ants/pool.go

273 lines
7.0 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"
"github.com/panjf2000/ants/v2/internal"
)
// Pool accepts the tasks from client, it limits the total of goroutines to a given number by recycling goroutines.
type Pool struct {
// capacity of the pool, a negative value means that the capacity of pool is limitless, an infinite pool is used to
// avoid potential issue of endless blocking caused by nested usage of a pool: submitting a task to pool
// which submits a new task to the same pool.
capacity int32
// running is the number of the currently running goroutines.
running int32
// workers is a slice that store the available workers.
workers workerArray
// state is used to notice the pool to closed itself.
state int32
// lock for synchronous operation.
lock sync.Locker
// cond for waiting to get a idle worker.
cond *sync.Cond
// workerCache speeds up the obtainment of the an usable worker in function:retrieveWorker.
workerCache sync.Pool
// blockingNum is the number of the goroutines already been blocked on pool.Submit, protected by pool.lock
blockingNum int
options *Options
}
// purgePeriodically clears expired workers periodically which runs in an individual goroutine, as a scavenger.
func (p *Pool) purgePeriodically() {
heartbeat := time.NewTicker(p.options.ExpiryDuration)
defer heartbeat.Stop()
for range heartbeat.C {
if atomic.LoadInt32(&p.state) == CLOSED {
break
}
p.lock.Lock()
expiredWorkers := p.workers.retrieveExpiry(p.options.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 := range expiredWorkers {
expiredWorkers[i].task <- nil
expiredWorkers[i] = nil
}
// There might be a situation that all workers have been cleaned up(no any worker is running)
// while some invokers still get stuck in "p.cond.Wait()",
// then it ought to wakes all those invokers.
if p.Running() == 0 {
p.cond.Broadcast()
}
}
}
// NewPool generates an instance of ants pool.
func NewPool(size int, options ...Option) (*Pool, error) {
opts := loadOptions(options...)
if size <= 0 {
size = -1
}
if expiry := opts.ExpiryDuration; expiry < 0 {
return nil, ErrInvalidPoolExpiry
} else if expiry == 0 {
opts.ExpiryDuration = DefaultCleanIntervalTime
}
if opts.Logger == nil {
opts.Logger = defaultLogger
}
p := &Pool{
capacity: int32(size),
lock: internal.NewSpinLock(),
options: opts,
}
p.workerCache.New = func() interface{} {
return &goWorker{
pool: p,
task: make(chan func(), workerChanCap),
}
}
if p.options.PreAlloc {
if size == -1 {
return nil, ErrInvalidPreAllocSize
}
p.workers = newWorkerArray(loopQueueType, size)
} else {
p.workers = newWorkerArray(stackType, 0)
}
p.cond = sync.NewCond(p.lock)
// Start a goroutine to clean up expired workers periodically.
go p.purgePeriodically()
return p, nil
}
// ---------------------------------------------------------------------------
// Submit submits a task to this pool.
func (p *Pool) Submit(task func()) error {
if atomic.LoadInt32(&p.state) == CLOSED {
return ErrPoolClosed
}
var w *goWorker
if w = p.retrieveWorker(); w == nil {
return ErrPoolOverload
}
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 p.Cap() - p.Running()
}
// Cap returns the capacity of this pool.
func (p *Pool) Cap() int {
return int(atomic.LoadInt32(&p.capacity))
}
// Tune changes the capacity of this pool, this method is noneffective to the infinite pool.
func (p *Pool) Tune(size int) {
if capacity := p.Cap(); capacity == -1 || size <= 0 || size == capacity || p.options.PreAlloc {
return
}
atomic.StoreInt32(&p.capacity, int32(size))
}
// Release Closes this pool.
func (p *Pool) Release() {
atomic.StoreInt32(&p.state, CLOSED)
p.lock.Lock()
p.workers.reset()
p.lock.Unlock()
}
// Reboot reboots a released pool.
func (p *Pool) Reboot() {
if atomic.CompareAndSwapInt32(&p.state, CLOSED, OPENED) {
go p.purgePeriodically()
}
}
// ---------------------------------------------------------------------------
// 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)
}
// retrieveWorker returns a available worker to run the tasks.
func (p *Pool) retrieveWorker() (w *goWorker) {
spawnWorker := func() {
w = p.workerCache.Get().(*goWorker)
w.run()
}
p.lock.Lock()
w = p.workers.detach()
if w != nil {
p.lock.Unlock()
} else if capacity := p.Cap(); capacity == -1 {
p.lock.Unlock()
spawnWorker()
} else if p.Running() < capacity {
p.lock.Unlock()
spawnWorker()
} else {
if p.options.Nonblocking {
p.lock.Unlock()
return
}
Reentry:
if p.options.MaxBlockingTasks != 0 && p.blockingNum >= p.options.MaxBlockingTasks {
p.lock.Unlock()
return
}
p.blockingNum++
p.cond.Wait()
p.blockingNum--
if p.Running() == 0 {
p.lock.Unlock()
spawnWorker()
return
}
w = p.workers.detach()
if w == nil {
goto Reentry
}
p.lock.Unlock()
}
return
}
// revertWorker puts a worker back into free pool, recycling the goroutines.
func (p *Pool) revertWorker(worker *goWorker) bool {
if capacity := p.Cap(); (capacity > 0 && p.Running() > capacity) || atomic.LoadInt32(&p.state) == CLOSED {
return false
}
worker.recycleTime = time.Now()
p.lock.Lock()
err := p.workers.insert(worker)
if err != nil {
p.lock.Unlock()
return false
}
// Notify the invoker stuck in 'retrieveWorker()' of there is an available worker in the worker queue.
p.cond.Signal()
p.lock.Unlock()
return true
}