From 6a2672c0619e3d2cfbfe61273413d764e0307315 Mon Sep 17 00:00:00 2001
From: Lynn <zimu_xia@126.com>
Date: Mon, 31 Jul 2023 11:50:19 +0800
Subject: [PATCH] ddl: simply refactor the code called "needCheckClusterState"
 (#45660)

ref pingcap/tidb#39751
---
 ddl/job_table.go | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/ddl/job_table.go b/ddl/job_table.go
index e2caff2a74b08..fd1bb28ff0b13 100644
--- a/ddl/job_table.go
+++ b/ddl/job_table.go
@@ -266,7 +266,7 @@ func (d *ddl) startDispatchLoop() {
 		notifyDDLJobByEtcdCh = d.etcdCli.Watch(d.ctx, addingDDLJobConcurrent)
 	}
 	ticker := time.NewTicker(dispatchLoopWaitingDuration)
-	if err := d.doCheckClusterState(false); err != nil {
+	if err := d.checkAndUpdateClusterState(true); err != nil {
 		logutil.BgLogger().Fatal("dispatch loop get cluster state failed, it should not happen, please try restart TiDB", zap.Error(err))
 	}
 	defer ticker.Stop()
@@ -294,7 +294,7 @@ func (d *ddl) startDispatchLoop() {
 		case <-d.ctx.Done():
 			return
 		}
-		if err := d.needCheckClusterState(isOnce); err != nil {
+		if err := d.checkAndUpdateClusterState(isOnce); err != nil {
 			continue
 		}
 		isOnce = false
@@ -303,23 +303,17 @@ func (d *ddl) startDispatchLoop() {
 	}
 }
 
-func (d *ddl) needCheckClusterState(mustCheck bool) error {
+func (d *ddl) checkAndUpdateClusterState(needUpdate bool) error {
 	select {
 	case _, ok := <-d.stateSyncer.WatchChan():
-		return d.doCheckClusterState(!ok)
+		if !ok {
+			d.stateSyncer.Rewatch(d.ctx)
+		}
 	default:
-		if mustCheck {
-			return d.doCheckClusterState(false)
+		if !needUpdate {
+			return nil
 		}
 	}
-	return nil
-}
-
-func (d *ddl) doCheckClusterState(needRewatch bool) error {
-	if needRewatch {
-		d.stateSyncer.Rewatch(d.ctx)
-		return nil
-	}
 
 	oldState := d.stateSyncer.IsUpgradingState()
 	stateInfo, err := d.stateSyncer.GetGlobalState(d.ctx)