refactor: review syncNodeAppendEntriesPeersSnapshot

source/libs/sync/src/syncMain.c

@@ -1169,7 +1169,15 @@ void syncNodeBecomeLeader(SSyncNode* pSyncNode) {
   for (int i = 0; i < pSyncNode->pNextIndex->replicaNum; ++i) {
     // maybe overwrite myself, no harm
     // just do it!
-    pSyncNode->pNextIndex->index[i] = pSyncNode->pLogStore->getLastIndex(pSyncNode->pLogStore) + 1;
+
+    // pSyncNode->pNextIndex->index[i] = pSyncNode->pLogStore->getLastIndex(pSyncNode->pLogStore) + 1;
+
+    // maybe wal is deleted
+    SyncIndex lastIndex;
+    SyncTerm  lastTerm;
+    int32_t   code = syncNodeGetLastIndexTerm(pSyncNode, &lastIndex, &lastTerm);
+    ASSERT(code == 0);
+    pSyncNode->pNextIndex->index[i] = lastIndex + 1;
   }
 
   for (int i = 0; i < pSyncNode->pMatchIndex->replicaNum; ++i) {
@@ -1299,9 +1307,13 @@ int32_t syncNodeGetPreIndexTerm(SSyncNode* pSyncNode, SyncIndex index, SyncIndex
     *pPreTerm = snapshot.lastApplyTerm;
   } else {
     SSyncRaftEntry* pPreEntry = pSyncNode->pLogStore->getEntry(pSyncNode->pLogStore, preIndex);
-    ASSERT(pPreEntry != NULL);
-    *pPreIndex = pPreEntry->index;
-    *pPreTerm = pPreEntry->term;
+    if (pPreEntry != NULL) {
+      *pPreIndex = pPreEntry->index;
+      *pPreTerm = pPreEntry->term;
+    } else {
+      *pPreIndex = SYNC_INDEX_INVALID;
+      *pPreTerm = 0;
+    }
   }
 
   return 0;

source/libs/sync/src/syncReplication.c

@@ -126,7 +126,6 @@ int32_t syncNodeAppendEntriesPeersSnapshot(SSyncNode* pSyncNode) {
   for (int i = 0; i < pSyncNode->peersNum; ++i) {
     SRaftId* pDestId = &(pSyncNode->peersId[i]);
 
-    // set prevLogIndex
     SyncIndex nextIndex = syncIndexMgrGetIndex(pSyncNode->pNextIndex, pDestId);
 
     SyncIndex preLogIndex;
@@ -139,6 +138,12 @@ int32_t syncNodeAppendEntriesPeersSnapshot(SSyncNode* pSyncNode) {
     // SyncIndex lastIndex = syncUtilMinIndex(pSyncNode->pLogStore->getLastIndex(pSyncNode->pLogStore), nextIndex);
 
     if (syncNodeIsIndexInSnapshot(pSyncNode, nextIndex)) {
+      // will send this msg until snapshot receive finish!
+      SSnapshot snapshot;
+      pSyncNode->pFsm->FpGetSnapshot(pSyncNode->pFsm, &snapshot);
+      sInfo("nextIndex:%ld in snapshot: <lastApplyIndex:%ld, lastApplyTerm:%lu>, begin snapshot", nextIndex,
+            snapshot.lastApplyIndex, snapshot.lastApplyTerm);
+
       // to claim leader
       SyncAppendEntries* pMsg = syncAppendEntriesBuild(0, pSyncNode->vgId);
       assert(pMsg != NULL);
@@ -163,7 +168,6 @@ int32_t syncNodeAppendEntriesPeersSnapshot(SSyncNode* pSyncNode) {
         }
       }
       ASSERT(pSender != NULL);
-
       snapshotSenderStart(pSender);
 
     } else {