| /* |
| * |
| * 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.client; |
| |
| import javax.jms.IllegalStateException; |
| import javax.jms.JMSException; |
| import java.util.concurrent.atomic.AtomicBoolean; |
| |
| /** |
| * Captures the 'closed' state of an object, that is initially open, can be tested to see if it is closed, and provides |
| * a 'close' method to close it. |
| * |
| * <p/><table id="crc"><caption>CRC Card</caption> |
| * <tr><th> Responsibilities <th> Collaborations |
| * <tr><td> Mark an object as closed. |
| * <tr><td> Check if an object is closed. |
| * <tr><td> Raise a JMS exception if an object is closed. |
| * </table> |
| * |
| * @todo Might be better to make this an interface. This whole class doesn't really encapsulate a terribly neat |
| * piece of re-usable functionality. A simple interface defining a close method would suffice. |
| * |
| * @todo The convenience method {@link #checkNotClosed} is not that helpfull, what if the caller wants to do something |
| * other than throw an exception? It doesn't really represent a very usefull re-usable piece of code. Consider |
| * inlining it and dropping the method. |
| */ |
| public abstract class Closeable |
| { |
| /** |
| * We use an atomic boolean so that we do not have to synchronized access to this flag. Synchronizing access to this |
| * flag would mean have a synchronized block in every method. |
| */ |
| private final AtomicBoolean _closed = new AtomicBoolean(false); |
| |
| /** |
| * Are we in the process of closing. We have this distinction so we can |
| * still signal we are in the process of closing so other objects can tell |
| * the difference and tidy up. |
| */ |
| private final AtomicBoolean _closing = new AtomicBoolean(false); |
| |
| /** |
| * Checks if this is closed, and raises a JMSException if it is. |
| * |
| * @throws JMSException If this is closed. |
| */ |
| protected void checkNotClosed() throws JMSException |
| { |
| if (isClosed()) |
| { |
| throw new IllegalStateException("Object " + toString() + " has been closed"); |
| } |
| } |
| |
| /** |
| * Checks if this is closed. |
| * |
| * @return <tt>true</tt> if this is closed, <tt>false</tt> otherwise. |
| */ |
| public boolean isClosed() |
| { |
| return _closed.get(); |
| } |
| |
| /** |
| * Checks if this is closis. |
| * |
| * @return <tt>true</tt> if we are closing, <tt>false</tt> otherwise. |
| */ |
| public boolean isClosing() |
| { |
| return _closing.get(); |
| } |
| |
| protected boolean setClosed() |
| { |
| return _closed.getAndSet(true); |
| } |
| |
| protected void setClosing(boolean closing) |
| { |
| _closing.set(closing); |
| } |
| |
| /** |
| * Closes this object. |
| * |
| * @throws JMSException If this cannot be closed for any reason. |
| */ |
| public abstract void close() throws JMSException; |
| } |