enh: reduce retryBackoff if first timeMs less than last one for half the current retryWaitMs

source/libs/sync/src/syncPipeline.c

@@ -843,6 +843,14 @@ int32_t syncLogReplMgrReplicateAttemptedOnce(SSyncLogReplMgr* pMgr, SSyncNode* p
 int32_t syncLogReplMgrProcessReplyInNormalMode(SSyncLogReplMgr* pMgr, SSyncNode* pNode, SyncAppendEntriesReply* pMsg) {
   ASSERT(pMgr->restored == true);
   if (pMgr->startIndex <= pMsg->lastSendIndex && pMsg->lastSendIndex < pMgr->endIndex) {
+     if (pMgr->startIndex < pMgr->matchIndex && pMgr->retryBackoff > 0) {
+        int64_t firstSentMs = pMgr->states[pMgr->startIndex % pMgr->size].timeMs;
+        int64_t lastSentMs = pMgr->states[(pMgr->endIndex - 1) % pMgr->size].timeMs;
+        int64_t timeDiffMs = lastSentMs - firstSentMs;
+        if (timeDiffMs > 0 && timeDiffMs < (SYNC_LOG_REPL_RETRY_WAIT_MS << (pMgr->retryBackoff - 1))) {
+            pMgr->retryBackoff -= 1;
+        }
+    }
     pMgr->states[pMsg->lastSendIndex % pMgr->size].acked = true;
     pMgr->matchIndex = TMAX(pMgr->matchIndex, pMsg->matchIndex);
     for (SyncIndex index = pMgr->startIndex; index < pMgr->matchIndex; index++) {