enh: add disk cache

This commit is contained in:
dapan1121 2023-07-21 19:25:38 +08:00
parent 3725cafe00
commit ae8caa8275
2 changed files with 158 additions and 86 deletions

View File

@ -27,11 +27,11 @@ typedef struct SGcBlkBufBasic {
int64_t blkId; int64_t blkId;
int64_t offset; int64_t offset;
int64_t bufSize; int64_t bufSize;
uint32_t fileId;
} SGcBlkBufBasic; } SGcBlkBufBasic;
typedef struct SGcBlkBufInfo { typedef struct SGcBlkBufInfo {
SGcBlkBufBasic basic; SGcBlkBufBasic basic;
uint32_t fileId;
void* next; void* next;
void* pBuf; void* pBuf;
SGcDownstreamCtx* pCtx; SGcDownstreamCtx* pCtx;
@ -39,10 +39,10 @@ typedef struct SGcBlkBufInfo {
} SGcBlkBufInfo; } SGcBlkBufInfo;
#pragma pack(pop) #pragma pack(pop)
typedef struct SGcVgroupFileFd { typedef struct SGroupCacheFileFd {
TdThreadMutex mutex; TdThreadMutex mutex;
TdFilePtr fd; TdFilePtr fd;
} SGcVgroupFileFd; } SGroupCacheFileFd;
typedef struct SGcVgroupCtx { typedef struct SGcVgroupCtx {
SArray* pTbList; SArray* pTbList;
@ -117,7 +117,7 @@ typedef struct SGcDownstreamCtx {
SHashObj* pSessions; SHashObj* pSessions;
SHashObj* pWaitSessions; SHashObj* pWaitSessions;
int32_t cacheFileFdNum; int32_t cacheFileFdNum;
TdFilePtr cacheFileFd[GROUP_CACHE_MAX_FILE_FDS]; SGroupCacheFileFd cacheFileFd;
char baseFilename[PATH_MAX]; char baseFilename[PATH_MAX];
} SGcDownstreamCtx; } SGcDownstreamCtx;
@ -126,7 +126,6 @@ typedef struct SGcSessionCtx {
SGcOperatorParam* pParam; SGcOperatorParam* pParam;
SGroupCacheData* pGroupData; SGroupCacheData* pGroupData;
int64_t lastBlkId; int64_t lastBlkId;
int64_t nextOffset;
bool semInit; bool semInit;
tsem_t waitSem; tsem_t waitSem;
bool newFetch; bool newFetch;

View File

@ -85,7 +85,7 @@ static void destroyGroupCacheOperator(void* param) {
taosMemoryFreeClear(param); taosMemoryFreeClear(param);
} }
static FORCE_INLINE int32_t initOpenCacheFile(SGcVgroupFileFd* pFileFd, char* filename) { static FORCE_INLINE int32_t initOpenCacheFile(SGroupCacheFileFd* pFileFd, char* filename) {
TdFilePtr newFd = taosOpenFile(filename, TD_FILE_CREATE|TD_FILE_READ|TD_FILE_WRITE|TD_FILE_AUTO_DEL); TdFilePtr newFd = taosOpenFile(filename, TD_FILE_CREATE|TD_FILE_READ|TD_FILE_WRITE|TD_FILE_AUTO_DEL);
if (NULL == newFd) { if (NULL == newFd) {
return TAOS_SYSTEM_ERROR(errno); return TAOS_SYSTEM_ERROR(errno);
@ -95,13 +95,13 @@ static FORCE_INLINE int32_t initOpenCacheFile(SGcVgroupFileFd* pFileFd, char* fi
return TSDB_CODE_SUCCESS; return TSDB_CODE_SUCCESS;
} }
static int32_t acquireVgroupFileFd(SGroupCacheOperatorInfo* pGCache, SGcDownstreamCtx* pCtx, SGcVgroupCtx* pVgCtx, uint32_t fileId, SGcVgroupFileFd** ppFd) { static int32_t acquireVgroupFileFd(SGroupCacheOperatorInfo* pGCache, SGcDownstreamCtx* pCtx, SGcVgroupCtx* pVgCtx, uint32_t fileId, SGroupCacheFileFd** ppFd) {
int32_t code = TSDB_CODE_SUCCESS; int32_t code = TSDB_CODE_SUCCESS;
SGcVgroupFileFd* pTmp = tSimpleHashGet(pVgCtx->pCacheFile, &fileId, sizeof(fileId)); SGroupCacheFileFd* pTmp = tSimpleHashGet(pVgCtx->pCacheFile, &fileId, sizeof(fileId));
if (NULL == pTmp) { if (NULL == pTmp) {
sprintf(pVgCtx->baseFilename[pVgCtx->baseNameLen], "_%u", fileId); sprintf(pVgCtx->baseFilename[pVgCtx->baseNameLen], "_%u", fileId);
SGcVgroupFileFd newVgFd = {0}; SGroupCacheFileFd newVgFd = {0};
tSimpleHashPut(pVgCtx->pCacheFile, &fileId, sizeof(fileId), &newVgFd, sizeof(newVgFd)); tSimpleHashPut(pVgCtx->pCacheFile, &fileId, sizeof(fileId), &newVgFd, sizeof(newVgFd));
pTmp = tSimpleHashGet(pVgCtx->pCacheFile, &fileId, sizeof(fileId)); pTmp = tSimpleHashGet(pVgCtx->pCacheFile, &fileId, sizeof(fileId));
@ -117,7 +117,7 @@ static int32_t acquireVgroupFileFd(SGroupCacheOperatorInfo* pGCache, SGcDownstre
return TSDB_CODE_SUCCESS; return TSDB_CODE_SUCCESS;
} }
static FORCE_INLINE void releaseVgroupFileFd(SGcVgroupFileFd* pFd) { static FORCE_INLINE void releaseVgroupFileFd(SGroupCacheFileFd* pFd) {
taosThreadMutexUnlock(&pFd->mutex); taosThreadMutexUnlock(&pFd->mutex);
} }
@ -126,27 +126,30 @@ static int32_t saveBatchBlocksToDisk(SGroupCacheOperatorInfo* pGCache, SGcBlkBuf
SGcBlkBufBasic blkBasic; SGcBlkBufBasic blkBasic;
while (NULL != pHead) { while (NULL != pHead) {
if (NULL == pHead->pCtx->cacheFileFd[0]) { SGroupCacheFileFd *pFd;
pHead->pCtx->cacheFileFd[0] = taosOpenFile(pHead->pCtx->baseFilename, TD_FILE_CREATE|TD_FILE_READ|TD_FILE_WRITE|TD_FILE_AUTO_DEL); code = acquireDownstreamFileFd(pHead->pCtx, &pFd);
if (NULL == pHead->pCtx->cacheFileFd[0]) { if (code) {
return TAOS_SYSTEM_ERROR(errno); return code;
}
pHead->pCtx->cacheFileFdNum = 1;
} }
int32_t ret = taosLSeekFile(pHead->pCtx->cacheFileFd[0], pHead->offset, SEEK_SET); int32_t ret = taosLSeekFile(pFd->fd, pHead->basic.offset, SEEK_SET);
if (ret == -1) { if (ret == -1) {
releaseDownstreamFileFd();
return TAOS_SYSTEM_ERROR(errno); return TAOS_SYSTEM_ERROR(errno);
} }
ret = (int32_t)taosWriteFile(pHead->pCtx->cacheFileFd[0], pHead->pBuf, pHead->bufSize); ret = (int32_t)taosWriteFile(pFd->fd, pHead->pBuf, pHead->basic.bufSize);
if (ret != pHead->bufSize) { if (ret != pHead->basic.bufSize) {
releaseDownstreamFileFd();
return TAOS_SYSTEM_ERROR(errno); return TAOS_SYSTEM_ERROR(errno);
} }
releaseDownstreamFileFd();
taos taosWLockLatch(&pHead->pGroup->batchList.lock);
taosArrayPush(pHead->pGroup->batchList.pList, &pHead->basic);
taosWUnLockLatch(&pHead->pGroup->batchList.lock);
int64_t blkId = pHead->blkId; int64_t blkId = pHead->basic.blkId;
pHead = pHead->next; pHead = pHead->next;
taosHashRemove(pGCache->blkCache.pDirtyBlk, &blkId, sizeof(blkId)); taosHashRemove(pGCache->blkCache.pDirtyBlk, &blkId, sizeof(blkId));
@ -159,27 +162,32 @@ static int32_t saveBatchBlocksToDisk(SGroupCacheOperatorInfo* pGCache, SGcBlkBuf
static int32_t saveSeqBlocksToDisk(SGroupCacheOperatorInfo* pGCache, SGcBlkBufInfo* pHead) { static int32_t saveSeqBlocksToDisk(SGroupCacheOperatorInfo* pGCache, SGcBlkBufInfo* pHead) {
int32_t code = TSDB_CODE_SUCCESS; int32_t code = TSDB_CODE_SUCCESS;
SGcVgroupFileFd* pFd = NULL; SGroupCacheFileFd* pFd = NULL;
while (NULL != pHead) { while (NULL != pHead) {
code = acquireVgroupFileFd(pGCache, pHead->pCtx, pHead->pGroup->pVgCtx, pHead->fileId, &pFd); code = acquireVgroupFileFd(pGCache, pHead->pCtx, pHead->pGroup->pVgCtx, pHead->fileId, &pFd);
if (TSDB_CODE_SUCCESS != code) { if (TSDB_CODE_SUCCESS != code) {
return code; return code;
} }
int32_t ret = taosLSeekFile(pFd->fd, pHead->offset, SEEK_SET); int32_t ret = taosLSeekFile(pFd->fd, pHead->basic.offset, SEEK_SET);
if (ret == -1) { if (ret == -1) {
code= TAOS_SYSTEM_ERROR(errno); code= TAOS_SYSTEM_ERROR(errno);
return code; return code;
} }
code = (int32_t)taosWriteFile(pFd->fd, pHead->pBuf, pHead->bufSize); code = (int32_t)taosWriteFile(pFd->fd, pHead->pBuf, pHead->basic.bufSize);
releaseVgroupFileFd(pFd); releaseVgroupFileFd(pFd);
if (code != pHead->bufSize) { if (code != pHead->basic.bufSize) {
code= TAOS_SYSTEM_ERROR(errno); code= TAOS_SYSTEM_ERROR(errno);
return code; return code;
} }
int64_t blkId = pHead->blkId; taosWLockLatch(&pHead->pGroup->batchList.lock);
taosArrayPush(pHead->pGroup->batchList.pList, &pHead->basic);
taosWUnLockLatch(&pHead->pGroup->batchList.lock);
int64_t blkId = pHead->basic.blkId;
pHead = pHead->next; pHead = pHead->next;
taosHashRemove(pGCache->blkCache.pDirtyBlk, &blkId, sizeof(blkId)); taosHashRemove(pGCache->blkCache.pDirtyBlk, &blkId, sizeof(blkId));
@ -332,23 +340,114 @@ static int32_t buildGroupCacheResultBlock(SGroupCacheOperatorInfo* pGCache, int3
return blockDataFromBuf(*ppRes, pBuf); return blockDataFromBuf(*ppRes, pBuf);
} }
static int32_t retrieveBlkFromBufCache(SGroupCacheOperatorInfo* pGCache, SGroupCacheData* pGrp, int64_t sessionId, int64_t blkId, int64_t* nextOffset, SSDataBlock** ppRes) { static int32_t acquireDownstreamFileFd(SGcDownstreamCtx* pCtx, SGroupCacheFileFd** ppFd) {
int32_t code = TSDB_CODE_SUCCESS; if (NULL == pCtx->cacheFileFd.fd) {
SGcBlkCacheInfo* pCache = &pGCache->blkCache; pCtx->cacheFileFd.fd = taosOpenFile(pCtx->baseFilename, TD_FILE_CREATE|TD_FILE_READ|TD_FILE_WRITE|TD_FILE_AUTO_DEL);
SGcBlkBufInfo bufInfo; if (NULL == pCtx->cacheFileFd.fd) {
SGcBlkBufBasic* pBlkBasic = NULL; return TAOS_SYSTEM_ERROR(errno);
void* pBuf = NULL; }
pCtx->cacheFileFdNum = 1;
taosThreadMutexInit(&pCtx->cacheFileFd.mutex, NULL);
} else {
taosThreadMutexLock(&pCtx->cacheFileFd.mutex);
}
taosRLockLatch(&pCache->dirtyLock); *ppFd = &pCtx->cacheFileFd;
SGcBlkBufInfo* pBufInfo = taosHashAcquire(pCache->pDirtyBlk, &blkId, sizeof(blkId)); return TSDB_CODE_SUCCESS;
if (NULL == pBufInfo) { }
code = readBlockFromDisk(pGCache, pGrp, blkId, nextOffset, &bufInfo.basic, &pBuf);
static int32_t readBatchBlocksFromDisk(SGroupCacheOperatorInfo* pGCache, SGroupCacheData* pGrp, SGcBlkBufBasic* pBasic, void** ppBuf) {
TdFilePtr cacheFileFd = NULL;
SGcDownstreamCtx* pCtx = &pGCache->pDownstreams[pGrp->downstreamIdx];
int32_t code = acquireDownstreamFileFd(pCtx, &cacheFileFd);
if (code) {
return code;
}
int32_t ret = taosLSeekFile(cacheFileFd, pBasic->offset, SEEK_SET);
if (ret == -1) {
return TAOS_SYSTEM_ERROR(errno);
}
*ppBuf = taosMemoryMalloc(pBasic->bufSize);
if (NULL == *ppBuf) {
releaseDownstreamFileFd();
return TSDB_CODE_OUT_OF_MEMORY;
}
ret = (int32_t)taosReadFile(cacheFileFd, *ppBuf, pBasic->bufSize);
if (ret != pBasic->bufSize) {
taosMemoryFreeClear(*ppBuf);
return TAOS_SYSTEM_ERROR(errno);
}
releaseDownstreamFileFd();
return code;
}
static int32_t readSeqBlocksFromDisk(SGroupCacheOperatorInfo* pGCache, SGcBlkBufInfo* pHead) {
int32_t code = TSDB_CODE_SUCCESS;
SGroupCacheFileFd* pFd = NULL;
while (NULL != pHead) {
code = acquireVgroupFileFd(pGCache, pHead->pCtx, pHead->pGroup->pVgCtx, pHead->fileId, &pFd);
if (TSDB_CODE_SUCCESS != code) {
return code;
}
int32_t ret = taosLSeekFile(pFd->fd, pHead->basic.offset, SEEK_SET);
if (ret == -1) {
code= TAOS_SYSTEM_ERROR(errno);
return code;
}
code = (int32_t)taosWriteFile(pFd->fd, pHead->pBuf, pHead->basic.bufSize);
releaseVgroupFileFd(pFd);
if (code != pHead->basic.bufSize) {
code= TAOS_SYSTEM_ERROR(errno);
return code;
}
taosWLockLatch(&pHead->pGroup->batchList.lock);
taosArrayPush(pHead->pGroup->batchList.pList, &pHead->basic);
taosWUnLockLatch(&pHead->pGroup->batchList.lock);
int64_t blkId = pHead->basic.blkId;
pHead = pHead->next;
taosHashRemove(pGCache->blkCache.pDirtyBlk, &blkId, sizeof(blkId));
}
return code;
}
static int32_t readBlockFromDisk(SGroupCacheOperatorInfo* pGCache, SGroupCacheData* pGrp, SGcBlkBufBasic* pBasic, void** ppRes) {
int32_t code = TSDB_CODE_SUCCESS;
if (pGCache->batchFetch) {
code = readBatchBlocksFromDisk(pGCache, pGrp, pBasic, ppRes);
} else {
code = readSeqBlocksFromDisk(pGCache, pGrp, pBasic, ppRes);
}
return code;
}
static int32_t retrieveBlkFromBufCache(SGroupCacheOperatorInfo* pGCache, SGroupCacheData* pGrp, int64_t sessionId, SGcBlkBufBasic* pBasic, SSDataBlock** ppRes) {
int32_t code = TSDB_CODE_SUCCESS;
SGcBlkCacheInfo* pCache = &pGCache->blkCache;
void* pBuf = NULL;
taosRLockLatch(&pCache->dirtyLock);
SGcBlkBufInfo* pBufInfo = taosHashAcquire(pCache->pDirtyBlk, &pBasic->blkId, sizeof(pBasic->blkId));
if (NULL == pBufInfo) {
code = readBlockFromDisk(pGCache, pGrp, pBasic, &pBuf);
if (code) { if (code) {
return code; return code;
} }
pBlkBasic = &bufInfo.basic;
} else { } else {
pBlkBasic = &pBufInfo->basic;
pBuf = pBufInfo->pBuf; pBuf = pBufInfo->pBuf;
} }
@ -358,8 +457,6 @@ static int32_t retrieveBlkFromBufCache(SGroupCacheOperatorInfo* pGCache, SGroupC
return code; return code;
} }
*nextOffset = pBlkBasic->offset + pBlkBasic->bufSize;
taosHashPut(pCache->pReadBlk, &sessionId, sizeof(sessionId), ppRes, POINTER_BYTES); taosHashPut(pCache->pReadBlk, &sessionId, sizeof(sessionId), ppRes, POINTER_BYTES);
return TSDB_CODE_SUCCESS; return TSDB_CODE_SUCCESS;
} }
@ -594,29 +691,21 @@ static int32_t addNewGroupData(struct SOperatorInfo* pOperator, SOperatorParam*
return TSDB_CODE_SUCCESS; return TSDB_CODE_SUCCESS;
} }
static int32_t addBlkToGroupCache(bool batchFetch, SGroupCacheData* pGroup, SGcBlkBufInfo* pNewBlk) { static int32_t addBlkToGroupCache(bool batchFetch, SGroupCacheData* pGroup, SGcBlkBufInfo* pNewBlk, int32_t* pIdx) {
if (batchFetch) {
taosWLockLatch(&pGroup->batchList.lock); taosWLockLatch(&pGroup->batchList.lock);
if (batchFetch) {
taosArrayPush(pGroup->batchList.pList, &pNewBlk->basic); taosArrayPush(pGroup->batchList.pList, &pNewBlk->basic);
} else {
taosArrayPush(pGroup->batchList.pList, &pNewBlk->basic.offset);
}
*pIdx = taosArrayGetSize(pGroup->batchList.pList) - 1;
qError("block added to group cache, total block num:%" PRId64, (int64_t)taosArrayGetSize(pGroup->batchList.pList)); qError("block added to group cache, total block num:%" PRId64, (int64_t)taosArrayGetSize(pGroup->batchList.pList));
taosWUnLockLatch(&pGroup->batchList.lock); taosWUnLockLatch(&pGroup->batchList.lock);
return TSDB_CODE_SUCCESS; return TSDB_CODE_SUCCESS;
} }
taosWLockLatch(&pGroup->batchList.lock);
if (pGroup->seqList.endBlkId > 0) {
atomic_store_64(&pGroup->seqList.endBlkId, pNewBlk->blkId);
} else {
atomic_store_64(&pGroup->seqList.startBlkId, pNewBlk->blkId);
atomic_store_64(&pGroup->seqList.endBlkId, pNewBlk->blkId);
}
qError("block added to group cache, total block num:%" PRId64, pGroup->seqList.endBlkId - pGroup->seqList.startBlkId + 1);
return TSDB_CODE_SUCCESS;
}
static int32_t handleGroupCacheRetrievedBlk(struct SOperatorInfo* pOperator, SSDataBlock* pBlock, SGcSessionCtx* pSession, bool* continueFetch) { static int32_t handleGroupCacheRetrievedBlk(struct SOperatorInfo* pOperator, SSDataBlock* pBlock, SGcSessionCtx* pSession, bool* continueFetch) {
int32_t code = TSDB_CODE_SUCCESS; int32_t code = TSDB_CODE_SUCCESS;
SGroupCacheOperatorInfo* pGCache = pOperator->info; SGroupCacheOperatorInfo* pGCache = pOperator->info;
@ -651,15 +740,15 @@ static int32_t handleGroupCacheRetrievedBlk(struct SOperatorInfo* pOperator, SSD
return code; return code;
} }
code = addBlkToGroupCache(pGCache->batchFetch, pGroup, &newBlkBuf); int64_t blkIdx = 0;
code = addBlkToGroupCache(pGCache->batchFetch, pGroup, &newBlkBuf, &blkIdx);
if (code) { if (code) {
return code; return code;
} }
notifyWaitingSessions(pGroup->waitQueue); notifyWaitingSessions(pGroup->waitQueue);
if (pGroup == pSession->pGroupData) { if (pGroup == pSession->pGroupData) {
pSession->lastBlkId = newBlkBuf.blkId; pSession->lastBlkId = blkIdx;
pSession->nextOffset = newBlkBuf.offset + newBlkBuf.bufSize;
*continueFetch = false; *continueFetch = false;
} }
@ -746,7 +835,6 @@ static int32_t getBlkFromSessionCacheImpl(struct SOperatorInfo* pOperator, int64
SGroupCacheOperatorInfo* pGCache = pOperator->info; SGroupCacheOperatorInfo* pGCache = pOperator->info;
*got = true; *got = true;
if (pGCache->batchFetch) {
SGroupBatchBlkList* pBatchList = &pSession->pGroupData->batchList; SGroupBatchBlkList* pBatchList = &pSession->pGroupData->batchList;
taosRLockLatch(&pBatchList->lock); taosRLockLatch(&pBatchList->lock);
int64_t blkNum = taosArrayGetSize(pBatchList->pList); int64_t blkNum = taosArrayGetSize(pBatchList->pList);
@ -754,32 +842,18 @@ static int32_t getBlkFromSessionCacheImpl(struct SOperatorInfo* pOperator, int64
if (blkNum > 0) { if (blkNum > 0) {
SGcBlkBufBasic* pBasic = taosArrayGet(pBatchList->pList, 0); SGcBlkBufBasic* pBasic = taosArrayGet(pBatchList->pList, 0);
taosRUnLockLatch(&pBatchList->lock); taosRUnLockLatch(&pBatchList->lock);
code = retrieveBlkFromBufCache(pGCache, pSession->pGroupData, sessionId, pBasic->blkId, &pSession->nextOffset, ppRes); code = retrieveBlkFromBufCache(pGCache, pSession->pGroupData, sessionId, pBasic, ppRes);
pSession->lastBlkId = 0; pSession->lastBlkId = 0;
return code; return code;
} }
} else if ((pSession->lastBlkId + 1) < blkNum) { } else if ((pSession->lastBlkId + 1) < blkNum) {
SGcBlkBufBasic* pBasic = taosArrayGet(pBatchList->pList, pSession->lastBlkId + 1); SGcBlkBufBasic* pBasic = taosArrayGet(pBatchList->pList, pSession->lastBlkId + 1);
taosRUnLockLatch(&pBatchList->lock); taosRUnLockLatch(&pBatchList->lock);
code = retrieveBlkFromBufCache(pGCache, pSession->pGroupData, sessionId, pBasic->blkId, &pSession->nextOffset, ppRes); code = retrieveBlkFromBufCache(pGCache, pSession->pGroupData, sessionId, pBasic, ppRes);
pSession->lastBlkId++; pSession->lastBlkId++;
return code; return code;
} }
taosRUnLockLatch(&pBatchList->lock); taosRUnLockLatch(&pBatchList->lock);
} else {
if (pSession->lastBlkId < 0) {
int64_t startBlkId = atomic_load_64(&pSession->pGroupData->seqList.startBlkId);
if (startBlkId > 0) {
code = retrieveBlkFromBufCache(pGCache, pSession->pGroupData, sessionId, startBlkId, &pSession->nextOffset, ppRes);
pSession->lastBlkId = startBlkId;
return code;
}
} else if (pSession->lastBlkId < atomic_load_64(&pSession->pGroupData->seqList.endBlkId)) {
code = retrieveBlkFromBufCache(pGCache, pSession->pGroupData, sessionId, pSession->lastBlkId + 1, &pSession->nextOffset, ppRes);
pSession->lastBlkId++;
return code;
}
}
if (atomic_load_8((int8_t*)&pSession->pGroupData->fetchDone)) { if (atomic_load_8((int8_t*)&pSession->pGroupData->fetchDone)) {
*ppRes = NULL; *ppRes = NULL;
@ -897,7 +971,6 @@ static FORCE_INLINE void initGroupCacheSessionCtx(SGcSessionCtx* pSession, SGcOp
pSession->downstreamIdx = pGcParam->downstreamIdx; pSession->downstreamIdx = pGcParam->downstreamIdx;
pSession->pGroupData = pGroup; pSession->pGroupData = pGroup;
pSession->lastBlkId = -1; pSession->lastBlkId = -1;
pSession->nextOffset = 0;
} }
static int32_t initGroupCacheSession(struct SOperatorInfo* pOperator, SOperatorParam* pParam, SGcSessionCtx** ppSession) { static int32_t initGroupCacheSession(struct SOperatorInfo* pOperator, SOperatorParam* pParam, SGcSessionCtx** ppSession) {