more tdb

source/libs/tdb/src/db/tdbPFile.c

@@ -18,6 +18,7 @@
 struct SPFile {
   char *   dbFileName;
   char *   jFileName;
+  int      pageSize;
   uint8_t  fid[TDB_FILE_ID_LEN];
   int      fd;
   int      jfd;
@@ -26,6 +27,8 @@ struct SPFile {
   SPgno    dbOrigSize;
 };
 
+static int tdbPFileReadPage(SPFile *pFile, SPgHdr *pPage);
+
 int tdbPFileOpen(SPCache *pCache, const char *fileName, SPFile **ppFile) {
   uint8_t *pPtr;
   SPFile * pFile;
@@ -81,7 +84,13 @@ SPgHdr *tdbPFileGet(SPFile *pFile, SPgno pgno) {
   }
   tdbPCacheFetchFinish(pFile->pCache, pPage);
 
-  if (true /* not load from the file, then load the content from the file*/) {
+  if (pgno > pFile->dbFileSize /*TODO*/) {
+    memset(pPage->pData, 0, pFile->pageSize);
+  } else {
+    if (tdbPFileReadPage(pFile, pPage) < 0) {
+      // TODO: handle error
+      return NULL;
+    }
   }
 
   return pPage;
@@ -100,4 +109,19 @@ int tdbPFileCommit(SPFile *pFile) {
 int tdbPFileRollback(SPFile *pFile) {
   // TODO
   return 0;
+}
+
+static int tdbPFileReadPage(SPFile *pFile, SPgHdr *pPage) {
+  i64 offset;
+  int ret;
+
+  ASSERT(memcmp(pFile->fid, pPage->pgid.fileid, TDB_FILE_ID_LEN) == 0);
+
+  offset = (pPage->pgid.pgno - 1) * (i64)(pFile->pageSize);
+  ret = tdbPRead(pFile->fd, pPage->pData, pFile->pageSize, offset);
+  if (ret < 0) {
+    // TODO: handle error
+    return -1;
+  }
+  return 0;
 }

source/libs/tdb/src/db/tdbUtil.c

@@ -64,4 +64,29 @@ int tdbGetFileSize(const char *fname, int pgSize, SPgno *pSize) {
 
   *pSize = st.st_size / pgSize;
   return 0;
+}
+
+int tdbPRead(int fd, void *pData, int count, i64 offset) {
+  void *pBuf;
+  int   nbytes;
+  i64   ioffset;
+  int   iread;
+
+  pBuf = pData;
+  nbytes = count;
+  ioffset = offset;
+  while (nbytes > 0) {
+    iread = pread(fd, pBuf, nbytes, ioffset);
+    if (iread < 0) {
+      /* TODO */
+    } else if (iread == 0) {
+      return (count - iread);
+    }
+
+    nbytes = nbytes - iread;
+    pBuf = (void *)((u8 *)pBuf + iread);
+    ioffset += iread;
+  }
+
+  return count;
 }

source/libs/tdb/src/inc/tdbUtil.h

@@ -37,6 +37,8 @@ int tdbCheckFileAccess(const char *pathname, int mode);
 
 int tdbGetFileSize(const char *fname, int pgSize, SPgno *pSize);
 
+int tdbPRead(int fd, void *pData, int count, i64 offset);
+
 #ifdef __cplusplus
 }
 #endif