[TD-3963]fix tsdbGetCachedLastRow:when lastRow == NULL return TSDB_CODE_TDB_NO_CACHE_LAST_ROW

src/inc/taoserror.h

@@ -244,6 +244,7 @@ int32_t* taosGetErrno();
 #define TSDB_CODE_TDB_NO_AVAIL_DISK             TAOS_DEF_ERROR_CODE(0, 0x0613)  //"No available disk")
 #define TSDB_CODE_TDB_MESSED_MSG                TAOS_DEF_ERROR_CODE(0, 0x0614)  //"TSDB messed message")
 #define TSDB_CODE_TDB_IVLD_TAG_VAL              TAOS_DEF_ERROR_CODE(0, 0x0615)  //"TSDB invalid tag value")
+#define TSDB_CODE_TDB_NO_CACHE_LAST_ROW         TAOS_DEF_ERROR_CODE(0, 0x0616)  //"TSDB no cache last row data")
 
 // query
 #define TSDB_CODE_QRY_INVALID_QHANDLE           TAOS_DEF_ERROR_CODE(0, 0x0700)  //"Invalid handle")

src/tsdb/inc/tsdbint.h

@@ -78,7 +78,6 @@ struct STsdbRepo {
   bool            config_changed; // config changed flag
   pthread_mutex_t save_mutex;     // protect save config
   
-  uint8_t         hasCachedLastRow;
   uint8_t         hasCachedLastColumn;
 
   STsdbAppH       appH;

src/tsdb/src/tsdbMain.c

@@ -553,7 +553,6 @@ static STsdbRepo *tsdbNewRepo(STsdbCfg *pCfg, STsdbAppH *pAppH) {
     return NULL;
   }
   pRepo->config_changed = false;
-  atomic_store_8(&pRepo->hasCachedLastRow, 0);
   atomic_store_8(&pRepo->hasCachedLastColumn, 0);
 
   code = tsem_init(&(pRepo->readyToCommit), 0, 1);
@@ -857,9 +856,7 @@ int tsdbRestoreInfo(STsdbRepo *pRepo) {
   }
 
   tsdbDestroyReadH(&readh);
-  if (CACHE_LAST_ROW(pCfg)) {
-    atomic_store_8(&pRepo->hasCachedLastRow, 1);
-  }
+
   if (CACHE_LAST_NULL_COLUMN(pCfg)) {
     atomic_store_8(&pRepo->hasCachedLastColumn, 1);
   }
@@ -900,9 +897,6 @@ int tsdbCacheLastData(STsdbRepo *pRepo, STsdbCfg* oldCfg) {
 
   // if close last option,need to free data
   if (need_free_last_row || need_free_last_col) {
-    if (need_free_last_row) {
-      atomic_store_8(&pRepo->hasCachedLastRow, 0);
-    }
     if (need_free_last_col) {
       atomic_store_8(&pRepo->hasCachedLastColumn, 0);
     }
@@ -982,9 +976,6 @@ int tsdbCacheLastData(STsdbRepo *pRepo, STsdbCfg* oldCfg) {
 
   tsdbDestroyReadH(&readh);
 
-  if (cacheLastRow) {
-    atomic_store_8(&pRepo->hasCachedLastRow, 1);
-  }
   if (cacheLastCol) {
     atomic_store_8(&pRepo->hasCachedLastColumn, 1);
   }

src/tsdb/src/tsdbRead.c

@@ -2469,7 +2469,6 @@ static bool loadCachedLastRow(STsdbQueryHandle* pQueryHandle) {
     if (ret != TSDB_CODE_SUCCESS) {
       return false;
     }
-
     copyOneRowFromMem(pQueryHandle, pQueryHandle->outputCapacity, 0, pRow, numOfCols, pCheckInfo->pTableObj, NULL);
     tfree(pRow);
 
@@ -2860,24 +2859,27 @@ bool tsdbGetExternalRow(TsdbQueryHandleT pHandle) {
 }
 
 /*
- * 1. no data at all (pTable->lastKey = TSKEY_INITIAL_VAL), just return TSKEY_INITIAL_VAL
- * 2. has data but not loaded, just return lastKey but not set pRes
- * 3. has data and loaded, return lastKey and set pRes
+ * if lastRow == NULL, return TSDB_CODE_TDB_NO_CACHE_LAST_ROW
+ * else set pRes and return TSDB_CODE_SUCCESS
  */
 int32_t tsdbGetCachedLastRow(STable* pTable, SDataRow* pRes, TSKEY* lastKey) {
+  int32_t code = TSDB_CODE_SUCCESS;
+
   TSDB_RLOCK_TABLE(pTable);
-  *lastKey = pTable->lastKey;
 
-  if ((*lastKey) != TSKEY_INITIAL_VAL && pTable->lastRow) {
+  if (!pTable->lastRow) {
+    code = TSDB_CODE_TDB_NO_CACHE_LAST_ROW;
+    goto out;
+  }
+
   *pRes = tdDataRowDup(pTable->lastRow);
   if (*pRes == NULL) {
-      TSDB_RUNLOCK_TABLE(pTable);
-      return TSDB_CODE_TDB_OUT_OF_MEMORY;
-    }
+    code = TSDB_CODE_TDB_OUT_OF_MEMORY;
   }
 
+out:
   TSDB_RUNLOCK_TABLE(pTable);
-  return TSDB_CODE_SUCCESS;
+  return code;
 }
 
 bool isTsdbCacheLastRow(TsdbQueryHandleT* pQueryHandle) {