movingaverage: support concurrency safe queue in AvgOverTime (#3506) (#…

…3509)

* cherry pick #3506 to release-4.0

Signed-off-by: ti-srebot <ti-srebot@pingcap.com>

* fix conflict

Signed-off-by: yisaer <disxiaofei@163.com>

* use init

Signed-off-by: yisaer <disxiaofei@163.com>

Co-authored-by: Song Gao <disxiaofei@163.com>
Co-authored-by: Ti Chi Robot <71242396+ti-chi-bot@users.noreply.github.com>

server/core/region_option.go

@@ -269,3 +269,10 @@ func WithReplacePeerStore(oldStoreID, newStoreID uint64) RegionCreateOption {
 		}
 	}
 }
+
+// WithInterval sets the interval
+func WithInterval(interval *pdpb.TimeInterval) RegionCreateOption {
+	return func(region *RegionInfo) {
+		region.interval = interval
+	}
+}

server/statistics/avg_over_time.go

@@ -15,8 +15,6 @@ package statistics
 
 import (
 	"time"
-
-	"github.com/phf/go-queue/queue"
 )
 
 const (
@@ -35,7 +33,7 @@ type deltaWithInterval struct {
 // stores recent changes that happened in the last avgInterval,
 // then calculates the change rate by (sum of changes) / (sum of intervals).
 type AvgOverTime struct {
-	que         *queue.Queue
+	que         *SafeQueue
 	deltaSum    float64
 	intervalSum time.Duration
 	avgInterval time.Duration
@@ -44,7 +42,7 @@ type AvgOverTime struct {
 // NewAvgOverTime returns an AvgOverTime with given interval.
 func NewAvgOverTime(interval time.Duration) *AvgOverTime {
 	return &AvgOverTime{
-		que:         queue.New(),
+		que:         NewSafeQueue(),
 		deltaSum:    0,
 		intervalSum: 0,
 		avgInterval: interval,
@@ -58,7 +56,7 @@ func (aot *AvgOverTime) Get() float64 {
 
 // Clear clears the AvgOverTime.
 func (aot *AvgOverTime) Clear() {
-	aot.que = queue.New()
+	aot.que.Init()
 	aot.intervalSum = 0
 	aot.deltaSum = 0
 }

server/statistics/queue.go

@@ -0,0 +1,54 @@
+// Copyright 2021 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,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package statistics
+
+import (
+	"sync"
+
+	"github.com/phf/go-queue/queue"
+)
+
+// SafeQueue is a concurrency safe queue
+type SafeQueue struct {
+	mu  sync.Mutex
+	que *queue.Queue
+}
+
+// NewSafeQueue return a SafeQueue
+func NewSafeQueue() *SafeQueue {
+	sq := &SafeQueue{}
+	sq.que = queue.New()
+	return sq
+}
+
+// Init implement init
+func (sq *SafeQueue) Init() {
+	sq.mu.Lock()
+	defer sq.mu.Unlock()
+	sq.que.Init()
+}
+
+// PushBack implement PushBack
+func (sq *SafeQueue) PushBack(v interface{}) {
+	sq.mu.Lock()
+	defer sq.mu.Unlock()
+	sq.que.PushBack(v)
+}
+
+// PopFront implement PopFront
+func (sq *SafeQueue) PopFront() interface{} {
+	sq.mu.Lock()
+	defer sq.mu.Unlock()
+	return sq.que.PopFront()
+}

server/statistics/queue_test.go

@@ -0,0 +1,28 @@
+// Copyright 2021 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,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package statistics
+
+import (
+	. "github.com/pingcap/check"
+)
+
+func (t *testMovingAvg) TestQueue(c *C) {
+	sq := NewSafeQueue()
+	sq.PushBack(1)
+	sq.PushBack(2)
+	v1 := sq.PopFront()
+	v2 := sq.PopFront()
+	c.Assert(1, Equals, v1.(int))
+	c.Assert(2, Equals, v2.(int))
+}