fix: allow to rollback sync log buffer beyond startIndex with refill

source/libs/sync/src/syncPipeline.c

@@ -275,6 +275,8 @@ int32_t syncLogBufferAccept(SSyncLogBuffer* pBuf, SSyncNode* pNode, SSyncRaftEnt
   SyncIndex index = pEntry->index;
   SyncIndex prevIndex = pEntry->index - 1;
   SyncTerm  lastMatchTerm = syncLogBufferGetLastMatchTerm(pBuf);
+  SSyncRaftEntry* pExist = NULL;
+  bool            inBuf = true;
 
   if (index <= pBuf->commitIndex) {
     sTrace("vgId:%d, already committed. index: %" PRId64 ", term: %" PRId64 ". log buffer: [%" PRId64 " %" PRId64
@@ -306,10 +308,9 @@ int32_t syncLogBufferAccept(SSyncLogBuffer* pBuf, SSyncNode* pNode, SSyncRaftEnt
   }
 
   // check current in buffer
-  SSyncRaftEntry* pExist = pBuf->entries[index % pBuf->size].pItem;
+  pExist = syncLogBufferGetOneEntry(pBuf, pNode, index, &inBuf);
   if (pExist != NULL) {
     ASSERT(pEntry->index == pExist->index);
-
     if (pEntry->term != pExist->term) {
       (void)syncLogBufferRollback(pBuf, pNode, index);
     } else {
@@ -317,14 +318,15 @@ int32_t syncLogBufferAccept(SSyncLogBuffer* pBuf, SSyncNode* pNode, SSyncRaftEnt
              " %" PRId64 " %" PRId64 ", %" PRId64 ")",
              pNode->vgId, pEntry->index, pEntry->term, pBuf->startIndex, pBuf->commitIndex, pBuf->matchIndex,
              pBuf->endIndex);
-      SyncTerm existPrevTerm = pBuf->entries[index % pBuf->size].prevLogTerm;
-      ASSERT(pEntry->term == pExist->term && prevTerm == existPrevTerm);
+      SyncTerm existPrevTerm = syncLogReplMgrGetPrevLogTerm(NULL, pNode, index);
+      ASSERT(pEntry->term == pExist->term && (pEntry->index > pBuf->matchIndex || prevTerm == existPrevTerm));
       ret = 0;
       goto _out;
     }
   }
 
   // update
+  ASSERT(pBuf->entries[index % pBuf->size].pItem == NULL);
   SSyncLogBufEntry tmp = {.pItem = pEntry, .prevLogIndex = prevIndex, .prevLogTerm = prevTerm};
   pEntry = NULL;
   pBuf->entries[index % pBuf->size] = tmp;
@@ -337,6 +339,10 @@ int32_t syncLogBufferAccept(SSyncLogBuffer* pBuf, SSyncNode* pNode, SSyncRaftEnt
 
 _out:
   syncEntryDestroy(pEntry);
+  if (!inBuf) {
+    syncEntryDestroy(pExist);
+    pExist = NULL;
+  }
   syncLogBufferValidate(pBuf);
   taosThreadMutexUnlock(&pBuf->mutex);
   return ret;
@@ -1003,6 +1009,16 @@ int32_t syncLogBufferRollback(SSyncLogBuffer* pBuf, SSyncNode* pNode, SyncIndex
   lastVer = pNode->pLogStore->syncLogLastIndex(pNode->pLogStore);
   ASSERT(toIndex == lastVer + 1);
 
+  // refill buffer on need
+  if (toIndex <= pBuf->startIndex) {
+    int32_t ret = syncLogBufferInitWithoutLock(pBuf, pNode);
+    if (ret < 0) {
+      sError("vgId:%d, failed to refill sync log buffer since %s", pNode->vgId, terrstr());
+      return -1;
+    }
+  }
+
+  ASSERT(pBuf->endIndex == toIndex);
   syncLogBufferValidate(pBuf);
   return 0;
 }