k3s/pkg/watch/watch.go

/*
Copyright 2014 Google Inc. All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package watch

import (
	"sync"
)

// Interface can be implemented by anything that knows how to watch and report changes.
type Interface interface {
	// Stops watching. Will close the channel returned by ResultChan(). Releases
	// any resources used by the watch.
	Stop()

	// Returns a chan which will receive all the events. If an error occurs
	// or Stop() is called, this channel will be closed, in which case the
	// watch should be completely cleaned up.
	ResultChan() <-chan Event
}

// EventType defines the possible types of events.
type EventType string

const (
	Added    EventType = "ADDED"
	Modified EventType = "MODIFIED"
	Deleted  EventType = "DELETED"
)

// Event represents a single event to a watched resource.
type Event struct {
	Type EventType

	// If Type == Deleted, then this is the state of the object
	// immediately before deletion.
	Object interface{}
}

// FakeWatcher lets you test anything that consumes a watch.Interface; threadsafe.
type FakeWatcher struct {
	result  chan Event
	Stopped bool
	sync.Mutex
}

func NewFake() *FakeWatcher {
	return &FakeWatcher{
		result: make(chan Event),
	}
}

// Stop implements Interface.Stop().
func (f *FakeWatcher) Stop() {
	f.Lock()
	defer f.Unlock()
	if !f.Stopped {
		close(f.result)
		f.Stopped = true
	}
}

func (f *FakeWatcher) ResultChan() <-chan Event {
	return f.result
}

// Add sends an add event.
func (f *FakeWatcher) Add(obj interface{}) {
	f.result <- Event{Added, obj}
}

// Modify sends a modify event.
func (f *FakeWatcher) Modify(obj interface{}) {
	f.result <- Event{Modified, obj}
}

// Delete sends a delete event.
func (f *FakeWatcher) Delete(lastValue interface{}) {
	f.result <- Event{Deleted, lastValue}
}

// Action sends an event of the requested type, for table-based testing.
func (f *FakeWatcher) Action(action EventType, obj interface{}) {
	f.result <- Event{action, obj}
}