Go ?? ?????? ??? ???: ???, ???? ?? ? ????? ?? ??

Go?? ?? ??????? ??? ? ?? ???? ?? ??? ???? ????? ???? ?????. Mutex? Channel? Go?? ???? ?? ?? ?????.

? ????? ??? ??? ???? ???? ?? ?? ??? ?????. ?? ????? Mutex? ???? ? ??? ????? ???? ??? ????? ?? ??? ???? ??? ???????.

?? ??

??? ???? ??? ? ?? ???? ???? ???.

??? ??

package main

type Counter struct {
    count int
}

func (c *Counter) Inc() {
    c.count++
}

func (c *Counter) Value() int {
    return c.count
}

?? ???? ???? ??? ?? ? ?? ???? ??? ?????.

1. ???? ?????

Mutex(???)? ? ?? ??? ???? ??? ??? ??? ???? ? ??? ???? ??? ????????. ?? ?? ????? ?????. ???? Mutex? ??? ?? ???? ?? ???? Mutex? ?? ??? ??? ?????. ??? ?? ??? ???? ?? ?????? ???? ? ? ?? ?????.

package main

import (
    "sync"
    "testing"
)

func TestCounter(t *testing.T) {
    t.Run("using mutexes and wait groups", func(t *testing.T) {
        counter := Counter{}
        wantedCount := 1000

        var wg sync.WaitGroup
        var mut sync.Mutex

        wg.Add(wantedCount)

        for i := 0; i < wantedCount; i++ {
            go func() {
                defer wg.Done()
                mut.Lock()
                counter.Inc()
                mut.Unlock()
            }()
        }

        wg.Wait()
        if counter.Value() != wantedCount {
            t.Errorf("got %d, want %d", counter.Value(), wantedCount)
        }
    })
}

? ??? sync.WaitGroup? ???? ?? ???? ??? ????, sync.Mutex? ???? ?? ???? ??? ?? ???? ????? ?? ?????.

2. ?? ?? ??

??? Go? ???? ???? ??? ? ??? ?? ?????. ??? ?? ???? ???? ??? ???? ?? ???? ???? ???? ??? ? ????.

? ???? ??? ???? ???? ???? ??? ???? ?? ???? ?????? ?????. ???? ??? ??? ???? ????. ?, ?? ??? ???? ?? ?? ??? ?? ??? ??? ? ????. ???? ??? ?? ? ???? ?????.

package main

import (
    "sync"
    "testing"
)

func TestCounter(t *testing.T) {
    t.Run("using buffered channels and wait groups", func(t *testing.T) {
        counter := Counter{}
        wantedCount := 1000

        var wg sync.WaitGroup
        wg.Add(wantedCount)

        ch := make(chan struct{}, 1)

        ch <- struct{}{} // 允許第一個 goroutine 開始

        for i := 0; i < wantedCount; i++ {
            go func() {
                defer wg.Done()
                <-ch
                counter.Inc()
                ch <- struct{}{}
            }()
        }

        wg.Wait()
        if counter.Value() != wantedCount {
            t.Errorf("got %d, want %d", counter.Value(), wantedCount)
        }
    })
}

? ??? ??? 1? ???? ??? ????? ? ?? ??? ???? ???? ???? ? ????.

3. ????? ?? ??? ?????

???? ?? ???? ??? ????. ???? ???? ??? ??? ? ??? ???? ?????. ?? ? ?? ??? ??? ?? ???? ???? ??? ???? ?????.

package main

import (
    "sync"
    "testing"
)

func TestCounter(t *testing.T) {
    t.Run("using unbuffered channels and wait groups", func(t *testing.T) {
        counter := Counter{}
        wantedCount := 1000

        var wg sync.WaitGroup
        wg.Add(wantedCount)

        ch := make(chan struct{})

        go func() {
            for i := 0; i < wantedCount; i++ {
                ch <- struct{}{}
            }
            close(ch)
        }()

        for range ch {
            counter.Inc()
            wg.Done()
        }

        if counter.Value() != wantedCount {
            t.Errorf("got %d, want %d", counter.Value(), wantedCount)
        }
    })
}

? ??? ????? ?? ??? ???? ? ?? ??? ???? ???? ?????? ???.

4. WaitGroup ?? ?? ??? ?????

WaitGroup ?? ???? ??? ??? ?? ????. ?? ?? ?? ??? ?? ??? ???? ??? ??? ??? ? ????.

??

? ????? Go?? ??? ??? ???? ???? ??? ?? ??? ?????. ????? ??? ?? Go ????? ????? ??? ??? ?? ??? ?? ?? ?????.

????

? ??? "???? Go ???"? ??? ??? ??? ?????.

? ??? ??? ??? ????!

? ??? Go ???: ??? ??? ???? ??? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!