schedule: fix split-merge-interval update (#8405)

close #8404

Signed-off-by: lhy1024 <admin@liudos.us>

Co-authored-by: ti-chi-bot[bot] <108142056+ti-chi-bot[bot]@users.noreply.github.com>

pkg/schedule/checker/merge_checker.go

@@ -46,6 +46,8 @@ const (
 	mergeOptionValueDeny = "deny"
 )
 
+var gcInterval = time.Minute
+
 // MergeChecker ensures region to merge with adjacent region when size is small
 type MergeChecker struct {
 	PauseController
@@ -57,7 +59,7 @@ type MergeChecker struct {
 
 // NewMergeChecker creates a merge checker.
 func NewMergeChecker(ctx context.Context, cluster sche.CheckerCluster, conf config.CheckerConfigProvider) *MergeChecker {
-	splitCache := cache.NewIDTTL(ctx, time.Minute, conf.GetSplitMergeInterval())
+	splitCache := cache.NewIDTTL(ctx, gcInterval, conf.GetSplitMergeInterval())
 	return &MergeChecker{
 		cluster:    cluster,
 		conf:       conf,
@@ -88,13 +90,16 @@ func (m *MergeChecker) Check(region *core.RegionInfo) []*operator.Operator {
 		return nil
 	}
 
+	// update the split cache.
+	// It must be called before the following merge checker logic.
+	m.splitCache.UpdateTTL(m.conf.GetSplitMergeInterval())
+
 	expireTime := m.startTime.Add(m.conf.GetSplitMergeInterval())
 	if time.Now().Before(expireTime) {
 		mergeCheckerRecentlyStartCounter.Inc()
 		return nil
 	}
 
-	m.splitCache.UpdateTTL(m.conf.GetSplitMergeInterval())
 	if m.splitCache.Exists(region.GetID()) {
 		mergeCheckerRecentlySplitCounter.Inc()
 		return nil

pkg/schedule/checker/merge_checker_test.go

@@ -56,6 +56,7 @@ func TestMergeCheckerTestSuite(t *testing.T) {
 
 func (suite *mergeCheckerTestSuite) SetupTest() {
 	cfg := mockconfig.NewTestOptions()
+	gcInterval = 100 * time.Millisecond
 	suite.ctx, suite.cancel = context.WithCancel(context.Background())
 	suite.cluster = mockcluster.NewCluster(suite.ctx, cfg)
 	suite.cluster.SetMaxMergeRegionSize(2)
@@ -84,6 +85,7 @@ func (suite *mergeCheckerTestSuite) SetupTest() {
 }
 
 func (suite *mergeCheckerTestSuite) TearDownTest() {
+	gcInterval = time.Minute
 	suite.cancel()
 }
 
@@ -234,6 +236,7 @@ func (suite *mergeCheckerTestSuite) TestBasic() {
 	ops = suite.mc.Check(suite.regions[3])
 	re.Nil(ops)
 
+	// issue #4616
 	suite.cluster.SetSplitMergeInterval(500 * time.Millisecond)
 	ops = suite.mc.Check(suite.regions[2])
 	re.Nil(ops)
@@ -245,6 +248,19 @@ func (suite *mergeCheckerTestSuite) TestBasic() {
 	re.NotNil(ops)
 	ops = suite.mc.Check(suite.regions[3])
 	re.NotNil(ops)
+
+	// issue #8405
+	suite.mc.startTime = time.Now()
+	suite.cluster.SetSplitMergeInterval(time.Second)
+	suite.cluster.SetSplitMergeInterval(time.Hour)
+	suite.mc.RecordRegionSplit([]uint64{suite.regions[2].GetID()})
+	suite.cluster.SetSplitMergeInterval(time.Second)
+	suite.mc.Check(suite.regions[2]) // trigger the config update
+	time.Sleep(time.Second)          // wait for the cache to gc
+	ops = suite.mc.Check(suite.regions[2])
+	re.NotNil(ops)
+	ops = suite.mc.Check(suite.regions[3])
+	re.NotNil(ops)
 }
 
 func (suite *mergeCheckerTestSuite) TestMatchPeers() {