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本文主要研究一下gost的GenericTaskPool
GenericTaskPool
gost/sync/task_pool.go
// GenericTaskPool represents an generic task pool.
type GenericTaskPool interface {
// AddTask wait idle worker add task
AddTask(t task) bool
// AddTaskAlways add task to queues or do it immediately
AddTaskAlways(t task)
// AddTaskBalance add task to idle queue
AddTaskBalance(t task)
// Close use to close the task pool
Close()
// IsClosed use to check pool status.
IsClosed() bool
}GenericTaskPool接口定义了AddTask、AddTaskAlways、AddTaskBalance、Close、IsClosed接口
TaskPool
gost/sync/task_pool.go
type TaskPool struct {
TaskPoolOptions
idx uint32 // round robin index
qArray []chan task
wg sync.WaitGroup
once sync.Once
done chan struct{}
}
// return false when the pool is stop
func (p *TaskPool) AddTask(t task) (ok bool) {
idx := atomic.AddUint32(&p.idx, 1)
id := idx % uint32(p.tQNumber)
select {
case <-p.done:
return false
default:
p.qArray[id] <- t
return true
}
}
func (p *TaskPool) AddTaskAlways(t task) {
id := atomic.AddUint32(&p.idx, 1) % uint32(p.tQNumber)
select {
case p.qArray[id] <- t:
return
default:
goSafely(t)
}
}
// do it immediately when no idle queue
func (p *TaskPool) AddTaskBalance(t task) {
length := len(p.qArray)
// try len/2 times to lookup idle queue
for i := 0; i < length/2; i++ {
select {
case p.qArray[rand.Intn(length)] <- t:
return
default:
continue
}
}
goSafely(t)
}
// check whether the session has been closed.
func (p *TaskPool) IsClosed() bool {
select {
case <-p.done:
return true
default:
return false
}
}
func (p *TaskPool) Close() {
p.stop()
p.wg.Wait()
for i := range p.qArray {
close(p.qArray[i])
}
}TaskPool定义了TaskPoolOptions、idx、qArray、wg、once、done属性；它实现了GenericTaskPool接口；AddTask方法在pool是done的时候会返回false，其余情况会递增idx，然后根据tQNumber计算id，往qArray[id]写入task；AddTaskAlways方法会忽略pool的关闭信息；AddTaskBalance方法会尝试len/2次随机往qArray写入task，都写入不成功则goSafely执行；IsClosed主要是读取done的channel信息；Close方法执行stop及wg.Wait()，最后遍历qArray挨个执行close
NewTaskPool
gost/sync/task_pool.go
func NewTaskPool(opts ...TaskPoolOption) GenericTaskPool {
var tOpts TaskPoolOptions
for _, opt := range opts {
opt(&tOpts)
}
tOpts.validate()
p := &TaskPool{
TaskPoolOptions: tOpts,
qArray: make([]chan task, tOpts.tQNumber),
done: make(chan struct{}),
}
for i := 0; i < p.tQNumber; i++ {
p.qArray[i] = make(chan task, p.tQLen)
}
p.start()
return p
}NewTaskPool通过TaskPoolOptions来创建TaskPool
TaskPoolOption
gost/sync/options.go
const (
defaultTaskQNumber = 10
defaultTaskQLen = 128
)
/////////////////////////////////////////
// Task Pool Options
/////////////////////////////////////////
// TaskPoolOptions is optional settings for task pool
type TaskPoolOptions struct {
tQLen int // task queue length. buffer size per queue
tQNumber int // task queue number. number of queue
tQPoolSize int // task pool size. number of workers
}
func (o *TaskPoolOptions) validate() {
if o.tQPoolSize < 1 {
panic(fmt.Sprintf("illegal pool size %d", o.tQPoolSize))
}
if o.tQLen < 1 {
o.tQLen = defaultTaskQLen
}
if o.tQNumber < 1 {
o.tQNumber = defaultTaskQNumber
}
if o.tQNumber > o.tQPoolSize {
o.tQNumber = o.tQPoolSize
}
}
type TaskPoolOption func(*TaskPoolOptions)
// WithTaskPoolTaskPoolSize set @size of the task queue pool size
func WithTaskPoolTaskPoolSize(size int) TaskPoolOption {
return func(o *TaskPoolOptions) {
o.tQPoolSize = size
}
}
// WithTaskPoolTaskQueueLength set @length of the task queue length
func WithTaskPoolTaskQueueLength(length int) TaskPoolOption {
return func(o *TaskPoolOptions) {
o.tQLen = length
}
}
// WithTaskPoolTaskQueueNumber set @number of the task queue number
func WithTaskPoolTaskQueueNumber(number int) TaskPoolOption {
return func(o *TaskPoolOptions) {
o.tQNumber = number
}
}TaskPoolOptions定义了tQLen、tQNumber、tQPoolSize属性，提供了WithTaskPoolTaskPoolSize、WithTaskPoolTaskQueueLength、WithTaskPoolTaskQueueNumber、validate方法
start
gost/sync/task_pool.go
func (p *TaskPool) start() {
for i := 0; i < p.tQPoolSize; i++ {
p.wg.Add(1)
workerID := i
q := p.qArray[workerID%p.tQNumber]
p.safeRun(workerID, q)
}
}
func (p *TaskPool) safeRun(workerID int, q chan task) {
gxruntime.GoSafely(nil, false,
func() {
err := p.run(int(workerID), q)
if err != nil {
// log error to stderr
log.Printf("gost/TaskPool.run error: %s", err.Error())
}
},
nil,
)
}start方法根据tQPoolSize挨个执行safeRun；safeRun方法通过GoSafely执行p.run(int(workerID), q)
run
gost/sync/task_pool.go
// worker
func (p *TaskPool) run(id int, q chan task) error {
defer p.wg.Done()
var (
ok bool
t task
)
for {
select {
case <-p.done:
if 0 < len(q) {
return fmt.Errorf("task worker %d exit now while its task buffer length %d is greater than 0",
id, len(q))
}
return nil
case t, ok = <-q:
if ok {
func() {
defer func() {
if r := recover(); r != nil {
fmt.Fprintf(os.Stderr, "%s goroutine panic: %v\n%s\n",
time.Now(), r, string(debug.Stack()))
}
}()
t()
}()
}
}
}
}run方法通过for循环进行select，若读取到p.done则退出循环；若是读取到task则执行task
taskPoolSimple
gost/sync/task_pool.go
type taskPoolSimple struct {
work chan task // task channel
sem chan struct{} // gr pool size
wg sync.WaitGroup
once sync.Once
done chan struct{}
}taskPoolSimple定义了work、sem、wg、once、done属性；它实现了GenericTaskPool接口；AddTask方法先判断done，之后写入work及sem；AddTaskAlways方法在select不到channel的时候会执行goSafely；AddTaskBalance方法实际执行的是AddTaskAlways；IsClosed方法读取done信息；Close方法执行stop及wg.Wait()
实例
gost/sync/task_pool_test.go
func TestTaskPool(t *testing.T) {
numCPU := runtime.NumCPU()
//taskCnt := int64(numCPU * numCPU * 100)
tp := NewTaskPool(
WithTaskPoolTaskPoolSize(1),
WithTaskPoolTaskQueueNumber(1),
WithTaskPoolTaskQueueLength(1),
)
//task, cnt := newCountTask()
task, _ := newCountTask()
var wg sync.WaitGroup
for i := 0; i < numCPU*numCPU; i++ {
wg.Add(1)
go func() {
for j := 0; j < 100; j++ {
ok := tp.AddTask(task)
if !ok {
t.Log(j)
}
}
wg.Done()
}()
}
wg.Wait()
tp.Close()
//if taskCnt != atomic.LoadInt64(cnt) {
// //t.Error("want ", taskCnt, " got ", *cnt)
//}
}
func TestTaskPoolSimple(t *testing.T) {
numCPU := runtime.NumCPU()
taskCnt := int64(numCPU * numCPU * 100)
tp := NewTaskPoolSimple(1)
task, cnt := newCountTask()
var wg sync.WaitGroup
for i := 0; i < numCPU*numCPU; i++ {
wg.Add(1)
go func() {
for j := 0; j < 100; j++ {
ok := tp.AddTask(task)
if !ok {
t.Log(j)
}
}
wg.Done()
}()
}
wg.Wait()
cntValue := atomic.LoadInt64(cnt)
if taskCnt != cntValue {
t.Error("want ", taskCnt, " got ", cntValue)
}
}TaskPoolSimple的创建比较简单，只需要提供size参数即可；TaskPool的创建需要提供TaskPoolOption，有WithTaskPoolTaskPoolSize、WithTaskPoolTaskQueueNumber、WithTaskPoolTaskQueueLength这些option
小结
gost的GenericTaskPool接口定义了AddTask、AddTaskAlways、AddTaskBalance、Close、IsClosed接口；这里有TaskPool、taskPoolSimple两个实现。