refactor(store.go) handle short condition first

store/store.go

@@ -215,30 +215,30 @@ func (s *store) CompareAndSwap(nodePath string, prevValue string, prevIndex uint
 
 	// If both of the prevValue and prevIndex are given, we will test both of them.
 	// Command will be executed, only if both of the tests are successful.
-	if n.Compare(prevValue, prevIndex) {
-		// update etcd index
-		s.CurrentIndex++
+	if !n.Compare(prevValue, prevIndex) {
+		cause := fmt.Sprintf("[%v != %v] [%v != %v]", prevValue, n.Value, prevIndex, n.ModifiedIndex)
+		s.Stats.Inc(CompareAndSwapFail)
+		return nil, etcdErr.NewError(etcdErr.EcodeTestFailed, cause, s.CurrentIndex)
+	}
 
-		e := newEvent(CompareAndSwap, nodePath, s.CurrentIndex, n.CreatedIndex)
-		eNode := e.Node
+	// update etcd index
+	s.CurrentIndex++
 
-		eNode.PrevValue = n.Value
+	e := newEvent(CompareAndSwap, nodePath, s.CurrentIndex, n.CreatedIndex)
+	eNode := e.Node
 
-		// if test succeed, write the value
-		n.Write(value, s.CurrentIndex)
-		n.UpdateTTL(expireTime)
+	eNode.PrevValue = n.Value
 
-		eNode.Value = value
-		eNode.Expiration, eNode.TTL = n.ExpirationAndTTL()
+	// if test succeed, write the value
+	n.Write(value, s.CurrentIndex)
+	n.UpdateTTL(expireTime)
 
-		s.WatcherHub.notify(e)
-		s.Stats.Inc(CompareAndSwapSuccess)
-		return e, nil
-	}
+	eNode.Value = value
+	eNode.Expiration, eNode.TTL = n.ExpirationAndTTL()
 
-	cause := fmt.Sprintf("[%v != %v] [%v != %v]", prevValue, n.Value, prevIndex, n.ModifiedIndex)
-	s.Stats.Inc(CompareAndSwapFail)
-	return nil, etcdErr.NewError(etcdErr.EcodeTestFailed, cause, s.CurrentIndex)
+	s.WatcherHub.notify(e)
+	s.Stats.Inc(CompareAndSwapSuccess)
+	return e, nil
 }
 
 // Delete function deletes the node at the given path.
@@ -316,28 +316,28 @@ func (s *store) CompareAndDelete(nodePath string, prevValue string, prevIndex ui
 
 	// If both of the prevValue and prevIndex are given, we will test both of them.
 	// Command will be executed, only if both of the tests are successful.
-	if n.Compare(prevValue, prevIndex) {
-		// update etcd index
-		s.CurrentIndex++
-
-		e := newEvent(CompareAndDelete, nodePath, s.CurrentIndex, n.CreatedIndex)
+	if !n.Compare(prevValue, prevIndex) {
+		cause := fmt.Sprintf("[%v != %v] [%v != %v]", prevValue, n.Value, prevIndex, n.ModifiedIndex)
+		s.Stats.Inc(CompareAndDeleteFail)
+		return nil, etcdErr.NewError(etcdErr.EcodeTestFailed, cause, s.CurrentIndex)
+	}
 
-		callback := func(path string) { // notify function
-			// notify the watchers with deleted set true
-			s.WatcherHub.notifyWatchers(e, path, true)
-		}
+	// update etcd index
+	s.CurrentIndex++
 
-		// delete a key-value pair, no error should happen
-		n.Remove(false, false, callback)
+	e := newEvent(CompareAndDelete, nodePath, s.CurrentIndex, n.CreatedIndex)
 
-		s.WatcherHub.notify(e)
-		s.Stats.Inc(CompareAndDeleteSuccess)
-		return e, nil
+	callback := func(path string) { // notify function
+		// notify the watchers with deleted set true
+		s.WatcherHub.notifyWatchers(e, path, true)
 	}
 
-	cause := fmt.Sprintf("[%v != %v] [%v != %v]", prevValue, n.Value, prevIndex, n.ModifiedIndex)
-	s.Stats.Inc(CompareAndDeleteFail)
-	return nil, etcdErr.NewError(etcdErr.EcodeTestFailed, cause, s.CurrentIndex)
+	// delete a key-value pair, no error should happen
+	n.Remove(false, false, callback)
+
+	s.WatcherHub.notify(e)
+	s.Stats.Inc(CompareAndDeleteSuccess)
+	return e, nil
 }
 
 func (s *store) Watch(key string, recursive bool, sinceIndex uint64) (<-chan *Event, error) {