Go - 並行プログラミング - 競合状態 - イベントルーのの代わり、forループ、select、case、switch、チャンネル、通信

入門Goプログラミング
原著: Get Programming with Go
楽天ブックス Yahoo!

開発環境

macOS Catalina - Apple (OS)
Emacs (Text Editor)
Windows 10 Pro (OS)
Visual Studio Code (Text Editor)
Go (プログラミング言語)

入門Goプログラミング (Nathan Youngman(著)、Roger Peppé(著)、吉川邦夫(監修, 翻訳)、翔泳社)のUNIT 7(並行プログラミング)、LESSON 31(競合状態)の練習問題-2の解答を求めてみる。

コード

package main

import (
 "fmt"
 "image"
 "math/rand"
 "time"
)

type command int

const (
 right = command(0)
 left  = command(1)
 start = command(2)
 stop  = command(3)
)

type roverDriver struct {
 commandc chan command
}

func newRoverDriver() *roverDriver {
 rPtr := &roverDriver{
  commandc: make(chan command),
 }
 go rPtr.drive()
 return rPtr
}

func (r *roverDriver) right() {
 r.commandc <- right
}
func (r *roverDriver) left() {
 r.commandc <- left
}
func (r *roverDriver) start() {
 r.commandc <- start
}
func (r *roverDriver) stop() {
 r.commandc <- stop
}
func (r *roverDriver) drive() {
 pos := image.Point{X: 0, Y: 0}
 direction := image.Point{X: 1, Y: 0}
 updateInterval := 250 * time.Millisecond
 nextMove := time.After(updateInterval)
 speed := 0
 for {
  select {
  case c := <-r.commandc:
   switch c {
   case right:
    direction = image.Point{
     X: -direction.Y,
     Y: direction.X,
    }
   case left:
    direction = image.Point{
     X: direction.Y,
     Y: -direction.X,
    }
   case start:
    speed = 1
   case stop:
    speed = 0
   }
  case <-nextMove:
   pos = pos.Add(direction.Mul(speed))
   fmt.Printf("moved to %v\n", pos)
   nextMove = time.After(updateInterval)
  }
 }
}
func main() {
 rand.Seed(time.Now().UnixNano())
 rPtr := newRoverDriver()
 methods := []func(){
  rPtr.right,
  rPtr.left,
  rPtr.start,
  rPtr.stop,
 }
 for _, method := range methods {
  time.Sleep(time.Second)
  method()
 }
 for i := 0; i < 20; i++ {
  time.Sleep(time.Second)
  methods[rand.Intn(len(methods))]()
 }
}

入出力結果(Zsh、PowerShell、Terminal)

% go build rover.go
% ./rover          
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (1,0)
moved to (2,0)
moved to (3,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (5,0)
moved to (6,0)
moved to (7,0)
moved to (8,0)
moved to (9,0)
moved to (10,0)
moved to (11,0)
moved to (12,0)
moved to (12,-1)
moved to (12,-2)
moved to (12,-3)
moved to (12,-4)
moved to (11,-4)
moved to (10,-4)
moved to (9,-4)
moved to (8,-4)
moved to (8,-5)
moved to (8,-6)
moved to (8,-7)
moved to (8,-8)
moved to (8,-9)
moved to (8,-10)
moved to (8,-11)
moved to (8,-12)
moved to (9,-12)
moved to (10,-12)
moved to (11,-12)
moved to (12,-12)
moved to (13,-12)
moved to (14,-12)
moved to (15,-12)
moved to (16,-12)
moved to (16,-13)
moved to (16,-14)
moved to (16,-15)
moved to (16,-16)
moved to (15,-16)
moved to (14,-16)
moved to (13,-16)
moved to (12,-16)
moved to (12,-17)
moved to (12,-18)
moved to (12,-19)
moved to (12,-20)
moved to (11,-20)
moved to (10,-20)
moved to (9,-20)
moved to (8,-20)
moved to (8,-21)
moved to (8,-22)
moved to (8,-23)
moved to (8,-24)
moved to (8,-24)
moved to (8,-24)
moved to (8,-24)
moved to (8,-24)
moved to (8,-25)
moved to (8,-26)
moved to (8,-27)
moved to (8,-28)
moved to (8,-28)
moved to (8,-28)
moved to (8,-28)
moved to (8,-28)
% ./rover
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (0,0)
moved to (1,0)
moved to (2,0)
moved to (3,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (4,0)
moved to (5,0)
moved to (6,0)
moved to (7,0)
moved to (8,0)
moved to (8,-1)
moved to (8,-2)
moved to (8,-3)
moved to (8,-4)
moved to (9,-4)
moved to (10,-4)
moved to (11,-4)
moved to (12,-4)
moved to (12,-5)
moved to (12,-6)
moved to (12,-7)
moved to (12,-8)
moved to (11,-8)
moved to (10,-8)
moved to (9,-8)
moved to (8,-8)
moved to (8,-8)
moved to (8,-8)
moved to (8,-8)
moved to (8,-8)
moved to (7,-8)
moved to (6,-8)
moved to (5,-8)
moved to (4,-8)
moved to (4,-8)
moved to (4,-8)
moved to (4,-8)
moved to (4,-8)
moved to (3,-8)
moved to (2,-8)
moved to (1,-8)
moved to (0,-8)
moved to (0,-7)
moved to (0,-6)
moved to (0,-5)
moved to (0,-4)
moved to (0,-3)
moved to (0,-2)
moved to (0,-1)
moved to (0,0)
moved to (0,1)
moved to (0,2)
moved to (0,3)
moved to (0,4)
moved to (0,4)
moved to (0,4)
moved to (0,4)
moved to (0,4)
moved to (0,4)
moved to (0,4)
moved to (0,4)
moved to (0,4)
moved to (-1,4)
moved to (-2,4)
moved to (-3,4)
moved to (-4,4)
moved to (-4,3)
moved to (-4,2)
moved to (-4,1)
moved to (-4,0)
moved to (-3,0)
moved to (-2,0)
moved to (-1,0)
moved to (0,0)
moved to (0,1)
moved to (0,2)
moved to (0,3)
moved to (0,4)
moved to (-1,4)
moved to (-2,4)
moved to (-3,4)
moved to (-4,4)
%

Kamimura's blog

2020年5月16日土曜日

Go - 並行プログラミング - 競合状態 - イベントルーのの代わり、forループ、select、case、switch、チャンネル、通信

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