.

wcfs/wcfs.go

@@ -1411,18 +1411,16 @@ func (wlink *WatchLink) setupWatch(ctx context.Context, foid zodb.Oid, at zodb.T
 	defer head.zheadMu.RUnlock()
 	headAt := head.zconn.At()
 
-	if at < bfdir.δFtail.Tail() {
+	if at != zodb.InvalidTid && at < bfdir.δFtail.Tail() {
 		return fmt.Errorf("too far away back from head/at (@%s); δt = %s",
 			headAt, headAt.Time().Sub(at.Time().Time))
 	}
 
-	// XXX if watch was already established - we need to update it
-	// XXX locking (.byfile)
-	w := wlink.byfile[foid]
+	// if watch was already established - we need to update it
+	w := wlink.byfile[foid]	// XXX locking
 	if w == nil {
 		// watch was not previously established - set it up anew
-		// XXX locking (.fileTab)
-		f := bfdir.fileTab[foid]
+		f := bfdir.fileTab[foid]	// XXX locking
 		if f == nil {
 			// by "invalidation protocol" watch is setup after data file was opened
 			return fmt.Errorf("file not yet known to wcfs or is not a ZBigFile")
@@ -1437,10 +1435,9 @@ func (wlink *WatchLink) setupWatch(ctx context.Context, foid zodb.Oid, at zodb.T
 	}
 
 	// at="-" (InvalidTid) means "remove the watch"
-	// XXX locking
 	if at == zodb.InvalidTid {
-		delete(wlink.byfile, foid)
-		delete(w.file.watchTab, w)
+		delete(wlink.byfile, foid)	// XXX locking
+		delete(w.file.watchTab, w)	// XXX locking
 		return nil
 	}