上下文 - WithDeadline() 与 WithTimeout()

Question

下面的代码：

// Sample program to show how to use the WithDeadline function

// of the Context package.

package main

import (

    "context"

    "fmt"

    "time"

)

type data struct {

    UserID string

}

func main() {

    // Set a duration.

    // duration := 150 * time.Millisecond

    duration := time.Now().Add(3 * time.Second)

    // Create a context that is both manually cancellable and will signal

    // a cancel at the specified duration.

    ctx, cancel := context.WithDeadline(context.Background(), duration)

    defer cancel()

    // Create a channel to received a signal that work is done.

    ch := make(chan data, 1)

    // Ask the goroutine to do some work for us.

    go func() {

        // Simulate work.

        time.Sleep(50 * time.Millisecond)

        // Report the work is done.

        ch <- data{"123"}

    }()

    // Wait for the work to finish. If it takes too long move on.

    select {

    case d := <-ch:

        fmt.Println("work complete", d)

    case <-ctx.Done():

        fmt.Println("work cancelled")

    }

}

用于WithDeadline发送 timer'd cancel()。这可以使用以下方法完成：

duration := 150 * time.Millisecond

// Create a context that is both manually cancellable and will signal

// a cancel at the specified duration.

ctx, cancel := context.WithTimeout(context.Background(), duration)

在内部，context.WithTimeout调用该context.WithDeadline函数并通过将超时添加到当前时间来生成截止日期。

有多么context.WithTimeout()不同context.WithDeadline()

Answer 1

context.WithTimeout() 与 context.WithDeadline() 有何不同第一个需要一段持续时间，然后从现在开始取消，第二个是调用取消的绝对时间，如文档中所述，值得像往常一样阅读。

Answer 2

WithTimeout是执行的便捷函数WithDeadline(parent, time.Now().Add(timeout))。这些功能在应用程序如何指定截止日期方面有所不同。否则它们是相同的。调用适合您手头值的函数。