| package org.apache.commons.jcs3.engine.control.event; |
| |
| /* |
| * 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. |
| */ |
| |
| import java.io.IOException; |
| import java.util.concurrent.ExecutorService; |
| |
| import org.apache.commons.jcs3.engine.control.event.behavior.IElementEvent; |
| import org.apache.commons.jcs3.engine.control.event.behavior.IElementEventHandler; |
| import org.apache.commons.jcs3.engine.control.event.behavior.IElementEventQueue; |
| import org.apache.commons.jcs3.log.Log; |
| import org.apache.commons.jcs3.log.LogManager; |
| import org.apache.commons.jcs3.utils.threadpool.PoolConfiguration; |
| import org.apache.commons.jcs3.utils.threadpool.ThreadPoolManager; |
| import org.apache.commons.jcs3.utils.threadpool.PoolConfiguration.WhenBlockedPolicy; |
| |
| /** |
| * An event queue is used to propagate ordered cache events to one and only one target listener. |
| */ |
| public class ElementEventQueue |
| implements IElementEventQueue |
| { |
| private static final String THREAD_PREFIX = "JCS-ElementEventQueue-"; |
| |
| /** The logger */ |
| private static final Log log = LogManager.getLog( ElementEventQueue.class ); |
| |
| /** shutdown or not */ |
| private boolean destroyed = false; |
| |
| /** The worker thread pool. */ |
| private ExecutorService queueProcessor; |
| |
| /** |
| * Constructor for the ElementEventQueue object |
| */ |
| public ElementEventQueue() |
| { |
| queueProcessor = ThreadPoolManager.getInstance().createPool( |
| new PoolConfiguration(false, 0, 1, 1, 0, WhenBlockedPolicy.RUN, 1), THREAD_PREFIX); |
| |
| log.debug( "Constructed: {0}", this ); |
| } |
| |
| /** |
| * Dispose queue |
| */ |
| @Override |
| public void dispose() |
| { |
| if ( !destroyed ) |
| { |
| destroyed = true; |
| |
| // synchronize on queue so the thread will not wait forever, |
| // and then interrupt the QueueProcessor |
| queueProcessor.shutdownNow(); |
| queueProcessor = null; |
| |
| log.info( "Element event queue destroyed: {0}", this ); |
| } |
| } |
| |
| /** |
| * Adds an ElementEvent to be handled |
| * @param hand The IElementEventHandler |
| * @param event The IElementEventHandler IElementEvent event |
| * @throws IOException |
| */ |
| @Override |
| public <T> void addElementEvent( final IElementEventHandler hand, final IElementEvent<T> event ) |
| throws IOException |
| { |
| |
| log.debug( "Adding Event Handler to QUEUE, !destroyed = {0}", !destroyed ); |
| |
| if (destroyed) |
| { |
| log.warn("Event submitted to disposed element event queue {0}", event); |
| } |
| else |
| { |
| final ElementEventRunner runner = new ElementEventRunner( hand, event ); |
| |
| log.debug( "runner = {0}", runner ); |
| |
| queueProcessor.execute(runner); |
| } |
| } |
| |
| // /////////////////////////// Inner classes ///////////////////////////// |
| |
| /** |
| * Retries before declaring failure. |
| */ |
| protected abstract class AbstractElementEventRunner |
| implements Runnable |
| { |
| /** |
| * Main processing method for the AbstractElementEvent object |
| */ |
| @SuppressWarnings("synthetic-access") |
| @Override |
| public void run() |
| { |
| try |
| { |
| doRun(); |
| // happy and done. |
| } |
| catch ( final IOException e ) |
| { |
| // Too bad. The handler has problems. |
| log.warn( "Giving up element event handling {0}", ElementEventQueue.this, e ); |
| } |
| } |
| |
| /** |
| * This will do the work or trigger the work to be done. |
| * <p> |
| * @throws IOException |
| */ |
| protected abstract void doRun() |
| throws IOException; |
| } |
| |
| /** |
| * ElementEventRunner. |
| */ |
| private class ElementEventRunner |
| extends AbstractElementEventRunner |
| { |
| /** the handler */ |
| private final IElementEventHandler hand; |
| |
| /** event */ |
| private final IElementEvent<?> event; |
| |
| /** |
| * Constructor for the PutEvent object. |
| * <p> |
| * @param hand |
| * @param event |
| * @throws IOException |
| */ |
| @SuppressWarnings("synthetic-access") |
| ElementEventRunner( final IElementEventHandler hand, final IElementEvent<?> event ) |
| throws IOException |
| { |
| log.debug( "Constructing {0}", this ); |
| this.hand = hand; |
| this.event = event; |
| } |
| |
| /** |
| * Tells the handler to handle the event. |
| * <p> |
| * @throws IOException |
| */ |
| @Override |
| protected void doRun() |
| throws IOException |
| { |
| hand.handleElementEvent( event ); |
| } |
| } |
| } |