From 84f90f464ae58c26b7eb97a4518e7de97242730f Mon Sep 17 00:00:00 2001
From: okJiang <819421878@qq.com>
Date: Wed, 31 Jul 2024 14:43:18 +0800
Subject: [PATCH] *: add some comments to exported function, part of enable
 revive.exported (#8459)

ref tikv/pd#8458

Signed-off-by: okJiang <819421878@qq.com>

Co-authored-by: ti-chi-bot[bot] <108142056+ti-chi-bot[bot]@users.noreply.github.com>
---
 .golangci.yml                            |  3 +
 pkg/core/metrics.go                      | 77 ++++++++++++++++++++----
 pkg/core/region_tree.go                  |  3 +
 pkg/core/storelimit/store_limit.go       |  1 +
 pkg/id/id.go                             |  1 +
 pkg/ratelimit/metrics.go                 | 20 +++---
 pkg/ratelimit/runner.go                  | 12 ++--
 pkg/schedule/filter/counter.go           |  1 +
 pkg/schedule/filter/filters.go           | 35 +++++++++++
 pkg/schedule/filter/region_filters.go    |  2 +
 pkg/schedule/operator/builder.go         |  1 +
 pkg/schedule/operator/operator_queue.go  |  5 ++
 pkg/schedule/schedulers/split_bucket.go  |  8 +--
 pkg/schedule/splitter/region_splitter.go |  2 +
 pkg/schedule/type/type.go                |  7 ++-
 pkg/statistics/collector.go              | 24 ++++----
 pkg/statistics/hot_peer.go               | 10 +--
 pkg/statistics/hot_peer_cache.go         |  7 ++-
 pkg/statistics/store_collection.go       | 11 ++--
 pkg/statistics/store_hot_peers_infos.go  |  6 +-
 pkg/statistics/utils/topn.go             | 46 +++++++-------
 pkg/storage/kv/etcd_kv.go                |  4 ++
 pkg/storage/kv/mem_kv.go                 |  5 ++
 pkg/syncer/client.go                     | 12 ++--
 pkg/syncer/history_buffer.go             |  8 +--
 pkg/syncer/history_buffer_test.go        | 12 ++--
 pkg/syncer/server.go                     | 14 ++---
 pkg/window/counter.go                    | 10 +++
 plugin/scheduler_example/evict_leader.go | 14 +++++
 29 files changed, 253 insertions(+), 108 deletions(-)

diff --git a/.golangci.yml b/.golangci.yml
index d5b2e4e7f5a..bc1ba393f39 100644
--- a/.golangci.yml
+++ b/.golangci.yml
@@ -214,3 +214,6 @@ issues:
     - path: (pd-analysis|pd-api-bench|pd-backup|pd-ctl|pd-heartbeat-bench|pd-recover|pd-simulator|pd-tso-bench|pd-ut|regions-dump|stores-dump)
       linters:
         - errcheck
+  include:
+    # remove the comment after the path is ready
+    # - EXC0012
diff --git a/pkg/core/metrics.go b/pkg/core/metrics.go
index 7d2c904f319..65cc8be861e 100644
--- a/pkg/core/metrics.go
+++ b/pkg/core/metrics.go
@@ -108,19 +108,33 @@ type saveCacheStats struct {
 
 // RegionHeartbeatProcessTracer is used to trace the process of handling region heartbeat.
 type RegionHeartbeatProcessTracer interface {
+	// Begin starts the tracing.
 	Begin()
+	// OnPreCheckFinished will be called when the pre-check is finished.
 	OnPreCheckFinished()
+	// OnAsyncHotStatsFinished will be called when the async hot stats is finished.
 	OnAsyncHotStatsFinished()
+	// OnRegionGuideFinished will be called when the region guide is finished.
 	OnRegionGuideFinished()
+	// OnSaveCacheBegin will be called when the save cache begins.
 	OnSaveCacheBegin()
+	// OnSaveCacheFinished will be called when the save cache is finished.
 	OnSaveCacheFinished()
+	// OnCheckOverlapsFinished will be called when the check overlaps is finished.
 	OnCheckOverlapsFinished()
+	// OnValidateRegionFinished will be called when the validate region is finished.
 	OnValidateRegionFinished()
+	// OnSetRegionFinished will be called when the set region is finished.
 	OnSetRegionFinished()
+	// OnUpdateSubTreeFinished will be called when the update sub tree is finished.
 	OnUpdateSubTreeFinished()
+	// OnCollectRegionStatsFinished will be called when the collect region stats is finished.
 	OnCollectRegionStatsFinished()
+	// OnAllStageFinished will be called when all stages are finished.
 	OnAllStageFinished()
+	// LogFields returns the log fields.
 	LogFields() []zap.Field
+	// Release releases the tracer.
 	Release()
 }
 
@@ -131,21 +145,48 @@ func NewNoopHeartbeatProcessTracer() RegionHeartbeatProcessTracer {
 	return &noopHeartbeatProcessTracer{}
 }
 
-func (*noopHeartbeatProcessTracer) Begin()                        {}
-func (*noopHeartbeatProcessTracer) OnPreCheckFinished()           {}
-func (*noopHeartbeatProcessTracer) OnAsyncHotStatsFinished()      {}
-func (*noopHeartbeatProcessTracer) OnRegionGuideFinished()        {}
-func (*noopHeartbeatProcessTracer) OnSaveCacheBegin()             {}
-func (*noopHeartbeatProcessTracer) OnSaveCacheFinished()          {}
-func (*noopHeartbeatProcessTracer) OnCheckOverlapsFinished()      {}
-func (*noopHeartbeatProcessTracer) OnValidateRegionFinished()     {}
-func (*noopHeartbeatProcessTracer) OnSetRegionFinished()          {}
-func (*noopHeartbeatProcessTracer) OnUpdateSubTreeFinished()      {}
+// Begin implements the RegionHeartbeatProcessTracer interface.
+func (*noopHeartbeatProcessTracer) Begin() {}
+
+// OnPreCheckFinished implements the RegionHeartbeatProcessTracer interface.
+func (*noopHeartbeatProcessTracer) OnPreCheckFinished() {}
+
+// OnAsyncHotStatsFinished implements the RegionHeartbeatProcessTracer interface.
+func (*noopHeartbeatProcessTracer) OnAsyncHotStatsFinished() {}
+
+// OnRegionGuideFinished implements the RegionHeartbeatProcessTracer interface.
+func (*noopHeartbeatProcessTracer) OnRegionGuideFinished() {}
+
+// OnSaveCacheBegin implements the RegionHeartbeatProcessTracer interface.
+func (*noopHeartbeatProcessTracer) OnSaveCacheBegin() {}
+
+// OnSaveCacheFinished implements the RegionHeartbeatProcessTracer interface.
+func (*noopHeartbeatProcessTracer) OnSaveCacheFinished() {}
+
+// OnCheckOverlapsFinished implements the RegionHeartbeatProcessTracer interface.
+func (*noopHeartbeatProcessTracer) OnCheckOverlapsFinished() {}
+
+// OnValidateRegionFinished implements the RegionHeartbeatProcessTracer interface.
+func (*noopHeartbeatProcessTracer) OnValidateRegionFinished() {}
+
+// OnSetRegionFinished implements the RegionHeartbeatProcessTracer interface.
+func (*noopHeartbeatProcessTracer) OnSetRegionFinished() {}
+
+// OnUpdateSubTreeFinished implements the RegionHeartbeatProcessTracer interface.
+func (*noopHeartbeatProcessTracer) OnUpdateSubTreeFinished() {}
+
+// OnCollectRegionStatsFinished implements the RegionHeartbeatProcessTracer interface.
 func (*noopHeartbeatProcessTracer) OnCollectRegionStatsFinished() {}
-func (*noopHeartbeatProcessTracer) OnAllStageFinished()           {}
+
+// OnAllStageFinished implements the RegionHeartbeatProcessTracer interface.
+func (*noopHeartbeatProcessTracer) OnAllStageFinished() {}
+
+// LogFields implements the RegionHeartbeatProcessTracer interface.
 func (*noopHeartbeatProcessTracer) LogFields() []zap.Field {
 	return nil
 }
+
+// Release implements the RegionHeartbeatProcessTracer interface.
 func (*noopHeartbeatProcessTracer) Release() {}
 
 type regionHeartbeatProcessTracer struct {
@@ -163,12 +204,14 @@ func NewHeartbeatProcessTracer() RegionHeartbeatProcessTracer {
 	return tracerPool.Get().(*regionHeartbeatProcessTracer)
 }
 
+// Begin implements the RegionHeartbeatProcessTracer interface.
 func (h *regionHeartbeatProcessTracer) Begin() {
 	now := time.Now()
 	h.startTime = now
 	h.lastCheckTime = now
 }
 
+// OnPreCheckFinished implements the RegionHeartbeatProcessTracer interface.
 func (h *regionHeartbeatProcessTracer) OnPreCheckFinished() {
 	now := time.Now()
 	h.preCheckDuration = now.Sub(h.lastCheckTime)
@@ -177,6 +220,7 @@ func (h *regionHeartbeatProcessTracer) OnPreCheckFinished() {
 	preCheckCount.Inc()
 }
 
+// OnAsyncHotStatsFinished implements the RegionHeartbeatProcessTracer interface.
 func (h *regionHeartbeatProcessTracer) OnAsyncHotStatsFinished() {
 	now := time.Now()
 	h.asyncHotStatsDuration = now.Sub(h.lastCheckTime)
@@ -185,6 +229,7 @@ func (h *regionHeartbeatProcessTracer) OnAsyncHotStatsFinished() {
 	asyncHotStatsCount.Inc()
 }
 
+// OnRegionGuideFinished implements the RegionHeartbeatProcessTracer interface.
 func (h *regionHeartbeatProcessTracer) OnRegionGuideFinished() {
 	now := time.Now()
 	h.regionGuideDuration = now.Sub(h.lastCheckTime)
@@ -193,6 +238,7 @@ func (h *regionHeartbeatProcessTracer) OnRegionGuideFinished() {
 	regionGuideCount.Inc()
 }
 
+// OnSaveCacheBegin implements the RegionHeartbeatProcessTracer interface.
 func (h *regionHeartbeatProcessTracer) OnSaveCacheBegin() {
 	now := time.Now()
 	h.saveCacheStats.startTime = now
@@ -200,11 +246,13 @@ func (h *regionHeartbeatProcessTracer) OnSaveCacheBegin() {
 	h.lastCheckTime = now
 }
 
+// OnSaveCacheFinished implements the RegionHeartbeatProcessTracer interface.
 func (h *regionHeartbeatProcessTracer) OnSaveCacheFinished() {
 	// update the outer checkpoint time
 	h.lastCheckTime = time.Now()
 }
 
+// OnCollectRegionStatsFinished implements the RegionHeartbeatProcessTracer interface.
 func (h *regionHeartbeatProcessTracer) OnCollectRegionStatsFinished() {
 	now := time.Now()
 	regionCollectDurationSum.Add(now.Sub(h.lastCheckTime).Seconds())
@@ -212,6 +260,7 @@ func (h *regionHeartbeatProcessTracer) OnCollectRegionStatsFinished() {
 	h.lastCheckTime = now
 }
 
+// OnCheckOverlapsFinished implements the RegionHeartbeatProcessTracer interface.
 func (h *regionHeartbeatProcessTracer) OnCheckOverlapsFinished() {
 	now := time.Now()
 	h.saveCacheStats.checkOverlapsDuration = now.Sub(h.lastCheckTime)
@@ -220,6 +269,7 @@ func (h *regionHeartbeatProcessTracer) OnCheckOverlapsFinished() {
 	checkOverlapsCount.Inc()
 }
 
+// OnValidateRegionFinished implements the RegionHeartbeatProcessTracer interface.
 func (h *regionHeartbeatProcessTracer) OnValidateRegionFinished() {
 	now := time.Now()
 	h.saveCacheStats.validateRegionDuration = now.Sub(h.saveCacheStats.lastCheckTime)
@@ -228,6 +278,7 @@ func (h *regionHeartbeatProcessTracer) OnValidateRegionFinished() {
 	validateRegionCount.Inc()
 }
 
+// OnSetRegionFinished implements the RegionHeartbeatProcessTracer interface.
 func (h *regionHeartbeatProcessTracer) OnSetRegionFinished() {
 	now := time.Now()
 	h.saveCacheStats.setRegionDuration = now.Sub(h.saveCacheStats.lastCheckTime)
@@ -236,6 +287,7 @@ func (h *regionHeartbeatProcessTracer) OnSetRegionFinished() {
 	setRegionCount.Inc()
 }
 
+// OnUpdateSubTreeFinished implements the RegionHeartbeatProcessTracer interface.
 func (h *regionHeartbeatProcessTracer) OnUpdateSubTreeFinished() {
 	now := time.Now()
 	h.saveCacheStats.updateSubTreeDuration = now.Sub(h.saveCacheStats.lastCheckTime)
@@ -244,6 +296,7 @@ func (h *regionHeartbeatProcessTracer) OnUpdateSubTreeFinished() {
 	updateSubTreeCount.Inc()
 }
 
+// OnAllStageFinished implements the RegionHeartbeatProcessTracer interface.
 func (h *regionHeartbeatProcessTracer) OnAllStageFinished() {
 	now := time.Now()
 	h.OtherDuration = now.Sub(h.lastCheckTime)
@@ -251,6 +304,7 @@ func (h *regionHeartbeatProcessTracer) OnAllStageFinished() {
 	otherCount.Inc()
 }
 
+// LogFields implements the RegionHeartbeatProcessTracer interface.
 func (h *regionHeartbeatProcessTracer) LogFields() []zap.Field {
 	return []zap.Field{
 		zap.Duration("pre-check-duration", h.preCheckDuration),
@@ -264,6 +318,7 @@ func (h *regionHeartbeatProcessTracer) LogFields() []zap.Field {
 	}
 }
 
+// Release implements the RegionHeartbeatProcessTracer interface.
 // Release puts the tracer back into the pool.
 func (h *regionHeartbeatProcessTracer) Release() {
 	// Reset the fields of h to their zero values.
diff --git a/pkg/core/region_tree.go b/pkg/core/region_tree.go
index 9a148eeed18..0be207d515d 100644
--- a/pkg/core/region_tree.go
+++ b/pkg/core/region_tree.go
@@ -437,6 +437,7 @@ func (t *regionTree) RandomRegions(n int, ranges []KeyRange) []*RegionInfo {
 	return regions
 }
 
+// TotalSize returns the total size of all regions.
 func (t *regionTree) TotalSize() int64 {
 	if t.length() == 0 {
 		return 0
@@ -444,6 +445,8 @@ func (t *regionTree) TotalSize() int64 {
 	return t.totalSize
 }
 
+// TotalWriteRate returns the total write bytes rate and the total write keys
+// rate of all regions.
 func (t *regionTree) TotalWriteRate() (bytesRate, keysRate float64) {
 	if t.length() == 0 {
 		return 0, 0
diff --git a/pkg/core/storelimit/store_limit.go b/pkg/core/storelimit/store_limit.go
index e35ec773d80..fb7cad442bb 100644
--- a/pkg/core/storelimit/store_limit.go
+++ b/pkg/core/storelimit/store_limit.go
@@ -178,6 +178,7 @@ func (l *limit) Take(count int64) bool {
 	return l.limiter.AllowN(int(count))
 }
 
+// GetRatePerSec returns the rate per second.
 func (l *limit) GetRatePerSec() float64 {
 	l.ratePerSecMutex.RLock()
 	defer l.ratePerSecMutex.RUnlock()
diff --git a/pkg/id/id.go b/pkg/id/id.go
index d0889717242..ea4a2a54341 100644
--- a/pkg/id/id.go
+++ b/pkg/id/id.go
@@ -105,6 +105,7 @@ func (alloc *allocatorImpl) Alloc() (uint64, error) {
 	return alloc.base, nil
 }
 
+// SetBase sets the base.
 func (alloc *allocatorImpl) SetBase(newBase uint64) error {
 	alloc.mu.Lock()
 	defer alloc.mu.Unlock()
diff --git a/pkg/ratelimit/metrics.go b/pkg/ratelimit/metrics.go
index c5510e66b26..0096a76de4c 100644
--- a/pkg/ratelimit/metrics.go
+++ b/pkg/ratelimit/metrics.go
@@ -24,35 +24,35 @@ const (
 )
 
 var (
-	RunnerTaskMaxWaitingDuration = prometheus.NewGaugeVec(
+	runnerTaskMaxWaitingDuration = prometheus.NewGaugeVec(
 		prometheus.GaugeOpts{
 			Namespace: "pd",
 			Subsystem: "ratelimit",
 			Name:      "runner_task_max_waiting_duration_seconds",
 			Help:      "The duration of tasks waiting in the runner.",
 		}, []string{nameStr})
-	RunnerPendingTasks = prometheus.NewGaugeVec(
+	runnerPendingTasks = prometheus.NewGaugeVec(
 		prometheus.GaugeOpts{
 			Namespace: "pd",
 			Subsystem: "ratelimit",
 			Name:      "runner_pending_tasks",
 			Help:      "The number of pending tasks in the runner.",
 		}, []string{nameStr, taskStr})
-	RunnerFailedTasks = prometheus.NewCounterVec(
+	runnerFailedTasks = prometheus.NewCounterVec(
 		prometheus.CounterOpts{
 			Namespace: "pd",
 			Subsystem: "ratelimit",
 			Name:      "runner_failed_tasks_total",
 			Help:      "The number of failed tasks in the runner.",
 		}, []string{nameStr, taskStr})
-	RunnerSucceededTasks = prometheus.NewCounterVec(
+	runnerSucceededTasks = prometheus.NewCounterVec(
 		prometheus.CounterOpts{
 			Namespace: "pd",
 			Subsystem: "ratelimit",
 			Name:      "runner_success_tasks_total",
 			Help:      "The number of tasks in the runner.",
 		}, []string{nameStr, taskStr})
-	RunnerTaskExecutionDuration = prometheus.NewHistogramVec(
+	runnerTaskExecutionDuration = prometheus.NewHistogramVec(
 		prometheus.HistogramOpts{
 			Namespace: "pd",
 			Subsystem: "ratelimit",
@@ -63,9 +63,9 @@ var (
 )
 
 func init() {
-	prometheus.MustRegister(RunnerTaskMaxWaitingDuration)
-	prometheus.MustRegister(RunnerPendingTasks)
-	prometheus.MustRegister(RunnerFailedTasks)
-	prometheus.MustRegister(RunnerTaskExecutionDuration)
-	prometheus.MustRegister(RunnerSucceededTasks)
+	prometheus.MustRegister(runnerTaskMaxWaitingDuration)
+	prometheus.MustRegister(runnerPendingTasks)
+	prometheus.MustRegister(runnerFailedTasks)
+	prometheus.MustRegister(runnerTaskExecutionDuration)
+	prometheus.MustRegister(runnerSucceededTasks)
 }
diff --git a/pkg/ratelimit/runner.go b/pkg/ratelimit/runner.go
index a230177ac73..4b1b51f1768 100644
--- a/pkg/ratelimit/runner.go
+++ b/pkg/ratelimit/runner.go
@@ -90,7 +90,7 @@ func NewConcurrentRunner(name string, limiter *ConcurrencyLimiter, maxPendingDur
 		pendingTasks:       make([]*Task, 0, initialCapacity),
 		pendingTaskCount:   make(map[string]int),
 		existTasks:         make(map[taskID]*Task),
-		maxWaitingDuration: RunnerTaskMaxWaitingDuration.WithLabelValues(name),
+		maxWaitingDuration: runnerTaskMaxWaitingDuration.WithLabelValues(name),
 	}
 	return s
 }
@@ -136,7 +136,7 @@ func (cr *ConcurrentRunner) Start(ctx context.Context) {
 					maxDuration = time.Since(cr.pendingTasks[0].submittedAt)
 				}
 				for taskName, cnt := range cr.pendingTaskCount {
-					RunnerPendingTasks.WithLabelValues(cr.name, taskName).Set(float64(cnt))
+					runnerPendingTasks.WithLabelValues(cr.name, taskName).Set(float64(cnt))
 				}
 				cr.pendingMu.Unlock()
 				cr.maxWaitingDuration.Set(maxDuration.Seconds())
@@ -157,8 +157,8 @@ func (cr *ConcurrentRunner) run(ctx context.Context, task *Task, token *TaskToke
 		cr.limiter.ReleaseToken(token)
 		cr.processPendingTasks()
 	}
-	RunnerTaskExecutionDuration.WithLabelValues(cr.name, task.name).Observe(time.Since(start).Seconds())
-	RunnerSucceededTasks.WithLabelValues(cr.name, task.name).Inc()
+	runnerTaskExecutionDuration.WithLabelValues(cr.name, task.name).Observe(time.Since(start).Seconds())
+	runnerSucceededTasks.WithLabelValues(cr.name, task.name).Inc()
 }
 
 func (cr *ConcurrentRunner) processPendingTasks() {
@@ -214,12 +214,12 @@ func (cr *ConcurrentRunner) RunTask(id uint64, name string, f func(context.Conte
 		if !task.retained {
 			maxWait := time.Since(cr.pendingTasks[0].submittedAt)
 			if maxWait > cr.maxPendingDuration {
-				RunnerFailedTasks.WithLabelValues(cr.name, task.name).Inc()
+				runnerFailedTasks.WithLabelValues(cr.name, task.name).Inc()
 				return ErrMaxWaitingTasksExceeded
 			}
 		}
 		if pendingTaskNum > maxPendingTaskNum {
-			RunnerFailedTasks.WithLabelValues(cr.name, task.name).Inc()
+			runnerFailedTasks.WithLabelValues(cr.name, task.name).Inc()
 			return ErrMaxWaitingTasksExceeded
 		}
 	}
diff --git a/pkg/schedule/filter/counter.go b/pkg/schedule/filter/counter.go
index 9742d2d0c9d..41211c1acce 100644
--- a/pkg/schedule/filter/counter.go
+++ b/pkg/schedule/filter/counter.go
@@ -128,6 +128,7 @@ func NewCounter(scope string) *Counter {
 	return &Counter{counter: counter, scope: scope}
 }
 
+// SetScope sets the scope for the counter.
 func (c *Counter) SetScope(scope string) {
 	c.scope = scope
 }
diff --git a/pkg/schedule/filter/filters.go b/pkg/schedule/filter/filters.go
index 1838f0104f4..6c5dd748d17 100644
--- a/pkg/schedule/filter/filters.go
+++ b/pkg/schedule/filter/filters.go
@@ -181,14 +181,17 @@ func NewExcludedFilter(scope string, sources, targets map[uint64]struct{}) Filte
 	}
 }
 
+// Scope returns the scheduler or the checker which the filter acts on.
 func (f *excludedFilter) Scope() string {
 	return f.scope
 }
 
+// Type returns the type of the filter.
 func (*excludedFilter) Type() filterType {
 	return excluded
 }
 
+// Source filters stores when select them as schedule source.
 func (f *excludedFilter) Source(_ config.SharedConfigProvider, store *core.StoreInfo) *plan.Status {
 	if _, ok := f.sources[store.GetID()]; ok {
 		return statusStoreAlreadyHasPeer
@@ -196,6 +199,7 @@ func (f *excludedFilter) Source(_ config.SharedConfigProvider, store *core.Store
 	return statusOK
 }
 
+// Target filters stores when select them as schedule target.
 func (f *excludedFilter) Target(_ config.SharedConfigProvider, store *core.StoreInfo) *plan.Status {
 	if _, ok := f.targets[store.GetID()]; ok {
 		return statusStoreAlreadyHasPeer
@@ -211,18 +215,22 @@ func NewStorageThresholdFilter(scope string) Filter {
 	return &storageThresholdFilter{scope: scope}
 }
 
+// Scope returns the scheduler or the checker which the filter acts on.
 func (f *storageThresholdFilter) Scope() string {
 	return f.scope
 }
 
+// Type returns the name of the filter.
 func (*storageThresholdFilter) Type() filterType {
 	return storageThreshold
 }
 
+// Source filters stores when select them as schedule source.
 func (*storageThresholdFilter) Source(config.SharedConfigProvider, *core.StoreInfo) *plan.Status {
 	return statusOK
 }
 
+// Target filters stores when select them as schedule target.
 func (*storageThresholdFilter) Target(conf config.SharedConfigProvider, store *core.StoreInfo) *plan.Status {
 	if !store.IsLowSpace(conf.GetLowSpaceRatio()) {
 		return statusOK
@@ -279,18 +287,22 @@ func newDistinctScoreFilter(scope string, labels []string, stores []*core.StoreI
 	}
 }
 
+// Scope returns the scheduler or the checker which the filter acts on.
 func (f *distinctScoreFilter) Scope() string {
 	return f.scope
 }
 
+// Type returns the type of the filter.
 func (*distinctScoreFilter) Type() filterType {
 	return distinctScore
 }
 
+// Source filters stores when select them as schedule source.
 func (*distinctScoreFilter) Source(config.SharedConfigProvider, *core.StoreInfo) *plan.Status {
 	return statusOK
 }
 
+// Target filters stores when select them as schedule target.
 func (f *distinctScoreFilter) Target(_ config.SharedConfigProvider, store *core.StoreInfo) *plan.Status {
 	score := core.DistinctScore(f.labels, f.stores, store)
 	switch f.policy {
@@ -630,14 +642,17 @@ func newRuleFitFilter(scope string, cluster *core.BasicCluster, ruleManager *pla
 	}
 }
 
+// Scope returns the scheduler or the checker which the filter acts on.
 func (f *ruleFitFilter) Scope() string {
 	return f.scope
 }
 
+// Type returns the name of the filter.
 func (*ruleFitFilter) Type() filterType {
 	return ruleFit
 }
 
+// Source filters stores when select them as schedule source.
 func (*ruleFitFilter) Source(config.SharedConfigProvider, *core.StoreInfo) *plan.Status {
 	return statusOK
 }
@@ -683,18 +698,22 @@ func newRuleLeaderFitFilter(scope string, cluster *core.BasicCluster, ruleManage
 	}
 }
 
+// Scope returns the scheduler or the checker which the filter acts on.
 func (f *ruleLeaderFitFilter) Scope() string {
 	return f.scope
 }
 
+// Type returns the name of the filter.
 func (*ruleLeaderFitFilter) Type() filterType {
 	return ruleLeader
 }
 
+// Source filters stores when select them as schedule source.
 func (*ruleLeaderFitFilter) Source(config.SharedConfigProvider, *core.StoreInfo) *plan.Status {
 	return statusOK
 }
 
+// Target filters stores when select them as schedule target.
 func (f *ruleLeaderFitFilter) Target(_ config.SharedConfigProvider, store *core.StoreInfo) *plan.Status {
 	targetStoreID := store.GetID()
 	targetPeer := f.region.GetStorePeer(targetStoreID)
@@ -739,18 +758,22 @@ func newRuleWitnessFitFilter(scope string, cluster *core.BasicCluster, ruleManag
 	}
 }
 
+// Scope returns the scheduler or the checker which the filter acts on.
 func (f *ruleWitnessFitFilter) Scope() string {
 	return f.scope
 }
 
+// Type returns the name of the filter.
 func (*ruleWitnessFitFilter) Type() filterType {
 	return ruleFit
 }
 
+// Source filters stores when select them as schedule source.
 func (*ruleWitnessFitFilter) Source(config.SharedConfigProvider, *core.StoreInfo) *plan.Status {
 	return statusOK
 }
 
+// Target filters stores when select them as schedule target.
 func (f *ruleWitnessFitFilter) Target(_ config.SharedConfigProvider, store *core.StoreInfo) *plan.Status {
 	targetStoreID := store.GetID()
 	targetPeer := f.region.GetStorePeer(targetStoreID)
@@ -811,14 +834,17 @@ func NewEngineFilter(scope string, constraint placement.LabelConstraint) Filter
 	}
 }
 
+// Scope returns the scheduler or the checker which the filter acts on.
 func (f *engineFilter) Scope() string {
 	return f.scope
 }
 
+// Type returns the name of the filter.
 func (*engineFilter) Type() filterType {
 	return engine
 }
 
+// Source filters stores when select them as schedule source.
 func (f *engineFilter) Source(_ config.SharedConfigProvider, store *core.StoreInfo) *plan.Status {
 	if f.constraint.MatchStore(store) {
 		return statusOK
@@ -826,6 +852,7 @@ func (f *engineFilter) Source(_ config.SharedConfigProvider, store *core.StoreIn
 	return statusStoreNotMatchRule
 }
 
+// Target filters stores when select them as schedule target.
 func (f *engineFilter) Target(_ config.SharedConfigProvider, store *core.StoreInfo) *plan.Status {
 	if f.constraint.MatchStore(store) {
 		return statusOK
@@ -854,14 +881,17 @@ func NewSpecialUseFilter(scope string, allowUses ...string) Filter {
 	}
 }
 
+// Scope returns the scheduler or the checker which the filter acts on.
 func (f *specialUseFilter) Scope() string {
 	return f.scope
 }
 
+// Type returns the name of the filter.
 func (*specialUseFilter) Type() filterType {
 	return specialUse
 }
 
+// Source filters stores when select them as schedule source.
 func (f *specialUseFilter) Source(conf config.SharedConfigProvider, store *core.StoreInfo) *plan.Status {
 	if store.IsLowSpace(conf.GetLowSpaceRatio()) || !f.constraint.MatchStore(store) {
 		return statusOK
@@ -869,6 +899,7 @@ func (f *specialUseFilter) Source(conf config.SharedConfigProvider, store *core.
 	return statusStoreNotMatchRule
 }
 
+// Target filters stores when select them as schedule target.
 func (f *specialUseFilter) Target(_ config.SharedConfigProvider, store *core.StoreInfo) *plan.Status {
 	if !f.constraint.MatchStore(store) {
 		return statusOK
@@ -928,18 +959,22 @@ func NewIsolationFilter(scope, isolationLevel string, locationLabels []string, r
 	return isolationFilter
 }
 
+// Scope returns the scheduler or the checker which the filter acts on.
 func (f *isolationFilter) Scope() string {
 	return f.scope
 }
 
+// Type returns the name of the filter.
 func (*isolationFilter) Type() filterType {
 	return isolation
 }
 
+// Source filters stores when select them as schedule source.
 func (*isolationFilter) Source(config.SharedConfigProvider, *core.StoreInfo) *plan.Status {
 	return statusOK
 }
 
+// Target filters stores when select them as schedule target.
 func (f *isolationFilter) Target(_ config.SharedConfigProvider, store *core.StoreInfo) *plan.Status {
 	// No isolation constraint to fit
 	if len(f.constraintSet) == 0 {
diff --git a/pkg/schedule/filter/region_filters.go b/pkg/schedule/filter/region_filters.go
index 7cd015412c2..e233ec75973 100644
--- a/pkg/schedule/filter/region_filters.go
+++ b/pkg/schedule/filter/region_filters.go
@@ -76,6 +76,7 @@ func NewRegionPendingFilter() RegionFilter {
 	return &regionPendingFilter{}
 }
 
+// Select implements the RegionFilter interface.
 func (*regionPendingFilter) Select(region *core.RegionInfo) *plan.Status {
 	if hasPendingPeers(region) {
 		return statusRegionPendingPeer
@@ -91,6 +92,7 @@ func NewRegionDownFilter() RegionFilter {
 	return &regionDownFilter{}
 }
 
+// Select implements the RegionFilter interface.
 func (*regionDownFilter) Select(region *core.RegionInfo) *plan.Status {
 	if hasDownPeers(region) {
 		return statusRegionDownPeer
diff --git a/pkg/schedule/operator/builder.go b/pkg/schedule/operator/builder.go
index 1852f292db0..e28e7de973a 100644
--- a/pkg/schedule/operator/builder.go
+++ b/pkg/schedule/operator/builder.go
@@ -959,6 +959,7 @@ func (p stepPlan) String() string {
 		p.leaderBeforeAdd, p.add, p.promote, p.leaderBeforeRemove, p.demote, p.remove, p.nonWitness, p.promoteNonWitness, p.witness)
 }
 
+// IsEmpty checks if the plan is empty.
 func (p stepPlan) IsEmpty() bool {
 	return p.promote == nil && p.demote == nil && p.add == nil && p.remove == nil && p.nonWitness == nil && p.promoteNonWitness == nil && p.witness == nil
 }
diff --git a/pkg/schedule/operator/operator_queue.go b/pkg/schedule/operator/operator_queue.go
index 2233845724e..8643717d5ad 100644
--- a/pkg/schedule/operator/operator_queue.go
+++ b/pkg/schedule/operator/operator_queue.go
@@ -27,21 +27,26 @@ type operatorWithTime struct {
 
 type operatorQueue []*operatorWithTime
 
+// Len implements heap.Interface.
 func (opn operatorQueue) Len() int { return len(opn) }
 
+// Less implements heap.Interface.
 func (opn operatorQueue) Less(i, j int) bool {
 	return opn[i].time.Before(opn[j].time)
 }
 
+// Swap implements heap.Interface.
 func (opn operatorQueue) Swap(i, j int) {
 	opn[i], opn[j] = opn[j], opn[i]
 }
 
+// Push implements heap.Interface.
 func (opn *operatorQueue) Push(x any) {
 	item := x.(*operatorWithTime)
 	*opn = append(*opn, item)
 }
 
+// Pop implements heap.Interface.
 func (opn *operatorQueue) Pop() any {
 	old := *opn
 	n := len(old)
diff --git a/pkg/schedule/schedulers/split_bucket.go b/pkg/schedule/schedulers/split_bucket.go
index 4516dfe4433..7df3ee8f552 100644
--- a/pkg/schedule/schedulers/split_bucket.go
+++ b/pkg/schedule/schedulers/split_bucket.go
@@ -98,12 +98,12 @@ type splitBucketHandler struct {
 	rd   *render.Render
 }
 
-func (h *splitBucketHandler) ListConfig(w http.ResponseWriter, _ *http.Request) {
+func (h *splitBucketHandler) listConfig(w http.ResponseWriter, _ *http.Request) {
 	conf := h.conf.Clone()
 	h.rd.JSON(w, http.StatusOK, conf)
 }
 
-func (h *splitBucketHandler) UpdateConfig(w http.ResponseWriter, r *http.Request) {
+func (h *splitBucketHandler) updateConfig(w http.ResponseWriter, r *http.Request) {
 	h.conf.Lock()
 	defer h.conf.Unlock()
 	rd := render.New(render.Options{IndentJSON: true})
@@ -148,8 +148,8 @@ func newSplitBucketHandler(conf *splitBucketSchedulerConfig) http.Handler {
 		rd:   render.New(render.Options{IndentJSON: true}),
 	}
 	router := mux.NewRouter()
-	router.HandleFunc("/list", h.ListConfig).Methods(http.MethodGet)
-	router.HandleFunc("/config", h.UpdateConfig).Methods(http.MethodPost)
+	router.HandleFunc("/list", h.listConfig).Methods(http.MethodGet)
+	router.HandleFunc("/config", h.updateConfig).Methods(http.MethodPost)
 	return router
 }
 
diff --git a/pkg/schedule/splitter/region_splitter.go b/pkg/schedule/splitter/region_splitter.go
index aeab4b70cf0..124ad935655 100644
--- a/pkg/schedule/splitter/region_splitter.go
+++ b/pkg/schedule/splitter/region_splitter.go
@@ -187,6 +187,7 @@ type splitRegionsHandler struct {
 	oc      *operator.Controller
 }
 
+// SplitRegionByKeys split region by keys.
 func (h *splitRegionsHandler) SplitRegionByKeys(region *core.RegionInfo, splitKeys [][]byte) error {
 	op, err := operator.CreateSplitRegionOperator("region-splitter", region, 0, pdpb.CheckPolicy_USEKEY, splitKeys)
 	if err != nil {
@@ -200,6 +201,7 @@ func (h *splitRegionsHandler) SplitRegionByKeys(region *core.RegionInfo, splitKe
 	return nil
 }
 
+// ScanRegionsByKeyRange scans regions by key range.
 func (h *splitRegionsHandler) ScanRegionsByKeyRange(groupKeys *regionGroupKeys, results *splitKeyResults) {
 	splitKeys := groupKeys.keys
 	startKey, endKey := groupKeys.region.GetStartKey(), groupKeys.region.GetEndKey()
diff --git a/pkg/schedule/type/type.go b/pkg/schedule/type/type.go
index 26e1b6a737a..16910c631fd 100644
--- a/pkg/schedule/type/type.go
+++ b/pkg/schedule/type/type.go
@@ -14,10 +14,12 @@
 
 package types
 
+// CheckerSchedulerType is the type of checker/scheduler.
 type CheckerSchedulerType string
 
-func (n CheckerSchedulerType) String() string {
-	return string(n)
+// String implements fmt.Stringer.
+func (t CheckerSchedulerType) String() string {
+	return string(t)
 }
 
 const (
@@ -93,6 +95,7 @@ var SchedulerTypeCompatibleMap = map[CheckerSchedulerType]string{
 	LabelScheduler:                 "label",
 }
 
+// SchedulerStr2Type is a map to convert the scheduler string to the CheckerSchedulerType.
 var SchedulerStr2Type = map[string]CheckerSchedulerType{
 	"balance-leader-scheduler":     BalanceLeaderScheduler,
 	"balance-region-scheduler":     BalanceRegionScheduler,
diff --git a/pkg/statistics/collector.go b/pkg/statistics/collector.go
index 88986b93d4b..4e3e2fa2c7a 100644
--- a/pkg/statistics/collector.go
+++ b/pkg/statistics/collector.go
@@ -22,12 +22,12 @@ import (
 
 // storeCollector define the behavior of different engines of stores.
 type storeCollector interface {
-	// Engine returns the type of Store.
-	Engine() string
-	// Filter determines whether the Store needs to be handled by itself.
-	Filter(info *StoreSummaryInfo, kind constant.ResourceKind) bool
-	// GetLoads obtains available loads from storeLoads and peerLoadSum according to rwTy and kind.
-	GetLoads(storeLoads, peerLoadSum []float64, rwTy utils.RWType, kind constant.ResourceKind) (loads []float64)
+	// engine returns the type of Store.
+	engine() string
+	// filter determines whether the Store needs to be handled by itself.
+	filter(info *StoreSummaryInfo, kind constant.ResourceKind) bool
+	// getLoads obtains available loads from storeLoads and peerLoadSum according to rwTy and kind.
+	getLoads(storeLoads, peerLoadSum []float64, rwTy utils.RWType, kind constant.ResourceKind) (loads []float64)
 }
 
 type tikvCollector struct{}
@@ -36,11 +36,11 @@ func newTikvCollector() storeCollector {
 	return tikvCollector{}
 }
 
-func (tikvCollector) Engine() string {
+func (tikvCollector) engine() string {
 	return core.EngineTiKV
 }
 
-func (tikvCollector) Filter(info *StoreSummaryInfo, kind constant.ResourceKind) bool {
+func (tikvCollector) filter(info *StoreSummaryInfo, kind constant.ResourceKind) bool {
 	if info.IsTiFlash() {
 		return false
 	}
@@ -53,7 +53,7 @@ func (tikvCollector) Filter(info *StoreSummaryInfo, kind constant.ResourceKind)
 	return false
 }
 
-func (tikvCollector) GetLoads(storeLoads, peerLoadSum []float64, rwTy utils.RWType, kind constant.ResourceKind) (loads []float64) {
+func (tikvCollector) getLoads(storeLoads, peerLoadSum []float64, rwTy utils.RWType, kind constant.ResourceKind) (loads []float64) {
 	loads = make([]float64, utils.DimLen)
 	switch rwTy {
 	case utils.Read:
@@ -87,11 +87,11 @@ func newTiFlashCollector(isTraceRegionFlow bool) storeCollector {
 	return tiflashCollector{isTraceRegionFlow: isTraceRegionFlow}
 }
 
-func (tiflashCollector) Engine() string {
+func (tiflashCollector) engine() string {
 	return core.EngineTiFlash
 }
 
-func (tiflashCollector) Filter(info *StoreSummaryInfo, kind constant.ResourceKind) bool {
+func (tiflashCollector) filter(info *StoreSummaryInfo, kind constant.ResourceKind) bool {
 	switch kind {
 	case constant.LeaderKind:
 		return false
@@ -101,7 +101,7 @@ func (tiflashCollector) Filter(info *StoreSummaryInfo, kind constant.ResourceKin
 	return false
 }
 
-func (c tiflashCollector) GetLoads(storeLoads, peerLoadSum []float64, rwTy utils.RWType, kind constant.ResourceKind) (loads []float64) {
+func (c tiflashCollector) getLoads(storeLoads, peerLoadSum []float64, rwTy utils.RWType, kind constant.ResourceKind) (loads []float64) {
 	loads = make([]float64, utils.DimLen)
 	switch rwTy {
 	case utils.Read:
diff --git a/pkg/statistics/hot_peer.go b/pkg/statistics/hot_peer.go
index 79757d6e27f..8f92fbff542 100644
--- a/pkg/statistics/hot_peer.go
+++ b/pkg/statistics/hot_peer.go
@@ -41,7 +41,7 @@ func newDimStat(reportInterval time.Duration) *dimStat {
 	}
 }
 
-func (d *dimStat) Add(delta float64, interval time.Duration) {
+func (d *dimStat) add(delta float64, interval time.Duration) {
 	d.Lock()
 	defer d.Unlock()
 	d.lastIntervalSum += int(interval.Seconds())
@@ -74,13 +74,13 @@ func (d *dimStat) clearLastAverage() {
 	d.lastDelta = 0
 }
 
-func (d *dimStat) Get() float64 {
+func (d *dimStat) get() float64 {
 	d.RLock()
 	defer d.RUnlock()
 	return d.rolling.Get()
 }
 
-func (d *dimStat) Clone() *dimStat {
+func (d *dimStat) clone() *dimStat {
 	d.RLock()
 	defer d.RUnlock()
 	return &dimStat{
@@ -162,7 +162,7 @@ func (stat *HotPeerStat) GetActionType() utils.ActionType {
 // GetLoad returns denoising load if possible.
 func (stat *HotPeerStat) GetLoad(dim int) float64 {
 	if stat.rollingLoads != nil {
-		return math.Round(stat.rollingLoads[dim].Get())
+		return math.Round(stat.rollingLoads[dim].get())
 	}
 	return math.Round(stat.Loads[dim])
 }
@@ -172,7 +172,7 @@ func (stat *HotPeerStat) GetLoads() []float64 {
 	if stat.rollingLoads != nil {
 		ret := make([]float64, len(stat.rollingLoads))
 		for dim := range ret {
-			ret[dim] = math.Round(stat.rollingLoads[dim].Get())
+			ret[dim] = math.Round(stat.rollingLoads[dim].get())
 		}
 		return ret
 	}
diff --git a/pkg/statistics/hot_peer_cache.go b/pkg/statistics/hot_peer_cache.go
index 4db0c304bb9..8d1f64ca540 100644
--- a/pkg/statistics/hot_peer_cache.go
+++ b/pkg/statistics/hot_peer_cache.go
@@ -102,6 +102,7 @@ func (f *HotPeerCache) RegionStats(minHotDegree int) map[uint64][]*HotPeerStat {
 	return res
 }
 
+// UpdateStat updates the stat cache.
 func (f *HotPeerCache) UpdateStat(item *HotPeerStat) {
 	switch item.actionType {
 	case utils.Remove:
@@ -439,7 +440,7 @@ func (f *HotPeerCache) updateHotPeerStat(region *core.RegionInfo, newItem, oldIt
 
 	if source == utils.Inherit {
 		for _, dim := range oldItem.rollingLoads {
-			newItem.rollingLoads = append(newItem.rollingLoads, dim.Clone())
+			newItem.rollingLoads = append(newItem.rollingLoads, dim.clone())
 		}
 		newItem.allowInherited = false
 	} else {
@@ -462,7 +463,7 @@ func (f *HotPeerCache) updateHotPeerStat(region *core.RegionInfo, newItem, oldIt
 	}
 
 	for i, k := range regionStats {
-		newItem.rollingLoads[i].Add(deltaLoads[k], interval)
+		newItem.rollingLoads[i].add(deltaLoads[k], interval)
 	}
 
 	isFull := newItem.rollingLoads[0].isFull(f.interval()) // The intervals of dims are the same, so it is only necessary to determine whether any of them
@@ -505,7 +506,7 @@ func (f *HotPeerCache) updateNewHotPeerStat(newItem *HotPeerStat, deltaLoads []f
 	newItem.rollingLoads = make([]*dimStat, len(regionStats))
 	for i, k := range regionStats {
 		ds := newDimStat(f.interval())
-		ds.Add(deltaLoads[k], interval)
+		ds.add(deltaLoads[k], interval)
 		if ds.isFull(f.interval()) {
 			ds.clearLastAverage()
 		}
diff --git a/pkg/statistics/store_collection.go b/pkg/statistics/store_collection.go
index 6d5df0bda62..f55c23b27b7 100644
--- a/pkg/statistics/store_collection.go
+++ b/pkg/statistics/store_collection.go
@@ -61,7 +61,7 @@ func newStoreStatistics(opt config.ConfProvider) *storeStatistics {
 	}
 }
 
-func (s *storeStatistics) Observe(store *core.StoreInfo) {
+func (s *storeStatistics) observe(store *core.StoreInfo) {
 	for _, k := range s.opt.GetLocationLabels() {
 		v := store.GetLabelValue(k)
 		if v == "" {
@@ -147,6 +147,7 @@ func (s *storeStatistics) Observe(store *core.StoreInfo) {
 	}
 }
 
+// ObserveHotStat records the hot region metrics for the store.
 func ObserveHotStat(store *core.StoreInfo, stats *StoresStats) {
 	// Store flows.
 	storeAddress := store.GetAddress()
@@ -178,7 +179,7 @@ func ObserveHotStat(store *core.StoreInfo, stats *StoresStats) {
 	storeStatusGauge.WithLabelValues(storeAddress, id, "store_regions_write_rate_keys_instant").Set(storeFlowStats.GetInstantLoad(utils.StoreRegionsWriteKeys))
 }
 
-func (s *storeStatistics) Collect() {
+func (s *storeStatistics) collect() {
 	placementStatusGauge.Reset()
 
 	metrics := make(map[string]float64)
@@ -307,12 +308,14 @@ func NewStoreStatisticsMap(opt config.ConfProvider) *storeStatisticsMap {
 	}
 }
 
+// Observe observes the store.
 func (m *storeStatisticsMap) Observe(store *core.StoreInfo) {
-	m.stats.Observe(store)
+	m.stats.observe(store)
 }
 
+// Collect collects the metrics.
 func (m *storeStatisticsMap) Collect() {
-	m.stats.Collect()
+	m.stats.collect()
 }
 
 // Reset resets the metrics.
diff --git a/pkg/statistics/store_hot_peers_infos.go b/pkg/statistics/store_hot_peers_infos.go
index f7873bdd744..f64c7743d16 100644
--- a/pkg/statistics/store_hot_peers_infos.go
+++ b/pkg/statistics/store_hot_peers_infos.go
@@ -158,7 +158,7 @@ func summaryStoresLoadByEngine(
 		store := info.StoreInfo
 		id := store.GetID()
 		storeLoads, ok := storesLoads[id]
-		if !ok || !collector.Filter(info, kind) {
+		if !ok || !collector.filter(info, kind) {
 			continue
 		}
 
@@ -172,7 +172,7 @@ func summaryStoresLoadByEngine(
 			}
 			hotPeers = append(hotPeers, peer.Clone())
 		}
-		currentLoads := collector.GetLoads(storeLoads, peerLoadSum, rwTy, kind)
+		currentLoads := collector.getLoads(storeLoads, peerLoadSum, rwTy, kind)
 
 		var historyLoads [][]float64
 		if storesHistoryLoads != nil {
@@ -240,7 +240,7 @@ func summaryStoresLoadByEngine(
 
 	{
 		// Metric for debug.
-		engine := collector.Engine()
+		engine := collector.engine()
 		ty := "exp-byte-rate-" + rwTy.String() + "-" + kind.String()
 		hotPeerSummary.WithLabelValues(ty, engine).Set(expectLoads[utils.ByteDim])
 		ty = "exp-key-rate-" + rwTy.String() + "-" + kind.String()
diff --git a/pkg/statistics/utils/topn.go b/pkg/statistics/utils/topn.go
index 7ab6c6eaf3e..cb97251edd9 100644
--- a/pkg/statistics/utils/topn.go
+++ b/pkg/statistics/utils/topn.go
@@ -58,35 +58,35 @@ func NewTopN(k, n int, ttl time.Duration) *TopN {
 func (tn *TopN) Len() int {
 	tn.rw.RLock()
 	defer tn.rw.RUnlock()
-	return tn.ttlLst.Len()
+	return tn.ttlLst.len()
 }
 
 // GetTopNMin returns the min item in top N of the `k`th dimension.
 func (tn *TopN) GetTopNMin(k int) TopNItem {
 	tn.rw.RLock()
 	defer tn.rw.RUnlock()
-	return tn.topns[k].GetTopNMin()
+	return tn.topns[k].getTopNMin()
 }
 
 // GetAllTopN returns the top N items of the `k`th dimension.
 func (tn *TopN) GetAllTopN(k int) []TopNItem {
 	tn.rw.RLock()
 	defer tn.rw.RUnlock()
-	return tn.topns[k].GetAllTopN()
+	return tn.topns[k].getAllTopN()
 }
 
 // GetAll returns all items.
 func (tn *TopN) GetAll() []TopNItem {
 	tn.rw.RLock()
 	defer tn.rw.RUnlock()
-	return tn.topns[0].GetAll()
+	return tn.topns[0].getAll()
 }
 
 // Get returns the item with given id, nil if there is no such item.
 func (tn *TopN) Get(id uint64) TopNItem {
 	tn.rw.RLock()
 	defer tn.rw.RUnlock()
-	return tn.topns[0].Get(id)
+	return tn.topns[0].get(id)
 }
 
 // Put inserts item or updates the old item if it exists.
@@ -94,9 +94,9 @@ func (tn *TopN) Put(item TopNItem) (isUpdate bool) {
 	tn.rw.Lock()
 	defer tn.rw.Unlock()
 	for _, stn := range tn.topns {
-		isUpdate = stn.Put(item)
+		isUpdate = stn.put(item)
 	}
-	tn.ttlLst.Put(item.ID())
+	tn.ttlLst.put(item.ID())
 	tn.maintain()
 	return
 }
@@ -113,17 +113,17 @@ func (tn *TopN) Remove(id uint64) (item TopNItem) {
 	tn.rw.Lock()
 	defer tn.rw.Unlock()
 	for _, stn := range tn.topns {
-		item = stn.Remove(id)
+		item = stn.remove(id)
 	}
-	_ = tn.ttlLst.Remove(id)
+	_ = tn.ttlLst.remove(id)
 	tn.maintain()
 	return
 }
 
 func (tn *TopN) maintain() {
-	for _, id := range tn.ttlLst.TakeExpired() {
+	for _, id := range tn.ttlLst.takeExpired() {
 		for _, stn := range tn.topns {
-			stn.Remove(id)
+			stn.remove(id)
 		}
 	}
 }
@@ -144,31 +144,27 @@ func newSingleTopN(k, n int) *singleTopN {
 	}
 }
 
-func (stn *singleTopN) Len() int {
-	return stn.topn.Len() + stn.rest.Len()
-}
-
-func (stn *singleTopN) GetTopNMin() TopNItem {
+func (stn *singleTopN) getTopNMin() TopNItem {
 	return stn.topn.Top()
 }
 
-func (stn *singleTopN) GetAllTopN() []TopNItem {
+func (stn *singleTopN) getAllTopN() []TopNItem {
 	return stn.topn.GetAll()
 }
 
-func (stn *singleTopN) GetAll() []TopNItem {
+func (stn *singleTopN) getAll() []TopNItem {
 	topn := stn.topn.GetAll()
 	return append(topn, stn.rest.GetAll()...)
 }
 
-func (stn *singleTopN) Get(id uint64) TopNItem {
+func (stn *singleTopN) get(id uint64) TopNItem {
 	if item := stn.topn.Get(id); item != nil {
 		return item
 	}
 	return stn.rest.Get(id)
 }
 
-func (stn *singleTopN) Put(item TopNItem) (isUpdate bool) {
+func (stn *singleTopN) put(item TopNItem) (isUpdate bool) {
 	if stn.topn.Get(item.ID()) != nil {
 		isUpdate = true
 		stn.topn.Put(item)
@@ -179,7 +175,7 @@ func (stn *singleTopN) Put(item TopNItem) (isUpdate bool) {
 	return
 }
 
-func (stn *singleTopN) Remove(id uint64) TopNItem {
+func (stn *singleTopN) remove(id uint64) TopNItem {
 	item := stn.topn.Remove(id)
 	if item == nil {
 		item = stn.rest.Remove(id)
@@ -340,11 +336,11 @@ func newTTLList(ttl time.Duration) *ttlList {
 	}
 }
 
-func (tl *ttlList) Len() int {
+func (tl *ttlList) len() int {
 	return tl.lst.Len()
 }
 
-func (tl *ttlList) TakeExpired() []uint64 {
+func (tl *ttlList) takeExpired() []uint64 {
 	expired := []uint64{}
 	now := time.Now()
 	for ele := tl.lst.Front(); ele != nil; ele = tl.lst.Front() {
@@ -359,7 +355,7 @@ func (tl *ttlList) TakeExpired() []uint64 {
 	return expired
 }
 
-func (tl *ttlList) Put(id uint64) (isUpdate bool) {
+func (tl *ttlList) put(id uint64) (isUpdate bool) {
 	item := ttlItem{id: id}
 	if ele, ok := tl.index[id]; ok {
 		isUpdate = true
@@ -370,7 +366,7 @@ func (tl *ttlList) Put(id uint64) (isUpdate bool) {
 	return
 }
 
-func (tl *ttlList) Remove(id uint64) (removed bool) {
+func (tl *ttlList) remove(id uint64) (removed bool) {
 	if ele, ok := tl.index[id]; ok {
 		_ = tl.lst.Remove(ele)
 		delete(tl.index, id)
diff --git a/pkg/storage/kv/etcd_kv.go b/pkg/storage/kv/etcd_kv.go
index 767aeff77a6..e2eb8c979eb 100644
--- a/pkg/storage/kv/etcd_kv.go
+++ b/pkg/storage/kv/etcd_kv.go
@@ -55,6 +55,7 @@ func NewEtcdKVBase(client *clientv3.Client, rootPath string) *etcdKVBase {
 	}
 }
 
+// NewEtcdKV creates a new etcd kv.
 func (kv *etcdKVBase) Load(key string) (string, error) {
 	key = path.Join(kv.rootPath, key)
 
@@ -70,6 +71,7 @@ func (kv *etcdKVBase) Load(key string) (string, error) {
 	return string(resp.Kvs[0].Value), nil
 }
 
+// LoadRange loads a range of keys [key, endKey) from etcd.
 func (kv *etcdKVBase) LoadRange(key, endKey string, limit int) ([]string, []string, error) {
 	// Note: reason to use `strings.Join` instead of `path.Join` is that the latter will
 	// removes suffix '/' of the joined string.
@@ -99,6 +101,7 @@ func (kv *etcdKVBase) LoadRange(key, endKey string, limit int) ([]string, []stri
 	return keys, values, nil
 }
 
+// Save puts a key-value pair to etcd.
 func (kv *etcdKVBase) Save(key, value string) error {
 	failpoint.Inject("etcdSaveFailed", func() {
 		failpoint.Return(errors.New("save failed"))
@@ -117,6 +120,7 @@ func (kv *etcdKVBase) Save(key, value string) error {
 	return nil
 }
 
+// Remove removes the key from etcd.
 func (kv *etcdKVBase) Remove(key string) error {
 	key = path.Join(kv.rootPath, key)
 
diff --git a/pkg/storage/kv/mem_kv.go b/pkg/storage/kv/mem_kv.go
index 91d13c04e61..b97a3d6cfa1 100644
--- a/pkg/storage/kv/mem_kv.go
+++ b/pkg/storage/kv/mem_kv.go
@@ -41,10 +41,12 @@ type memoryKVItem struct {
 	key, value string
 }
 
+// Less compares two memoryKVItem.
 func (s *memoryKVItem) Less(than *memoryKVItem) bool {
 	return s.key < than.key
 }
 
+// Load loads the value for the key.
 func (kv *memoryKV) Load(key string) (string, error) {
 	kv.RLock()
 	defer kv.RUnlock()
@@ -55,6 +57,7 @@ func (kv *memoryKV) Load(key string) (string, error) {
 	return item.value, nil
 }
 
+// LoadRange loads the keys in the range of [key, endKey).
 func (kv *memoryKV) LoadRange(key, endKey string, limit int) ([]string, []string, error) {
 	failpoint.Inject("withRangeLimit", func(val failpoint.Value) {
 		rangeLimit, ok := val.(int)
@@ -77,6 +80,7 @@ func (kv *memoryKV) LoadRange(key, endKey string, limit int) ([]string, []string
 	return keys, values, nil
 }
 
+// Save saves the key-value pair.
 func (kv *memoryKV) Save(key, value string) error {
 	kv.Lock()
 	defer kv.Unlock()
@@ -84,6 +88,7 @@ func (kv *memoryKV) Save(key, value string) error {
 	return nil
 }
 
+// Remove removes the key.
 func (kv *memoryKV) Remove(key string) error {
 	kv.Lock()
 	defer kv.Unlock()
diff --git a/pkg/syncer/client.go b/pkg/syncer/client.go
index 00fa8dc389b..a94f5c41f3f 100644
--- a/pkg/syncer/client.go
+++ b/pkg/syncer/client.go
@@ -69,7 +69,7 @@ func (s *RegionSyncer) syncRegion(ctx context.Context, conn *grpc.ClientConn) (C
 	err = syncStream.Send(&pdpb.SyncRegionRequest{
 		Header:     &pdpb.RequestHeader{ClusterId: s.server.ClusterID()},
 		Member:     s.server.GetMemberInfo(),
-		StartIndex: s.history.GetNextIndex(),
+		StartIndex: s.history.getNextIndex(),
 	})
 	if err != nil {
 		return nil, err
@@ -154,7 +154,7 @@ func (s *RegionSyncer) StartSyncWithLeader(addr string) {
 				time.Sleep(time.Second)
 				continue
 			}
-			log.Info("server starts to synchronize with leader", zap.String("server", s.server.Name()), zap.String("leader", s.server.GetLeader().GetName()), zap.Uint64("request-index", s.history.GetNextIndex()))
+			log.Info("server starts to synchronize with leader", zap.String("server", s.server.Name()), zap.String("leader", s.server.GetLeader().GetName()), zap.Uint64("request-index", s.history.getNextIndex()))
 			for {
 				resp, err := stream.Recv()
 				if err != nil {
@@ -166,14 +166,14 @@ func (s *RegionSyncer) StartSyncWithLeader(addr string) {
 					time.Sleep(time.Second)
 					break
 				}
-				if s.history.GetNextIndex() != resp.GetStartIndex() {
+				if s.history.getNextIndex() != resp.GetStartIndex() {
 					log.Warn("server sync index not match the leader",
 						zap.String("server", s.server.Name()),
-						zap.Uint64("own", s.history.GetNextIndex()),
+						zap.Uint64("own", s.history.getNextIndex()),
 						zap.Uint64("leader", resp.GetStartIndex()),
 						zap.Int("records-length", len(resp.GetRegions())))
 					// reset index
-					s.history.ResetWithIndex(resp.GetStartIndex())
+					s.history.resetWithIndex(resp.GetStartIndex())
 				}
 				stats := resp.GetRegionStats()
 				regions := resp.GetRegions()
@@ -224,7 +224,7 @@ func (s *RegionSyncer) StartSyncWithLeader(addr string) {
 						err = regionStorage.SaveRegion(r)
 					}
 					if err == nil {
-						s.history.Record(region)
+						s.history.record(region)
 					}
 					for _, old := range overlaps {
 						_ = regionStorage.DeleteRegion(old.GetMeta())
diff --git a/pkg/syncer/history_buffer.go b/pkg/syncer/history_buffer.go
index 08fe85cc8c5..7ff6f202ad3 100644
--- a/pkg/syncer/history_buffer.go
+++ b/pkg/syncer/history_buffer.go
@@ -84,7 +84,7 @@ func (h *historyBuffer) firstIndex() uint64 {
 	return h.index - uint64(h.len())
 }
 
-func (h *historyBuffer) Record(r *core.RegionInfo) {
+func (h *historyBuffer) record(r *core.RegionInfo) {
 	h.Lock()
 	defer h.Unlock()
 	syncIndexGauge.Set(float64(h.index))
@@ -101,7 +101,7 @@ func (h *historyBuffer) Record(r *core.RegionInfo) {
 	}
 }
 
-func (h *historyBuffer) RecordsFrom(index uint64) []*core.RegionInfo {
+func (h *historyBuffer) recordsFrom(index uint64) []*core.RegionInfo {
 	h.RLock()
 	defer h.RUnlock()
 	var pos int
@@ -117,7 +117,7 @@ func (h *historyBuffer) RecordsFrom(index uint64) []*core.RegionInfo {
 	return records
 }
 
-func (h *historyBuffer) ResetWithIndex(index uint64) {
+func (h *historyBuffer) resetWithIndex(index uint64) {
 	h.Lock()
 	defer h.Unlock()
 	h.index = index
@@ -126,7 +126,7 @@ func (h *historyBuffer) ResetWithIndex(index uint64) {
 	h.flushCount = defaultFlushCount
 }
 
-func (h *historyBuffer) GetNextIndex() uint64 {
+func (h *historyBuffer) getNextIndex() uint64 {
 	h.RLock()
 	defer h.RUnlock()
 	return h.index
diff --git a/pkg/syncer/history_buffer_test.go b/pkg/syncer/history_buffer_test.go
index 4bca5b7f603..70a1caf13dc 100644
--- a/pkg/syncer/history_buffer_test.go
+++ b/pkg/syncer/history_buffer_test.go
@@ -34,7 +34,7 @@ func TestBufferSize(t *testing.T) {
 	h := newHistoryBuffer(1, kv.NewMemoryKV())
 	re.Equal(0, h.len())
 	for _, r := range regions {
-		h.Record(r)
+		h.record(r)
 	}
 	re.Equal(1, h.len())
 	re.Equal(regions[h.nextIndex()-1], h.get(100))
@@ -43,7 +43,7 @@ func TestBufferSize(t *testing.T) {
 	// size equals 2
 	h = newHistoryBuffer(2, kv.NewMemoryKV())
 	for _, r := range regions {
-		h.Record(r)
+		h.record(r)
 	}
 	re.Equal(2, h.len())
 	re.Equal(regions[h.nextIndex()-1], h.get(100))
@@ -54,7 +54,7 @@ func TestBufferSize(t *testing.T) {
 	kvMem := kv.NewMemoryKV()
 	h1 := newHistoryBuffer(100, kvMem)
 	for i := 0; i < 6; i++ {
-		h1.Record(regions[i])
+		h1.record(regions[i])
 	}
 	re.Equal(6, h1.len())
 	re.Equal(uint64(6), h1.nextIndex())
@@ -68,7 +68,7 @@ func TestBufferSize(t *testing.T) {
 	re.Equal(0, h2.len())
 	for _, r := range regions {
 		index := h2.nextIndex()
-		h2.Record(r)
+		h2.record(r)
 		re.Equal(r, h2.get(index))
 	}
 
@@ -79,9 +79,9 @@ func TestBufferSize(t *testing.T) {
 	// flush in index 106
 	re.Equal("106", s)
 
-	histories := h2.RecordsFrom(uint64(1))
+	histories := h2.recordsFrom(uint64(1))
 	re.Empty(histories)
-	histories = h2.RecordsFrom(h2.firstIndex())
+	histories = h2.recordsFrom(h2.firstIndex())
 	re.Len(histories, 100)
 	re.Equal(uint64(7), h2.firstIndex())
 	re.Equal(regions[1:], histories)
diff --git a/pkg/syncer/server.go b/pkg/syncer/server.go
index 132b06aec69..2cdc01053f6 100644
--- a/pkg/syncer/server.go
+++ b/pkg/syncer/server.go
@@ -136,8 +136,8 @@ func (s *RegionSyncer) RunServer(ctx context.Context, regionNotifier <-chan *cor
 			}
 			buckets = append(buckets, bucket)
 			leaders = append(leaders, first.GetLeader())
-			startIndex := s.history.GetNextIndex()
-			s.history.Record(first)
+			startIndex := s.history.getNextIndex()
+			s.history.record(first)
 			pending := len(regionNotifier)
 			for i := 0; i < pending && i < maxSyncRegionBatchSize; i++ {
 				region := <-regionNotifier
@@ -150,7 +150,7 @@ func (s *RegionSyncer) RunServer(ctx context.Context, regionNotifier <-chan *cor
 				}
 				buckets = append(buckets, bucket)
 				leaders = append(leaders, region.GetLeader())
-				s.history.Record(region)
+				s.history.record(region)
 			}
 			regions := &pdpb.SyncRegionResponse{
 				Header:        &pdpb.ResponseHeader{ClusterId: s.server.ClusterID()},
@@ -164,7 +164,7 @@ func (s *RegionSyncer) RunServer(ctx context.Context, regionNotifier <-chan *cor
 		case <-ticker.C:
 			alive := &pdpb.SyncRegionResponse{
 				Header:     &pdpb.ResponseHeader{ClusterId: s.server.ClusterID()},
-				StartIndex: s.history.GetNextIndex(),
+				StartIndex: s.history.getNextIndex(),
 			}
 			s.broadcast(alive)
 		}
@@ -223,9 +223,9 @@ func (s *RegionSyncer) Sync(ctx context.Context, stream pdpb.PD_SyncRegionsServe
 func (s *RegionSyncer) syncHistoryRegion(ctx context.Context, request *pdpb.SyncRegionRequest, stream pdpb.PD_SyncRegionsServer) error {
 	startIndex := request.GetStartIndex()
 	name := request.GetMember().GetName()
-	records := s.history.RecordsFrom(startIndex)
+	records := s.history.recordsFrom(startIndex)
 	if len(records) == 0 {
-		if s.history.GetNextIndex() == startIndex {
+		if s.history.getNextIndex() == startIndex {
 			log.Info("requested server has already in sync with server",
 				zap.String("requested-server", name), zap.String("server", s.server.Name()), zap.Uint64("last-index", startIndex))
 			// still send a response to follower to show the history region sync.
@@ -306,7 +306,7 @@ func (s *RegionSyncer) syncHistoryRegion(ctx context.Context, request *pdpb.Sync
 	log.Info("sync the history regions with server",
 		zap.String("server", name),
 		zap.Uint64("from-index", startIndex),
-		zap.Uint64("last-index", s.history.GetNextIndex()),
+		zap.Uint64("last-index", s.history.getNextIndex()),
 		zap.Int("records-length", len(records)))
 	regions := make([]*metapb.Region, len(records))
 	stats := make([]*pdpb.RegionStat, len(records))
diff --git a/pkg/window/counter.go b/pkg/window/counter.go
index 8eaf164b7c0..84325cdc14b 100644
--- a/pkg/window/counter.go
+++ b/pkg/window/counter.go
@@ -76,34 +76,44 @@ func NewRollingCounter(opts RollingCounterOpts) RollingCounter {
 	}
 }
 
+// Add adds the given value to the counter.
 func (r *rollingCounter) Add(val int64) {
 	r.policy.Add(float64(val))
 }
 
+// Reduce applies the reduction function to all buckets within the window.
 func (r *rollingCounter) Reduce(f func(Iterator) float64) float64 {
 	return r.policy.Reduce(f)
 }
 
+// Avg computes average value within the window.
 func (r *rollingCounter) Avg() float64 {
 	return r.policy.Reduce(Avg)
 }
 
+// Min finds the min value within the window.
 func (r *rollingCounter) Min() float64 {
 	return r.policy.Reduce(Min)
 }
 
+// Max finds the max value within the window.
 func (r *rollingCounter) Max() float64 {
 	return r.policy.Reduce(Max)
 }
 
+// Sum computes sum value within the window.
 func (r *rollingCounter) Sum() float64 {
 	return r.policy.Reduce(Sum)
 }
 
+// Value gets the current value.
 func (r *rollingCounter) Value() int64 {
 	return int64(r.Sum())
 }
 
+// Timespan returns passed bucket number since lastAppendTime,
+// if it is one bucket duration earlier than the last recorded
+// time, it will return the size.
 func (r *rollingCounter) Timespan() int {
 	r.policy.mu.RLock()
 	defer r.policy.mu.RUnlock()
diff --git a/plugin/scheduler_example/evict_leader.go b/plugin/scheduler_example/evict_leader.go
index a37874a8461..9ad797e0ae4 100644
--- a/plugin/scheduler_example/evict_leader.go
+++ b/plugin/scheduler_example/evict_leader.go
@@ -96,6 +96,7 @@ type evictLeaderSchedulerConfig struct {
 	cluster          *core.BasicCluster
 }
 
+// BuildWithArgs builds the config with the args.
 func (conf *evictLeaderSchedulerConfig) BuildWithArgs(args []string) error {
 	if len(args) != 1 {
 		return errors.New("should specify the store-id")
@@ -115,6 +116,7 @@ func (conf *evictLeaderSchedulerConfig) BuildWithArgs(args []string) error {
 	return nil
 }
 
+// Clone clones the config.
 func (conf *evictLeaderSchedulerConfig) Clone() *evictLeaderSchedulerConfig {
 	conf.mu.RLock()
 	defer conf.mu.RUnlock()
@@ -123,6 +125,7 @@ func (conf *evictLeaderSchedulerConfig) Clone() *evictLeaderSchedulerConfig {
 	}
 }
 
+// Persist saves the config.
 func (conf *evictLeaderSchedulerConfig) Persist() error {
 	name := conf.getScheduleName()
 	conf.mu.RLock()
@@ -166,24 +169,29 @@ func newEvictLeaderScheduler(opController *operator.Controller, conf *evictLeade
 	}
 }
 
+// ServeHTTP implements the http.Handler interface.
 func (s *evictLeaderScheduler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	s.handler.ServeHTTP(w, r)
 }
 
+// GetName returns the scheduler name.
 func (*evictLeaderScheduler) GetName() string {
 	return EvictLeaderName
 }
 
+// GetType returns the scheduler type.
 func (*evictLeaderScheduler) GetType() string {
 	return EvictLeaderType
 }
 
+// EncodeConfig serializes the config.
 func (s *evictLeaderScheduler) EncodeConfig() ([]byte, error) {
 	s.conf.mu.RLock()
 	defer s.conf.mu.RUnlock()
 	return schedulers.EncodeConfig(s.conf)
 }
 
+// PrepareConfig ensures the scheduler config is valid.
 func (s *evictLeaderScheduler) PrepareConfig(cluster sche.SchedulerCluster) error {
 	s.conf.mu.RLock()
 	defer s.conf.mu.RUnlock()
@@ -196,6 +204,7 @@ func (s *evictLeaderScheduler) PrepareConfig(cluster sche.SchedulerCluster) erro
 	return res
 }
 
+// CleanConfig is used to clean the scheduler config.
 func (s *evictLeaderScheduler) CleanConfig(cluster sche.SchedulerCluster) {
 	s.conf.mu.RLock()
 	defer s.conf.mu.RUnlock()
@@ -204,6 +213,7 @@ func (s *evictLeaderScheduler) CleanConfig(cluster sche.SchedulerCluster) {
 	}
 }
 
+// IsScheduleAllowed checks if the scheduler is allowed to schedule.
 func (s *evictLeaderScheduler) IsScheduleAllowed(cluster sche.SchedulerCluster) bool {
 	allowed := s.OpController.OperatorCount(operator.OpLeader) < cluster.GetSchedulerConfig().GetLeaderScheduleLimit()
 	if !allowed {
@@ -212,6 +222,7 @@ func (s *evictLeaderScheduler) IsScheduleAllowed(cluster sche.SchedulerCluster)
 	return allowed
 }
 
+// Schedule schedules the evict leader operator.
 func (s *evictLeaderScheduler) Schedule(cluster sche.SchedulerCluster, _ bool) ([]*operator.Operator, []plan.Plan) {
 	ops := make([]*operator.Operator, 0, len(s.conf.StoreIDWitRanges))
 	s.conf.mu.RLock()
@@ -246,6 +257,7 @@ type evictLeaderHandler struct {
 	config *evictLeaderSchedulerConfig
 }
 
+// UpdateConfig updates the config.
 func (handler *evictLeaderHandler) UpdateConfig(w http.ResponseWriter, r *http.Request) {
 	var input map[string]any
 	if err := apiutil.ReadJSONRespondError(handler.rd, w, r.Body, &input); err != nil {
@@ -286,11 +298,13 @@ func (handler *evictLeaderHandler) UpdateConfig(w http.ResponseWriter, r *http.R
 	handler.rd.JSON(w, http.StatusOK, nil)
 }
 
+// ListConfig lists the config.
 func (handler *evictLeaderHandler) ListConfig(w http.ResponseWriter, _ *http.Request) {
 	conf := handler.config.Clone()
 	handler.rd.JSON(w, http.StatusOK, conf)
 }
 
+// DeleteConfig deletes the config.
 func (handler *evictLeaderHandler) DeleteConfig(w http.ResponseWriter, r *http.Request) {
 	idStr := mux.Vars(r)["store_id"]
 	id, err := strconv.ParseUint(idStr, 10, 64)