signal

README

What Is It ?

Utility package to be used in tandem with runner package.

Used in gracefully shutdown multiple components that should not know each other, by listening system signals.

Documentation

Index

• func Closed(ctx context.Context) (os.Signal, error)
• func WithSignals(parent context.Context, signals ...os.Signal) (context.Context, context.CancelFunc)
• func WithTermination(ctx context.Context) (context.Context, context.CancelFunc)

Examples

• Closed
• WithSignals
• WithTermination

Functions

func Closed

func Closed(ctx context.Context) (os.Signal, error)

Closed gets the signal that closed a context channel.

Example

package main

import (
	"context"
	"fmt"
	"os"
	"syscall"

	"github.com/badu/wg-cc/pkg/signal"
)

func main() {
	ctx, cancel := signal.WithSignals(context.Background(), syscall.SIGHUP)
	defer cancel()

	// Remove this Go routine to test manually with kill -HUP PID.
	go func() {
		p, _ := os.FindProcess(os.Getpid()) // always check your errors!
		_ = p.Signal(syscall.SIGHUP)        // don't ignore errors!
	}()

	<-ctx.Done()

	sig, err := signal.Closed(ctx)

	if err != nil {
		_, _ = fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}

	fmt.Println(sig)
}

Output:

hangup

func WithSignals

func WithSignals(parent context.Context, signals ...os.Signal) (context.Context, context.CancelFunc)

WithSignals returns a copy of the parent context cancelable by the given system signals. The signals are reset when the context's Done channel is closed.

Example

package main

import (
	"context"
	"fmt"
	"os"
	"syscall"

	"github.com/badu/wg-cc/pkg/signal"
)

func main() {
	ctx, cancel := signal.WithSignals(context.Background(), syscall.SIGUSR2)
	defer cancel()

	// Remove this Go routine to test manually with kill -USR2 PID.
	go func() {
		p, _ := os.FindProcess(os.Getpid()) // always check your errors!
		_ = p.Signal(syscall.SIGUSR2)       // don't ignore errors!
	}()

	<-ctx.Done()
	fmt.Println("Signaled!")
}

Output:

Signaled!

func WithTermination

func WithTermination(ctx context.Context) (context.Context, context.CancelFunc)

WithTermination creates a context canceled on signals SIGINT or SIGTERM.

Example

package main

import (
	"context"
	"fmt"
	"os"
	"syscall"

	"github.com/badu/wg-cc/pkg/signal"
)

func main() {
	ctx, cancel := signal.WithTermination(context.Background())
	defer cancel()

	// Remove this Go routine to test manually.
	go func() {
		p, _ := os.FindProcess(os.Getpid()) // always check your errors!
		_ = p.Signal(syscall.SIGINT)        // don't ignore errors!
	}()

	<-ctx.Done()
	fmt.Println("Interrupted!")
}

Output:

Interrupted!