| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more contributor license |
| * agreements. See the NOTICE file distributed with this work for additional information regarding |
| * copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance with the License. You may obtain a |
| * copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software distributed under the License |
| * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express |
| * or implied. See the License for the specific language governing permissions and limitations under |
| * the License. |
| */ |
| package org.apache.geode.internal.cache; |
| |
| import org.apache.geode.annotations.Immutable; |
| import org.apache.geode.annotations.internal.MakeNotStatic; |
| import org.apache.geode.cache.query.internal.Support; |
| |
| /** |
| * This class is intended to hold a single 'observer' which will receive callbacks. There can be |
| * only one such observer at a time. If no observer is needed, this member variable should point to |
| * an object with 'do-nothing' methods, such as ClientServerObserverAdapter. |
| * |
| * @since GemFire 5.1 |
| */ |
| public class ClientServerObserverHolder { |
| |
| /** |
| * The default 'do-nothing' bridge observer * |
| */ |
| @Immutable |
| private static final ClientServerObserver NO_OBSERVER = new ClientServerObserverAdapter(); |
| |
| /** |
| * The current observer which will be notified of all query events. |
| */ |
| @MakeNotStatic |
| private static ClientServerObserver _instance = NO_OBSERVER; |
| |
| /** |
| * Set the given observer to be notified of events. Returns the current observer. |
| */ |
| public static ClientServerObserver setInstance(ClientServerObserver observer) { |
| Support.assertArg(observer != null, "setInstance expects a non-null argument!"); |
| ClientServerObserver oldObserver = _instance; |
| _instance = observer; |
| return oldObserver; |
| } |
| |
| /** Return the current BridgeObserver instance */ |
| public static ClientServerObserver getInstance() { |
| return _instance; |
| } |
| |
| public static ClientServerObserver clearInstance() { |
| ClientServerObserver oldObserver = _instance; |
| _instance = NO_OBSERVER; |
| return oldObserver; |
| } |
| } |