AbstractExecutorService.java revision 0
/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun in the LICENSE file that accompanied this code.
*
* This code 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 General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
/*
* This file is available under and governed by the GNU General Public
* License version 2 only, as published by the Free Software Foundation.
* However, the following notice accompanied the original version of this
* file:
*
* Written by Doug Lea with assistance from members of JCP JSR-166
* Expert Group and released to the public domain, as explained at
*/
/**
* Provides default implementations of {@link ExecutorService}
* execution methods. This class implements the <tt>submit</tt>,
* <tt>invokeAny</tt> and <tt>invokeAll</tt> methods using a
* {@link RunnableFuture} returned by <tt>newTaskFor</tt>, which defaults
* to the {@link FutureTask} class provided in this package. For example,
* the implementation of <tt>submit(Runnable)</tt> creates an
* associated <tt>RunnableFuture</tt> that is executed and
* returned. Subclasses may override the <tt>newTaskFor</tt> methods
* to return <tt>RunnableFuture</tt> implementations other than
* <tt>FutureTask</tt>.
*
* <p> <b>Extension example</b>. Here is a sketch of a class
* that customizes {@link ThreadPoolExecutor} to use
* a <tt>CustomTask</tt> class instead of the default <tt>FutureTask</tt>:
* <pre>
* public class CustomThreadPoolExecutor extends ThreadPoolExecutor {
*
* static class CustomTask<V> implements RunnableFuture<V> {...}
*
* protected <V> RunnableFuture<V> newTaskFor(Callable<V> c) {
* return new CustomTask<V>(c);
* }
* protected <V> RunnableFuture<V> newTaskFor(Runnable r, V v) {
* return new CustomTask<V>(r, v);
* }
* // ... add constructors, etc.
* }
* </pre>
* @since 1.5
* @author Doug Lea
*/
public abstract class AbstractExecutorService implements ExecutorService {
/**
* Returns a <tt>RunnableFuture</tt> for the given runnable and default
* value.
*
* @param runnable the runnable task being wrapped
* @param value the default value for the returned future
* @return a <tt>RunnableFuture</tt> which when run will run the
* underlying runnable and which, as a <tt>Future</tt>, will yield
* the given value as its result and provide for cancellation of
* the underlying task.
* @since 1.6
*/
}
/**
* Returns a <tt>RunnableFuture</tt> for the given callable task.
*
* @param callable the callable task being wrapped
* @return a <tt>RunnableFuture</tt> which when run will call the
* underlying callable and which, as a <tt>Future</tt>, will yield
* the callable's result as its result and provide for
* cancellation of the underlying task.
* @since 1.6
*/
return new FutureTask<T>(callable);
}
/**
* @throws RejectedExecutionException {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
*/
return ftask;
}
/**
* @throws RejectedExecutionException {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
*/
return ftask;
}
/**
* @throws RejectedExecutionException {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
*/
return ftask;
}
/**
* the main mechanics of invokeAny.
*/
throw new NullPointerException();
if (ntasks == 0)
throw new IllegalArgumentException();
new ExecutorCompletionService<T>(this);
// For efficiency, especially in executors with limited
// parallelism, check to see if previously submitted tasks are
// done before submitting more of them. This interleaving
// plus the exception mechanics account for messiness of main
// loop.
try {
// Record exceptions so that if we fail to obtain any
// result, we can throw the last exception we got.
// Start one task for sure; the rest incrementally
--ntasks;
int active = 1;
for (;;) {
if (f == null) {
if (ntasks > 0) {
--ntasks;
++active;
}
else if (active == 0)
break;
else if (timed) {
if (f == null)
throw new TimeoutException();
}
else
}
if (f != null) {
--active;
try {
return f.get();
} catch (InterruptedException ie) {
throw ie;
} catch (ExecutionException eex) {
} catch (RuntimeException rex) {
}
}
}
ee = new ExecutionException();
throw ee;
} finally {
f.cancel(true);
}
}
throws InterruptedException, ExecutionException {
try {
} catch (TimeoutException cannotHappen) {
assert false;
return null;
}
}
}
throws InterruptedException {
throw new NullPointerException();
boolean done = false;
try {
RunnableFuture<T> f = newTaskFor(t);
execute(f);
}
if (!f.isDone()) {
try {
f.get();
} catch (CancellationException ignore) {
} catch (ExecutionException ignore) {
}
}
}
done = true;
return futures;
} finally {
if (!done)
f.cancel(true);
}
}
throws InterruptedException {
throw new NullPointerException();
boolean done = false;
try {
// Interleave time checks and calls to execute in case
if (nanos <= 0)
return futures;
}
if (!f.isDone()) {
if (nanos <= 0)
return futures;
try {
} catch (CancellationException ignore) {
} catch (ExecutionException ignore) {
} catch (TimeoutException toe) {
return futures;
}
}
}
done = true;
return futures;
} finally {
if (!done)
f.cancel(true);
}
}
}