v3api: Bug in watchable ranges with catchup

[barakmich]

The API is there, and works if you don't set StartRevision -- ie, in https://github.com/coreos/etcd/blob/master/storage/watchable_store.go if the watcher is unsynced, it will never become synced, for prefixes. I added a quick (failing) test to prove it's right in here:

(add to storage/watcher_test.go)

func TestWatcherPrefix(t *testing.T) {
        b, tmpPath := backend.NewDefaultTmpBackend()
        s := WatchableKV(newWatchableStore(b, &lease.FakeLessor{}))
        defer cleanup(s, b, tmpPath)

        w := s.NewWatchStream()
        defer w.Close()

        idm := make(map[WatchID]struct{})

        for i := 0; i < 10; i++ {
                id := w.Watch([]byte("foo"), true, 0)
                if _, ok := idm[id]; ok {
                        t.Errorf("#%d: id %d exists", i, id)
                }
                idm[id] = struct{}{}

                s.Put([]byte("foobar"), []byte("baz"), lease.NoLease)

                resp := <-w.Chan()
                if resp.WatchID != id {
                        t.Errorf("#%d: watch id in event = %d, want %d", i, resp.WatchID, id)
                }

                if err := w.Cancel(id); err != nil {
                        t.Error(err)
                }
        }
        s.Put([]byte("foo2bar"), []byte("bar"), lease.NoLease)
        // unsynced watchers
        for i := 10; i < 20; i++ {
                id := w.Watch([]byte("foo2"), true, 1)
                if _, ok := idm[id]; ok {
                        t.Errorf("#%d: id %d exists", i, id)
                }
                idm[id] = struct{}{}

                resp := <-w.Chan()
                if resp.WatchID != id {
                        t.Errorf("#%d: watch id in event = %d, want %d", i, resp.WatchID, id)
                }

                if err := w.Cancel(id); err != nil {
                        t.Error(err)
                }
        }
}

Everything above unsynced watchers will pass -- but it hangs if we add the unsynced watchers part.

[gyuho]

@barakmich Please try again with master branch.
#4202 has just been merged.

Please ping me if you still have issues with watch.

Thanks for reporting!