example_test.go

package group_test

import (
	"context"
	"errors"
	"fmt"
	"time"

	"github.com/pkg/group"
)

type Group = group.G

func ExampleGroup_Wait() {
	// A Group's zero value is ready to use.
	var g group.G

	// Add a goroutine to the group.
	g.Add(func(c context.Context) error {
		select {
		case <-c.Done():
			return c.Err()
		case <-time.After(1 * time.Second):
			return errors.New("timed out")
		}
	})

	// Wait for all goroutines to finish.
	if err := g.Wait(); err != nil {
		fmt.Println(err)
	}

	// Output: timed out
}

func ExampleGroup_Wait_with_shutdown() {
	// A Group's zero value is ready to use.
	var g group.G

	shutdown := make(chan struct{})

	// Add a goroutine to the group.
	g.Add(func(c context.Context) error {
		select {
		case <-c.Done():
			return errors.New("stopped")
		case <-shutdown:
			return errors.New("shutdown")
		}
	})

	time.AfterFunc(100*time.Millisecond, func() {
		close(shutdown)
	})

	// Wait for all goroutines to finish.
	if err := g.Wait(); err != nil {
		fmt.Println(err)
	}

	// Output: shutdown
}

func ExampleGroup_Wait_with_context_cancel() {
	ctx := context.Background()
	ctx, cancel := context.WithDeadline(ctx, time.Now().Add(100*time.Millisecond))

	// pass WithContext option to New to use the provided context.
	g := group.New(group.WithContext(ctx))

	// Add a goroutine to the group.
	g.Add(func(c context.Context) error {
		select {
		case <-c.Done():
			return c.Err()
		}
	})

	// Cancel the context.
	cancel()

	// Wait for all goroutines to finish.
	if err := g.Wait(); err != nil {
		fmt.Println(err)
	}

	// Output: context canceled
}

func ExampleGroup_Wait_with_panic() {
	// A Group's zero value is ready to use.
	var g group.G

	// Add a goroutine to the group.
	g.Add(func(c context.Context) error {
		panic("boom")
	})

	// Wait for all goroutines to finish.
	if err := g.Wait(); err != nil {
		fmt.Println(err)
	}

	// Output: panic: boom
}