uniqlo.go

package main

import (
	"sync"
	"time"
)

type clothes struct {
	Price  int
	Folded bool
}

type commer struct {
	sync.Mutex
	Goods []*clothes
}

func (c *clothes) Fold() {
	c.Folded = true
}

func main() {
	// とりあえず100人くらい並べる
	tasks := make(chan commer, 100)

	go func() {
		for {
			tasks <- commer{Goods: []*clothes{&clothes{Price: 1000, Folded: false}, &clothes{Price: 2000, Folded: false}, &clothes{Price: 1500, Folded: false}}}
		}
	}()

	// レジには5人
	semaphore := make(chan struct{}, 5)

	for i := 0; i < 200; i++ {
		go func() {
			semaphore <- struct{}{}
			task := <-tasks
			sum := 0
			for _, c := range task.Goods {
				sum += c.Price
			}

			folded := make(chan struct{})

			go func() {
				task.Lock()
				for _, cl := range task.Goods {
					cl.Fold()
				}
				task.Unlock()

				folded <- struct{}{}
			}()

			// お金を払う

			<-folded
			<-semaphore
		}()
	}

	// goroutineの終了は待たない
	time.Sleep(2 * time.Second)
}