001: /*
002: * JBoss, Home of Professional Open Source.
003: * Copyright 2006, Red Hat Middleware LLC, and individual contributors
004: * as indicated by the @author tags. See the copyright.txt file in the
005: * distribution for a full listing of individual contributors.
006: *
007: * This is free software; you can redistribute it and/or modify it
008: * under the terms of the GNU Lesser General Public License as
009: * published by the Free Software Foundation; either version 2.1 of
010: * the License, or (at your option) any later version.
011: *
012: * This software is distributed in the hope that it will be useful,
013: * but WITHOUT ANY WARRANTY; without even the implied warranty of
014: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015: * Lesser General Public License for more details.
016: *
017: * You should have received a copy of the GNU Lesser General Public
018: * License along with this software; if not, write to the Free
019: * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
020: * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
021: */
022: package org.jboss.ha.framework.server;
023:
024: import org.jboss.logging.Logger;
025:
026: import EDU.oswego.cs.dl.util.concurrent.LinkedQueue;
027:
028: /**
029: * Utility class that accepts objects into a queue and maintains a separate
030: * thread that reads them off the queue and passes them to a registered
031: * "processor".
032: *
033: * @todo find a better home for this than the cluster module
034: *
035: * @author <a href="mailto://brian.stansberry@jboss.com">Brian Stansberry</a>
036: * @version $Revision$
037: */
038: class AsynchEventHandler implements Runnable {
039: /**
040: * Interface implemented by classes able to process the objects
041: * placed into an AsynchEventHandler's queue.
042: */
043: public static interface AsynchEventProcessor {
044: public void processEvent(Object event);
045: }
046:
047: private String name;
048: /** The LinkedQueue of events to pass to our processor */
049: private LinkedQueue events = new LinkedQueue();
050: /** Whether we're blocking on the queue */
051: private boolean blocking;
052: private AsynchEventProcessor processor;
053: private boolean stopped = true;
054: private Thread handlerThread;
055: private Logger log;
056:
057: /**
058: * Create a new AsynchEventHandler.
059: *
060: * @param processor object to which objects placed in the queue should
061: * be handed when dequeued
062: * @param name name for this instance. Appended to the processor's
063: * class name to create a log category, and used
064: * to name to handler thread
065: */
066: public AsynchEventHandler(AsynchEventProcessor processor,
067: String name) {
068: super ();
069: this .processor = processor;
070: if (name == null)
071: name = "AsynchEventHandler";
072: this .name = name;
073: this .log = Logger.getLogger(processor.getClass().getName()
074: + "." + name);
075: }
076:
077: /**
078: * Place the given object in the queue.
079: *
080: * @param event the object to asynchronously pass to the
081: * AsynchEventHandler.
082: *
083: * @throws InterruptedException if the thread is interrupted while blocking
084: * on the queue.
085: */
086: public void queueEvent(Object event) throws InterruptedException {
087: if (event != null)
088: events.put(event);
089: }
090:
091: public void run() {
092: log.debug("Begin " + name + " Thread");
093: stopped = false;
094: while (!stopped) {
095: try {
096: blocking = true;
097: Object event = events.take();
098: blocking = false;
099:
100: if (!stopped) {
101: processor.processEvent(event);
102: }
103: } catch (InterruptedException e) {
104: blocking = false;
105: log.debug(name + " Thread interrupted", e);
106: if (stopped)
107: break;
108: } catch (Throwable t) {
109: log.error("Caught Throwable handling asynch events", t);
110: }
111: }
112: log.debug("End " + name + " Thread");
113: }
114:
115: /**
116: * Starts the handler thread.
117: */
118: public void start() {
119: handlerThread = new Thread(this , name + " Thread");
120: handlerThread.start();
121: }
122:
123: /**
124: * Stops the handler thread.
125: */
126: public void stop() {
127: stopped = true;
128: if (blocking)
129: handlerThread.interrupt(); // it's just waiting on the LinkedQueue
130:
131: if (handlerThread.isAlive()) {
132: // Give it up to 100ms to finish whatever it's doing
133: try {
134: handlerThread.join(100);
135: } catch (Exception ignored) {
136: }
137: }
138:
139: if (handlerThread.isAlive())
140: handlerThread.interrupt(); // kill it
141: }
142:
143: public boolean isStopped() {
144: return stopped;
145: }
146:
147: }
|