etcd backend not passing watcher errors up the stack, and errors not …

…triggering full resync in watcher cache

lib/backend/etcdv3/watcher.go

@@ -98,6 +98,7 @@ func (wc *watcher) watchLoop() {
 		if kvps, err = wc.listCurrent(); err != nil {
 			log.Errorf("failed to list current with latest state: %v", err)
 			// Error considered as terminating error, hence terminate watcher.
+			wc.sendError(err)
 			return
 		}
 
@@ -125,6 +126,7 @@ func (wc *watcher) watchLoop() {
 			// A watch channel error is a terminating event, so exit the loop.
 			err := wres.Err()
 			log.WithError(err).Error("Watch channel error")
+			wc.sendError(err)
 			return
 		}
 		for _, e := range wres.Events {

lib/backend/watchersyncer/watchercache.go

@@ -115,13 +115,12 @@ mainLoop:
 				wc.handleWatchListEvent(kvp)
 			case api.WatchError:
 				// Handle a WatchError. This error triggered from upstream, all type
-				// of WatchError are treated equally,log the Error and trigger a full resync.
-
-				wc.logger.WithField("EventType", event.Type).Errorf("Watch error received from Upstream")
-				wc.onWaitForDatastore()
+				// of WatchError are treated equally,log the Error and trigger a full resync. We only log at info
+				// because errors may occur due to compaction causing revisions to no longer be valid - in this case
+				// we simply need to do a full resync.
+				wc.logger.WithError(event.Error).Infof("Watch error received from Upstream")
 				wc.currentWatchRevision = ""
 				wc.resyncAndCreateWatcher(ctx)
-
 			default:
 				// Unknown event type - not much we can do other than log.
 				wc.logger.WithField("EventType", event.Type).Errorf("Unknown event type received from the datastore")
@@ -172,7 +171,7 @@ func (wc *watcherCache) resyncAndCreateWatcher(ctx context.Context) {
 		}
 
 		if performFullResync {
-			wc.logger.Debug("Full resync is required")
+			wc.logger.Info("Full resync is required")
 
 			// Notify the converter that we are resyncing.
 			if wc.resourceType.UpdateProcessor != nil {
@@ -185,7 +184,6 @@ func (wc *watcherCache) resyncAndCreateWatcher(ctx context.Context) {
 			if err != nil {
 				// Failed to perform the list.  Pause briefly (so we don't tight loop) and retry.
 				wc.logger.WithError(err).Info("Failed to perform list of current data during resync")
-				wc.onWaitForDatastore()
 				select {
 				case <-time.After(ListRetryInterval):
 					continue
@@ -242,11 +240,7 @@ func (wc *watcherCache) resyncAndCreateWatcher(ctx context.Context) {
 			}
 
 			// We hit an error creating the Watch.  Trigger a full resync.
-			// TODO We should be able to improve this by handling specific error cases with another
-			//      watch retry.  This would require some care to ensure the correct errors are captured
-			//      for the different datastore drivers.
 			wc.logger.WithError(err).WithField("performFullResync", performFullResync).Info("Failed to create watcher")
-			wc.onWaitForDatastore()
 			performFullResync = true
 			continue
 		}
@@ -271,9 +265,8 @@ func (wc *watcherCache) cleanExistingWatcher() {
 // We may also need to send deleted messages for old resources that were not validated in the
 // resync (i.e. they must have since been deleted).
 func (wc *watcherCache) finishResync() {
-	// If we haven't already sent an InSync event (or signalled the inverse by sending a WaitForDatastore event),
-	// then send a synced notification.  The watcherSyncer will send a Synced event when it has received synced
-	// events from each cache.
+	// If we haven't already sent an InSync event then send a synced notification.  The watcherSyncer will send a Synced
+	// event when it has received synced events from each cache. Once in-sync the cache remains in-sync.
 	if !wc.hasSynced {
 		wc.logger.Info("Sending synced update")
 		wc.results <- api.InSync
@@ -408,13 +401,3 @@ func (wc *watcherCache) markAsValid(resourceKey string) {
 		}
 	}
 }
-
-// If a syncer is in-sync state, the onWaitForDatastore method, sends WaitForDatastore event.
-// See finishResync() for how the watcherCache goes back to in-sync.
-func (wc *watcherCache) onWaitForDatastore() {
-	wc.logger.Debug("Send WaitforDatastore event if sync isn't in-sync")
-	if wc.hasSynced {
-		wc.results <- api.WaitForDatastore
-		wc.hasSynced = false
-	}
-}

lib/backend/watchersyncer/watchersyncer.go

@@ -222,13 +222,6 @@ func (ws *watcherSyncer) processResult(updates []api.Update, result interface{})
 				updates = ws.sendUpdates(updates)
 				ws.sendStatusUpdate(api.InSync)
 			}
-		} else if r == api.WaitForDatastore {
-			// If we received a WaitForDatastore from a watcherCache and we're in-sync or re-syncing, send a status
-			// update signalling that we're not in-sync.
-			if ws.status == api.InSync || ws.status == api.ResyncInProgress {
-				ws.sendStatusUpdate(api.WaitForDatastore)
-			}
-			ws.numSynced--
 		}
 	}
 

lib/backend/watchersyncer/watchersyncer_test.go

@@ -248,7 +248,7 @@ var _ = Describe("Test the backend datastore multi-watch syncer", func() {
 		rs.clientWatchResponse(r3, nil)
 		rs.sendEvent(r3, api.WatchEvent{
 			Type:  api.WatchError,
-			Error: cerrors.ErrorWatchTerminated{Err: dsError},
+			Error: dsError,
 		})
 		rs.ExpectStatusUpdate(api.WaitForDatastore)
 		rs.clientListResponse(r3, emptyList)
@@ -308,7 +308,7 @@ var _ = Describe("Test the backend datastore multi-watch syncer", func() {
 		rs.clientWatchResponse(r3, nil)
 		rs.sendEvent(r3, api.WatchEvent{
 			Type:  api.WatchError,
-			Error: cerrors.ErrorWatchTerminated{Err: dsError},
+			Error: dsError,
 		})
 		rs.ExpectStatusUpdate(api.WaitForDatastore)
 		rs.clientListResponse(r3, emptyList)
@@ -433,7 +433,7 @@ var _ = Describe("Test the backend datastore multi-watch syncer", func() {
 		By("Failing the watch, and resyncing with another modified entry")
 		rs.sendEvent(r1, api.WatchEvent{
 			Type:  api.WatchError,
-			Error: cerrors.ErrorWatchTerminated{Err: dsError},
+			Error: dsError,
 		})
 		rs.ExpectStatusUpdate(api.WaitForDatastore)
 		rs.clientListResponse(r1, &model.KVPairList{

lib/errors/errors.go

@@ -171,16 +171,6 @@ func UpdateErrorIdentifier(err error, id interface{}) error {
 	return err
 }
 
-// Error indicating the watcher has been terminated.
-type ErrorWatchTerminated struct {
-	Err            error
-	ClosedByRemote bool
-}
-
-func (e ErrorWatchTerminated) Error() string {
-	return fmt.Sprintf("watch terminated (closedByRemote:%v): %v", e.ClosedByRemote, e.Err)
-}
-
 // Error indicating the datastore has failed to parse an entry.
 type ErrorParsingDatastoreEntry struct {
 	RawKey   string