Merge pull request #4063 from taosdata/patch/rpc-race

remove an invalid/read

go @ 8c58c512

-Subproject commit 8d7bf743852897110cbdcc7c4322cd7a74d4167b
+Subproject commit 8c58c512b6acda8bcdfa48fdc7140227b5221766

src/rpc/src/rpcMain.c

@@ -557,10 +557,7 @@ void rpcCancelRequest(void *handle) {
   int code = taosAcquireRef(tsRpcRefId, pContext);
   if (code < 0) return;
 
-  if (pContext->pConn) {
-    tDebug("%s, app tries to cancel request", pContext->pConn->info);
   rpcCloseConn(pContext->pConn);
-  }
 
   taosReleaseRef(tsRpcRefId, pContext);
 }
@@ -655,6 +652,7 @@ static void rpcReleaseConn(SRpcConn *pConn) {
 
 static void rpcCloseConn(void *thandle) {
   SRpcConn *pConn = (SRpcConn *)thandle;
+  if (pConn == NULL) return;
 
   rpcLockConn(pConn);
 
@@ -1026,6 +1024,7 @@ static void rpcProcessBrokenLink(SRpcConn *pConn) {
   if (pConn->outType) {
     SRpcReqContext *pContext = pConn->pContext;
     pContext->code = TSDB_CODE_RPC_NETWORK_UNAVAIL;
+    pContext->pConn = NULL;
     pConn->pReqMsg = NULL;
     taosTmrStart(rpcProcessConnError, 0, pContext, pRpc->tmrCtrl);
   }
@@ -1135,6 +1134,7 @@ static void rpcProcessIncomingMsg(SRpcConn *pConn, SRpcHead *pHead, SRpcReqConte
     // it's a response
     rpcMsg.handle = pContext;
     rpcMsg.ahandle = pContext->ahandle;
+    pContext->pConn = NULL;
 
     // for UDP, port may be changed by server, the port in epSet shall be used for cache
     if (pHead->code != TSDB_CODE_RPC_TOO_SLOW) {
@@ -1370,6 +1370,7 @@ static void rpcProcessRetryTimer(void *param, void *tmrId) {
       tDebug("%s, failed to send msg:%s to %s:%hu", pConn->info, taosMsg[pConn->outType], pConn->peerFqdn, pConn->peerPort);
       if (pConn->pContext) {
         pConn->pContext->code = TSDB_CODE_RPC_NETWORK_UNAVAIL;
+        pConn->pContext->pConn = NULL;
         pConn->pReqMsg = NULL;
         taosTmrStart(rpcProcessConnError, 0, pConn->pContext, pRpc->tmrCtrl);
         rpcReleaseConn(pConn);