From f76261dcb567fcdd89e561a9a62fde0a5c3f5666 Mon Sep 17 00:00:00 2001
From: Shengliang Guan <slguan@taosdata.com>
Date: Tue, 18 Oct 2022 12:31:15 +0800
Subject: [PATCH] fix: become leader if replica num is 1

---
 source/dnode/mnode/impl/src/mndMain.c  | 19 ++++++++++++-------
 source/dnode/mnode/impl/src/mndMnode.c |  6 ++++++
 source/libs/sync/src/syncElection.c    | 13 +++++++++++++
 source/libs/sync/src/syncMain.c        |  2 +-
 4 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/source/dnode/mnode/impl/src/mndMain.c b/source/dnode/mnode/impl/src/mndMain.c
index 5fb23b045c..8314601df3 100644
--- a/source/dnode/mnode/impl/src/mndMain.c
+++ b/source/dnode/mnode/impl/src/mndMain.c
@@ -603,22 +603,27 @@ static int32_t mndCheckMnodeState(SRpcMsg *pMsg) {
     return 0;
   }
   if (mndAcquireRpc(pMsg->info.node) == 0) return 0;
+
+  SMnode     *pMnode = pMsg->info.node;
+  const char *role = syncGetMyRoleStr(pMnode->syncMgmt.sync);
+  bool        restored = syncIsRestoreFinish(pMnode->syncMgmt.sync);
   if (pMsg->msgType == TDMT_MND_MQ_TIMER || pMsg->msgType == TDMT_MND_TELEM_TIMER ||
       pMsg->msgType == TDMT_MND_TRANS_TIMER || pMsg->msgType == TDMT_MND_TTL_TIMER ||
       pMsg->msgType == TDMT_MND_UPTIME_TIMER) {
+    mTrace("timer not process since mnode restored:%d stopped:%d, sync restored:%d role:%s ", pMnode->restored,
+           pMnode->stopped, restored, role);
     return -1;
   }
 
-  SEpSet  epSet = {0};
-  SMnode *pMnode = pMsg->info.node;
+  const STraceId *trace = &pMsg->info.traceId;
+  SEpSet          epSet = {0};
   mndGetMnodeEpSet(pMnode, &epSet);
 
-  const STraceId *trace = &pMsg->info.traceId;
   mDebug(
-      "msg:%p, failed to check mnode state since %s, mnode restored:%d stopped:%d, sync restored:%d role:%s type:%s "
-      "numOfEps:%d inUse:%d",
-      pMsg, terrstr(), pMnode->restored, pMnode->stopped, syncIsRestoreFinish(pMnode->syncMgmt.sync),
-      syncGetMyRoleStr(pMnode->syncMgmt.sync), TMSG_INFO(pMsg->msgType), epSet.numOfEps, epSet.inUse);
+      "msg:%p, type:%s failed to process since %s, mnode restored:%d stopped:%d, sync restored:%d "
+      "role:%s, redirect numOfEps:%d inUse:%d",
+      pMsg, TMSG_INFO(pMsg->msgType), terrstr(), pMnode->restored, pMnode->stopped, restored, role, epSet.numOfEps,
+      epSet.inUse);
 
   if (epSet.numOfEps > 0) {
     for (int32_t i = 0; i < epSet.numOfEps; ++i) {
diff --git a/source/dnode/mnode/impl/src/mndMnode.c b/source/dnode/mnode/impl/src/mndMnode.c
index 63ce538536..f25d436aee 100644
--- a/source/dnode/mnode/impl/src/mndMnode.c
+++ b/source/dnode/mnode/impl/src/mndMnode.c
@@ -747,7 +747,13 @@ static void mndReloadSyncConfig(SMnode *pMnode) {
   }
 
   if (cfg.myIndex == -1) {
+#if 1
     mInfo("vgId:1, mnode sync not reconfig since selfIndex is -1");
+#else
+    // cannot reconfig because the leader may fail to elect after reboot
+    mInfo("vgId:1, mnode sync not reconfig since selfIndex is -1, do sync stop oper");
+    syncStop(pMnode->syncMgmt.sync);
+#endif
     return;
   }
 
diff --git a/source/libs/sync/src/syncElection.c b/source/libs/sync/src/syncElection.c
index 375f2e5730..3f13249ce6 100644
--- a/source/libs/sync/src/syncElection.c
+++ b/source/libs/sync/src/syncElection.c
@@ -96,6 +96,19 @@ int32_t syncNodeElect(SSyncNode* pSyncNode) {
     syncNodeCandidate2Leader(pSyncNode);
     pSyncNode->pVotesGranted->toLeader = true;
     return ret;
+  } 
+
+  if (pSyncNode->replicaNum == 1) {
+    // only myself, to leader
+    voteGrantedUpdate(pSyncNode->pVotesGranted, pSyncNode);
+    votesRespondUpdate(pSyncNode->pVotesRespond, pSyncNode);
+
+    pSyncNode->quorum = syncUtilQuorum(pSyncNode->pRaftCfg->cfg.replicaNum);
+
+    syncNodeCandidate2Leader(pSyncNode);
+    pSyncNode->pVotesGranted->toLeader = true;
+    return ret;
+
   }
 
   switch (pSyncNode->pRaftCfg->snapshotStrategy) {
diff --git a/source/libs/sync/src/syncMain.c b/source/libs/sync/src/syncMain.c
index b255d83933..83bd7a5f38 100644
--- a/source/libs/sync/src/syncMain.c
+++ b/source/libs/sync/src/syncMain.c
@@ -2282,7 +2282,7 @@ void syncNodeBecomeLeader(SSyncNode* pSyncNode, const char* debugStr) {
 
 void syncNodeCandidate2Leader(SSyncNode* pSyncNode) {
   ASSERT(pSyncNode->state == TAOS_SYNC_STATE_CANDIDATE);
-  ASSERT(voteGrantedMajority(pSyncNode->pVotesGranted));
+  //ASSERT(voteGrantedMajority(pSyncNode->pVotesGranted));
   syncNodeBecomeLeader(pSyncNode, "candidate to leader");
 
   syncNodeLog2("==state change syncNodeCandidate2Leader==", pSyncNode);