ants/pool.go

226 lines
5.3 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 (
"math"
"sync"
"sync/atomic"
"time"
)
type sig struct{}
type f func() error
// 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
// freeSignal is used to notice pool there are available
// workers which can be sent to work.
freeSignal chan sig
// workers is a slice that store the available workers.
workers []*Worker
// release is used to notice the pool to closed itself.
release chan sig
// lock for synchronous operation
lock sync.Mutex
once sync.Once
}
func (p *Pool) monitorAndClear() {
heartbeat := time.NewTicker(p.expiryDuration)
go func() {
for range heartbeat.C {
currentTime := time.Now()
p.lock.Lock()
idleWorkers := p.workers
if len(idleWorkers) == 0 && p.Running() == 0 && len(p.release) > 0 {
p.lock.Unlock()
return
}
n := 0
for i, w := range idleWorkers {
if currentTime.Sub(w.recycleTime) <= p.expiryDuration {
break
}
n = i
<-p.freeSignal
w.task <- nil
idleWorkers[i] = nil
}
if n > 0 {
n++
p.workers = idleWorkers[n:]
}
p.lock.Unlock()
}
}()
}
// NewPool generates a instance of ants pool
func NewPool(size int) (*Pool, error) {
return NewTimingPool(size, DefaultCleanIntervalTime)
}
// NewTimingPool generates a 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),
freeSignal: make(chan sig, math.MaxInt32),
release: make(chan sig, 1),
expiryDuration: time.Duration(expiry) * time.Second,
}
p.monitorAndClear()
return p, nil
}
//-------------------------------------------------------------------------
// Submit submit a task to pool
func (p *Pool) Submit(task f) error {
if len(p.release) > 0 {
return ErrPoolClosed
}
w := p.getWorker()
w.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 change 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
if diff > 0 {
for i := 0; i < diff; i++ {
p.getWorker().task <- nil
}
}
}
// Release Closed this pool
func (p *Pool) Release() error {
p.once.Do(func() {
p.release <- sig{}
p.lock.Lock()
idleWorkers := p.workers
for i, w := range idleWorkers {
<-p.freeSignal
w.task <- nil
idleWorkers[i] = nil
}
p.workers = nil
p.lock.Unlock()
})
return nil
}
//-------------------------------------------------------------------------
// getWorker returns a available worker to run the tasks.
func (p *Pool) getWorker() *Worker {
var w *Worker
waiting := false
p.lock.Lock()
idleWorkers := p.workers
n := len(idleWorkers) - 1
if n < 0 {
if p.Running() >= p.Cap() {
waiting = true
} else {
atomic.AddInt32(&p.running, 1)
}
} else {
<-p.freeSignal
w = idleWorkers[n]
idleWorkers[n] = nil
p.workers = idleWorkers[:n]
}
p.lock.Unlock()
if waiting {
<-p.freeSignal
p.lock.Lock()
idleWorkers = p.workers
l := len(idleWorkers) - 1
w = idleWorkers[l]
idleWorkers[l] = nil
p.workers = idleWorkers[:l]
p.lock.Unlock()
} else if w == nil {
w = &Worker{
pool: p,
task: make(chan f),
}
w.run()
}
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)
p.lock.Unlock()
p.freeSignal <- sig{}
}