enh(query): stop tsdb reader ASAP.

source/dnode/vnode/src/tsdb/tsdbRead.c

@@ -197,7 +197,6 @@ struct STsdbReader {
   SVersionRange      verRange;
   TdThreadMutex      readerMutex;
   EReaderExecStatus  flag;
-//  bool               suspended;
   uint64_t           suid;
   int16_t            order;
   EReadMode          readMode;
@@ -2995,9 +2994,15 @@ static int32_t moveToNextFile(STsdbReader* pReader, SBlockNumber* pBlockNum, SAr
   SArray* pIndexList = taosArrayInit(numOfTables, sizeof(SBlockIdx));
 
   while (1) {
+    // only check here, since the iterate data in memory is very fast.
+    if (pReader->flag == READER_STATUS_SHOULD_STOP) {
+      tsdbWarn("tsdb reader is stopped ASAP, %s", pReader->idStr);
+      return TSDB_CODE_SUCCESS;
+    }
+
     bool    hasNext = false;
     int32_t code = filesetIteratorNext(&pStatus->fileIter, pReader, &hasNext);
-    if (code) {
+    if (code != TSDB_CODE_SUCCESS) {
       taosArrayDestroy(pIndexList);
       return code;
     }
@@ -3088,6 +3093,11 @@ static int32_t doLoadLastBlockSequentially(STsdbReader* pReader) {
   SSDataBlock* pResBlock = pReader->resBlockInfo.pResBlock;
 
   while (1) {
+    if (pReader->flag == READER_STATUS_SHOULD_STOP) {
+      tsdbWarn("tsdb reader is stopped ASAP, %s", pReader->idStr);
+      return TSDB_CODE_SUCCESS;
+    }
+
     // load the last data block of current table
     STableBlockScanInfo* pScanInfo = *(STableBlockScanInfo**)pStatus->pTableIter;
 
@@ -5425,3 +5435,5 @@ void tsdbReaderSetId(STsdbReader* pReader, const char* idstr) {
   taosMemoryFreeClear(pReader->idStr);
   pReader->idStr = taosStrdup(idstr);
 }
+
+void tsdbReaderSetCloseFlag(STsdbReader* pReader) { pReader->flag = READER_STATUS_SHOULD_STOP; }