refactor: get sdb snapshot in atomic way

source/dnode/mnode/impl/src/mndSync.c

@@ -75,12 +75,10 @@ void mndSyncCommitMsg(struct SSyncFSM *pFsm, const SRpcMsg *pMsg, SFsmCbMeta cbM
 }
 
 int32_t mndSyncGetSnapshot(struct SSyncFSM *pFsm, SSnapshot *pSnapshot, void *pReaderParam, void **ppReader) {
-  // TODO:
-
-  // atomic operation
-  // step1. sdbGetCommitInfo
-  // step2. create ppReader with pReaderParam
-
+  mInfo("start to read snapshot from sdb in atomic way");
+  SMnode *pMnode = pFsm->data;
+  return sdbStartRead(pMnode->pSdb, (SSdbIter **)ppReader, &pSnapshot->lastApplyIndex, &pSnapshot->lastApplyTerm,
+                      &pSnapshot->lastConfigIndex);
   return 0;
 }
 
@@ -106,14 +104,6 @@ void mndReConfig(struct SSyncFSM *pFsm, const SRpcMsg *pMsg, SReConfigCbMeta cbM
   SMnode    *pMnode = pFsm->data;
   SSyncMgmt *pMgmt = &pMnode->syncMgmt;
 
-#if 0
-// send response
-  SRpcMsg rpcMsg = {.msgType = pMsg->msgType, .contLen = pMsg->contLen, .conn.applyIndex = cbMeta.index};
-  rpcMsg.pCont = rpcMallocCont(rpcMsg.contLen);
-  memcpy(rpcMsg.pCont, pMsg->pCont, pMsg->contLen);
-  syncGetAndDelRespRpc(pMnode->syncMgmt.sync, cbMeta.seqNum, &rpcMsg.info);
-#endif
-
   pMgmt->errCode = cbMeta.code;
   mInfo("trans:-1, sync reconfig is proposed, saved:%d code:0x%x, index:%" PRId64 " term:%" PRId64, pMgmt->transId,
         cbMeta.code, cbMeta.index, cbMeta.term);
@@ -130,7 +120,7 @@ void mndReConfig(struct SSyncFSM *pFsm, const SRpcMsg *pMsg, SReConfigCbMeta cbM
 int32_t mndSnapshotStartRead(struct SSyncFSM *pFsm, void **ppReader) {
   mInfo("start to read snapshot from sdb");
   SMnode *pMnode = pFsm->data;
-  return sdbStartRead(pMnode->pSdb, (SSdbIter **)ppReader);
+  return sdbStartRead(pMnode->pSdb, (SSdbIter **)ppReader, NULL, NULL, NULL);
 }
 
 int32_t mndSnapshotStopRead(struct SSyncFSM *pFsm, void *pReader) {

source/dnode/mnode/impl/test/sdb/sdbTest.cpp

@@ -910,7 +910,7 @@ TEST_F(MndTestSdb, 01_Read_Str) {
     int32_t   len = 0;
     int32_t   code = 0;
 
-    code = sdbStartRead(pSdb, &pReader);
+    code = sdbStartRead(pSdb, &pReader, NULL, NULL, NULL);
     ASSERT_EQ(code, 0);
     code = sdbStartWrite(pSdb, &pWritter);
     ASSERT_EQ(code, 0);

source/dnode/mnode/sdb/inc/sdb.h

@@ -388,7 +388,7 @@ SSdbRow *sdbAllocRow(int32_t objSize);
 void    *sdbGetRowObj(SSdbRow *pRow);
 void     sdbFreeRow(SSdb *pSdb, SSdbRow *pRow, bool callFunc);
 
-int32_t sdbStartRead(SSdb *pSdb, SSdbIter **ppIter);
+int32_t sdbStartRead(SSdb *pSdb, SSdbIter **ppIter, int64_t *index, int64_t *term, int64_t *config);
 int32_t sdbStopRead(SSdb *pSdb, SSdbIter *pIter);
 int32_t sdbDoRead(SSdb *pSdb, SSdbIter *pIter, void **ppBuf, int32_t *len);
 

source/dnode/mnode/sdb/src/sdbFile.c

@@ -523,7 +523,7 @@ static void sdbCloseIter(SSdbIter *pIter) {
   taosMemoryFree(pIter);
 }
 
-int32_t sdbStartRead(SSdb *pSdb, SSdbIter **ppIter) {
+int32_t sdbStartRead(SSdb *pSdb, SSdbIter **ppIter, int64_t *index, int64_t *term, int64_t *config) {
   SSdbIter *pIter = sdbCreateIter(pSdb);
   if (pIter == NULL) return -1;
 
@@ -552,6 +552,10 @@ int32_t sdbStartRead(SSdb *pSdb, SSdbIter **ppIter) {
   }
 
   *ppIter = pIter;
+  if (index != NULL) *index = commitIndex;
+  if (term != NULL) *term = commitTerm;
+  if (config != NULL) *config = commitConfig;
+
   mInfo("sdbiter:%p, is created to read snapshot, commit index:%" PRId64 " term:%" PRId64 " config:%" PRId64 " file:%s",
         pIter, commitIndex, commitTerm, commitConfig, pIter->name);
   return 0;