/* * * 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.qpid.server.logging.actors; import org.apache.qpid.server.logging.LogActor; import java.util.EmptyStackException; import java.util.Stack; /** * The CurrentActor is a ThreadLocal wrapper that allows threads in the broker * to retrieve an actor to perform logging. This approach is used so for two * reasons: * 1) We do not have to pass a logging actor around the system * 2) We can set new actors at the point we have enough information. i.e. * - Set a low level ConnectionActor when processing bytes from the wire. * - Set a ChannelActor when we are processing the frame * - Set a SubscriptionActor when we are handling the subscription. *
* The code performing the logging need not worry about what type of actor is * currently set so can perform its logging. The resulting log entry though will * contain customised details from the the currently set Actor. * * The Actor model also allows the pre-creation of fixed messages so the * performance impact of the additional logging data is minimised. * * This class does not perform any checks to ensure that there is an Actor set * when calling remove or get. As a result the application developer must ensure * that they have called set before they attempt to use the actor via get or * remove the set actor. * * The checking of the return via get should not be done as the logging is * desired. It is preferable to cause the NullPointerException to highlight the * programming error rather than miss a log message. * * The same is true for the remove. A NPE will occur if no set has been called * highlighting the programming error. */ public class CurrentActor { /** The ThreadLocal variable with initialiser */ private static final ThreadLocal