Method Subscribe

runtime/controller.go:464–489

Subscribe registers a callback that will receive resource update events. The same callback function will not be invoked concurrently. The callback function is invoked under a lock and must not call the controller.

(ctx context.Context, fn SubscribeCallback)

// The same callback function will not be invoked concurrently.
// The callback function is invoked under a lock and must not call the controller.
func (c *Controller) Subscribe(ctx context.Context, fn SubscribeCallback) error {
	if err := c.checkRunning(); err != nil {
		return err
	}

	c.mu.Lock()
	id := c.nextSubscriberID
	c.nextSubscriberID++
	c.subscribers[id] = fn
	c.mu.Unlock()

	defer func() {
		c.mu.Lock()
		delete(c.subscribers, id)
		c.mu.Unlock()
	}()

	for {
		select {
		case <-c.closedCh:
			return ErrControllerClosed
		case <-ctx.Done():
			return ctx.Err()
		}
	}
}

// Create creates a resource and enqueues it for reconciliation.
// If a resource with the same name is currently being deleted, the deletion will be cancelled.