add loop queue (#53)

* add loop queue

* add loop queue

* fix the bugs

add loop queue

move the worker queue to directory

按照新的接口实现 lifo 队列

添加新接口的环形队列实现

rename the slice queue

修复了 unlock

使用 queue 管理 goWorkerWithFunc

使用 dequeue 判断队列

add remainder

增加测试文件

循环队列需要一个空闲位

* remove interface{}

* Refine the logic of sync.Pool

* Add flowcharts of ants into READMEs

* Add the installation about ants v2

* Renew the functional options in READMEs

* Renew English and Chinese flowcharts

* rename package name

移动 worker queue 位置

worker queue 都修改为私有接口

考虑到性能问题，把 interface{} 改回到  *goworker

* 修改 releaseExpiry 和 releaseAll

* remove files

* fix some bug

pool.go

@@ -42,7 +42,7 @@ type Pool struct {
 	expiryDuration time.Duration
 
 	// workers is a slice that store the available workers.
-	workers []*goWorker
+	workers workerQueue
 
 	// release is used to notice the pool to closed itself.
 	release int32
@@ -82,35 +82,21 @@ func (p *Pool) periodicallyPurge() {
 	heartbeat := time.NewTicker(p.expiryDuration)
 	defer heartbeat.Stop()
 
-	var expiredWorkers []*goWorker
 	for range heartbeat.C {
 		if atomic.LoadInt32(&p.release) == CLOSED {
 			break
 		}
-		currentTime := time.Now()
+
 		p.lock.Lock()
-		idleWorkers := p.workers
-		n := len(idleWorkers)
-		var i int
-		for i = 0; i < n && currentTime.Sub(idleWorkers[i].recycleTime) > p.expiryDuration; i++ {
-		}
-		expiredWorkers = append(expiredWorkers[:0], idleWorkers[:i]...)
-		if i > 0 {
-			m := copy(idleWorkers, idleWorkers[i:])
-			for i = m; i < n; i++ {
-				idleWorkers[i] = nil
-			}
-			p.workers = idleWorkers[:m]
-		}
+		stream := p.workers.releaseExpiry(p.expiryDuration)
 		p.lock.Unlock()
 
 		// Notify obsolete workers to stop.
 		// This notification must be outside the p.lock, since w.task
 		// may be blocking and may consume a lot of time if many workers
 		// are located on non-local CPUs.
-		for i, w := range expiredWorkers {
+		for w := range stream {
 			w.task <- nil
-			expiredWorkers[i] = nil
 		}
 
 		// There might be a situation that all workers have been cleaned up(no any worker is running)
@@ -156,8 +142,11 @@ func NewPool(size int, options ...Option) (*Pool, error) {
 		},
 	}
 	if opts.PreAlloc {
-		p.workers = make([]*goWorker, 0, size)
+		p.workers = newQueue(loopQueueType, size)
+	} else {
+		p.workers = newQueue(stackType, 0)
 	}
+
 	p.cond = sync.NewCond(p.lock)
 
 	// Start a goroutine to clean up expired workers periodically.
@@ -166,7 +155,7 @@ func NewPool(size int, options ...Option) (*Pool, error) {
 	return p, nil
 }
 
-//---------------------------------------------------------------------------
+// ---------------------------------------------------------------------------
 
 // Submit submits a task to this pool.
 func (p *Pool) Submit(task func()) error {
@@ -209,17 +198,12 @@ func (p *Pool) Release() {
 	p.once.Do(func() {
 		atomic.StoreInt32(&p.release, 1)
 		p.lock.Lock()
-		idleWorkers := p.workers
-		for i, w := range idleWorkers {
-			w.task <- nil
-			idleWorkers[i] = nil
-		}
-		p.workers = nil
+		p.workers.releaseAll()
 		p.lock.Unlock()
 	})
 }
 
-//---------------------------------------------------------------------------
+// ---------------------------------------------------------------------------
 
 // incRunning increases the number of the currently running goroutines.
 func (p *Pool) incRunning() {
@@ -240,12 +224,9 @@ func (p *Pool) retrieveWorker() *goWorker {
 	}
 
 	p.lock.Lock()
-	idleWorkers := p.workers
-	n := len(idleWorkers) - 1
-	if n >= 0 {
-		w = idleWorkers[n]
-		idleWorkers[n] = nil
-		p.workers = idleWorkers[:n]
+
+	w = p.workers.dequeue()
+	if w != nil {
 		p.lock.Unlock()
 	} else if p.Running() < p.Cap() {
 		p.lock.Unlock()
@@ -268,13 +249,12 @@ func (p *Pool) retrieveWorker() *goWorker {
 			spawnWorker()
 			return w
 		}
-		l := len(p.workers) - 1
-		if l < 0 {
+
+		w = p.workers.dequeue()
+		if w == nil {
 			goto Reentry
 		}
-		w = p.workers[l]
-		p.workers[l] = nil
-		p.workers = p.workers[:l]
+
 		p.lock.Unlock()
 	}
 	return w
@@ -287,7 +267,11 @@ func (p *Pool) revertWorker(worker *goWorker) bool {
 	}
 	worker.recycleTime = time.Now()
 	p.lock.Lock()
-	p.workers = append(p.workers, worker)
+
+	err := p.workers.enqueue(worker)
+	if err != nil {
+		return false
+	}
 
 	// Notify the invoker stuck in 'retrieveWorker()' of there is an available worker in the worker queue.
 	p.cond.Signal()

worker_loop_queue.go

@@ -0,0 +1,137 @@
+package ants
+
+import "time"
+
+type loopQueue struct {
+	items     []*goWorker
+	expiry    []*goWorker
+	head      int
+	tail      int
+	remainder int
+}
+
+func newLoopQueue(size int) *loopQueue {
+	if size <= 0 {
+		return nil
+	}
+
+	wq := loopQueue{
+		items:     make([]*goWorker, size+1),
+		expiry:    make([]*goWorker, 0),
+		head:      0,
+		tail:      0,
+		remainder: size + 1,
+	}
+
+	return &wq
+}
+
+func (wq *loopQueue) len() int {
+	if wq.remainder == 0 {
+		return 0
+	}
+
+	return (wq.tail - wq.head + wq.remainder) % wq.remainder
+}
+
+func (wq *loopQueue) cap() int {
+	if wq.remainder == 0 {
+		return 0
+	}
+	return wq.remainder - 1
+}
+
+func (wq *loopQueue) isEmpty() bool {
+	return wq.tail == wq.head
+}
+
+func (wq *loopQueue) enqueue(worker *goWorker) error {
+	if wq.remainder == 0 {
+		return ErrQueueLengthIsZero
+	}
+	if (wq.tail+1)%wq.remainder == wq.head {
+		return ErrQueueIsFull
+	}
+
+	wq.items[wq.tail] = worker
+	wq.tail = (wq.tail + 1) % wq.remainder
+
+	return nil
+}
+
+func (wq *loopQueue) dequeue() *goWorker {
+	if wq.len() == 0 {
+		return nil
+	}
+
+	w := wq.items[wq.head]
+	wq.head = (wq.head + 1) % wq.remainder
+
+	return w
+}
+
+func (wq *loopQueue) releaseExpiry(duration time.Duration) chan *goWorker {
+	stream := make(chan *goWorker)
+
+	if wq.len() == 0 {
+		close(stream)
+		return stream
+	}
+
+	wq.expiry = wq.expiry[:0]
+	expiryTime := time.Now().Add(-duration)
+
+	for wq.head != wq.tail {
+		if expiryTime.After(wq.items[wq.head].recycleTime) {
+			wq.expiry = append(wq.expiry, wq.items[wq.head])
+			wq.head = (wq.head + 1) % wq.remainder
+			continue
+		}
+		break
+	}
+
+	go func() {
+		defer close(stream)
+
+		for i := 0; i < len(wq.expiry); i++ {
+			stream <- wq.expiry[i]
+		}
+	}()
+
+	return stream
+}
+
+//func (wq *LoopQueue)search(compareTime time.Time, l, r int) int {
+//	if l == r {
+//		if wq.items[l].recycleTime.After(compareTime) {
+//			return -1
+//		} else {
+//			return l
+//		}
+//	}
+//
+//	c := cap(wq.items)
+//	mid := ((r-l+c)/2 + l) % c
+//	if mid == l {
+//		return wq.search(compareTime, l, l)
+//	} else if wq.items[mid].recycleTime.After(compareTime) {
+//		return wq.search(compareTime, l, mid-1)
+//	} else {
+//		return wq.search(compareTime, mid+1, r)
+//	}
+//}
+
+func (wq *loopQueue) releaseAll() {
+	if wq.len() == 0 {
+		return
+	}
+
+	for wq.head != wq.tail {
+		wq.items[wq.head].task <- nil
+		wq.head = (wq.head + 1) % wq.remainder
+	}
+	wq.items = wq.items[:0]
+	wq.remainder = 0
+	wq.head = 0
+	wq.tail = 0
+}

worker_loop_queue_test.go

@@ -0,0 +1,73 @@
+package ants
+
+import (
+	"testing"
+	"time"
+)
+
+func TestNewLoopQueue(t *testing.T) {
+	size := 100
+	q := newLoopQueue(size)
+	if q.len() != 0 {
+		t.Fatalf("Len error")
+	}
+
+	if q.cap() != size {
+		t.Fatalf("Cap error")
+	}
+
+	if !q.isEmpty() {
+		t.Fatalf("IsEmpty error")
+	}
+
+	if q.dequeue() != nil {
+		t.Fatalf("Dequeue error")
+	}
+}
+
+func TestLoopQueue(t *testing.T) {
+	size := 10
+	q := newLoopQueue(size)
+
+	for i := 0; i < 5; i++ {
+		err := q.enqueue(&goWorker{recycleTime: time.Now()})
+		if err != nil {
+			break
+		}
+	}
+
+	if q.len() != 5 {
+		t.Fatalf("Len error")
+	}
+
+	v := q.dequeue()
+	t.Log(v)
+
+	if q.len() != 4 {
+		t.Fatalf("Len error")
+	}
+
+	time.Sleep(time.Second)
+
+	for i := 0; i < 6; i++ {
+		err := q.enqueue(&goWorker{recycleTime: time.Now()})
+		if err != nil {
+			break
+		}
+	}
+
+	if q.len() != 10 {
+		t.Fatalf("Len error")
+	}
+
+	err := q.enqueue(&goWorker{recycleTime: time.Now()})
+	if err == nil {
+		t.Fatalf("Enqueue error")
+	}
+
+	q.releaseExpiry(time.Second)
+
+	if q.len() != 6 {
+		t.Fatalf("Len error: %d", q.len())
+	}
+}

worker_queue.go

@@ -0,0 +1,39 @@
+package ants
+
+import (
+	"errors"
+	"time"
+)
+
+var (
+	ErrQueueIsFull       = errors.New("the queue is full")
+	ErrQueueLengthIsZero = errors.New("the queue length is zero")
+)
+
+type workerQueue interface {
+	len() int
+	cap() int
+	isEmpty() bool
+	enqueue(worker *goWorker) error
+	dequeue() *goWorker
+	releaseExpiry(duration time.Duration) chan *goWorker
+	releaseAll()
+}
+
+type queueType int
+
+const (
+	stackType queueType = 1 << iota
+	loopQueueType
+)
+
+func newQueue(qType queueType, size int) workerQueue {
+	switch qType {
+	case stackType:
+		return newWorkerStack(size)
+	case loopQueueType:
+		return newLoopQueue(size)
+	default:
+		return newWorkerStack(size)
+	}
+}