etcd/store/watcher.go

package store

import (
	"path"
	"strings"
	//"fmt"
	"time"
	)


type Watchers struct {
	chanMap map[string][]chan Response
}

// global watcher
var w *Watchers


// init the global watcher
func init() {
	w = createWatcher()
}

// create a new watcher
func createWatcher() *Watchers {
	w := new(Watchers)
	w.chanMap = make(map[string][]chan Response)
	return w
}

func Watcher() *Watchers {
	return w
}

// register a function with channel and prefix to the watcher
func AddWatcher(prefix string, c chan Response) error {

	prefix = "/" + path.Clean(prefix)

	_, ok := w.chanMap[prefix]
	if !ok {
		w.chanMap[prefix] = make([]chan Response, 0)
		w.chanMap[prefix] = append(w.chanMap[prefix], c)
	} else {
		w.chanMap[prefix] = append(w.chanMap[prefix], c)
	}

	return nil
}

// notify the watcher a action happened
func notify(action int, key string, oldValue string, newValue string, exist bool) error {
	key = path.Clean(key)
	segments := strings.Split(key, "/")
	currPath := "/"

	// walk through all the pathes
	for _, segment := range segments {
		currPath = path.Join(currPath, segment)

		chans, ok := w.chanMap[currPath]

		if ok {

			n := Response {action, key, oldValue, newValue, exist, time.Unix(0, 0)}

			// notify all the watchers
			for _, c := range chans {
				c <- n
			}
			
			// we have notified all the watchers at this path
			// delete the map
			delete(w.chanMap, currPath)
		}

	}

	return nil
}