主页 / 问题 / 1410545
Accepted
Quester
Asked:2022-07-16 22:59:35 +0000 UTC2022-07-16 22:59:35 +0000 UTC

竞争环境下的柜台结构

  • 772

大家好。任务是开发一个在竞争环境中工作的计数器结构。我不确定我是否正确理解了“结构计数器”一词。也许有人知道计数器结构是什么意思？我是这么理解的

package main

import (
    "sync"

    "github.com/udonetsm/help/helper"
)

type Counter struct {
    num int
    sync.RWMutex
}

func (c *Counter) Count(wg *sync.WaitGroup, finish, start int) int {
    defer helper.PanicCapture("Count")
    wg.Add(finish - start)
    for c.num < finish {
        go func() {
            c.Lock()
            c.num += 1
            c.Unlock()
            wg.Done()
        }()
    }
    return c.num
}

func New(start int) *Counter {
    defer helper.PanicCapture("INIT")
    return &Counter{
        num: start,
    }
}

func Counting(start, finish int) {
    defer helper.PanicCapture("Counting")
    c := New(start)
    wg := sync.WaitGroup{}
    c.Count(&wg, finish, start)
    wg.Wait()
}

不断地给人一种恐慌 panic: sync: negative WaitGroup counter

package main

import (
    "log"
    "sync"
    "time"

    "github.com/udonetsm/help/helper"
)

type Counter struct {
    num int
    sync.RWMutex
}

func (c *Counter) Count(wg *sync.WaitGroup, finish, start int) int {
    defer helper.PanicCapture("Count")
    wg.Add(1)
    go func() {
        for i := start; i <= finish; i++ {
            c.Lock()
            c.num += 1
            c.Unlock()
            log.Println(c.num)
            time.Sleep(time.Second)
        }
        wg.Done()
    }()
    wg.Wait()
    return c.num
}

func New(start int) *Counter {
    defer helper.PanicCapture("INIT")
    return &Counter{
        num: -1,
    }
}

func Counting(start, finish int) {
    defer helper.PanicCapture("Counting")
    c := New(start)
    wg := sync.WaitGroup{}
    log.Println(c.Count(&wg, finish, start))
}

所以他并不恐慌，他没有正确使用 Wait 。但是不知道有没有看懂counter的结构

golang

1 个回答

  1. Best Answer

    首先 - 你正确地制作了计数器的结构

    但是你让柜台工作变得非常困难 - 出于某种原因输入了一些 finsih 和 start 。它有一个简单的界面：

    Inc()用于增量和Value()获取当前值

    剩下的只是一个竞争环境：有些东西是通过努力工作的，有些东西会考虑这项工作的结果……主要是结果是正确的，也就是说，goroutines 不会在竞争的同时读取状态不要增加（例如，一对/三个 goroutine 没有一次增加计数器5状态6）

    package main

import (
    "fmt"
    "log"
    "sync"
)

type Counter struct {
    num int
    sync.Mutex
}

func (c *Counter) Inc() {
    c.Lock()
    defer c.Unlock()

    c.num += 1
}

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

func main() {
    cnt := &Counter{
        num: 0,
    }

    finish := make(chan struct{})

    go Do(cnt, finish)

    select {
    case <-finish:
        log.Printf("Work done with count: %d", cnt.Value())
    }
}

func Do(cnt *Counter, finish chan struct{}) {
    wg := sync.WaitGroup{}

    // Hard work in goroutine and finish work
    for i := 0; i < 20; i++ {
        wg.Add(1)

        // Тяжелая работа
        go func(num int, cnt *Counter, wg *sync.WaitGroup) {
            defer wg.Done()

            fmt.Printf("Worker %d starting\n", num)
            cnt.Inc()
            fmt.Printf("Worker %d done\n", num)
        }(i, cnt, &wg)
    }

    wg.Wait()
    finish <- struct{}{}
    close(finish)
}

    https://go.dev/play/p/mb9NGCVBC-K

    • 2

相关问题