Goの複数スレッドを制御するための一案

main.go

package main

import (
	"context"
	"fmt"
	"strings"
	"time"
)

const SLEEP_SEC = 0

type SampleRunner struct {
	identifier string
}

func (r *SampleRunner) Run(ctx context.Context, in <-chan int, out chan<- int) {
	for {
		select {
		case <-ctx.Done():
			for {
				select {
				case v, ok := <-in:
					if !ok {
						close(out)
						return
					}
					time.Sleep(SLEEP_SEC * time.Second)
					fmt.Println(strings.Repeat("\t", v), r.identifier, "Done:", v)
					out <- v
				}
			}
		case v, ok := <-in:
			if !ok {
				close(out)
				return
			}
			time.Sleep(SLEEP_SEC * time.Second)
			fmt.Println(strings.Repeat("\t", v), r.identifier, ":", v)
			out <- v
		}
	}
}


func main() {
	ctx, cancel := context.WithCancel(context.Background())

	ch1 := make(chan int)
	ch2 := make(chan int)
	ch3 := make(chan int)
	ch4 := make(chan int)
	ch5 := make(chan int)
	ch6 := make(chan int)
	ch7 := make(chan int)
	ch8 := make(chan int)

	s1 := &SampleRunner{identifier: "sample1"}
	s2 := &SampleRunner{identifier: "sample2"}
	s3 := &SampleRunner{identifier: "sample3"}
	s4 := &SampleRunner{identifier: "sample4"}
	s5 := &SampleRunner{identifier: "sample5"}
	s6 := &SampleRunner{identifier: "sample6"}
	s7 := &SampleRunner{identifier: "sample7"}

	go s1.Run(ctx, ch1, ch2)
	go s2.Run(ctx, ch2, ch3)
	go s3.Run(ctx, ch3, ch4)
	go s4.Run(ctx, ch4, ch5)
	go s5.Run(ctx, ch5, ch6)
	go s6.Run(ctx, ch6, ch7)
	go s7.Run(ctx, ch7, ch8)

	go func() {
		for i := 0; i < 10; i++ {
			fmt.Println(strings.Repeat("\t", i), "input   :", i)
			ch1 <- i
		}
		close(ch1)
		cancel()
	}()

	for {
		select {
		case v, ok := <-ch8:
			if !ok {
				return
			}
			fmt.Println(strings.Repeat("\t", v), "output  :", v)
		}
	}

}