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The basic runtime tools and interfaces for intarsys components.
/*
* Copyright (c) 2007, intarsys consulting GmbH
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - 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.
*
* - Neither the name of intarsys 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.
*/
package de.intarsys.tools.concurrent;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* This is an alternate implementation for {@link FutureTask}, which is in some
* cases not flexible enough.
*
* @param
*/
abstract public class AbstractFutureTask implements Runnable, Future {
protected final static Logger Log = PACKAGE.Log;
static private int COUNTER = 0;
final private Object lockTask = new Object();
private Throwable exception;
private R result;
private boolean cancelled = false;
private boolean computed = false;
final private int id = COUNTER++;
private boolean active = false;
protected AbstractFutureTask() {
super();
}
protected Throwable basicGetException() {
synchronized (lockTask) {
return exception;
}
}
protected R basicGetResult() {
return result;
}
public boolean cancel(boolean interrupt) {
synchronized (lockTask) {
if (cancelled) {
if (Log.isLoggable(Level.FINEST)) {
Log.finest("" + this + " can't cancel, already canceled"); //$NON-NLS-1$
}
return false;
}
if (computed) {
if (Log.isLoggable(Level.FINEST)) {
Log.finest("" + this + " can't cancel, already computed"); //$NON-NLS-1$
}
return false;
}
if (Log.isLoggable(Level.FINEST)) {
Log
.finest("" + this + " cancel " + (active ? "active" : "inactive") + " task"); //$NON-NLS-1$
}
cancelled = true;
active = false;
lockTask.notifyAll();
return true;
}
}
protected abstract R compute() throws Exception;
protected void computeAsync() {
new Thread(this, "Task computation " + id).start();
}
public R get() throws InterruptedException, ExecutionException {
try {
return get(0, TimeUnit.MILLISECONDS);
} catch (TimeoutException e) {
throw new InterruptedException();
}
}
public R get(final long pMillisecTimeout, TimeUnit unit)
throws InterruptedException, ExecutionException, TimeoutException {
long millisecTimeout = pMillisecTimeout;
long lastTime = System.currentTimeMillis();
synchronized (lockTask) {
while (true) {
if (cancelled) {
// TODO 2 throw an exception instead of null?
return null;
}
if (computed) {
if (exception != null) {
throw new ExecutionException(exception);
}
// may be null!
return result;
}
if (pMillisecTimeout >= 0) {
lockTask.wait(millisecTimeout);
if (pMillisecTimeout != 0) {
long now = System.currentTimeMillis();
millisecTimeout -= now - lastTime;
lastTime = now;
if (millisecTimeout <= 0) {
throw new TimeoutException();
}
}
} else {
// support a unblocked "get current value"
return null;
}
}
}
}
public Throwable getException() {
synchronized (lockTask) {
return exception;
}
}
final protected void handleException() {
try {
if (cancelled) {
if (Log.isLoggable(Level.FINEST)) {
Log.finest("" + this + " exception after cancel"); //$NON-NLS-1$
}
undo();
taskCancelled();
} else {
if (Log.isLoggable(Level.FINEST)) {
Log.finest("" + this + " exception, propagate"); //$NON-NLS-1$
}
taskFailed();
}
} catch (Exception e) {
Log.log(Level.SEVERE,
"" + this + " exception in exception handling", e); //$NON-NLS-1$
}
}
final protected void handleFinally() {
try {
if (Log.isLoggable(Level.FINEST)) {
Log.finest("" + this + " finally, propagate"); //$NON-NLS-1$
}
taskFinally();
} catch (Exception e) {
Log.log(Level.SEVERE,
"" + this + " exception in finally handling", e); //$NON-NLS-1$
}
}
final protected void handleResult() {
try {
if (cancelled) {
if (Log.isLoggable(Level.FINEST)) {
Log.finest("" + this + " computed after cancel, undo"); //$NON-NLS-1$
}
undo();
taskCancelled();
} else {
if (Log.isLoggable(Level.FINEST)) {
Log.finest("" + this + " computed, propagate"); //$NON-NLS-1$
}
taskFinished();
}
} catch (Exception e) {
Log.log(Level.SEVERE,
"" + this + " exception in result handling", e); //$NON-NLS-1$
}
}
public boolean isActive() {
synchronized (lockTask) {
return active;
}
}
public boolean isCancelled() {
synchronized (lockTask) {
return cancelled;
}
}
public boolean isDone() {
synchronized (lockTask) {
return computed || cancelled;
}
}
public boolean isFailed() {
synchronized (lockTask) {
return exception != null;
}
}
public void reset() {
synchronized (lockTask) {
active = false;
computed = false;
exception = null;
result = null;
}
}
final public void run() {
synchronized (lockTask) {
if (active || cancelled || computed) {
if (Log.isLoggable(Level.FINEST)) {
Log
.finest("" + this + " will not run" + (cancelled ? " (canceled)" : "")); //$NON-NLS-1$
}
return;
}
active = true;
}
taskStarted();
try {
setResult(compute());
} catch (Throwable e) {
setException(e);
} finally {
handleFinally();
}
}
public void runAsync() {
synchronized (this) {
if (active || cancelled || computed) {
if (Log.isLoggable(Level.FINEST)) {
Log
.finest("" + this + " will not run" + (cancelled ? " (canceled)" : "")); //$NON-NLS-1$
}
return;
}
active = true;
}
computeAsync();
}
protected void setException(Throwable e) {
synchronized (lockTask) {
computed = true;
active = false;
exception = e;
lockTask.notifyAll();
}
if (Log.isLoggable(Level.FINEST)) {
Log.finest("" + this + " computation failed"); //$NON-NLS-1$
}
handleException();
}
protected void setResult(R object) {
synchronized (lockTask) {
computed = true;
active = false;
result = object;
lockTask.notifyAll();
}
if (Log.isLoggable(Level.FINEST)) {
Log.finest("" + this + " computation ready"); //$NON-NLS-1$
}
handleResult();
}
protected void taskCancelled() {
// redefine
}
protected void taskFailed() {
// redefine
}
protected void taskFinally() {
// redefine
}
protected void taskFinished() {
// redefine
}
protected void taskStarted() {
// redefine
}
@Override
public String toString() {
return getClass().getName() + " - " + id;
}
protected void undo() {
// redefine
}
}
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