cache/dclp: double check to load from tsdb

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

@@ -190,6 +190,25 @@ void tsdbCacheSerialize(SLastCol *pLastCol, char **value, size_t *size) {
   *size = length;
 }
 
+static SLastCol *tsdbCacheLookup(STsdb *pTsdb, tb_uid_t uid, int16_t cid, char const *lstring) {
+  SLastCol *pLastCol = NULL;
+
+  char  *err = NULL;
+  size_t vlen = 0;
+  char   key[ROCKS_KEY_LEN];
+  size_t klen = snprintf(key, ROCKS_KEY_LEN, "%" PRIi64 ":%" PRIi16 ":%s", uid, cid, lstring);
+  char  *value = NULL;
+  value = rocksdb_get(pTsdb->rCache.db, pTsdb->rCache.readoptions, key, klen, &vlen, &err);
+  if (NULL != err) {
+    tsdbError("vgId:%d, %s failed at line %d since %s", TD_VID(pTsdb->pVnode), __func__, __LINE__, err);
+    rocksdb_free(err);
+  }
+
+  pLastCol = tsdbCacheDeserialize(value);
+
+  return pLastCol;
+}
+
 int32_t tsdbCacheUpdate(STsdb *pTsdb, tb_uid_t suid, tb_uid_t uid, TSDBROW *pRow) {
   int32_t code = 0;
 
@@ -362,6 +381,7 @@ int32_t tsdbCacheGet(STsdb *pTsdb, tb_uid_t uid, SArray *pLastArray, SCacheRowsR
   taosMemoryFree(errs);
 
   for (int i = 0; i < num_keys; ++i) {
+    bool      freeCol = true;
     SArray   *pTmpColArray = NULL;
     SLastCol *pLastCol = tsdbCacheDeserialize(values_list[i]);
     int16_t   cid = *(int16_t *)taosArrayGet(pCidList, i);
@@ -376,48 +396,59 @@ int32_t tsdbCacheGet(STsdb *pTsdb, tb_uid_t uid, SArray *pLastArray, SCacheRowsR
         }
       }
     } else {
-      // recalc: load from tsdb
-      int16_t aCols[1] = {cid};
-      int16_t slotIds[1] = {pr->pSlotIds[i]};
-      pTmpColArray = NULL;
+      taosThreadMutexLock(&pTsdb->rCache.rMutex);
 
-      if (ltype) {
-        mergeLastCid(uid, pTsdb, &pTmpColArray, pr, aCols, 1, slotIds);
-      } else {
-        mergeLastRowCid(uid, pTsdb, &pTmpColArray, pr, aCols, 1, slotIds);
-      }
+      pLastCol = tsdbCacheLookup(pTsdb, uid, cid, lstring);
+      if (!pLastCol) {
+        // recalc: load from tsdb
+        int16_t aCols[1] = {cid};
+        int16_t slotIds[1] = {pr->pSlotIds[i]};
+        pTmpColArray = NULL;
 
-      if (pTmpColArray && TARRAY_SIZE(pTmpColArray) >= 1) {
-        pLastCol = taosArrayGet(pTmpColArray, 0);
-      }
+        if (ltype) {
+          mergeLastCid(uid, pTsdb, &pTmpColArray, pr, aCols, 1, slotIds);
+        } else {
+          mergeLastRowCid(uid, pTsdb, &pTmpColArray, pr, aCols, 1, slotIds);
+        }
 
-      // still null, then make up a none col value
-      if (!pLastCol) {
-        pLastCol = &noneCol;
-      }
+        if (pTmpColArray && TARRAY_SIZE(pTmpColArray) >= 1) {
+          pLastCol = taosArrayGet(pTmpColArray, 0);
+        }
 
-      // store result back to rocks cache
-      rocksdb_writebatch_t *wb = pTsdb->rCache.writebatch;
-      char                 *value = NULL;
-      size_t                vlen = 0;
-      tsdbCacheSerialize(pLastCol, &value, &vlen);
-      char   key[ROCKS_KEY_LEN];
-      size_t klen = snprintf(key, ROCKS_KEY_LEN, "%" PRIi64 ":%" PRIi16 ":last", uid, pLastCol->colVal.cid);
-      rocksdb_writebatch_put(wb, key, klen, value, vlen);
-      char *err = NULL;
-      rocksdb_write(pTsdb->rCache.db, pTsdb->rCache.writeoptions, wb, &err);
-      if (NULL != err) {
-        tsdbError("vgId:%d, %s failed at line %d since %s", TD_VID(pTsdb->pVnode), __func__, __LINE__, err);
-        rocksdb_free(err);
+        // still null, then make up a none col value
+        if (!pLastCol) {
+          pLastCol = &noneCol;
+          freeCol = false;
+        }
+
+        // store result back to rocks cache
+        rocksdb_writebatch_t *wb = pTsdb->rCache.writebatch;
+        char                 *value = NULL;
+        size_t                vlen = 0;
+        tsdbCacheSerialize(pLastCol, &value, &vlen);
+        char   key[ROCKS_KEY_LEN];
+        size_t klen = snprintf(key, ROCKS_KEY_LEN, "%" PRIi64 ":%" PRIi16 ":%s", uid, pLastCol->colVal.cid, lstring);
+        rocksdb_writebatch_put(wb, key, klen, value, vlen);
+
+        taosMemoryFree(value);
+
+        char *err = NULL;
+        rocksdb_write(pTsdb->rCache.db, pTsdb->rCache.writeoptions, wb, &err);
+        if (NULL != err) {
+          tsdbError("vgId:%d, %s failed at line %d since %s", TD_VID(pTsdb->pVnode), __func__, __LINE__, err);
+          rocksdb_free(err);
+        }
       }
 
-      taosMemoryFree(value);
+      taosThreadMutexUnlock(&pTsdb->rCache.rMutex);
     }
 
     taosArrayPush(pLastArray, pLastCol);
 
     taosArrayDestroy(pTmpColArray);
-    taosMemoryFree(values_list[i]);
+    if (freeCol) {
+      taosMemoryFree(pLastCol);
+    }
   }
   taosMemoryFree(values_list);
   taosMemoryFree(values_list_sizes);