[ 文章收集 ] Go by Example: Signals

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Preface
Sometimes we’d like our Go programs to intelligently handle Unix signals. For example, we might want a server to gracefully shutdown when it receives a SIGTERM, or a command-line tool to stop processing input if it receives a SIGINT. Here’s how to handle signals in Go with channels.

HowTo

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1. package main  
2.   
3. import (  
4.     "fmt"  
5.     "os"  
6.     "os/signal"  
7.     "syscall"  
8. )  
9.   
10. func main() {  
11.   
12.     sigs := make(chan os.Signal, 1)  
13.     done := make(chan bool, 1)  
14.   
15.     signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)  
16.   
17.     go func() {  
18.         sig := <-sigs  
19.         fmt.Println()  
20.         fmt.Println(sig)  
21.         done <- true  
22.     }()  
23.   
24.     fmt.Println("awaiting signal")  
25.     <-done  
26.     fmt.Println("exiting")  
27. }  

Go signal notification works by sending os.Signal values on a channel. We’ll create a channel to receive these notifications (we’ll also make one to notify us when the program can exit).

* Line15

signal.Notify registers the given channel to receive notifications of the specified signals.

* Line17-21

This goroutine executes a blocking receive for signals. When it gets one it’ll print it out and then notify the program that it can finish.

* Line24-26

The program will wait here until it gets the expected signal (as indicated by the goroutine above sending a value on done) and then exit.

When we run this program it will block waiting for a signal. By typing ctrl-C (which the terminal shows as ^C) we can send a SIGINT signal, causing the program to print interrupt and then exit:

$ go run signals.go
awaiting signal
^C
interrupt
exiting