/*
* Copyright 2012 Red Hat, Inc. and/or its affiliates.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301 USA
*/
package org.infinispan.executors;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Properties;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* A delegating executor that lazily constructs and initializes the underlying executor, since unused JDK executors
* are expensive.
*
* @author Manik Surtani
* @since 5.1
*/
public final class LazyInitializingExecutorService implements ExecutorService {
private volatile ExecutorService delegate;
private final ExecutorFactory factory;
private final Properties executorProperties;
public LazyInitializingExecutorService(ExecutorFactory factory, Properties executorProperties) {
this.factory = factory;
this.executorProperties = executorProperties;
}
private void initIfNeeded() {
if (delegate == null) {
synchronized (this) {
if (delegate == null) {
delegate = factory.getExecutor(executorProperties);
}
}
}
}
@Override
public void shutdown() {
if (delegate != null) delegate.shutdown();
}
@Override
public List<Runnable> shutdownNow() {
if (delegate == null)
return Collections.emptyList();
else
return delegate.shutdownNow();
}
@Override
public boolean isShutdown() {
return delegate == null || delegate.isShutdown();
}
@Override
public boolean isTerminated() {
return delegate == null || delegate.isTerminated();
}
@Override
public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException {
if (delegate == null)
return true;
else
return delegate.awaitTermination(timeout, unit);
}
@Override
public <T> Future<T> submit(Callable<T> task) {
initIfNeeded();
return delegate.submit(task);
}
@Override
public <T> Future<T> submit(Runnable task, T result) {
initIfNeeded();
return delegate.submit(task, result);
}
@Override
public Future<?> submit(Runnable task) {
initIfNeeded();
return delegate.submit(task);
}
@Override
public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) throws InterruptedException {
initIfNeeded();
return delegate.invokeAll(tasks);
}
@Override
public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit) throws InterruptedException {
initIfNeeded();
return delegate.invokeAll(tasks, timeout, unit);
}
@Override
public <T> T invokeAny(Collection<? extends Callable<T>> tasks) throws InterruptedException, ExecutionException {
initIfNeeded();
return delegate.invokeAny(tasks);
}
@Override
public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
initIfNeeded();
return delegate.invokeAny(tasks, timeout, unit);
}
@Override
public void execute(Runnable command) {
initIfNeeded();
delegate.execute(command);
}
}