statistics: fix empty region count when resuming (tikv#7009)

close tikv#7008

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

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

pkg/core/region.go

@@ -147,8 +147,9 @@ const (
 func RegionFromHeartbeat(heartbeat *pdpb.RegionHeartbeatRequest, opts ...RegionCreateOption) *RegionInfo {
 	// Convert unit to MB.
 	// If region isn't empty and less than 1MB, use 1MB instead.
-	// The size of empty region will be correct by the previous RegionInfo.
 	regionSize := heartbeat.GetApproximateSize() / units.MiB
+	// Due to https://github.com/tikv/tikv/pull/11170, if region size is not initialized,
+	// approximate size will be zero, and region size is zero not EmptyRegionApproximateSize
 	if heartbeat.GetApproximateSize() > 0 && regionSize < EmptyRegionApproximateSize {
 		regionSize = EmptyRegionApproximateSize
 	}
@@ -193,19 +194,9 @@ func RegionFromHeartbeat(heartbeat *pdpb.RegionHeartbeatRequest, opts ...RegionC
 	return region
 }
 
-// Inherit inherits the buckets and region size from the parent region if bucket enabled.
-// correct approximate size and buckets by the previous size if here exists a reported RegionInfo.
-// See https://github.com/tikv/tikv/issues/11114
-func (r *RegionInfo) Inherit(origin *RegionInfo, bucketEnable bool) {
-	// regionSize should not be zero if region is not empty.
-	if r.GetApproximateSize() == 0 {
-		if origin != nil {
-			r.approximateSize = origin.approximateSize
-		} else {
-			r.approximateSize = EmptyRegionApproximateSize
-		}
-	}
-	if bucketEnable && origin != nil && r.buckets == nil {
+// InheritBuckets inherits the buckets from the parent region if bucket enabled.
+func (r *RegionInfo) InheritBuckets(origin *RegionInfo) {
+	if origin != nil && r.buckets == nil {
 		r.buckets = origin.buckets
 	}
 }
@@ -515,6 +506,13 @@ func (r *RegionInfo) GetApproximateSize() int64 {
 	return r.approximateSize
 }
 
+// IsEmptyRegion returns whether the region is empty.
+func (r *RegionInfo) IsEmptyRegion() bool {
+	// When cluster resumes, the region size may be not initialized, but region heartbeat is send.
+	// So use `==` here.
+	return r.approximateSize == EmptyRegionApproximateSize
+}
+
 // GetStorePeerApproximateKeys returns the approximate keys of the peer on the specified store.
 func (r *RegionInfo) GetStorePeerApproximateKeys(storeID uint64) int64 {
 	peer := r.GetStorePeer(storeID)

pkg/core/region_test.go

@@ -186,35 +186,9 @@ func TestSortedEqual(t *testing.T) {
 	}
 }
 
-func TestInherit(t *testing.T) {
+func TestInheritBuckets(t *testing.T) {
 	re := require.New(t)
-	// size in MB
-	// case for approximateSize
-	testCases := []struct {
-		originExists bool
-		originSize   uint64
-		size         uint64
-		expect       uint64
-	}{
-		{false, 0, 0, 1},
-		{false, 0, 2, 2},
-		{true, 0, 2, 2},
-		{true, 1, 2, 2},
-		{true, 2, 0, 2},
-	}
-	for _, testCase := range testCases {
-		var origin *RegionInfo
-		if testCase.originExists {
-			origin = NewRegionInfo(&metapb.Region{Id: 100}, nil)
-			origin.approximateSize = int64(testCase.originSize)
-		}
-		r := NewRegionInfo(&metapb.Region{Id: 100}, nil)
-		r.approximateSize = int64(testCase.size)
-		r.Inherit(origin, false)
-		re.Equal(int64(testCase.expect), r.approximateSize)
-	}
 
-	// bucket
 	data := []struct {
 		originBuckets *metapb.Buckets
 		buckets       *metapb.Buckets
@@ -227,12 +201,11 @@ func TestInherit(t *testing.T) {
 	for _, d := range data {
 		origin := NewRegionInfo(&metapb.Region{Id: 100}, nil, SetBuckets(d.originBuckets))
 		r := NewRegionInfo(&metapb.Region{Id: 100}, nil)
-		r.Inherit(origin, true)
+		r.InheritBuckets(origin)
 		re.Equal(d.originBuckets, r.GetBuckets())
 		// region will not inherit bucket keys.
 		if origin.GetBuckets() != nil {
 			newRegion := NewRegionInfo(&metapb.Region{Id: 100}, nil)
-			newRegion.Inherit(origin, false)
 			re.NotEqual(d.originBuckets, newRegion.GetBuckets())
 		}
 	}

pkg/statistics/region.go

@@ -59,10 +59,12 @@ func (s *RegionStats) Observe(r *core.RegionInfo) {
 	approximateKeys := r.GetApproximateKeys()
 	approximateSize := r.GetApproximateSize()
 	approximateKvSize := r.GetApproximateKvSize()
-	if approximateSize <= core.EmptyRegionApproximateSize {
+	if approximateSize == core.EmptyRegionApproximateSize {
 		s.EmptyCount++
 	}
-	s.StorageSize += approximateSize
+	if !r.IsEmptyRegion() {
+		s.StorageSize += approximateSize
+	}
 	s.UserStorageSize += approximateKvSize
 	s.StorageKeys += approximateKeys
 	leader := r.GetLeader()

pkg/statistics/region_collection.go

@@ -198,15 +198,15 @@ func (r *RegionStatistics) Observe(region *core.RegionInfo, stores []*core.Store
 			return false
 		}(),
 		LearnerPeer: len(region.GetLearners()) > 0,
-		EmptyRegion: region.GetApproximateSize() <= core.EmptyRegionApproximateSize,
+		EmptyRegion: region.IsEmptyRegion(),
 		OversizedRegion: region.IsOversized(
 			int64(r.conf.GetRegionMaxSize()),
 			int64(r.conf.GetRegionMaxKeys()),
 		),
 		UndersizedRegion: region.NeedMerge(
 			int64(r.conf.GetMaxMergeRegionSize()),
 			int64(r.conf.GetMaxMergeRegionKeys()),
-		),
+		) && region.GetApproximateSize() >= core.EmptyRegionApproximateSize,
 		WitnessLeader: region.GetLeader().GetIsWitness(),
 	}
 	// Check if the region meets any of the conditions and update the corresponding info.

pkg/statistics/region_collection_test.go

@@ -63,7 +63,7 @@ func TestRegionStatistics(t *testing.T) {
 	stores[3] = store3
 	r1 := &metapb.Region{Id: 1, Peers: peers, StartKey: []byte("aa"), EndKey: []byte("bb")}
 	r2 := &metapb.Region{Id: 2, Peers: peers[0:2], StartKey: []byte("cc"), EndKey: []byte("dd")}
-	region1 := core.NewRegionInfo(r1, peers[0])
+	region1 := core.NewRegionInfo(r1, peers[0], core.SetApproximateSize(1))
 	region2 := core.NewRegionInfo(r2, peers[0])
 	regionStats := NewRegionStatistics(nil, opt, manager)
 	regionStats.Observe(region1, stores)
@@ -97,7 +97,8 @@ func TestRegionStatistics(t *testing.T) {
 	re.Len(regionStats.stats[PendingPeer], 1)
 	re.Len(regionStats.stats[LearnerPeer], 1)
 	re.Len(regionStats.stats[OversizedRegion], 1)
-	re.Len(regionStats.stats[UndersizedRegion], 1)
+	re.Len(regionStats.stats[UndersizedRegion], 0)
+	re.Len(regionStats.stats[EmptyRegion], 0)
 	re.Len(regionStats.stats[OfflinePeer], 1)
 
 	region1 = region1.Clone(core.WithRemoveStorePeer(7))

server/api/stats_test.go

@@ -142,7 +142,7 @@ func (suite *statsTestSuite) TestRegionStats() {
 	statsAll := &statistics.RegionStats{
 		Count:            4,
 		EmptyCount:       1,
-		StorageSize:      351,
+		StorageSize:      350,
 		UserStorageSize:  291,
 		StorageKeys:      221,
 		StoreLeaderCount: map[uint64]int{1: 1, 4: 2, 5: 1},
@@ -156,7 +156,7 @@ func (suite *statsTestSuite) TestRegionStats() {
 	stats23 := &statistics.RegionStats{
 		Count:            2,
 		EmptyCount:       1,
-		StorageSize:      201,
+		StorageSize:      200,
 		UserStorageSize:  181,
 		StorageKeys:      151,
 		StoreLeaderCount: map[uint64]int{4: 1, 5: 1},

server/cluster/cluster.go

@@ -1090,7 +1090,9 @@ func (c *RaftCluster) processRegionHeartbeat(region *core.RegionInfo) error {
 	if err != nil {
 		return err
 	}
-	region.Inherit(origin, c.GetStoreConfig().IsEnableRegionBucket())
+	if c.GetStoreConfig().IsEnableRegionBucket() {
+		region.InheritBuckets(origin)
+	}
 
 	if !c.isAPIServiceMode {
 		c.hotStat.CheckWriteAsync(statistics.NewCheckExpiredItemTask(region))