Function Example_subscription

example_subscription_test.go:42–133

Example_subscription demonstrates the use of client subscriptions to receive events containing information about worked jobs.

()

// Example_subscription demonstrates the use of client subscriptions to receive
// events containing information about worked jobs.
func Example_subscription() {
	ctx := context.Background()

	dbPool, err := pgxpool.New(ctx, riversharedtest.TestDatabaseURL())
	if err != nil {
		panic(err)
	}
	defer dbPool.Close()

	workers := river.NewWorkers()
	river.AddWorker(workers, &SubscriptionWorker{})

	riverClient, err := river.NewClient(riverpgxv5.New(dbPool), initTestConfig(ctx, dbPool, &river.Config{
		Logger: slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{Level: slog.Level(9), ReplaceAttr: slogutil.NoLevelTime})), // Suppress logging so example output is cleaner (9 > slog.LevelError).
		Queues: map[string]river.QueueConfig{
			river.QueueDefault: {MaxWorkers: 100},
		},
		Workers: workers,
	}))
	if err != nil {
		panic(err)
	}

	// Subscribers tell the River client the kinds of events they'd like to receive.
	completedChan, completedSubscribeCancel := riverClient.Subscribe(river.EventKindJobCompleted)
	defer completedSubscribeCancel()

	// Multiple simultaneous subscriptions are allowed.
	failedChan, failedSubscribeCancel := riverClient.Subscribe(river.EventKindJobFailed)
	defer failedSubscribeCancel()

	otherChan, otherSubscribeCancel := riverClient.Subscribe(river.EventKindJobCancelled, river.EventKindJobSnoozed)
	defer otherSubscribeCancel()

	if err := riverClient.Start(ctx); err != nil {
		panic(err)
	}

	// Insert one job for each subscription above: one to succeed, one to fail,
	// and one that's cancelled that'll arrive on the "other" channel.
	_, err = riverClient.Insert(ctx, SubscriptionArgs{}, nil)
	if err != nil {
		panic(err)
	}
	_, err = riverClient.Insert(ctx, SubscriptionArgs{Fail: true}, nil)
	if err != nil {
		panic(err)
	}
	_, err = riverClient.Insert(ctx, SubscriptionArgs{Cancel: true}, nil)
	if err != nil {
		panic(err)
	}

	waitForJob := func(subscribeChan <-chan *river.Event) {
		select {
		case event := <-subscribeChan:
			if event == nil {
				fmt.Printf("Channel is closed\n")