statistics: fix data race in IsRegionHot (#8336)

close #8335

Signed-off-by: lhy1024 <[email protected]>

pkg/statistics/hot_cache.go

@@ -113,18 +113,20 @@ func (w *HotCache) IsRegionHot(region *core.RegionInfo, minHotDegree int) bool {
 	succ1 := w.CheckWriteAsync(checkRegionHotWriteTask)
 	succ2 := w.CheckReadAsync(checkRegionHotReadTask)
 	if succ1 && succ2 {
-		select {
-		case <-w.ctx.Done():
-			return false
-		case r := <-retWrite:
-			return r
-		case r := <-retRead:
-			return r
-		}
+		return waitRet(w.ctx, retWrite) || waitRet(w.ctx, retRead)
 	}
 	return false
 }
 
+func waitRet(ctx context.Context, ret chan bool) bool {
+	select {
+	case <-ctx.Done():
+		return false
+	case r := <-ret:
+		return r
+	}
+}
+
 // GetHotPeerStat returns hot peer stat with specified regionID and storeID.
 func (w *HotCache) GetHotPeerStat(kind utils.RWType, regionID, storeID uint64) *HotPeerStat {
 	ret := make(chan *HotPeerStat, 1)

pkg/statistics/hot_cache_test.go

@@ -0,0 +1,36 @@
+// Copyright 2024 TiKV Project Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package statistics
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"github.com/tikv/pd/pkg/statistics/utils"
+)
+
+func TestIsHot(t *testing.T) {
+	re := require.New(t)
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	cache := NewHotCache(ctx)
+	region := buildRegion(utils.Read, 3, 60)
+	stats := cache.CheckReadPeerSync(region, region.GetPeers(), []float64{100000000, 1000, 1000}, 60)
+	cache.Update(stats[0], utils.Read)
+	for i := 0; i < 100; i++ {
+		re.True(cache.IsRegionHot(region, 1))
+	}
+}