config: add a check to reject changing some config items during runtime

config/config_handler.go

@@ -168,22 +168,35 @@ func (ch *pdConfHandler) register() {
 		return
 	}
 
-	newConf, err := decodeConfig(conf)
+	if ch.updateConfig(conf, version) {
+		ch.registered = true
+		logutil.Logger(context.Background()).Info("PDConfHandler register successfully")
+	}
+}
+
+func (ch *pdConfHandler) updateConfig(newConfContent string, newVersion *configpb.Version) (ok bool) {
+	newConf, err := decodeConfig(newConfContent)
 	if err != nil {
-		logutil.Logger(context.Background()).Warn("decode config error when registering", zap.Error(err))
-		return
+		logutil.Logger(context.Background()).Warn("decode config error", zap.Error(err))
+		return false
 	} else if err := newConf.Valid(); err != nil {
-		logutil.Logger(context.Background()).Warn("invalid remote config when registering", zap.Error(err))
-		return
+		logutil.Logger(context.Background()).Warn("invalid remote config", zap.Error(err))
+		return false
 	}
-
-	ch.registered = true
-	ch.reloadFunc(ch.curConf.Load().(*Config), newConf)
-	ch.curConf.Store(newConf)
-	ch.version = version
-	logutil.Logger(context.Background()).Info("PDConfHandler register config successfully",
-		zap.String("version", version.String()),
-		zap.Any("new_config", newConf))
+	oldConf := ch.curConf.Load().(*Config)
+	mergedConf, err := CloneConf(oldConf)
+	if err != nil {
+		logutil.Logger(context.Background()).Warn("clone config error", zap.Error(err))
+		return false
+	}
+	as, rs := MergeConfigItems(mergedConf, newConf)
+	ch.reloadFunc(oldConf, mergedConf)
+	ch.curConf.Store(mergedConf)
+	ch.version = newVersion
+	logutil.Logger(context.Background()).Info("PDConfHandler updates config successfully",
+		zap.String("new_version", newVersion.String()),
+		zap.Any("accepted_conf_items", as), zap.Any("rejected_conf_items", rs))
+	return true
 }
 
 func (ch *pdConfHandler) run() {
@@ -220,22 +233,8 @@ func (ch *pdConfHandler) run() {
 					zap.Int("code", int(status.Code)), zap.String("message", status.Message))
 				continue
 			}
-			newConf, err := decodeConfig(newConfContent)
-			if err != nil {
-				logutil.Logger(context.Background()).Error("PDConfHandler decode config error", zap.Error(err))
-				continue
-			}
-			if err := newConf.Valid(); err != nil {
-				logutil.Logger(context.Background()).Error("PDConfHandler invalid config", zap.Error(err))
-				continue
-			}
 
-			ch.reloadFunc(ch.curConf.Load().(*Config), newConf)
-			ch.curConf.Store(newConf)
-			logutil.Logger(context.Background()).Info("PDConfHandler update config successfully",
-				zap.String("fromVersion", ch.version.String()), zap.String("toVersion", version.String()),
-				zap.Any("new_config", newConf))
-			ch.version = version
+			ch.updateConfig(newConfContent, version)
 		case <-ch.exit:
 			return
 		}

config/config_handler_test.go

@@ -115,20 +115,21 @@ func (s *testConfigSuite) TestPDConfHandler(c *C) {
 	wg := sync.WaitGroup{}
 	wg.Add(1)
 	mockReloadFunc := func(oldConf, newConf *Config) {
-		c.Assert(oldConf.Log.Level, Equals, "info")
-		c.Assert(newConf.Log.Level, Equals, "debug")
+		c.Assert(oldConf.Performance.MaxMemory, Equals, uint64(233))
+		c.Assert(newConf.Performance.MaxMemory, Equals, uint64(123))
 		wg.Done()
 	}
+	conf.Performance.MaxMemory = 233
 	ch, err = newPDConfHandler(&conf, mockReloadFunc, newMockPDConfigClient)
 	c.Assert(err, IsNil)
 	ch.interval = time.Second
 	newConf := conf
-	newConf.Log.Level = "debug"
+	newConf.Performance.MaxMemory = 123
 	newContent, _ := encodeConfig(&newConf)
 	mockPDConfigClient0.confContent.Store(newContent)
 	ch.Start()
 	wg.Wait()
-	c.Assert(ch.GetConfig().Log.Level, Equals, "debug")
+	c.Assert(ch.GetConfig().Performance.MaxMemory, Equals, uint64(123))
 	ch.Close()
 }
 

config/config_util.go

@@ -0,0 +1,82 @@
+// Copyright 2020 PingCAP, Inc.
+//
+// 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 config
+
+import (
+	"encoding/json"
+	"reflect"
+)
+
+// CloneConf deeply clones this config.
+func CloneConf(conf *Config) (*Config, error) {
+	content, err := json.Marshal(conf)
+	if err != nil {
+		return nil, err
+	}
+	var clonedConf Config
+	if err := json.Unmarshal(content, &clonedConf); err != nil {
+		return nil, err
+	}
+	return &clonedConf, nil
+}
+
+var (
+	// dynamicConfigItems contains all config items that can be changed during runtime.
+	dynamicConfigItems = map[string]struct{}{
+		"Performance.MaxProcs":            {},
+		"Performance.MaxMemory":           {},
+		"Performance.CrossJoin":           {},
+		"Performance.FeedbackProbability": {},
+		"Performance.QueryFeedbackLimit":  {},
+		"Performance.PseudoEstimateRatio": {},
+		"OOMAction":                       {},
+		"MemQuotaQuery":                   {},
+		"TiKVClient.StoreLimit":           {},
+	}
+)
+
+// MergeConfigItems overwrites the dynamic config items and leaves the other items unchanged.
+func MergeConfigItems(dstConf, newConf *Config) (acceptedItems, rejectedItems []string) {
+	return mergeConfigItems(reflect.ValueOf(dstConf), reflect.ValueOf(newConf), "")
+}
+
+func mergeConfigItems(dstConf, newConf reflect.Value, fieldPath string) (acceptedItems, rejectedItems []string) {
+	t := dstConf.Type()
+	if t.Kind() == reflect.Ptr {
+		t = t.Elem()
+		dstConf = dstConf.Elem()
+		newConf = newConf.Elem()
+	}
+	if t.Kind() != reflect.Struct {
+		if reflect.DeepEqual(dstConf.Interface(), newConf.Interface()) {
+			return
+		}
+		if _, ok := dynamicConfigItems[fieldPath]; ok {
+			dstConf.Set(newConf)
+			return []string{fieldPath}, nil
+		}
+		return nil, []string{fieldPath}
+	}
+
+	for i := 0; i < t.NumField(); i++ {
+		fieldName := t.Field(i).Name
+		if fieldPath != "" {
+			fieldName = fieldPath + "." + fieldName
+		}
+		as, rs := mergeConfigItems(dstConf.Field(i), newConf.Field(i), fieldName)
+		acceptedItems = append(acceptedItems, as...)
+		rejectedItems = append(rejectedItems, rs...)
+	}
+	return
+}

config/config_util_test.go

@@ -0,0 +1,88 @@
+// Copyright 2020 PingCAP, Inc.
+//
+// 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 config
+
+import (
+	"fmt"
+	"reflect"
+
+	. "github.com/pingcap/check"
+)
+
+func (s *testConfigSuite) TestCloneConf(c *C) {
+	c1, err := CloneConf(&defaultConf)
+	c.Assert(err, IsNil)
+	c2, err := CloneConf(c1)
+	c.Assert(err, IsNil)
+	c.Assert(reflect.DeepEqual(c1, c2), IsTrue)
+
+	c1.Store = "abc"
+	c1.Port = 2333
+	c1.Log.EnableSlowLog = !c1.Log.EnableSlowLog
+	c1.RepairTableList = append(c1.RepairTableList, "abc")
+	c.Assert(c1.Store, Not(Equals), c2.Store)
+	c.Assert(c1.Port, Not(Equals), c2.Port)
+	c.Assert(c1.Log.EnableSlowLog, Not(Equals), c2.Log.EnableSlowLog)
+	c.Assert(fmt.Sprintf("%v", c1.RepairTableList), Not(Equals), fmt.Sprintf("%v", c2.RepairTableList))
+}
+
+func (s *testConfigSuite) TestMergeConfigItems(c *C) {
+	oriConf, _ := CloneConf(&defaultConf)
+	oldConf, _ := CloneConf(oriConf)
+	newConf, _ := CloneConf(oldConf)
+
+	// allowed
+	newConf.Performance.MaxProcs = 123
+	newConf.Performance.MaxMemory = 123
+	newConf.Performance.CrossJoin = false
+	newConf.Performance.FeedbackProbability = 123
+	newConf.Performance.QueryFeedbackLimit = 123
+	newConf.Performance.PseudoEstimateRatio = 123
+	newConf.OOMAction = "panic"
+	newConf.MemQuotaQuery = 123
+	newConf.TiKVClient.StoreLimit = 123
+
+	// rejected
+	newConf.Store = "tiflash"
+	newConf.Port = 2333
+	newConf.AdvertiseAddress = "1.2.3.4"
+	newConf.Log.SlowThreshold = 2345
+
+	as, rs := MergeConfigItems(oldConf, newConf)
+	c.Assert(len(as), Equals, 9)
+	c.Assert(len(rs), Equals, 4)
+	for _, a := range as {
+		_, ok := dynamicConfigItems[a]
+		c.Assert(ok, IsTrue)
+	}
+	for _, a := range rs {
+		_, ok := dynamicConfigItems[a]
+		c.Assert(ok, IsFalse)
+	}
+
+	c.Assert(oldConf.Performance.MaxProcs, Equals, newConf.Performance.MaxProcs)
+	c.Assert(oldConf.Performance.MaxMemory, Equals, newConf.Performance.MaxMemory)
+	c.Assert(oldConf.Performance.CrossJoin, Equals, newConf.Performance.CrossJoin)
+	c.Assert(oldConf.Performance.FeedbackProbability, Equals, newConf.Performance.FeedbackProbability)
+	c.Assert(oldConf.Performance.QueryFeedbackLimit, Equals, newConf.Performance.QueryFeedbackLimit)
+	c.Assert(oldConf.Performance.PseudoEstimateRatio, Equals, newConf.Performance.PseudoEstimateRatio)
+	c.Assert(oldConf.OOMAction, Equals, newConf.OOMAction)
+	c.Assert(oldConf.MemQuotaQuery, Equals, newConf.MemQuotaQuery)
+	c.Assert(oldConf.TiKVClient.StoreLimit, Equals, newConf.TiKVClient.StoreLimit)
+
+	c.Assert(oldConf.Store, Equals, oriConf.Store)
+	c.Assert(oldConf.Port, Equals, oriConf.Port)
+	c.Assert(oldConf.AdvertiseAddress, Equals, oriConf.AdvertiseAddress)
+	c.Assert(oldConf.Log.SlowThreshold, Equals, oriConf.Log.SlowThreshold)
+}