ants/pool.go

235 lines
5.7 KiB
Go

// MIT License
// Copyright (c) 2018 Andy Pan
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
package ants
import (
"sync"
"sync/atomic"
"time"
)
type f func()
// Pool accept the tasks from client,it limits the total
// of goroutines to a given number by recycling goroutines.
type Pool struct {
// capacity of the pool.
capacity int32
// running is the number of the currently running goroutines.
running int32
// expiryDuration set the expired time (second) of every worker.
expiryDuration time.Duration
// workers is a slice that store the available workers.
workers []*Worker
// release is used to notice the pool to closed itself.
release int32
// lock for synchronous operation.
lock sync.Mutex
// cond for waiting to get a idle worker
cond *sync.Cond
once sync.Once
// PanicHandler is used to handle panics from each worker goroutine.
// if nil, panics will be thrown out again from worker goroutines.
PanicHandler func(interface{})
}
// clear expired workers periodically.
func (p *Pool) periodicallyPurge() {
heartbeat := time.NewTicker(p.expiryDuration)
defer heartbeat.Stop()
for range heartbeat.C {
currentTime := time.Now()
p.lock.Lock()
idleWorkers := p.workers
if len(idleWorkers) == 0 && p.Running() == 0 && atomic.LoadInt32(&p.release) == 1 {
p.lock.Unlock()
return
}
n := -1
for i, w := range idleWorkers {
if currentTime.Sub(w.recycleTime) <= p.expiryDuration {
break
}
n = i
w.task <- nil
idleWorkers[i] = nil
}
if n > -1 {
if n >= len(idleWorkers)-1 {
p.workers = idleWorkers[:0]
} else {
p.workers = idleWorkers[n+1:]
}
}
p.lock.Unlock()
}
}
// NewPool generates an instance of ants pool.
func NewPool(size int) (*Pool, error) {
return NewTimingPool(size, DefaultCleanIntervalTime)
}
// NewTimingPool generates an instance of ants pool with a custom timed task.
func NewTimingPool(size, expiry int) (*Pool, error) {
if size <= 0 {
return nil, ErrInvalidPoolSize
}
if expiry <= 0 {
return nil, ErrInvalidPoolExpiry
}
p := &Pool{
capacity: int32(size),
expiryDuration: time.Duration(expiry) * time.Second,
}
p.cond = sync.NewCond(&p.lock)
go p.periodicallyPurge()
return p, nil
}
//---------------------------------------------------------------------------
// Submit submits a task to this pool.
func (p *Pool) Submit(task f) error {
if 1 == atomic.LoadInt32(&p.release) {
return ErrPoolClosed
}
p.getWorker().task <- task
return nil
}
// Running returns the number of the currently running goroutines.
func (p *Pool) Running() int {
return int(atomic.LoadInt32(&p.running))
}
// Free returns the available goroutines to work.
func (p *Pool) Free() int {
return int(atomic.LoadInt32(&p.capacity) - atomic.LoadInt32(&p.running))
}
// Cap returns the capacity of this pool.
func (p *Pool) Cap() int {
return int(atomic.LoadInt32(&p.capacity))
}
// ReSize changes the capacity of this pool.
func (p *Pool) ReSize(size int) {
if size == p.Cap() {
return
}
atomic.StoreInt32(&p.capacity, int32(size))
diff := p.Running() - size
for i := 0; i < diff; i++ {
p.getWorker().task <- nil
}
}
// Release Closes this pool.
func (p *Pool) Release() error {
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.lock.Unlock()
})
return nil
}
//---------------------------------------------------------------------------
// incRunning increases the number of the currently running goroutines.
func (p *Pool) incRunning() {
atomic.AddInt32(&p.running, 1)
}
// decRunning decreases the number of the currently running goroutines.
func (p *Pool) decRunning() {
atomic.AddInt32(&p.running, -1)
}
// getWorker returns a available worker to run the tasks.
func (p *Pool) getWorker() *Worker {
var w *Worker
waiting := false
p.lock.Lock()
defer p.lock.Unlock()
idleWorkers := p.workers
n := len(idleWorkers) - 1
if n < 0 {
waiting = p.Running() >= p.Cap()
} else {
w = idleWorkers[n]
idleWorkers[n] = nil
p.workers = idleWorkers[:n]
}
if waiting {
for {
p.cond.Wait()
l := len(p.workers) - 1
if l < 0 {
continue
}
w = p.workers[l]
p.workers[l] = nil
p.workers = p.workers[:l]
break
}
} else if w == nil {
w = &Worker{
pool: p,
task: make(chan f, workerChanCap),
}
w.run()
p.incRunning()
}
return w
}
// putWorker puts a worker back into free pool, recycling the goroutines.
func (p *Pool) putWorker(worker *Worker) {
worker.recycleTime = time.Now()
p.lock.Lock()
p.workers = append(p.workers, worker)
// Notify the invoker stuck in 'getWorker()' of there is an available worker in the worker queue.
p.cond.Signal()
p.lock.Unlock()
}