type Worker interface {
	Task()
}

type Worker interface {
	Task()
}

type Pool struct {
	// 使用無緩沖通道實(shí)現(xiàn)協(xié)程池
	work chan Worker
	// 輔助計(jì)數(shù)器，用于協(xié)程池同步
	wg   sync.WaitGroup
}

// New 創(chuàng)建一個工作池
func New(maxGoroutine int) *Pool {
	p := Pool{
		work: make(chan Worker),
	}
	p.wg.Add(maxGoroutine)
	for i := 0; i < maxGoroutine; i++ {
		go func() {
			// 一直循環(huán)取任務(wù)，直到work被關(guān)閉為止并且通道中的任務(wù)執(zhí)行完畢為止
			for w := range p.work {
				w.Task()
			}
			// 退出時候，減少一個計(jì)數(shù)器
			p.wg.Done()
		}()
	}
	return &p
}

// Run 將任務(wù)放入工作池
func (p *Pool) Run(w Worker) {
	p.work <- w
}

// Shutdown 等待所有g(shù)oroutine完成工作
func (p *Pool) Shutdown() {
	// 關(guān)閉work所有協(xié)程完成任務(wù)之后會退出for循環(huán)
	close(p.work)
	p.wg.Wait()
}

package work

import "sync"

// Worker interface 必須滿足worker的要求才能使用工作池
type Worker interface {
	Task()
}

// Pool 提供一個goroutine池，這個池可以完成任何已提交的woker任務(wù)
type Pool struct {
	work chan Worker
	wg   sync.WaitGroup
}

// New 創(chuàng)建一個工作池
func New(maxGoroutine int) *Pool {
	p := Pool{
		work: make(chan Worker),
	}
	p.wg.Add(maxGoroutine)
	for i := 0; i < maxGoroutine; i++ {
		go func() {
			// 一直循環(huán)取任務(wù)，直到work被關(guān)閉為止
			for w := range p.work {
				w.Task()
			}
			// 退出時候，減少一個計(jì)數(shù)器
			p.wg.Done()
		}()
	}
	return &p
}

// Run 將任務(wù)放入工作池
func (p *Pool) Run(w Worker) {
	p.work <- w
}

// Shutdown 等待所有g(shù)oroutine完成工作
func (p *Pool) Shutdown() {
	// 關(guān)閉work所有協(xié)程完成任務(wù)之后會退出for循環(huán)
	close(p.work)
	p.wg.Wait()
}

// This sample program demonstrates how to use the work package
// to use a pool of goroutines to get work done.
package main

import (
	"log"
	"sync"
	"time"

	"work"
)

// names provides a set of names to display.
var names = []string{
	"steve",
	"bob",
	"mary",
	"therese",
	"jason",
}

// namePrinter provides special support for printing names.
type namePrinter struct {
	name string
}

// Task implements the Worker interface.
func (m *namePrinter) Task() {
	log.Println(m.name)
	time.Sleep(time.Second)
}

// main is the entry point for all Go programs.
func main() {
	// Create a work pool with 2 goroutines.
	p := work.New(2)

	var wg sync.WaitGroup
	wg.Add(100 * len(names))

	for i := 0; i < 100; i++ {
		// Iterate over the slice of names.
		for _, name := range names {
			// Create a namePrinter and provide the
			// specific name.
			np := namePrinter{
				name: name,
			}

			go func() {
				// Submit the task to be worked on. When RunTask
				// returns we know it is being handled.
				p.Run(&np)
				wg.Done()
			}()
		}
	}

	wg.Wait()

	// Shutdown the work pool and wait for all existing work
	// to be completed.
	p.Shutdown()
}