fix: ignore update messages from itself

[sasakiyori]

Fix: #22

When policy changes, etcd-watcher will Put a message into etcd, then the revision of key will be updated.

resp, err := w.client.Put(context.TODO(), w.keyName, "")

At the same time, etcd-watcher will get this new revision because it is watching this key.

func (w *Watcher) startWatch() error {
	watcher := w.client.Watch(context.Background(), w.keyName)

So in last pr #22 , to prevent consuming the messages put by self, every time etcd-watcher put a message, it will record the revision from the Put response. And in the goroutine for Watch, it will verify the revision of received message is bigger than recorded one or not.

for res := range watcher {
    t := res.Events[0]
    if t.IsCreate() || t.IsModify() {
	  w.lock.RLock()
	  //ignore self update
	  if rev := t.Kv.ModRevision; rev > w.lastSentRev && w.callback != nil {
		  w.callback(strconv.FormatInt(rev, 10))
	  }
	  w.lock.RUnlock()
    }
}

But in the Update function, it only update local recorded revision when Put fails, it means this feature will be never triggered.

func (w *Watcher) Update() error {
	w.lock.Lock()
	defer w.lock.Unlock()
	resp, err := w.client.Put(context.TODO(), w.keyName, "")
        // We should update lastSentRev when put operation succeeds, but not when it fails.
        // if err != nil {
	if err == nil {
		w.lastSentRev = resp.Header.GetRevision()
	}
	return err
}

[coveralls]

Coverage increased (+3.03%) to 80.303% when pulling 9fd1f9e on sasakiyori:ignore_self_update into bb800b6 on casbin:master.

[casbin-bot]

@tangyang9464 @JalinWang @imp2002 please review

[sasakiyori]

oh why the coverage is decreased to 0.0%? I saw the coverage result from CI (Go/test (1.16)) is 85.4%

[hsluoyz]

@imp2002 plz review

[sasakiyori]

Can someone review this PR? @hsluoyz @JalinWang @imp2002

[sasakiyori]

oh why the coverage is decreased to 0.0%? I saw the coverage result from CI (Go/test (1.16)) is 85.4%

I don't know why the coverage from coveralls is different from CI. And I think using time.Sleep in the unit test is not graceful. Thus I revert the changes of unit tests.

[imp2002]

LGTM

[github-actions]

🎉 This PR is included in version 2.1.2 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀