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fix race condition in release cache resource.

This commit is contained in:
hjxilinx 2019-10-11 10:27:58 +08:00
parent c214e229cb
commit 4e45a4fd74
1 changed files with 44 additions and 70 deletions
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112
src/util/src/tcache.c
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@ -89,7 +89,6 @@ typedef struct {
_hashFunc hashFp;
int numOfElemsInTrash; // number of element in trash
int16_t deleting; // set the deleting flag to stop refreshing asap.
int16_t refreshing; // if refreshing is invoked, it will be set 1
#if defined LINUX
pthread_rwlock_t lock;
@ -500,7 +499,7 @@ static SDataNode *taosUpdateCacheImpl(SCacheObj *pObj, SDataNode *pNode, char *k
// only a node is not referenced by any other object, in-place update it
if (pNode->refCount == 0) {
size_t newSize = sizeof(SDataNode) + dataSize + (keyLen + 1);
size_t newSize = sizeof(SDataNode) + dataSize + keyLen;
pNewNode = (SDataNode *)realloc(pNode, newSize);
if (pNewNode == NULL) {
@ -725,6 +724,34 @@ void *taosUpdateDataFromCache(void *handle, char *key, char *pData, int size, in
return (pNew != NULL) ? pNew->data : NULL;
}
static void doCleanUpDataCache(SCacheObj* pObj) {
SDataNode *pNode, *pNext;
__cache_wr_lock(pObj);
if (pObj->hashList && pObj->size > 0) {
for (int i = 0; i < pObj->capacity; ++i) {
pNode = pObj->hashList[i];
while (pNode) {
pNext = pNode->next;
free(pNode);
pNode = pNext;
}
}
tfree(pObj->hashList);
}
__cache_unlock(pObj);
taosClearCacheTrash(pObj, true);
__cache_lock_destroy(pObj);
memset(pObj, 0, sizeof(SCacheObj));
free(pObj);
}
/**
* refresh cache to remove data in both hash list and trash, if any nodes' refcount == 0, every pObj->refreshTime
* @param handle Cache object handle
@ -733,21 +760,13 @@ void taosRefreshDataCache(void *handle, void *tmrId) {
SDataNode *pNode, *pNext;
SCacheObj *pObj = (SCacheObj *)handle;
if (pObj == NULL || pObj->capacity <= 0 || pObj->deleting == 1) {
if (pObj == NULL || pObj->capacity <= 0) {
pTrace("object is destroyed. no refresh retry");
return;
}
pObj->refreshing = 1;
#if defined LINUX
__sync_synchronize();
#else
MemoryBarrier();
#endif
if (pObj->deleting == 1) {
pObj->refreshing = 0;
doCleanUpDataCache(pObj);
return;
}
@ -760,8 +779,7 @@ void taosRefreshDataCache(void *handle, void *tmrId) {
for (int i = 0; i < pObj->capacity; ++i) {
// in deleting process, quit refreshing immediately
if (pObj->deleting == 1) {
pObj->refreshing = 0;
return;
break;
}
__cache_wr_lock(pObj);
@ -786,12 +804,8 @@ void taosRefreshDataCache(void *handle, void *tmrId) {
__cache_unlock(pObj);
}
int16_t isDeleting = pObj->deleting;
pObj->refreshing = 0;
// the SCacheObj may have been released now.
if (isDeleting == 1) {
return;
if (pObj->deleting == 1) { // clean up resources and abort
doCleanUpDataCache(pObj);
} else {
taosClearCacheTrash(pObj, false);
taosTmrReset(taosRefreshDataCache, pObj->refreshTime, pObj, pObj->tmrCtrl, &pObj->pTimer);
@ -829,7 +843,6 @@ void taosClearDataCache(void *handle) {
}
/**
*
* @param capacity maximum slots available for hash elements
* @param tmrCtrl timer ctrl
* @param refreshTime refresh operation interval time, the maximum survival time when one element is expired and
@ -877,61 +890,22 @@ void *taosInitDataCache(int capacity, void *tmrCtrl, int64_t refreshTime) {
}
/**
* release all allocated memory and destroy the cache object
* release all allocated memory and destroy the cache object.
*
* This function only set the deleting flag, and the specific work of clean up cache is delegated to
* taosRefreshDataCache function, which will executed every SCacheObj->refreshTime sec.
*
* If the value of SCacheObj->refreshTime is too large, the taosRefreshDataCache function may not be invoked
* before the main thread terminated, in which case all allocated resources are simply recycled by OS.
*
* @param handle
*/
void taosCleanUpDataCache(void *handle) {
SCacheObj *pObj;
SDataNode *pNode, *pNext;
pObj = (SCacheObj *)handle;
SCacheObj *pObj = (SCacheObj *)handle;
if (pObj == NULL) {
return;
}
if (pObj->capacity <= 0) {
__cache_lock_destroy(pObj);
free(pObj);
return;
}
taosTmrStopA(&pObj->pTimer);
pObj->deleting = 1;
#if defined LINUX
__sync_synchronize();
#else
MemoryBarrier();
#endif
while (pObj->refreshing == 1) {
taosMsleep(0);
}
__cache_wr_lock(pObj);
if (pObj->hashList && pObj->size > 0) {
for (int i = 0; i < pObj->capacity; ++i) {
pNode = pObj->hashList[i];
while (pNode) {
pNext = pNode->next;
free(pNode);
pNode = pNext;
}
}
tfree(pObj->hashList);
}
__cache_unlock(pObj);
taosClearCacheTrash(pObj, true);
__cache_lock_destroy(pObj);
memset(pObj, 0, sizeof(SCacheObj));
free(pObj);
return;
}