Support arbitrary statistic duration for flow control and refactor internal implementation (#200)

* Support arbitrary statistic duration for flow control. Add `StatIntervalInMs` attribute in flow.Rule. When StatIntervalInMs > globalInterval or < bucketLength, we create a new sliding window for it.
* Add stat reuse mechanism for flow rules
* Make threshold of flow rule "request amount per interval" rather than QPS.
* Refine internal implementation

Author: louyuting

adapter/echo/middleware_test.go

@@ -24,12 +24,14 @@ func initSentinel(t *testing.T) {
 			Threshold:              1,
 			TokenCalculateStrategy: flow.Direct,
 			ControlBehavior:        flow.Reject,
+			StatIntervalInMs:       1000,
 		},
 		{
 			Resource:               "/api/:uid",
 			Threshold:              0,
 			TokenCalculateStrategy: flow.Direct,
 			ControlBehavior:        flow.Reject,
+			StatIntervalInMs:       1000,
 		},
 	})
 	if err != nil {

adapter/gin/middleware_test.go

@@ -24,12 +24,14 @@ func initSentinel(t *testing.T) {
 			Threshold:              1,
 			TokenCalculateStrategy: flow.Direct,
 			ControlBehavior:        flow.Reject,
+			StatIntervalInMs:       1000,
 		},
 		{
 			Resource:               "/api/users/:id",
 			Threshold:              0,
 			TokenCalculateStrategy: flow.Direct,
 			ControlBehavior:        flow.Reject,
+			StatIntervalInMs:       1000,
 		},
 	})
 	if err != nil {

api/slot_chain.go

@@ -38,5 +38,6 @@ func BuildDefaultSlotChain() *base.SlotChain {
 	sc.AddStatSlotLast(&log.Slot{})
 	sc.AddStatSlotLast(&circuitbreaker.MetricStatSlot{})
 	sc.AddStatSlotLast(&hotspot.ConcurrencyStatSlot{})
+	sc.AddStatSlotLast(&flow.StandaloneStatSlot{})
 	return sc
 }

core/base/stat.go

@@ -1,5 +1,9 @@
 package base
 
+import (
+	"github.com/pkg/errors"
+)
+
 type TimePredicate func(uint64) bool
 
 type MetricEvent int8
@@ -31,7 +35,7 @@ type ReadStat interface {
 }
 
 type WriteStat interface {
-	AddMetric(event MetricEvent, count uint64)
+	AddCount(event MetricEvent, count int64)
 }
 
 // StatNode holds real-time statistics for resources.
@@ -46,4 +50,47 @@ type StatNode interface {
 	DecreaseGoroutineNum()
 
 	Reset()
+
+	// GenerateReadStat generates the readonly metric statistic based on resource level global statistic
+	// If parameters, sampleCount and intervalInMs, are not suitable for resource level global statistic, return (nil, error)
+	GenerateReadStat(sampleCount uint32, intervalInMs uint32) (ReadStat, error)
+}
+
+var (
+	IllegalGlobalStatisticParamsError = errors.New("Invalid parameters, sampleCount or interval, for resource's global statistic")
+	IllegalStatisticParamsError       = errors.New("Invalid parameters, sampleCount or interval, for metric statistic")
+	GlobalStatisticNonReusableError   = errors.New("The parameters, sampleCount and interval, mismatch for reusing between resource's global statistic and readonly metric statistic.")
+)
+
+func CheckValidityForStatistic(sampleCount, intervalInMs uint32) error {
+	if intervalInMs == 0 || sampleCount == 0 || intervalInMs%sampleCount != 0 {
+		return IllegalStatisticParamsError
+	}
+	return nil
+}
+
+// CheckValidityForReuseStatistic check the compliance whether readonly metric statistic can be built based on resource's global statistic
+// The parameters, sampleCount and intervalInMs, are the parameters of the metric statistic you want to build
+// The parameters, parentSampleCount and parentIntervalInMs, are the parameters of the resource's global statistic
+// If compliance passes, return nil, if not returns specific error
+func CheckValidityForReuseStatistic(sampleCount, intervalInMs uint32, parentSampleCount, parentIntervalInMs uint32) error {
+	if intervalInMs == 0 || sampleCount == 0 || intervalInMs%sampleCount != 0 {
+		return IllegalStatisticParamsError
+	}
+	bucketLengthInMs := intervalInMs / sampleCount
+
+	if parentIntervalInMs == 0 || parentSampleCount == 0 || parentIntervalInMs%parentSampleCount != 0 {
+		return IllegalGlobalStatisticParamsError
+	}
+	parentBucketLengthInMs := parentIntervalInMs / parentSampleCount
+
+	//SlidingWindowMetric's intervalInMs is not divisible by BucketLeapArray's intervalInMs
+	if parentIntervalInMs%intervalInMs != 0 {
+		return GlobalStatisticNonReusableError
+	}
+	// BucketLeapArray's BucketLengthInMs is not divisible by SlidingWindowMetric's BucketLengthInMs
+	if bucketLengthInMs%parentBucketLengthInMs != 0 {
+		return GlobalStatisticNonReusableError
+	}
+	return nil
 }

core/base/stat_test.go

@@ -1,12 +1,17 @@
 package base
 
-import "github.com/stretchr/testify/mock"
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+)
 
 type StatNodeMock struct {
 	mock.Mock
 }
 
-func (m *StatNodeMock) AddMetric(event MetricEvent, count uint64) {
+func (m *StatNodeMock) AddCount(event MetricEvent, count int64) {
 	m.Called(event, count)
 }
 
@@ -64,3 +69,19 @@ func (m *StatNodeMock) Reset() {
 	m.Called()
 	return
 }
+
+func (m *StatNodeMock) GenerateReadStat(sampleCount uint32, intervalInMs uint32) (ReadStat, error) {
+	args := m.Called(sampleCount, intervalInMs)
+	return args.Get(0).(ReadStat), args.Error(1)
+}
+
+func TestCheckValidityForReuseStatistic(t *testing.T) {
+	assert.Equal(t, CheckValidityForReuseStatistic(3, 1000, 20, 10000), IllegalStatisticParamsError)
+	assert.Equal(t, CheckValidityForReuseStatistic(0, 1000, 20, 10000), IllegalStatisticParamsError)
+	assert.Equal(t, CheckValidityForReuseStatistic(2, 1000, 21, 10000), IllegalGlobalStatisticParamsError)
+	assert.Equal(t, CheckValidityForReuseStatistic(2, 1000, 0, 10000), IllegalGlobalStatisticParamsError)
+	assert.Equal(t, CheckValidityForReuseStatistic(2, 8000, 20, 10000), GlobalStatisticNonReusableError)
+	assert.Equal(t, CheckValidityForReuseStatistic(2, 1000, 10, 10000), GlobalStatisticNonReusableError)
+	assert.Equal(t, CheckValidityForReuseStatistic(1, 1000, 100, 10000), nil)
+	assert.Equal(t, CheckValidityForReuseStatistic(2, 1000, 20, 10000), nil)
+}

core/config/config.go

@@ -205,3 +205,22 @@ func SystemStatCollectIntervalMs() uint32 {
 func UseCacheTime() bool {
 	return globalCfg.UseCacheTime()
 }
+
+func GlobalStatisticIntervalMsTotal() uint32 {
+	return globalCfg.GlobalStatisticIntervalMsTotal()
+}
+
+func GlobalStatisticSampleCountTotal() uint32 {
+	return globalCfg.GlobalStatisticSampleCountTotal()
+}
+
+func GlobalStatisticBucketLengthInMs() uint32 {
+	return globalCfg.GlobalStatisticIntervalMsTotal() / GlobalStatisticSampleCountTotal()
+}
+
+func MetricStatisticIntervalMs() uint32 {
+	return globalCfg.MetricStatisticIntervalMs()
+}
+func MetricStatisticSampleCount() uint32 {
+	return globalCfg.MetricStatisticSampleCount()
+}

core/config/entity.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"fmt"
 
+	"github.com/alibaba/sentinel-golang/core/base"
 	"github.com/alibaba/sentinel-golang/logging"
 	"github.com/pkg/errors"
 )
@@ -52,6 +53,15 @@ type MetricLogConfig struct {
 
 // StatConfig represents the configuration items of statistics.
 type StatConfig struct {
+	// GlobalStatisticSampleCountTotal and GlobalStatisticIntervalMsTotal is the per resource's global default statistic sliding window config
+	GlobalStatisticSampleCountTotal uint32 `yaml:"globalStatisticSampleCountTotal"`
+	GlobalStatisticIntervalMsTotal  uint32 `yaml:"globalStatisticIntervalMsTotal"`
+
+	// MetricStatisticSampleCount and MetricStatisticIntervalMs is the per resource's default readonly metric statistic
+	// This default readonly metric statistic must be reusable based on global statistic.
+	MetricStatisticSampleCount uint32 `yaml:"metricStatisticSampleCount"`
+	MetricStatisticIntervalMs  uint32 `yaml:"metricStatisticIntervalMs"`
+
 	System SystemStatConfig `yaml:"system"`
 }
 
@@ -84,6 +94,10 @@ func NewDefaultConfig() *Entity {
 				},
 			},
 			Stat: StatConfig{
+				GlobalStatisticSampleCountTotal: base.DefaultSampleCountTotal,
+				GlobalStatisticIntervalMsTotal:  base.DefaultIntervalMsTotal,
+				MetricStatisticSampleCount:      base.DefaultSampleCount,
+				MetricStatisticIntervalMs:       base.DefaultIntervalMs,
 				System: SystemStatConfig{
 					CollectIntervalMs: DefaultSystemStatCollectIntervalMs,
 				},
@@ -117,6 +131,10 @@ func checkConfValid(conf *SentinelConfig) error {
 	if mc.SingleFileMaxSize <= 0 {
 		return errors.New("Illegal metric log globalCfg: singleFileMaxSize <= 0")
 	}
+	if err := base.CheckValidityForReuseStatistic(conf.Stat.MetricStatisticSampleCount, conf.Stat.MetricStatisticIntervalMs,
+		conf.Stat.GlobalStatisticSampleCountTotal, conf.Stat.GlobalStatisticIntervalMsTotal); err != nil {
+		return err
+	}
 	return nil
 }
 
@@ -168,3 +186,18 @@ func (entity *Entity) SystemStatCollectIntervalMs() uint32 {
 func (entity *Entity) UseCacheTime() bool {
 	return entity.Sentinel.UseCacheTime
 }
+
+func (entity *Entity) GlobalStatisticIntervalMsTotal() uint32 {
+	return entity.Sentinel.Stat.GlobalStatisticIntervalMsTotal
+}
+
+func (entity *Entity) GlobalStatisticSampleCountTotal() uint32 {
+	return entity.Sentinel.Stat.GlobalStatisticSampleCountTotal
+}
+
+func (entity *Entity) MetricStatisticIntervalMs() uint32 {
+	return entity.Sentinel.Stat.MetricStatisticIntervalMs
+}
+func (entity *Entity) MetricStatisticSampleCount() uint32 {
+	return entity.Sentinel.Stat.MetricStatisticSampleCount
+}

core/flow/rule.go

@@ -70,22 +70,54 @@ type Rule struct {
 	Resource               string                 `json:"resource"`
 	TokenCalculateStrategy TokenCalculateStrategy `json:"tokenCalculateStrategy"`
 	ControlBehavior        ControlBehavior        `json:"controlBehavior"`
-	Threshold              float64                `json:"threshold"`
-	RelationStrategy       RelationStrategy       `json:"relationStrategy"`
-	RefResource            string                 `json:"refResource"`
-	MaxQueueingTimeMs      uint32                 `json:"maxQueueingTimeMs"`
-	WarmUpPeriodSec        uint32                 `json:"warmUpPeriodSec"`
-	WarmUpColdFactor       uint32                 `json:"warmUpColdFactor"`
+	// Threshold means the threshold during StatIntervalInMs
+	// If StatIntervalInMs is 1000(1 second), Threshold means QPS
+	Threshold         float64          `json:"threshold"`
+	RelationStrategy  RelationStrategy `json:"relationStrategy"`
+	RefResource       string           `json:"refResource"`
+	MaxQueueingTimeMs uint32           `json:"maxQueueingTimeMs"`
+	WarmUpPeriodSec   uint32           `json:"warmUpPeriodSec"`
+	WarmUpColdFactor  uint32           `json:"warmUpColdFactor"`
+	// StatIntervalInMs indicates the statistic interval and it's the optional setting for flow Rule.
+	// If user doesn't set StatIntervalInMs, that means using default metric statistic of resource.
+	// If the StatIntervalInMs user specifies can not reuse the global statistic of resource,
+	// 		sentinel will generate independent statistic structure for this rule.
+	StatIntervalInMs uint32 `json:"statIntervalInMs"`
+}
+
+func (r *Rule) isEqualsTo(newRule *Rule) bool {
+	if newRule == nil {
+		return false
+	}
+	if !(r.Resource == newRule.Resource && r.RelationStrategy == newRule.RelationStrategy &&
+		r.RefResource == newRule.RefResource && r.StatIntervalInMs == newRule.StatIntervalInMs &&
+		r.TokenCalculateStrategy == newRule.TokenCalculateStrategy && r.ControlBehavior == newRule.ControlBehavior && r.Threshold == newRule.Threshold &&
+		r.MaxQueueingTimeMs == newRule.MaxQueueingTimeMs && r.WarmUpPeriodSec == newRule.WarmUpPeriodSec && r.WarmUpColdFactor == newRule.WarmUpColdFactor) {
+		return false
+	}
+	return true
+}
+
+func (r *Rule) isStatReusable(newRule *Rule) bool {
+	if newRule == nil {
+		return false
+	}
+	return r.Resource == newRule.Resource && r.RelationStrategy == newRule.RelationStrategy &&
+		r.RefResource == newRule.RefResource && r.StatIntervalInMs == newRule.StatIntervalInMs
+}
+
+func (r *Rule) needStatistic() bool {
+	return !(r.TokenCalculateStrategy == Direct && r.ControlBehavior == Throttling)
 }
 
 func (r *Rule) String() string {
 	b, err := json.Marshal(r)
 	if err != nil {
 		// Return the fallback string
 		return fmt.Sprintf("Rule{Resource=%s, TokenCalculateStrategy=%s, ControlBehavior=%s, "+
-			"Threshold=%.2f, RelationStrategy=%s, RefResource=%s, MaxQueueingTimeMs=%d, WarmUpPeriodSec=%d, WarmUpColdFactor=%d}",
-			r.Resource, r.TokenCalculateStrategy, r.ControlBehavior, r.Threshold, r.RelationStrategy,
-			r.RefResource, r.MaxQueueingTimeMs, r.WarmUpPeriodSec, r.WarmUpColdFactor)
+			"Threshold=%.2f, RelationStrategy=%s, RefResource=%s, MaxQueueingTimeMs=%d, WarmUpPeriodSec=%d, WarmUpColdFactor=%d, StatIntervalInMs=%d}",
+			r.Resource, r.TokenCalculateStrategy, r.ControlBehavior, r.Threshold, r.RelationStrategy, r.RefResource,
+			r.MaxQueueingTimeMs, r.WarmUpPeriodSec, r.WarmUpColdFactor, r.StatIntervalInMs)
 	}
 	return string(b)
 }