Merge pull request #7804 from heyitsanthony/current-watch-fix

clientv3: set current revision to create rev regardless of CreateNotify

clientv3/watch.go

@@ -615,13 +615,18 @@ func (w *watchGrpcStream) serveSubstream(ws *watcherStream, resumec chan struct{
 					// send first creation event only if requested
 					if ws.initReq.createdNotify {
 						ws.outc <- *wr
-						if ws.initReq.rev == 0 {
-							// current revision of store; returning the
-							// create response binds the current revision to
-							// this revision, so restart with it if there's a
-							// disconnect before receiving any events.
-							nextRev = wr.Header.Revision
-						}
+					}
+					// once the watch channel is returned, a current revision
+					// watch must resume at the store revision. This is necessary
+					// for the following case to work as expected:
+					//	wch := m1.Watch("a")
+					//	m2.Put("a", "b")
+					//	<-wch
+					// If the revision is only bound on the first observed event,
+					// if wch is disconnected before the Put is issued, then reconnects
+					// after it is committed, it'll miss the Put.
+					if ws.initReq.rev == 0 {
+						nextRev = wr.Header.Revision
 					}
 				}
 			} else {