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/*
* Copyright (c) 2003 - 2007 Israfil Consulting Services Corporation
* Copyright (c) 2003 - 2007 Christian Edward Gruber
* All Rights Reserved
*
* This software is licensed under the Berkeley Standard Distribution license,
* (BSD license), as defined below:
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. Neither the name of Israfil Consulting Services nor the names of its contributors
* may be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
* OF SUCH DAMAGE.
*
* $Id: Worker.java 401 2007-01-26 02:05:20Z cgruber $
*/
package net.israfil.foundation.concurrent;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* An object that wraps a Thread and performs units of work within that
* thread.
*
* @author <a href="mailto:cgruber@israfil.net">Christian Edward Gruber </a>
*/
public abstract class AbstractWorker implements Runnable, Worker {
private static Logger logger = Logger.getLogger(AbstractWorker.class.getName());
private Thread _thread = null;
private String _name = this.getClass().getName();
private Throwable _error = null;
private WorkerState state = WorkerState.Stopped;
public AbstractWorker() { }
public AbstractWorker(String name) {
this._name = name;
}
/**
* Runnable.run() implementation.
*
*/
public void run() {
try {
//execute lifecycle
state = WorkerState.Starting;
_thread = Thread.currentThread();
_thread.setName(_name);
_error = null;
if (init()) {
state = WorkerState.Running;
executeLifecycle();
}
state = WorkerState.Stopping;
deinit();
state = WorkerState.Stopped;
} catch (InterruptedException e){
state = WorkerState.Stopped;
logger.log(Level.FINE,this.getName() + " interrupted, setting stopped state.",e);
_error = e;
} catch (RuntimeInterruptedException e){
state = WorkerState.Stopped;
logger.log(Level.FINE,this.getName() + " interrupted, setting stopped state.",e);
_error=e;
} catch (Throwable e){
state = WorkerState.Stopped;
logger.log(Level.SEVERE,e.getClass().getName() + " thrown within run() method of " +
this.getName() + ", setting stopped state.",e);
_error = e;
}
}
abstract void executeLifecycle() throws InterruptedException;
// Lifecycle phases
protected boolean init() throws InterruptedException {
validate();
return _thread != null && _thread.isAlive();
}
protected void preProcess() throws InterruptedException { }
protected abstract void process() throws InterruptedException;
protected void postProcess() throws InterruptedException { }
protected void deinit() throws InterruptedException { }
protected void validate() {
if (getName() == null || getName().equals(""))
throw new IllegalStateException(getClass().getName() + " cannot start without a name.");
}
//
// SIGNALING
//
// TODO: Validate signaling.
// TODO: Implement cleaner signaling.
//
public boolean isRunning() {
return _thread != null && _thread.isAlive() && state == WorkerState.Running;
}
public boolean isStopping(){
return state == WorkerState.Stopping;
}
public boolean isStarting(){
return state == WorkerState.Starting;
}
public boolean isStopped(){
return state == WorkerState.Stopped;
}
// Accessors
public Thread getThread() { return _thread; }
public String getName() { return _name; }
public void setName(String name) { this._name = name; }
/**
* If the worker has stopped due to a thrown error, it should be captured
* and available via this method. This method will throw an IllegalStateException
* if called when the worker is not in a Stopped state.
*
*/
public Throwable getError() {
if (!isStopped()) throw new IllegalStateException("No error available when worker not stopped.");
else return this._error;
}
/**
* Start the worker
* @return boolean Did the Worker startup properly.
*/
public boolean start() {
try {
if (!isStopped())
throw new IllegalStateException("Attempted to start a worker that wasn't stopped");
Thread t = new Thread(this);
t.start();
Thread.yield();
return true;
} catch (Exception e) {
logger.log(Level.INFO,this.getName() + "Thread failed to start",e);
return false;
}
}
/**
* Attempts to gracefully shutdown the worker, but interrupts the
* thread after 20ms if the worker does not stop on its own.
* @throws InterruptedException
*/
public void stop() throws InterruptedException{
stop(20);
}
/**
* Attempts to gracefully shutdown the worker, but interrupts the
* thread after a given timeout if the worker does not stop on its own.
* @throws InterruptedException
*/
public void stop(long timeout_miliseconds) throws InterruptedException{
if (state == WorkerState.Stopped) return; // succeed fast.
state = WorkerState.Stopping;
if (getThread() != null) getThread().join(timeout_miliseconds);
hardStop();
}
/**
* Attempts to gracefully shutdown the worker, but interrupts the
* thread after a given timeout if the worker does not stop on its own.
* @throws InterruptedException
*/
public void stop(long timeout_miliseconds,int timeout_nanoseconds) throws InterruptedException{
if (state == WorkerState.Stopped) return; // succeed fast.
state = WorkerState.Stopping;
if (getThread() != null) getThread().join(timeout_miliseconds,timeout_nanoseconds);
hardStop();
}
protected void hardStop() {
if (isStopped() || getThread() == null) return;
getThread().interrupt();
this._thread = null;
this.state = WorkerState.Stopped;
}
}
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