How to implement the function of canceling commands in golang

In programming, sometimes we need to allow users to operate the execution process of the program through the command line interface. In this case, the program must be able to receive user input and process it accordingly. However, in some cases, the user may want to cancel the execution of the program. In this case, the program needs to have the function of canceling the command. This article will introduce how to use Go language to implement this function.

In the Go language, the main function that processes command line input usually looks like this:

func main() {
    // 处理命令行输入
    // ...
    // 执行主程序流程
    // ...
}

In order to support the cancellation of commands, we need to introduce a channel (channel) for use in the main program process Receive cancellation signal. When receiving a cancellation signal, we need to exit the main program process and recycle related resources.

First, we define a channel called interrupt, of type os.Signal. os.Signal is a signal type used to send signals to processes at the operating system level.

var interrupt = make(chan os.Signal, 1)

Next, we need to associate the interrupt channel with the operating system level interrupt signal. In this way, when the program receives an operating system level interrupt signal (such as Ctrl C), the interrupt channel will receive the corresponding signal.

signal.Notify(interrupt, os.Interrupt)

The above code associates the interrupt channel with the os.Interrupt signal. This means that when the operating system sends an interrupt signal to a process, the interrupt channel will receive an os.Interrupt signal.

Now, we can listen to the interrupt channel in the main program process. If a signal is received, we know that the user wants to cancel the execution of the program. In this case we need to reclaim the resources and exit the program.

select {
case <-interrupt:
    // 收到取消信号
    // 回收资源并退出程序
    // ...
default:
    // 继续执行主程序流程
    // ...
}

The above code uses the select mechanism in the Go language and monitors the interrupt channel. select The characteristic of the mechanism is that only one of the case statements will be executed. If the interrupt channel receives the signal, case <-interrupt: will be executed; otherwise, the default: branch will be executed and the main program flow will continue.

Now, we have the function of canceling the command. The user can cancel the execution of the program by sending an interrupt signal to the program by pressing Ctrl C during program execution.

The complete code is as follows:

package main

import (
    "fmt"
    "os"
    "os/signal"
)

func main() {
    // 创建一个用于接收取消信号的通道
    var interrupt = make(chan os.Signal, 1)
    // 将 interrupt 通道与操作系统的中断信号关联
    signal.Notify(interrupt, os.Interrupt)

    // 执行主程序流程
    for {
        select {
        case <-interrupt:
            // 收到取消信号
            // 回收资源并退出程序
            fmt.Println("程序被取消")
            // ...
            return
        default:
            // 继续执行主程序流程
            fmt.Println("程序正在执行")
            // ...
        }
    }
}

When running this program, you can send an interrupt signal to the program by pressing Ctrl C to cancel the execution of the program.

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