be written out to the database file.
// */
// if( rc==SQLITE_OK && needSync ){
// assert( !MEMDB );
// for(ii=0; ii<nPage; ii++){
// PgHdr *pPage = sqlite3PagerLookup(pPager, pg1+ii);
// if( pPage ){
// pPage->flags |= PGHDR_NEED_SYNC;
// sqlite3PagerUnrefNotNull(pPage);
// }
// }
// }
// assert( (pPager->doNotSpill & SPILLFLAG_NOSYNC)!=0 );
// pPager->doNotSpill &= ~SPILLFLAG_NOSYNC;
// return rc;
// }
// /*
// ** Mark a data page as writeable. This routine must be called before
// ** making changes to a page. The caller must check the return value
// ** of this function and be careful not to change any page data unless
// ** this routine returns SQLITE_OK.
// **
// ** The difference between this function and pager_write() is that this
// ** function also deals with the special case where 2 or more pages
// ** fit on a single disk sector. In this case all co-resident pages
// ** must have been written to the journal file before returning.
// **
// ** If an error occurs, SQLITE_NOMEM or an IO error code is returned
// ** as appropriate. Otherwise, SQLITE_OK.
// */
// int sqlite3PagerWrite(PgHdr *pPg){
// Pager *pPager = pPg->pPager;
// assert( (pPg->flags & PGHDR_MMAP)==0 );
// assert( pPager->eState>=PAGER_WRITER_LOCKED );
// assert( assert_pager_state(pPager) );
// if( (pPg->flags & PGHDR_WRITEABLE)!=0 && pPager->dbSize>=pPg->pgno ){
// if( pPager->nSavepoint ) return subjournalPageIfRequired(pPg);
// return SQLITE_OK;
// }else if( pPager->errCode ){
// return pPager->errCode;
// }else if( pPager->sectorSize > (u32)pPager->pageSize ){
// assert( pPager->tempFile==0 );
// return pagerWriteLargeSector(pPg);
// }else{
// return pager_write(pPg);
// }
// }
// /*
// ** Return TRUE if the page given in the argument was previously passed
// ** to sqlite3PagerWrite(). In other words, return TRUE if it is ok
// ** to change the content of the page.
// */
// #ifndef NDEBUG
// int sqlite3PagerIswriteable(DbPage *pPg){
// return pPg->flags & PGHDR_WRITEABLE;
// }
// #endif
// /*
// ** A call to this routine tells the pager that it is not necessary to
// ** write the information on page pPg back to the disk, even though
// ** that page might be marked as dirty. This happens, for example, when
// ** the page has been added as a leaf of the freelist and so its
// ** content no longer matters.
// **
// ** The overlying software layer calls this routine when all of the data
// ** on the given page is unused. The pager marks the page as clean so
// ** that it does not get written to disk.
// **
// ** Tests show that this optimization can quadruple the speed of large
// ** DELETE operations.
// **
// ** This optimization cannot be used with a temp-file, as the page may
// ** have been dirty at the start of the transaction. In that case, if
// ** memory pressure forces page pPg out of the cache, the data does need
// ** to be written out to disk so that it may be read back in if the
// ** current transaction is rolled back.
// */
// void sqlite3PagerDontWrite(PgHdr *pPg){
// Pager *pPager = pPg->pPager;
// if( !pPager->tempFile && (pPg->flags&PGHDR_DIRTY) && pPager->nSavepoint==0 ){
// PAGERTRACE(("DONT_WRITE page %d of %d\n", pPg->pgno, PAGERID(pPager)));
// IOTRACE(("CLEAN %p %d\n", pPager, pPg->pgno))
// pPg->flags |= PGHDR_DONT_WRITE;
// pPg->flags &= ~PGHDR_WRITEABLE;
// testcase( pPg->flags & PGHDR_NEED_SYNC );
// pager_set_pagehash(pPg);
// }
// }
// /*
// ** This routine is called to increment the value of the database file
// ** change-counter, stored as a 4-byte big-endian integer starting at
// ** byte offset 24 of the pager file. The secondary change counter at
// ** 92 is also updated, as is the SQLite version number at offset 96.
// **
// ** But this only happens if the pPager->changeCountDone flag is false.
// ** To avoid excess churning of page 1, the update only happens once.
// ** See also the pager_write_changecounter() routine that does an
// ** unconditional update of the change counters.
// **
// ** If the isDirectMode flag is zero, then this is done by calling
// ** sqlite3PagerWrite() on page 1, then modifying the contents of the
// ** page data. In this case the file will be updated when the current
// ** transaction is committed.
// **
// ** The isDirectMode flag may only be non-zero if the library was compiled
// ** with the SQLITE_ENABLE_ATOMIC_WRITE macro defined. In this case,
// ** if isDirect is non-zero, then the database file is updated directly
// ** by writing an updated version of page 1 using a call to the
// ** sqlite3OsWrite() function.
// */
// static int pager_incr_changecounter(Pager *pPager, int isDirectMode){
// int rc = SQLITE_OK;
// assert( pPager->eState==PAGER_WRITER_CACHEMOD
// || pPager->eState==PAGER_WRITER_DBMOD
// );
// assert( assert_pager_state(pPager) );
// /* Declare and initialize constant integer 'isDirect'. If the
// ** atomic-write optimization is enabled in this build, then isDirect
// ** is initialized to the value passed as the isDirectMode parameter
// ** to this function. Otherwise, it is always set to zero.
// **
// ** The idea is that if the atomic-write optimization is not
// ** enabled at compile time, the compiler can omit the tests of
// ** 'isDirect' below, as well as the block enclosed in the
// ** "if( isDirect )" condition.
// */
// #ifndef SQLITE_ENABLE_ATOMIC_WRITE
// # define DIRECT_MODE 0
// assert( isDirectMode==0 );
// UNUSED_PARAMETER(isDirectMode);
// #else
// # define DIRECT_MODE isDirectMode
// #endif
// if( !pPager->changeCountDone && ALWAYS(pPager->dbSize>0) ){
// PgHdr *pPgHdr; /* Reference to page 1 */
// assert( !pPager->tempFile && isOpen(pPager->fd) );
// /* Open page 1 of the file for writing. */
// rc = sqlite3PagerGet(pPager, 1, &pPgHdr, 0);
// assert( pPgHdr==0 || rc==SQLITE_OK );
// /* If page one was fetched successfully, and this function is not
// ** operating in direct-mode, make page 1 writable. When not in
// ** direct mode, page 1 is always held in cache and hence the PagerGet()
// ** above is always successful - hence the ALWAYS on rc==SQLITE_OK.
// */
// if( !DIRECT_MODE && ALWAYS(rc==SQLITE_OK) ){
// rc = sqlite3PagerWrite(pPgHdr);
// }
// if( rc==SQLITE_OK ){
// /* Actually do the update of the change counter */
// pager_write_changecounter(pPgHdr);
// /* If running in direct mode, write the contents of page 1 to the file. */
// if( DIRECT_MODE ){
// const void *zBuf;
// assert( pPager->dbFileSize>0 );
// zBuf = pPgHdr->pData;
// if( rc==SQLITE_OK ){
// rc = sqlite3OsWrite(pPager->fd, zBuf, pPager->pageSize, 0);
// pPager->aStat[PAGER_STAT_WRITE]++;
// }
// if( rc==SQLITE_OK ){
// /* Update the pager's copy of the change-counter. Otherwise, the
// ** next time a read transaction is opened the cache will be
// ** flushed (as the change-counter values will not match). */
// const void *pCopy = (const void *)&((const char *)zBuf)[24];
// memcpy(&pPager->dbFileVers, pCopy, sizeof(pPager->dbFileVers));
// pPager->changeCountDone = 1;
// }
// }else{
// pPager->changeCountDone = 1;
// }
// }
// /* Release the page reference. */
// sqlite3PagerUnref(pPgHdr);
// }
// return rc;
// }
// /*
// ** Sync the database file to disk. This is a no-op for in-memory databases
// ** or pages with the Pager.noSync flag set.
// **
// ** If successful, or if called on a pager for which it is a no-op, this
// ** function returns SQLITE_OK. Otherwise, an IO error code is returned.
// */
// int sqlite3PagerSync(Pager *pPager, const char *zSuper){
// int rc = SQLITE_OK;
// void *pArg = (void*)zSuper;
// rc = sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_SYNC, pArg);
// if( rc==SQLITE_NOTFOUND ) rc = SQLITE_OK;
// if( rc==SQLITE_OK && !pPager->noSync ){
// assert( !MEMDB );
// rc = sqlite3OsSync(pPager->fd, pPager->syncFlags);
// }
// return rc;
// }
// /*
// ** This function may only be called while a write-transaction is active in
// ** rollback. If the connection is in WAL mode, this call is a no-op.
// ** Otherwise, if the connection does not already have an EXCLUSIVE lock on
// ** the database file, an attempt is made to obtain one.
// **
// ** If the EXCLUSIVE lock is already held or the attempt to obtain it is
// ** successful, or the connection is in WAL mode, SQLITE_OK is returned.
// ** Otherwise, either SQLITE_BUSY or an SQLITE_IOERR_XXX error code is
// ** returned.
// */
// int sqlite3PagerExclusiveLock(Pager *pPager){
// int rc = pPager->errCode;
// assert( assert_pager_state(pPager) );
// if( rc==SQLITE_OK ){
// assert( pPager->eState==PAGER_WRITER_CACHEMOD
// || pPager->eState==PAGER_WRITER_DBMOD
// || pPager->eState==PAGER_WRITER_LOCKED
// );
// assert( assert_pager_state(pPager) );
// if( 0==pagerUseWal(pPager) ){
// rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
// }
// }
// return rc;
// }
// /*
// ** Sync the database file for the pager pPager. zSuper points to the name
// ** of a super-journal file that should be written into the individual
// ** journal file. zSuper may be NULL, which is interpreted as no
// ** super-journal (a single database transaction).
// **
// ** This routine ensures that:
// **
// ** * The database file change-counter is updated,
// ** * the journal is synced (unless the atomic-write optimization is used),
// ** * all dirty pages are written to the database file,
// ** * the database file is truncated (if required), and
// ** * the database file synced.
// **
// ** The only thing that remains to commit the transaction is to finalize
// ** (delete, truncate or zero the first part of) the journal file (or
// ** delete the super-journal file if specified).
// **
// ** Note that if zSuper==NULL, this does not overwrite a previous value
// ** passed to an sqlite3PagerCommitPhaseOne() call.
// **
// ** If the final parameter - noSync - is true, then the database file itself
// ** is not synced. The caller must call sqlite3PagerSync() directly to
// ** sync the database file before calling CommitPhaseTwo() to delete the
// ** journal file in this case.
// */
// int sqlite3PagerCommitPhaseOne(
// Pager *pPager, /* Pager object */
// const char *zSuper, /* If not NULL, the super-journal name */
// int noSync /* True to omit the xSync on the db file */
// ){
// int rc = SQLITE_OK; /* Return code */
// assert( pPager->eState==PAGER_WRITER_LOCKED
// || pPager->eState==PAGER_WRITER_CACHEMOD
// || pPager->eState==PAGER_WRITER_DBMOD
// || pPager->eState==PAGER_ERROR
// );
// assert( assert_pager_state(pPager) );
// /* If a prior error occurred, report that error again. */
// if( NEVER(pPager->errCode) ) return pPager->errCode;
// /* Provide the ability to easily simulate an I/O error during testing */
// if( sqlite3FaultSim(400) ) return SQLITE_IOERR;
// PAGERTRACE(("DATABASE SYNC: File=%s zSuper=%s nSize=%d\n",
// pPager->zFilename, zSuper, pPager->dbSize));
// /* If no database changes have been made, return early. */
// if( pPager->eState<PAGER_WRITER_CACHEMOD ) return SQLITE_OK;
// assert( MEMDB==0 || pPager->tempFile );
// assert( isOpen(pPager->fd) || pPager->tempFile );
// if( 0==pagerFlushOnCommit(pPager, 1) ){
// /* If this is an in-memory db, or no pages have been written to, or this
// ** function has already been called, it is mostly a no-op. However, any
// ** backup in progress needs to be restarted. */
// sqlite3BackupRestart(pPager->pBackup);
// }else{
// PgHdr *pList;
// if( pagerUseWal(pPager) ){
// PgHdr *pPageOne = 0;
// pList = sqlite3PcacheDirtyList(pPager->pPCache);
// if( pList==0 ){
// /* Must have at least one page for the WAL commit flag.
// ** Ticket [2d1a5c67dfc2363e44f29d9bbd57f] 2011-05-18 */
// rc = sqlite3PagerGet(pPager, 1, &pPageOne, 0);
// pList = pPageOne;
// pList->pDirty = 0;
// }
// assert( rc==SQLITE_OK );
// if( ALWAYS(pList) ){
// rc = pagerWalFrames(pPager, pList, pPager->dbSize, 1);
// }
// sqlite3PagerUnref(pPageOne);
// if( rc==SQLITE_OK ){
// sqlite3PcacheCleanAll(pPager->pPCache);
// }
// }else{
// /* The bBatch boolean is true if the batch-atomic-write commit method
// ** should be used. No rollback journal is created if batch-atomic-write
// ** is enabled.
// */
// #ifdef SQLITE_ENABLE_BATCH_ATOMIC_WRITE
// sqlite3_file *fd = pPager->fd;
// int bBatch = zSuper==0 /* An SQLITE_IOCAP_BATCH_ATOMIC commit */
// && (sqlite3OsDeviceCharacteristics(fd) & SQLITE_IOCAP_BATCH_ATOMIC)
// && !pPager->noSync
// && sqlite3JournalIsInMemory(pPager->jfd);
// #else
// # define bBatch 0
// #endif
// #ifdef SQLITE_ENABLE_ATOMIC_WRITE
// /* The following block updates the change-counter. Exactly how it
// ** does this depends on whether or not the atomic-update optimization
// ** was enabled at compile time, and if this transaction meets the
// ** runtime criteria to use the operation:
// **
// ** * The file-system supports the atomic-write property for
// ** blocks of size page-size, and
// ** * This commit is not part of a multi-file transaction, and
// ** * Exactly one page has been modified and store in the journal file.
// **
// ** If the optimization was not enabled at compile time, then the
// ** pager_incr_changecounter() function is called to update the change
// ** counter in 'indirect-mode'. If the optimization is compiled in but
// ** is not applicable to this transaction, call sqlite3JournalCreate()
// ** to make sure the journal file has actually been created, then call
// ** pager_incr_changecounter() to update the change-counter in indirect
// ** mode.
// **
// ** Otherwise, if the optimization is both enabled and applicable,
// ** then call pager_incr_changecounter() to update the change-counter
// ** in 'direct' mode. In this case the journal file will never be
// ** created for this transaction.
// */
// if( bBatch==0 ){
// PgHdr *pPg;
// assert( isOpen(pPager->jfd)
// || pPager->journalMode==PAGER_JOURNALMODE_OFF
// || pPager->journalMode==PAGER_JOURNALMODE_WAL
// );
// if( !zSuper && isOpen(pPager->jfd)
// && pPager->journalOff==jrnlBufferSize(pPager)
// && pPager->dbSize>=pPager->dbOrigSize
// && (!(pPg = sqlite3PcacheDirtyList(pPager->pPCache)) || 0==pPg->pDirty)
// ){
// /* Update the db file change counter via the direct-write method. The
// ** following call will modify the in-memory representation of page 1
// ** to include the updated change counter and then write page 1
// ** directly to the database file. Because of the atomic-write
// ** property of the host file-system, this is safe.
// */
// rc = pager_incr_changecounter(pPager, 1);
// }else{
// rc = sqlite3JournalCreate(pPager->jfd);
// if( rc==SQLITE_OK ){
// rc = pager_incr_changecounter(pPager, 0);
// }
// }
// }
// #else /* SQLITE_ENABLE_ATOMIC_WRITE */
// #ifdef SQLITE_ENABLE_BATCH_ATOMIC_WRITE
// if( zSuper ){
// rc = sqlite3JournalCreate(pPager->jfd);
// if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
// assert( bBatch==0 );
// }
// #endif
// rc = pager_incr_changecounter(pPager, 0);
// #endif /* !SQLITE_ENABLE_ATOMIC_WRITE */
// if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
// /* Write the super-journal name into the journal file. If a
// ** super-journal file name has already been written to the journal file,
// ** or if zSuper is NULL (no super-journal), then this call is a no-op.
// */
// rc = writeSuperJournal(pPager, zSuper);
// if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
// /* Sync the journal file and write all dirty pages to the database.
// ** If the atomic-update optimization is being used, this sync will not
// ** create the journal file or perform any real IO.
// **
// ** Because the change-counter page was just modified, unless the
// ** atomic-update optimization is used it is almost certain that the
// ** journal requires a sync here. However, in locking_mode=exclusive
// ** on a system under memory pressure it is just possible that this is
// ** not the case. In this case it is likely enough that the redundant
// ** xSync() call will be changed to a no-op by the OS anyhow.
// */
// rc = syncJournal(pPager, 0);
// if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
// pList = sqlite3PcacheDirtyList(pPager->pPCache);
// #ifdef SQLITE_ENABLE_BATCH_ATOMIC_WRITE
// if( bBatch ){
// rc = sqlite3OsFileControl(fd, SQLITE_FCNTL_BEGIN_ATOMIC_WRITE, 0);
// if( rc==SQLITE_OK ){
// rc = pager_write_pagelist(pPager, pList);
// if( rc==SQLITE_OK ){
// rc = sqlite3OsFileControl(fd, SQLITE_FCNTL_COMMIT_ATOMIC_WRITE, 0);
// }
// if( rc!=SQLITE_OK ){
// sqlite3OsFileControlHint(fd, SQLITE_FCNTL_ROLLBACK_ATOMIC_WRITE, 0);
// }
// }
// if( (rc&0xFF)==SQLITE_IOERR && rc!=SQLITE_IOERR_NOMEM ){
// rc = sqlite3JournalCreate(pPager->jfd);
// if( rc!=SQLITE_OK ){
// sqlite3OsClose(pPager->jfd);
// goto commit_phase_one_exit;
// }
// bBatch = 0;
// }else{
// sqlite3OsClose(pPager->jfd);
// }
// }
// #endif /* SQLITE_ENABLE_BATCH_ATOMIC_WRITE */
// if( bBatch==0 ){
// rc = pager_write_pagelist(pPager, pList);
// }
// if( rc!=SQLITE_OK ){
// assert( rc!=SQLITE_IOERR_BLOCKED );
// goto commit_phase_one_exit;
// }
// sqlite3PcacheCleanAll(pPager->pPCache);
// /* If the file on disk is smaller than the database image, use
// ** pager_truncate to grow the file here. This can happen if the database
// ** image was extended as part of the current transaction and then the
// ** last page in the db image moved to the free-list. In this case the
// ** last page is never written out to disk, leaving the database file
// ** undersized. Fix this now if it is the case. */
// if( pPager->dbSize>pPager->dbFileSize ){
// Pgno nNew = pPager->dbSize - (pPager->dbSize==PAGER_MJ_PGNO(pPager));
// assert( pPager->eState==PAGER_WRITER_DBMOD );
// rc = pager_truncate(pPager, nNew);
// if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
// }
// /* Finally, sync the database file. */
// if( !noSync ){
// rc = sqlite3PagerSync(pPager, zSuper);
// }
// IOTRACE(("DBSYNC %p\n", pPager))
// }
// }
// commit_phase_one_exit:
// if( rc==SQLITE_OK && !pagerUseWal(pPager) ){
// pPager->eState = PAGER_WRITER_FINISHED;
// }
// return rc;
// }
// /*
// ** When this function is called, the database file has been completely
// ** updated to reflect the changes made by the current transaction and
// ** synced to disk. The journal file still exists in the file-system
// ** though, and if a failure occurs at this point it will eventually
// ** be used as a hot-journal and the current transaction rolled back.
// **
// ** This function finalizes the journal file, either by deleting,
// ** truncating or partially zeroing it, so that it cannot be used
// ** for hot-journal rollback. Once this is done the transaction is
// ** irrevocably committed.
// **
// ** If an error occurs, an IO error code is returned and the pager
// ** moves into the error state. Otherwise, SQLITE_OK is returned.
// */
// int sqlite3PagerCommitPhaseTwo(Pager *pPager){
// int rc = SQLITE_OK; /* Return code */
// /* This routine should not be called if a prior error has occurred.
// ** But if (due to a coding error elsewhere in the system) it does get
// ** called, just return the same error code without doing anything. */
// if( NEVER(pPager->errCode) ) return pPager->errCode;
// pPager->iDataVersion++;
// assert( pPager->eState==PAGER_WRITER_LOCKED
// || pPager->eState==PAGER_WRITER_FINISHED
// || (pagerUseWal(pPager) && pPager->eState==PAGER_WRITER_CACHEMOD)
// );
// assert( assert_pager_state(pPager) );
// /* An optimization. If the database was not actually modified during
// ** this transaction, the pager is running in exclusive-mode and is
// ** using persistent journals, then this function is a no-op.
// **
// ** The start of the journal file currently contains a single journal
// ** header with the nRec field set to 0. If such a journal is used as
// ** a hot-journal during hot-journal rollback, 0 changes will be made
// ** to the database file. So there is no need to zero the journal
// ** header. Since the pager is in exclusive mode, there is no need
// ** to drop any locks either.
// */
// if( pPager->eState==PAGER_WRITER_LOCKED
// && pPager->exclusiveMode
// && pPager->journalMode==PAGER_JOURNALMODE_PERSIST
// ){
// assert( pPager->journalOff==JOURNAL_HDR_SZ(pPager) || !pPager->journalOff );
// pPager->eState = PAGER_READER;
// return SQLITE_OK;
// }
// PAGERTRACE(("COMMIT %d\n", PAGERID(pPager)));
// rc = pager_end_transaction(pPager, pPager->setSuper, 1);
// return pager_error(pPager, rc);
// }
// /*
// ** If a write transaction is open, then all changes made within the
// ** transaction are reverted and the current write-transaction is closed.
// ** The pager falls back to PAGER_READER state if successful, or PAGER_ERROR
// ** state if an error occurs.
// **
// ** If the pager is already in PAGER_ERROR state when this function is called,
// ** it returns Pager.errCode immediately. No work is performed in this case.
// **
// ** Otherwise, in rollback mode, this function performs two functions:
// **
// ** 1) It rolls back the journal file, restoring all database file and
// ** in-memory cache pages to the state they were in when the transaction
// ** was opened, and
// **
// ** 2) It finalizes the journal file, so that it is not used for hot
// ** rollback at any point in the future.
// **
// ** Finalization of the journal file (task 2) is only performed if the
// ** rollback is successful.
// **
// ** In WAL mode, all cache-entries containing data modified within the
// ** current transaction are either expelled from the cache or reverted to
// ** their pre-transaction state by re-reading data from the database or
// ** WAL files. The WAL transaction is then closed.
// */
// int sqlite3PagerRollback(Pager *pPager){
// int rc = SQLITE_OK; /* Return code */
// PAGERTRACE(("ROLLBACK %d\n", PAGERID(pPager)));
// /* PagerRollback() is a no-op if called in READER or OPEN state. If
// ** the pager is already in the ERROR state, the rollback is not
// ** attempted here. Instead, the error code is returned to the caller.
// */
// assert( assert_pager_state(pPager) );
// if( pPager->eState==PAGER_ERROR ) return pPager->errCode;
// if( pPager->eState<=PAGER_READER ) return SQLITE_OK;
// if( pagerUseWal(pPager) ){
// int rc2;
// rc = sqlite3PagerSavepoint(pPager, SAVEPOINT_ROLLBACK, -1);
// rc2 = pager_end_transaction(pPager, pPager->setSuper, 0);
// if( rc==SQLITE_OK ) rc = rc2;
// }else if( !isOpen(pPager->jfd) || pPager->eState==PAGER_WRITER_LOCKED ){
// int eState = pPager->eState;
// rc = pager_end_transaction(pPager, 0, 0);
// if( !MEMDB && eState>PAGER_WRITER_LOCKED ){
// /* This can happen using journal_mode=off. Move the pager to the error
// ** state to indicate that the contents of the cache may not be trusted.
// ** Any active readers will get SQLITE_ABORT.
// */
// pPager->errCode = SQLITE_ABORT;
// pPager->eState = PAGER_ERROR;
// setGetterMethod(pPager);
// return rc;
// }
// }else{
// rc = pager_playback(pPager, 0);
// }
// assert( pPager->eState==PAGER_READER || rc!=SQLITE_OK );
// assert( rc==SQLITE_OK || rc==SQLITE_FULL || rc==SQLITE_CORRUPT
// || rc==SQLITE_NOMEM || (rc&0xFF)==SQLITE_IOERR
// || rc==SQLITE_CANTOPEN
// );
// /* If an error occurs during a ROLLBACK, we can no longer trust the pager
// ** cache. So call pager_error() on the way out to make any error persistent.
// */
// return pager_error(pPager, rc);
// }
// /*
// ** Return TRUE if the database file is opened read-only. Return FALSE
// ** if the database is (in theory) writable.
// */
// u8 sqlite3PagerIsreadonly(Pager *pPager){
// return pPager->readOnly;
// }
// #ifdef SQLITE_DEBUG
// /*
// ** Return the sum of the reference counts for all pages held by pPager.
// */
// int sqlite3PagerRefcount(Pager *pPager){
// return sqlite3PcacheRefCount(pPager->pPCache);
// }
// #endif
// /*
// ** Return the approximate number of bytes of memory currently
// ** used by the pager and its associated cache.
// */
// int sqlite3PagerMemUsed(Pager *pPager){
// int perPageSize = pPager->pageSize + pPager->nExtra
// + (int)(sizeof(PgHdr) + 5*sizeof(void*));
// return perPageSize*sqlite3PcachePagecount(pPager->pPCache)
// + sqlite3MallocSize(pPager)
// + pPager->pageSize;
// }
// /*
// ** Return the number of references to the specified page.
// */
// int sqlite3PagerPageRefcount(DbPage *pPage){
// return sqlite3PcachePageRefcount(pPage);
// }
// #ifdef SQLITE_TEST
// /*
// ** This routine is used for testing and analysis only.
// */
// int *sqlite3PagerStats(Pager *pPager){
// static int a[11];
// a[0] = sqlite3PcacheRefCount(pPager->pPCache);
// a[1] = sqlite3PcachePagecount(pPager->pPCache);
// a[2] = sqlite3PcacheGetCachesize(pPager->pPCache);
// a[3] = pPager->eState==PAGER_OPEN ? -1 : (int) pPager->dbSize;
// a[4] = pPager->eState;
// a[5] = pPager->errCode;
// a[6] = pPager->aStat[PAGER_STAT_HIT];
// a[7] = pPager->aStat[PAGER_STAT_MISS];
// a[8] = 0; /* Used to be pPager->nOvfl */
// a[9] = pPager->nRead;
// a[10] = pPager->aStat[PAGER_STAT_WRITE];
// return a;
// }
// #endif
// /*
// ** Parameter eStat must be one of SQLITE_DBSTATUS_CACHE_HIT, _MISS, _WRITE,
// ** or _WRITE+1. The SQLITE_DBSTATUS_CACHE_WRITE+1 case is a translation
// ** of SQLITE_DBSTATUS_CACHE_SPILL. The _SPILL case is not contiguous because
// ** it was added later.
// **
// ** Before returning, *pnVal is incremented by the
// ** current cache hit or miss count, according to the value of eStat. If the
// ** reset parameter is non-zero, the cache hit or miss count is zeroed before
// ** returning.
// */
// void sqlite3PagerCacheStat(Pager *pPager, int eStat, int reset, int *pnVal){
// assert( eStat==SQLITE_DBSTATUS_CACHE_HIT
// || eStat==SQLITE_DBSTATUS_CACHE_MISS
// || eStat==SQLITE_DBSTATUS_CACHE_WRITE
// || eStat==SQLITE_DBSTATUS_CACHE_WRITE+1
// );
// assert( SQLITE_DBSTATUS_CACHE_HIT+1==SQLITE_DBSTATUS_CACHE_MISS );
// assert( SQLITE_DBSTATUS_CACHE_HIT+2==SQLITE_DBSTATUS_CACHE_WRITE );
// assert( PAGER_STAT_HIT==0 && PAGER_STAT_MISS==1
// && PAGER_STAT_WRITE==2 && PAGER_STAT_SPILL==3 );
// eStat -= SQLITE_DBSTATUS_CACHE_HIT;
// *pnVal += pPager->aStat[eStat];
// if( reset ){
// pPager->aStat[eStat] = 0;
// }
// }
// /*
// ** Return true if this is an in-memory or temp-file backed pager.
// */
// int sqlite3PagerIsMemdb(Pager *pPager){
// return pPager->tempFile || pPager->memVfs;
// }
// /*
// ** Check that there are at least nSavepoint savepoints open. If there are
// ** currently less than nSavepoints open, then open one or more savepoints
// ** to make up the difference. If the number of savepoints is already
// ** equal to nSavepoint, then this function is a no-op.
// **
// ** If a memory allocation fails, SQLITE_NOMEM is returned. If an error
// ** occurs while opening the sub-journal file, then an IO error code is
// ** returned. Otherwise, SQLITE_OK.
// */
// static SQLITE_NOINLINE int pagerOpenSavepoint(Pager *pPager, int nSavepoint){
// int rc = SQLITE_OK; /* Return code */
// int nCurrent = pPager->nSavepoint; /* Current number of savepoints */
// int ii; /* Iterator variable */
// PagerSavepoint *aNew; /* New Pager.aSavepoint array */
// assert( pPager->eState>=PAGER_WRITER_LOCKED );
// assert( assert_pager_state(pPager) );
// assert( nSavepoint>nCurrent && pPager->useJournal );
// /* Grow the Pager.aSavepoint array using realloc(). Return SQLITE_NOMEM
// ** if the allocation fails. Otherwise, zero the new portion in case a
// ** malloc failure occurs while populating it in the for(...) loop below.
// */
// aNew = (PagerSavepoint *)sqlite3Realloc(
// pPager->aSavepoint, sizeof(PagerSavepoint)*nSavepoint
// );
// if( !aNew ){
// return SQLITE_NOMEM;
// }
// memset(&aNew[nCurrent], 0, (nSavepoint-nCurrent) * sizeof(PagerSavepoint));
// pPager->aSavepoint = aNew;
// /* Populate the PagerSavepoint structures just allocated. */
// for(ii=nCurrent; ii<nSavepoint; ii++){
// aNew[ii].nOrig = pPager->dbSize;
// if( isOpen(pPager->jfd) && pPager->journalOff>0 ){
// aNew[ii].iOffset = pPager->journalOff;
// }else{
// aNew[ii].iOffset = JOURNAL_HDR_SZ(pPager);
// }
// aNew[ii].iSubRec = pPager->nSubRec;
// aNew[ii].pInSavepoint = sqlite3BitvecCreate(pPager->dbSize);
// aNew[ii].bTruncateOnRelease = 1;
// if( !aNew[ii].pInSavepoint ){
// return SQLITE_NOMEM;
// }
// if( pagerUseWal(pPager) ){
// sqlite3WalSavepoint(pPager->pWal, aNew[ii].aWalData);
// }
// pPager->nSavepoint = ii+1;
// }
// assert( pPager->nSavepoint==nSavepoint );
// assertTruncateConstraint(pPager);
// return rc;
// }
// int sqlite3PagerOpenSavepoint(Pager *pPager, int nSavepoint){
// assert( pPager->eState>=PAGER_WRITER_LOCKED );
// assert( assert_pager_state(pPager) );
// if( nSavepoint>pPager->nSavepoint && pPager->useJournal ){
// return pagerOpenSavepoint(pPager, nSavepoint);
// }else{
// return SQLITE_OK;
// }
// }
// /*
// ** This function is called to rollback or release (commit) a savepoint.
// ** The savepoint to release or rollback need not be the most recently
// ** created savepoint.
// **
// ** Parameter op is always either SAVEPOINT_ROLLBACK or SAVEPOINT_RELEASE.
// ** If it is SAVEPOINT_RELEASE, then release and destroy the savepoint with
// ** index iSavepoint. If it is SAVEPOINT_ROLLBACK, then rollback all changes
// ** that have occurred since the specified savepoint was created.
// **
// ** The savepoint to rollback or release is identified by parameter
// ** iSavepoint. A value of 0 means to operate on the outermost savepoint
// ** (the first created). A value of (Pager.nSavepoint-1) means operate
// ** on the most recently created savepoint. If iSavepoint is greater than
// ** (Pager.nSavepoint-1), then this function is a no-op.
// **
// ** If a negative value is passed to this function, then the current
// ** transaction is rolled back. This is different to calling
// ** sqlite3PagerRollback() because this function does not terminate
// ** the transaction or unlock the database, it just restores the
// ** contents of the database to its original state.
// **
// ** In any case, all savepoints with an index greater than iSavepoint
// ** are destroyed. If this is a release operation (op==SAVEPOINT_RELEASE),
// ** then savepoint iSavepoint is also destroyed.
// **
// ** This function may return SQLITE_NOMEM if a memory allocation fails,
// ** or an IO error code if an IO error occurs while rolling back a
// ** savepoint. If no errors occur, SQLITE_OK is returned.
// */
// int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint){
// int rc = pPager->errCode;
// #ifdef SQLITE_ENABLE_ZIPVFS
// if( op==SAVEPOINT_RELEASE ) rc = SQLITE_OK;
// #endif
// assert( op==SAVEPOINT_RELEASE || op==SAVEPOINT_ROLLBACK );
// assert( iSavepoint>=0 || op==SAVEPOINT_ROLLBACK );
// if( rc==SQLITE_OK && iSavepoint<pPager->nSavepoint ){
// int ii; /* Iterator variable */
// int nNew; /* Number of remaining savepoints after this op. */
// /* Figure out how many savepoints will still be active after this
// ** operation. Store this value in nNew. Then free resources associated
// ** with any savepoints that are destroyed by this operation.
// */
// nNew = iSavepoint + (( op==SAVEPOINT_RELEASE ) ? 0 : 1);
// for(ii=nNew; ii<pPager->nSavepoint; ii++){
// sqlite3BitvecDestroy(pPager->aSavepoint[ii].pInSavepoint);
// }
// pPager->nSavepoint = nNew;
// /* Truncate the sub-journal so that it only includes the parts
// ** that are still in use. */
// if( op==SAVEPOINT_RELEASE ){
// PagerSavepoint *pRel = &pPager->aSavepoint[nNew];
// if( pRel->bTruncateOnRelease && isOpen(pPager->sjfd) ){
// /* Only truncate if it is an in-memory sub-journal. */
// if( sqlite3JournalIsInMemory(pPager->sjfd) ){
// i64 sz = (pPager->pageSize+4)*(i64)pRel->iSubRec;
// rc = sqlite3OsTruncate(pPager->sjfd, sz);
// assert( rc==SQLITE_OK );
// }
// pPager->nSubRec = pRel->iSubRec;
// }
// }
// /* Else this is a rollback operation, playback the specified savepoint.
// ** If this is a temp-file, it is possible that the journal file has
// ** not yet been opened. In this case there have been no changes to
// ** the database file, so the playback operation can be skipped.
// */
// else if( pagerUseWal(pPager) || isOpen(pPager->jfd) ){
// PagerSavepoint *pSavepoint = (nNew==0)?0:&pPager->aSavepoint[nNew-1];
// rc = pagerPlaybackSavepoint(pPager, pSavepoint);
// assert(rc!=SQLITE_DONE);
// }
// #ifdef SQLITE_ENABLE_ZIPVFS
// /* If the cache has been modified but the savepoint cannot be rolled
// ** back journal_mode=off, put the pager in the error state. This way,
// ** if the VFS used by this pager includes ZipVFS, the entire transaction
// ** can be rolled back at the ZipVFS level. */
// else if(
// pPager->journalMode==PAGER_JOURNALMODE_OFF
// && pPager->eState>=PAGER_WRITER_CACHEMOD
// ){
// pPager->errCode = SQLITE_ABORT;
// pPager->eState = PAGER_ERROR;
// setGetterMethod(pPager);
// }
// #endif
// }
// return rc;
// }
// /*
// ** Return the full pathname of the database file.
// **
// ** Except, if the pager is in-memory only, then return an empty string if
// ** nullIfMemDb is true. This routine is called with nullIfMemDb==1 when
// ** used to report the filename to the user, for compatibility with legacy
// ** behavior. But when the Btree needs to know the filename for matching to
// ** shared cache, it uses nullIfMemDb==0 so that in-memory databases can
// ** participate in shared-cache.
// **
// ** The return value to this routine is always safe to use with
// ** sqlite3_uri_parameter() and sqlite3_filename_database() and friends.
// */
// const char *sqlite3PagerFilename(const Pager *pPager, int nullIfMemDb){
// static const char zFake[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
// return (nullIfMemDb && pPager->memDb) ? &zFake[4] : pPager->zFilename;
// }
// /*
// ** Return the VFS structure for the pager.
// */
// sqlite3_vfs *sqlite3PagerVfs(Pager *pPager){
// return pPager->pVfs;
// }
// /*
// ** Return the file handle for the database file associated
// ** with the pager. This might return NULL if the file has
// ** not yet been opened.
// */
// sqlite3_file *sqlite3PagerFile(Pager *pPager){
// return pPager->fd;
// }
// /*
// ** Return the file handle for the journal file (if it exists).
// ** This will be either the rollback journal or the WAL file.
// */
// sqlite3_file *sqlite3PagerJrnlFile(Pager *pPager){
// #if SQLITE_OMIT_WAL
// return pPager->jfd;
// #else
// return pPager->pWal ? sqlite3WalFile(pPager->pWal) : pPager->jfd;
// #endif
// }
// /*
// ** Return the full pathname of the journal file.
// */
// const char *sqlite3PagerJournalname(Pager *pPager){
// return pPager->zJournal;
// }
// #ifndef SQLITE_OMIT_AUTOVACUUM
// /*
// ** Move the page pPg to location pgno in the file.
// **
// ** There must be no references to the page previously located at
// ** pgno (which we call pPgOld) though that page is allowed to be
// ** in cache. If the page previously located at pgno is not already
// ** in the rollback journal, it is not put there by by this routine.
// **
// ** References to the page pPg remain valid. Updating any
// ** meta-data associated with pPg (i.e. data stored in the nExtra bytes
// ** allocated along with the page) is the responsibility of the caller.
// **
// ** A transaction must be active when this routine is called. It used to be
// ** required that a statement transaction was not active, but this restriction
// ** has been removed (CREATE INDEX needs to move a page when a statement
// ** transaction is active).
// **
// ** If the fourth argument, isCommit, is non-zero, then this page is being
// ** moved as part of a database reorganization just before the transaction
// ** is being committed. In this case, it is guaranteed that the database page
// ** pPg refers to will not be written to again within this transaction.
// **
// ** This function may return SQLITE_NOMEM or an IO error code if an error
// ** occurs. Otherwise, it returns SQLITE_OK.
// */
// int sqlite3PagerMovepage(Pager *pPager, DbPage *pPg, Pgno pgno, int isCommit){
// PgHdr *pPgOld; /* The page being overwritten. */
// Pgno needSyncPgno = 0; /* Old value of pPg->pgno, if sync is required */
// int rc; /* Return code */
// Pgno origPgno; /* The original page number */
// assert( pPg->nRef>0 );
// assert( pPager->eState==PAGER_WRITER_CACHEMOD
// || pPager->eState==PAGER_WRITER_DBMOD
// );
// assert( assert_pager_state(pPager) );
// /* In order to be able to rollback, an in-memory database must journal
// ** the page we are moving from.
// */
// assert( pPager->tempFile || !MEMDB );
// if( pPager->tempFile ){
// rc = sqlite3PagerWrite(pPg);
// if( rc ) return rc;
// }
// /* If the page being moved is dirty and has not been saved by the latest
// ** savepoint, then save the current contents of the page into the
// ** sub-journal now. This is required to handle the following scenario:
// **
// ** BEGIN;
// ** <journal page X, then modify it in memory>
// ** SAVEPOINT one;
// ** <Move page X to location Y>
// ** ROLLBACK TO one;
// **
// ** If page X were not written to the sub-journal here, it would not
// ** be possible to restore its contents when the "ROLLBACK TO one"
// ** statement were is processed.
// **
// ** subjournalPage() may need to allocate space to store pPg->pgno into
// ** one or more savepoint bitvecs. This is the reason this function
// ** may return SQLITE_NOMEM.
// */
// if( (pPg->flags & PGHDR_DIRTY)!=0
// && SQLITE_OK!=(rc = subjournalPageIfRequired(pPg))
// ){
// return rc;
// }
// PAGERTRACE(("MOVE %d page %d (needSync=%d) moves to %d\n",
// PAGERID(pPager), pPg->pgno, (pPg->flags&PGHDR_NEED_SYNC)?1:0, pgno));
// IOTRACE(("MOVE %p %d %d\n", pPager, pPg->pgno, pgno))
// /* If the journal needs to be sync()ed before page pPg->pgno can
// ** be written to, store pPg->pgno in local variable needSyncPgno.
// **
// ** If the isCommit flag is set, there is no need to remember that
// ** the journal needs to be sync()ed before database page pPg->pgno
// ** can be written to. The caller has already promised not to write to it.
// */
// if( (pPg->flags&PGHDR_NEED_SYNC) && !isCommit ){
// needSyncPgno = pPg->pgno;
// assert( pPager->journalMode==PAGER_JOURNALMODE_OFF ||
// pageInJournal(pPager, pPg) || pPg->pgno>pPager->dbOrigSize );
// assert( pPg->flags&PGHDR_DIRTY );
// }
// /* If the cache contains a page with page-number pgno, remove it
// ** from its hash chain. Also, if the PGHDR_NEED_SYNC flag was set for
// ** page pgno before the 'move' operation, it needs to be retained
// ** for the page moved there.
// */
// pPg->flags &= ~PGHDR_NEED_SYNC;
// pPgOld = sqlite3PagerLookup(pPager, pgno);
// assert( !pPgOld || pPgOld->nRef==1 || CORRUPT_DB );
// if( pPgOld ){
// if( NEVER(pPgOld->nRef>1) ){
// sqlite3PagerUnrefNotNull(pPgOld);
// return SQLITE_CORRUPT_BKPT;
// }
// pPg->flags |= (pPgOld->flags&PGHDR_NEED_SYNC);
// if( pPager->tempFile ){
// /* Do not discard pages from an in-memory database since we might
// ** need to rollback later. Just move the page out of the way. */
// sqlite3PcacheMove(pPgOld, pPager->dbSize+1);
// }else{
// sqlite3PcacheDrop(pPgOld);
// }
// }
// origPgno = pPg->pgno;
// sqlite3PcacheMove(pPg, pgno);
// sqlite3PcacheMakeDirty(pPg);
// /* For an in-memory database, make sure the original page continues
// ** to exist, in case the transaction needs to roll back. Use pPgOld
// ** as the original page since it has already been allocated.
// */
// if( pPager->tempFile && pPgOld ){
// sqlite3PcacheMove(pPgOld, origPgno);
// sqlite3PagerUnrefNotNull(pPgOld);
// }
// if( needSyncPgno ){
// /* If needSyncPgno is non-zero, then the journal file needs to be
// ** sync()ed before any data is written to database file page needSyncPgno.
// ** Currently, no such page exists in the page-cache and the
// ** "is journaled" bitvec flag has been set. This needs to be remedied by
// ** loading the page into the pager-cache and setting the PGHDR_NEED_SYNC
// ** flag.
// **
// ** If the attempt to load the page into the page-cache fails, (due
// ** to a malloc() or IO failure), clear the bit in the pInJournal[]
// ** array. Otherwise, if the page is loaded and written again in
// ** this transaction, it may be written to the database file before
// ** it is synced into the journal file. This way, it may end up in
// ** the journal file twice, but that is not a problem.
// */
// PgHdr *pPgHdr;
// rc = sqlite3PagerGet(pPager, needSyncPgno, &pPgHdr, 0);
// if( rc!=SQLITE_OK ){
// if( needSyncPgno<=pPager->dbOrigSize ){
// assert( pPager->pTmpSpace!=0 );
// sqlite3BitvecClear(pPager->pInJournal, needSyncPgno, pPager->pTmpSpace);
// }
// return rc;
// }
// pPgHdr->flags |= PGHDR_NEED_SYNC;
// sqlite3PcacheMakeDirty(pPgHdr);
// sqlite3PagerUnrefNotNull(pPgHdr);
// }
// return SQLITE_OK;
// }
// #endif
// /*
// ** The page handle passed as the first argument refers to a dirty page
// ** with a page number other than iNew. This function changes the page's
// ** page number to iNew and sets the value of the PgHdr.flags field to
// ** the value passed as the third parameter.
// */
// void sqlite3PagerRekey(DbPage *pPg, Pgno iNew, u16 flags){
// assert( pPg->pgno!=iNew );
// pPg->flags = flags;
// sqlite3PcacheMove(pPg, iNew);
// }
// /*
// ** Return a pointer to the data for the specified page.
// */
// void *sqlite3PagerGetData(DbPage *pPg){
// assert( pPg->nRef>0 || pPg->pPager->memDb );
// return pPg->pData;
// }
// /*
// ** Return a pointer to the Pager.nExtra bytes of "extra" space
// ** allocated along with the specified page.
// */
// void *sqlite3PagerGetExtra(DbPage *pPg){
// return pPg->pExtra;
// }
// /*
// ** Get/set the locking-mode for this pager. Parameter eMode must be one
// ** of PAGER_LOCKINGMODE_QUERY, PAGER_LOCKINGMODE_NORMAL or
// ** PAGER_LOCKINGMODE_EXCLUSIVE. If the parameter is not _QUERY, then
// ** the locking-mode is set to the value specified.
// **
// ** The returned value is either PAGER_LOCKINGMODE_NORMAL or
// ** PAGER_LOCKINGMODE_EXCLUSIVE, indicating the current (possibly updated)
// ** locking-mode.
// */
// int sqlite3PagerLockingMode(Pager *pPager, int eMode){
// assert( eMode==PAGER_LOCKINGMODE_QUERY
// || eMode==PAGER_LOCKINGMODE_NORMAL
// || eMode==PAGER_LOCKINGMODE_EXCLUSIVE );
// assert( PAGER_LOCKINGMODE_QUERY<0 );
// assert( PAGER_LOCKINGMODE_NORMAL>=0 && PAGER_LOCKINGMODE_EXCLUSIVE>=0 );
// assert( pPager->exclusiveMode || 0==sqlite3WalHeapMemory(pPager->pWal) );
// if( eMode>=0 && !pPager->tempFile && !sqlite3WalHeapMemory(pPager->pWal) ){
// pPager->exclusiveMode = (u8)eMode;
// }
// return (int)pPager->exclusiveMode;
// }
// /*
// ** Set the journal-mode for this pager. Parameter eMode must be one of:
// **
// ** PAGER_JOURNALMODE_DELETE
// ** PAGER_JOURNALMODE_TRUNCATE
// ** PAGER_JOURNALMODE_PERSIST
// ** PAGER_JOURNALMODE_OFF
// ** PAGER_JOURNALMODE_MEMORY
// ** PAGER_JOURNALMODE_WAL
// **
// ** The journalmode is set to the value specified if the change is allowed.
// ** The change may be disallowed for the following reasons:
// **
// ** * An in-memory database can only have its journal_mode set to _OFF
// ** or _MEMORY.
// **
// ** * Temporary databases cannot have _WAL journalmode.
// **
// ** The returned indicate the current (possibly updated) journal-mode.
// */
// int sqlite3PagerSetJournalMode(Pager *pPager, int eMode){
// u8 eOld = pPager->journalMode; /* Prior journalmode */
// /* The eMode parameter is always valid */
// assert( eMode==PAGER_JOURNALMODE_DELETE
// || eMode==PAGER_JOURNALMODE_TRUNCATE
// || eMode==PAGER_JOURNALMODE_PERSIST
// || eMode==PAGER_JOURNALMODE_OFF
// || eMode==PAGER_JOURNALMODE_WAL
// || eMode==PAGER_JOURNALMODE_MEMORY );
// /* This routine is only called from the OP_JournalMode opcode, and
// ** the logic there will never allow a temporary file to be changed
// ** to WAL mode.
// */
// assert( pPager->tempFile==0 || eMode!=PAGER_JOURNALMODE_WAL );
// /* Do allow the journalmode of an in-memory database to be set to
// ** anything other than MEMORY or OFF
// */
// if( MEMDB ){
// assert( eOld==PAGER_JOURNALMODE_MEMORY || eOld==PAGER_JOURNALMODE_OFF );
// if( eMode!=PAGER_JOURNALMODE_MEMORY && eMode!=PAGER_JOURNALMODE_OFF ){
// eMode = eOld;
// }
// }
// if( eMode!=eOld ){
// /* Change the journal mode. */
// assert( pPager->eState!=PAGER_ERROR );
// pPager->journalMode = (u8)eMode;
// /* When transistioning from TRUNCATE or PERSIST to any other journal
// ** mode except WAL, unless the pager is in locking_mode=exclusive mode,
// ** delete the journal file.
// */
// assert( (PAGER_JOURNALMODE_TRUNCATE & 5)==1 );
// assert( (PAGER_JOURNALMODE_PERSIST & 5)==1 );
// assert( (PAGER_JOURNALMODE_DELETE & 5)==0 );
// assert( (PAGER_JOURNALMODE_MEMORY & 5)==4 );
// assert( (PAGER_JOURNALMODE_OFF & 5)==0 );
// assert( (PAGER_JOURNALMODE_WAL & 5)==5 );
// assert( isOpen(pPager->fd) || pPager->exclusiveMode );
// if( !pPager->exclusiveMode && (eOld & 5)==1 && (eMode & 1)==0 ){
// /* In this case we would like to delete the journal file. If it is
// ** not possible, then that is not a problem. Deleting the journal file
// ** here is an optimization only.
// **
// ** Before deleting the journal file, obtain a RESERVED lock on the
// ** database file. This ensures that the journal file is not deleted
// ** while it is in use by some other client.
// */
// sqlite3OsClose(pPager->jfd);
// if( pPager->eLock>=RESERVED_LOCK ){
// sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
// }else{
// int rc = SQLITE_OK;
// int state = pPager->eState;
// assert( state==PAGER_OPEN || state==PAGER_READER );
// if( state==PAGER_OPEN ){
// rc = sqlite3PagerSharedLock(pPager);
// }
// if( pPager->eState==PAGER_READER ){
// assert( rc==SQLITE_OK );
// rc = pagerLockDb(pPager, RESERVED_LOCK);
// }
// if( rc==SQLITE_OK ){
// sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
// }
// if( rc==SQLITE_OK && state==PAGER_READER ){
// pagerUnlockDb(pPager, SHARED_LOCK);
// }else if( state==PAGER_OPEN ){
// pager_unlock(pPager);
// }
// assert( state==pPager->eState );
// }
// }else if( eMode==PAGER_JOURNALMODE_OFF ){
// sqlite3OsClose(pPager->jfd);
// }
// }
// /* Return the new journal mode */
// return (int)pPager->journalMode;
// }
// /*
// ** Return the current journal mode.
// */
// int sqlite3PagerGetJournalMode(Pager *pPager){
// return (int)pPager->journalMode;
// }
// /*
// ** Return TRUE if the pager is in a state where it is OK to change the
// ** journalmode. Journalmode changes can only happen when the database
// ** is unmodified.
// */
// int sqlite3PagerOkToChangeJournalMode(Pager *pPager){
// assert( assert_pager_state(pPager) );
// if( pPager->eState>=PAGER_WRITER_CACHEMOD ) return 0;
// if( NEVER(isOpen(pPager->jfd) && pPager->journalOff>0) ) return 0;
// return 1;
// }
// /*
// ** Get/set the size-limit used for persistent journal files.
// **
// ** Setting the size limit to -1 means no limit is enforced.
// ** An attempt to set a limit smaller than -1 is a no-op.
// */
// i64 sqlite3PagerJournalSizeLimit(Pager *pPager, i64 iLimit){
// if( iLimit>=-1 ){
// pPager->journalSizeLimit = iLimit;
// sqlite3WalLimit(pPager->pWal, iLimit);
// }
// return pPager->journalSizeLimit;
// }
// /*
// ** Return a pointer to the pPager->pBackup variable. The backup module
// ** in backup.c maintains the content of this variable. This module
// ** uses it opaquely as an argument to sqlite3BackupRestart() and
// ** sqlite3BackupUpdate() only.
// */
// sqlite3_backup **sqlite3PagerBackupPtr(Pager *pPager){
// return &pPager->pBackup;
// }
// #ifndef SQLITE_OMIT_VACUUM
// /*
// ** Unless this is an in-memory or temporary database, clear the pager cache.
// */
// void sqlite3PagerClearCache(Pager *pPager){
// assert( MEMDB==0 || pPager->tempFile );
// if( pPager->tempFile==0 ) pager_reset(pPager);
// }
// #endif
// #ifndef SQLITE_OMIT_WAL
// /*
// ** This function is called when the user invokes "PRAGMA wal_checkpoint",
// ** "PRAGMA wal_blocking_checkpoint" or calls the sqlite3_wal_checkpoint()
// ** or wal_blocking_checkpoint() API functions.
// **
// ** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL or RESTART.
// */
// int sqlite3PagerCheckpoint(
// Pager *pPager, /* Checkpoint on this pager */
// sqlite3 *db, /* Db handle used to check for interrupts */
// int eMode, /* Type of checkpoint */
// int *pnLog, /* OUT: Final number of frames in log */
// int *pnCkpt /* OUT: Final number of checkpointed frames */
// ){
// int rc = SQLITE_OK;
// if( pPager->pWal ){
// rc = sqlite3WalCheckpoint(pPager->pWal, db, eMode,
// (eMode==SQLITE_CHECKPOINT_PASSIVE ? 0 : pPager->xBusyHandler),
// pPager->pBusyHandlerArg,
// pPager->walSyncFlags, pPager->pageSize, (u8 *)pPager->pTmpSpace,
// pnLog, pnCkpt
// );
// }
// return rc;
// }
// int sqlite3PagerWalCallback(Pager *pPager){
// return sqlite3WalCallback(pPager->pWal);
// }
// /*
// ** Return true if the underlying VFS for the given pager supports the
// ** primitives necessary for write-ahead logging.
// */
// int sqlite3PagerWalSupported(Pager *pPager){
// const sqlite3_io_methods *pMethods = pPager->fd->pMethods;
// if( pPager->noLock ) return 0;
// return pPager->exclusiveMode || (pMethods->iVersion>=2 && pMethods->xShmMap);
// }
// /*
// ** Attempt to take an exclusive lock on the database file. If a PENDING lock
// ** is obtained instead, immediately release it.
// */
// static int pagerExclusiveLock(Pager *pPager){
// int rc; /* Return code */
// assert( pPager->eLock==SHARED_LOCK || pPager->eLock==EXCLUSIVE_LOCK );
// rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
// if( rc!=SQLITE_OK ){
// /* If the attempt to grab the exclusive lock failed, release the
// ** pending lock that may have been obtained instead. */
// pagerUnlockDb(pPager, SHARED_LOCK);
// }
// return rc;
// }
// /*
// ** Call sqlite3WalOpen() to open the WAL handle. If the pager is in
// ** exclusive-locking mode when this function is called, take an EXCLUSIVE
// ** lock on the database file and use heap-memory to store the wal-index
// ** in. Otherwise, use the normal shared-memory.
// */
// static int pagerOpenWal(Pager *pPager){
// int rc = SQLITE_OK;
// assert( pPager->pWal==0 && pPager->tempFile==0 );
// assert( pPager->eLock==SHARED_LOCK || pPager->eLock==EXCLUSIVE_LOCK );
// /* If the pager is already in exclusive-mode, the WAL module will use
// ** heap-memory for the wal-index instead of the VFS shared-memory
// ** implementation. Take the exclusive lock now, before opening the WAL
// ** file, to make sure this is safe.
// */
// if( pPager->exclusiveMode ){
// rc = pagerExclusiveLock(pPager);
// }
// /* Open the connection to the log file. If this operation fails,
// ** (e.g. due to malloc() failure), return an error code.
// */
// if( rc==SQLITE_OK ){
// rc = sqlite3WalOpen(pPager->pVfs,
// pPager->fd, pPager->zWal, pPager->exclusiveMode,
// pPager->journalSizeLimit, &pPager->pWal
// );
// }
// pagerFixMaplimit(pPager);
// return rc;
// }
// /*
// ** The caller must be holding a SHARED lock on the database file to call
// ** this function.
// **
// ** If the pager passed as the first argument is open on a real database
// ** file (not a temp file or an in-memory database), and the WAL file
// ** is not already open, make an attempt to open it now. If successful,
// ** return SQLITE_OK. If an error occurs or the VFS used by the pager does
// ** not support the xShmXXX() methods, return an error code. *pbOpen is
// ** not modified in either case.
// **
// ** If the pager is open on a temp-file (or in-memory database), or if
// ** the WAL file is already open, set *pbOpen to 1 and return SQLITE_OK
// ** without doing anything.
// */
// int sqlite3PagerOpenWal(
// Pager *pPager, /* Pager object */
// int *pbOpen /* OUT: Set to true if call is a no-op */
// ){
// int rc = SQLITE_OK; /* Return code */
// assert( assert_pager_state(pPager) );
// assert( pPager->eState==PAGER_OPEN || pbOpen );
// assert( pPager->eState==PAGER_READER || !pbOpen );
// assert( pbOpen==0 || *pbOpen==0 );
// assert( pbOpen!=0 || (!pPager->tempFile && !pPager->pWal) );
// if( !pPager->tempFile && !pPager->pWal ){
// if( !sqlite3PagerWalSupported(pPager) ) return SQLITE_CANTOPEN;
// /* Close any rollback journal previously open */
// sqlite3OsClose(pPager->jfd);
// rc = pagerOpenWal(pPager);
// if( rc==SQLITE_OK ){
// pPager->journalMode = PAGER_JOURNALMODE_WAL;
// pPager->eState = PAGER_OPEN;
// }
// }else{
// *pbOpen = 1;
// }
// return rc;
// }
// /*
// ** This function is called to close the connection to the log file prior
// ** to switching from WAL to rollback mode.
// **
// ** Before closing the log file, this function attempts to take an
// ** EXCLUSIVE lock on the database file. If this cannot be obtained, an
// ** error (SQLITE_BUSY) is returned and the log connection is not closed.
// ** If successful, the EXCLUSIVE lock is not released before returning.
// */
// int sqlite3PagerCloseWal(Pager *pPager, sqlite3 *db){
// int rc = SQLITE_OK;
// assert( pPager->journalMode==PAGER_JOURNALMODE_WAL );
// /* If the log file is not already open, but does exist in the file-system,
// ** it may need to be checkpointed before the connection can switch to
// ** rollback mode. Open it now so this can happen.
// */
// if( !pPager->pWal ){
// int logexists = 0;
// rc = pagerLockDb(pPager, SHARED_LOCK);
// if( rc==SQLITE_OK ){
// rc = sqlite3OsAccess(
// pPager->pVfs, pPager->zWal, SQLITE_ACCESS_EXISTS, &logexists
// );
// }
// if( rc==SQLITE_OK && logexists ){
// rc = pagerOpenWal(pPager);
// }
// }
// /* Checkpoint and close the log. Because an EXCLUSIVE lock is held on
// ** the database file, the log and log-summary files will be deleted.
// */
// if( rc==SQLITE_OK && pPager->pWal ){
// rc = pagerExclusiveLock(pPager);
// if( rc==SQLITE_OK ){
// rc = sqlite3WalClose(pPager->pWal, db, pPager->walSyncFlags,
// pPager->pageSize, (u8*)pPager->pTmpSpace);
// pPager->pWal = 0;
// pagerFixMaplimit(pPager);
// if( rc && !pPager->exclusiveMode ) pagerUnlockDb(pPager, SHARED_LOCK);
// }
// }
// return rc;
// }
// #ifdef SQLITE_ENABLE_SETLK_TIMEOUT
// /*
// ** If pager pPager is a wal-mode database not in exclusive locking mode,
// ** invoke the sqlite3WalWriteLock() function on the associated Wal object
// ** with the same db and bLock parameters as were passed to this function.
// ** Return an SQLite error code if an error occurs, or SQLITE_OK otherwise.
// */
// int sqlite3PagerWalWriteLock(Pager *pPager, int bLock){
// int rc = SQLITE_OK;
// if( pagerUseWal(pPager) && pPager->exclusiveMode==0 ){
// rc = sqlite3WalWriteLock(pPager->pWal, bLock);
// }
// return rc;
// }
// /*
// ** Set the database handle used by the wal layer to determine if
// ** blocking locks are required.
// */
// void sqlite3PagerWalDb(Pager *pPager, sqlite3 *db){
// if( pagerUseWal(pPager) ){
// sqlite3WalDb(pPager->pWal, db);
// }
// }
// #endif
// #ifdef SQLITE_ENABLE_SNAPSHOT
// /*
// ** If this is a WAL database, obtain a snapshot handle for the snapshot
// ** currently open. Otherwise, return an error.
// */
// int sqlite3PagerSnapshotGet(Pager *pPager, sqlite3_snapshot **ppSnapshot){
// int rc = SQLITE_ERROR;
// if( pPager->pWal ){
// rc = sqlite3WalSnapshotGet(pPager->pWal, ppSnapshot);
// }
// return rc;
// }
// /*
// ** If this is a WAL database, store a pointer to pSnapshot. Next time a
// ** read transaction is opened, attempt to read from the snapshot it
// ** identifies. If this is not a WAL database, return an error.
// */
// int sqlite3PagerSnapshotOpen(
// Pager *pPager,
// sqlite3_snapshot *pSnapshot
// ){
// int rc = SQLITE_OK;
// if( pPager->pWal ){
// sqlite3WalSnapshotOpen(pPager->pWal, pSnapshot);
// }else{
// rc = SQLITE_ERROR;
// }
// return rc;
// }
// /*
// ** If this is a WAL database, call sqlite3WalSnapshotRecover(). If this
// ** is not a WAL database, return an error.
// */
// int sqlite3PagerSnapshotRecover(Pager *pPager){
// int rc;
// if( pPager->pWal ){
// rc = sqlite3WalSnapshotRecover(pPager->pWal);
// }else{
// rc = SQLITE_ERROR;
// }
// return rc;
// }
// /*
// ** The caller currently has a read transaction open on the database.
// ** If this is not a WAL database, SQLITE_ERROR is returned. Otherwise,
// ** this function takes a SHARED lock on the CHECKPOINTER slot and then
// ** checks if the snapshot passed as the second argument is still
// ** available. If so, SQLITE_OK is returned.
// **
// ** If the snapshot is not available, SQLITE_ERROR is returned. Or, if
// ** the CHECKPOINTER lock cannot be obtained, SQLITE_BUSY. If any error
// ** occurs (any value other than SQLITE_OK is returned), the CHECKPOINTER
// ** lock is released before returning.
// */
// int sqlite3PagerSnapshotCheck(Pager *pPager, sqlite3_snapshot *pSnapshot){
// int rc;
// if( pPager->pWal ){
// rc = sqlite3WalSnapshotCheck(pPager->pWal, pSnapshot);
// }else{
// rc = SQLITE_ERROR;
// }
// return rc;
// }
// /*
// ** Release a lock obtained by an earlier successful call to
// ** sqlite3PagerSnapshotCheck().
// */
// void sqlite3PagerSnapshotUnlock(Pager *pPager){
// assert( pPager->pWal );
// sqlite3WalSnapshotUnlock(pPager->pWal);
// }
// #endif /* SQLITE_ENABLE_SNAPSHOT */
// #endif /* !SQLITE_OMIT_WAL */
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