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提交 0aac167d 编写于 作者: D dl
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7132378: Race in FutureTask if used with explicit set ( not Runnable ) 

Reviewed-by: chegar, dholmes
上级 5bb0a44f
隐藏空白更改
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Showing with 576 addition and 204 deletion
src/share/classes/java/util/concurrent/FutureTask.java
浏览文件 @ 0aac167d
......@@ -34,51 +34,111 @@
*/
package java.util.concurrent;
import java.util.concurrent.locks.*;
import java.util.concurrent.locks.LockSupport;
/**
* A cancellable asynchronous computation. This class provides a base
* implementation of {@link Future}, with methods to start and cancel
* a computation, query to see if the computation is complete, and
* retrieve the result of the computation. The result can only be
* retrieved when the computation has completed; the <tt>get</tt>
* method will block if the computation has not yet completed. Once
* retrieved when the computation has completed; the {@code get}
* methods will block if the computation has not yet completed. Once
* the computation has completed, the computation cannot be restarted
* or cancelled.
* or cancelled (unless the computation is invoked using
* {@link #runAndReset}).
*
* <p>A <tt>FutureTask</tt> can be used to wrap a {@link Callable} or
* {@link java.lang.Runnable} object. Because <tt>FutureTask</tt>
* implements <tt>Runnable</tt>, a <tt>FutureTask</tt> can be
* submitted to an {@link Executor} for execution.
* <p>A {@code FutureTask} can be used to wrap a {@link Callable} or
* {@link Runnable} object. Because {@code FutureTask} implements
* {@code Runnable}, a {@code FutureTask} can be submitted to an
* {@link Executor} for execution.
*
* <p>In addition to serving as a standalone class, this class provides
* <tt>protected</tt> functionality that may be useful when creating
* {@code protected} functionality that may be useful when creating
* customized task classes.
*
* @since 1.5
* @author Doug Lea
* @param <V> The result type returned by this FutureTask's <tt>get</tt> method
* @param <V> The result type returned by this FutureTask's {@code get} methods
*/
public class FutureTask<V> implements RunnableFuture<V> {
/** Synchronization control for FutureTask */
private final Sync sync;
/*
* Revision notes: This differs from previous versions of this
* class that relied on AbstractQueuedSynchronizer, mainly to
* avoid surprising users about retaining interrupt status during
* cancellation races. Sync control in the current design relies
* on a "state" field updated via CAS to track completion, along
* with a simple Treiber stack to hold waiting threads.
*
* Style note: As usual, we bypass overhead of using
* AtomicXFieldUpdaters and instead directly use Unsafe intrinsics.
*/
/**
* The run state of this task, initially NEW. The run state
* transitions to a terminal state only in methods set,
* setException, and cancel. During completion, state may take on
* transient values of COMPLETING (while outcome is being set) or
* INTERRUPTING (only while interrupting the runner to satisfy a
* cancel(true)). Transitions from these intermediate to final
* states use cheaper ordered/lazy writes because values are unique
* and cannot be further modified.
*
* Possible state transitions:
* NEW -> COMPLETING -> NORMAL
* NEW -> COMPLETING -> EXCEPTIONAL
* NEW -> CANCELLED
* NEW -> INTERRUPTING -> INTERRUPTED
*/
private volatile int state;
private static final int NEW = 0;
private static final int COMPLETING = 1;
private static final int NORMAL = 2;
private static final int EXCEPTIONAL = 3;
private static final int CANCELLED = 4;
private static final int INTERRUPTING = 5;
private static final int INTERRUPTED = 6;
/** The underlying callable; nulled out after running */
private Callable<V> callable;
/** The result to return or exception to throw from get() */
private Object outcome; // non-volatile, protected by state reads/writes
/** The thread running the callable; CASed during run() */
private volatile Thread runner;
/** Treiber stack of waiting threads */
private volatile WaitNode waiters;
/**
* Returns result or throws exception for completed task.
*
* @param s completed state value
*/
@SuppressWarnings("unchecked")
private V report(int s) throws ExecutionException {
Object x = outcome;
if (s == NORMAL)
return (V)x;
if (s >= CANCELLED)
throw new CancellationException();
throw new ExecutionException((Throwable)x);
}
/**
* Creates a <tt>FutureTask</tt> that will, upon running, execute the
* given <tt>Callable</tt>.
* Creates a {@code FutureTask} that will, upon running, execute the
* given {@code Callable}.
*
* @param callable the callable task
* @throws NullPointerException if callable is null
* @throws NullPointerException if the callable is null
*/
public FutureTask(Callable<V> callable) {
if (callable == null)
throw new NullPointerException();
sync = new Sync(callable);
this.callable = callable;
this.state = NEW; // ensure visibility of callable
}
/**
* Creates a <tt>FutureTask</tt> that will, upon running, execute the
* given <tt>Runnable</tt>, and arrange that <tt>get</tt> will return the
* Creates a {@code FutureTask} that will, upon running, execute the
* given {@code Runnable}, and arrange that {@code get} will return the
* given result on successful completion.
*
* @param runnable the runnable task
......@@ -86,29 +146,46 @@ public class FutureTask<V> implements RunnableFuture<V> {
* you don't need a particular result, consider using
* constructions of the form:
* {@code Future<?> f = new FutureTask<Void>(runnable, null)}
* @throws NullPointerException if runnable is null
* @throws NullPointerException if the runnable is null
*/
public FutureTask(Runnable runnable, V result) {
sync = new Sync(Executors.callable(runnable, result));
this.callable = Executors.callable(runnable, result);
this.state = NEW; // ensure visibility of callable
}
public boolean isCancelled() {
return sync.innerIsCancelled();
return state >= CANCELLED;
}
public boolean isDone() {
return sync.innerIsDone();
return state != NEW;
}
public boolean cancel(boolean mayInterruptIfRunning) {
return sync.innerCancel(mayInterruptIfRunning);
if (state != NEW)
return false;
if (mayInterruptIfRunning) {
if (!UNSAFE.compareAndSwapInt(this, stateOffset, NEW, INTERRUPTING))
return false;
Thread t = runner;
if (t != null)
t.interrupt();
UNSAFE.putOrderedInt(this, stateOffset, INTERRUPTED); // final state
}
else if (!UNSAFE.compareAndSwapInt(this, stateOffset, NEW, CANCELLED))
return false;
finishCompletion();
return true;
}
/**
* @throws CancellationException {@inheritDoc}
*/
public V get() throws InterruptedException, ExecutionException {
return sync.innerGet();
int s = state;
if (s <= COMPLETING)
s = awaitDone(false, 0L);
return report(s);
}
/**
......@@ -116,12 +193,18 @@ public class FutureTask<V> implements RunnableFuture<V> {
*/
public V get(long timeout, TimeUnit unit)
throws InterruptedException, ExecutionException, TimeoutException {
return sync.innerGet(unit.toNanos(timeout));
if (unit == null)
throw new NullPointerException();
int s = state;
if (s <= COMPLETING &&
(s = awaitDone(true, unit.toNanos(timeout))) <= COMPLETING)
throw new TimeoutException();
return report(s);
}
/**
* Protected method invoked when this task transitions to state
* <tt>isDone</tt> (whether normally or via cancellation). The
* {@code isDone} (whether normally or via cancellation). The
* default implementation does nothing. Subclasses may override
* this method to invoke completion callbacks or perform
* bookkeeping. Note that you can query status inside the
......@@ -131,230 +214,269 @@ public class FutureTask<V> implements RunnableFuture<V> {
protected void done() { }
/**
* Sets the result of this Future to the given value unless
* Sets the result of this future to the given value unless
* this future has already been set or has been cancelled.
* This method is invoked internally by the <tt>run</tt> method
*
* <p>This method is invoked internally by the {@link #run} method
* upon successful completion of the computation.
*
* @param v the value
*/
protected void set(V v) {
sync.innerSet(v);
if (UNSAFE.compareAndSwapInt(this, stateOffset, NEW, COMPLETING)) {
outcome = v;
UNSAFE.putOrderedInt(this, stateOffset, NORMAL); // final state
finishCompletion();
}
}
/**
* Causes this future to report an <tt>ExecutionException</tt>
* with the given throwable as its cause, unless this Future has
* Causes this future to report an {@link ExecutionException}
* with the given throwable as its cause, unless this future has
* already been set or has been cancelled.
* This method is invoked internally by the <tt>run</tt> method
*
* <p>This method is invoked internally by the {@link #run} method
* upon failure of the computation.
*
* @param t the cause of failure
*/
protected void setException(Throwable t) {
sync.innerSetException(t);
if (UNSAFE.compareAndSwapInt(this, stateOffset, NEW, COMPLETING)) {
outcome = t;
UNSAFE.putOrderedInt(this, stateOffset, EXCEPTIONAL); // final state
finishCompletion();
}
}
// The following (duplicated) doc comment can be removed once
//
// 6270645: Javadoc comments should be inherited from most derived
// superinterface or superclass
// is fixed.
/**
* Sets this Future to the result of its computation
* unless it has been cancelled.
*/
public void run() {
sync.innerRun();
if (state != NEW ||
!UNSAFE.compareAndSwapObject(this, runnerOffset,
null, Thread.currentThread()))
return;
try {
Callable<V> c = callable;
if (c != null && state == NEW) {
V result;
boolean ran;
try {
result = c.call();
ran = true;
} catch (Throwable ex) {
result = null;
ran = false;
setException(ex);
}
if (ran)
set(result);
}
} finally {
// runner must be non-null until state is settled to
// prevent concurrent calls to run()
runner = null;
// state must be re-read after nulling runner to prevent
// leaked interrupts
int s = state;
if (s >= INTERRUPTING)
handlePossibleCancellationInterrupt(s);
}
}
/**
* Executes the computation without setting its result, and then
* resets this Future to initial state, failing to do so if the
* resets this future to initial state, failing to do so if the
* computation encounters an exception or is cancelled. This is
* designed for use with tasks that intrinsically execute more
* than once.
*
* @return true if successfully run and reset
*/
protected boolean runAndReset() {
return sync.innerRunAndReset();
if (state != NEW ||
!UNSAFE.compareAndSwapObject(this, runnerOffset,
null, Thread.currentThread()))
return false;
boolean ran = false;
int s = state;
try {
Callable<V> c = callable;
if (c != null && s == NEW) {
try {
c.call(); // don't set result
ran = true;
} catch (Throwable ex) {
setException(ex);
}
}
} finally {
// runner must be non-null until state is settled to
// prevent concurrent calls to run()
runner = null;
// state must be re-read after nulling runner to prevent
// leaked interrupts
s = state;
if (s >= INTERRUPTING)
handlePossibleCancellationInterrupt(s);
}
return ran && s == NEW;
}
/**
* Synchronization control for FutureTask. Note that this must be
* a non-static inner class in order to invoke the protected
* <tt>done</tt> method. For clarity, all inner class support
* methods are same as outer, prefixed with "inner".
*
* Uses AQS sync state to represent run status
* Ensures that any interrupt from a possible cancel(true) is only
* delivered to a task while in run or runAndReset.
*/
private final class Sync extends AbstractQueuedSynchronizer {
private static final long serialVersionUID = -7828117401763700385L;
/** State value representing that task is ready to run */
private static final int READY = 0;
/** State value representing that task is running */
private static final int RUNNING = 1;
/** State value representing that task ran */
private static final int RAN = 2;
/** State value representing that task was cancelled */
private static final int CANCELLED = 4;
/** The underlying callable */
private final Callable<V> callable;
/** The result to return from get() */
private V result;
/** The exception to throw from get() */
private Throwable exception;
/**
* The thread running task. When nulled after set/cancel, this
* indicates that the results are accessible. Must be
* volatile, to ensure visibility upon completion.
*/
private volatile Thread runner;
Sync(Callable<V> callable) {
this.callable = callable;
}
private boolean ranOrCancelled(int state) {
return (state & (RAN | CANCELLED)) != 0;
}
/**
* Implements AQS base acquire to succeed if ran or cancelled
*/
protected int tryAcquireShared(int ignore) {
return innerIsDone() ? 1 : -1;
}
/**
* Implements AQS base release to always signal after setting
* final done status by nulling runner thread.
*/
protected boolean tryReleaseShared(int ignore) {
runner = null;
return true;
}
boolean innerIsCancelled() {
return getState() == CANCELLED;
}
boolean innerIsDone() {
return ranOrCancelled(getState()) && runner == null;
}
V innerGet() throws InterruptedException, ExecutionException {
acquireSharedInterruptibly(0);
if (getState() == CANCELLED)
throw new CancellationException();
if (exception != null)
throw new ExecutionException(exception);
return result;
}
private void handlePossibleCancellationInterrupt(int s) {
// It is possible for our interrupter to stall before getting a
// chance to interrupt us. Let's spin-wait patiently.
if (s == INTERRUPTING)
while (state == INTERRUPTING)
Thread.yield(); // wait out pending interrupt
// assert state == INTERRUPTED;
// We want to clear any interrupt we may have received from
// cancel(true). However, it is permissible to use interrupts
// as an independent mechanism for a task to communicate with
// its caller, and there is no way to clear only the
// cancellation interrupt.
//
// Thread.interrupted();
}
V innerGet(long nanosTimeout) throws InterruptedException, ExecutionException, TimeoutException {
if (!tryAcquireSharedNanos(0, nanosTimeout))
throw new TimeoutException();
if (getState() == CANCELLED)
throw new CancellationException();
if (exception != null)
throw new ExecutionException(exception);
return result;
}
/**
* Simple linked list nodes to record waiting threads in a Treiber
* stack. See other classes such as Phaser and SynchronousQueue
* for more detailed explanation.
*/
static final class WaitNode {
volatile Thread thread;
volatile WaitNode next;
WaitNode() { thread = Thread.currentThread(); }
}
void innerSet(V v) {
for (;;) {
int s = getState();
if (s == RAN)
return;
if (s == CANCELLED) {
// aggressively release to set runner to null,
// in case we are racing with a cancel request
// that will try to interrupt runner
releaseShared(0);
return;
}
if (compareAndSetState(s, RAN)) {
result = v;
releaseShared(0);
done();
return;
/**
* Removes and signals all waiting threads, invokes done(), and
* nulls out callable.
*/
private void finishCompletion() {
// assert state > COMPLETING;
for (WaitNode q; (q = waiters) != null;) {
if (UNSAFE.compareAndSwapObject(this, waitersOffset, q, null)) {
for (;;) {
Thread t = q.thread;
if (t != null) {
q.thread = null;
LockSupport.unpark(t);
}
WaitNode next = q.next;
if (next == null)
break;
q.next = null; // unlink to help gc
q = next;
}
break;
}
}
void innerSetException(Throwable t) {
for (;;) {
int s = getState();
if (s == RAN)
return;
if (s == CANCELLED) {
// aggressively release to set runner to null,
// in case we are racing with a cancel request
// that will try to interrupt runner
releaseShared(0);
return;
}
if (compareAndSetState(s, RAN)) {
exception = t;
releaseShared(0);
done();
return;
}
done();
callable = null; // to reduce footprint
}
/**
* Awaits completion or aborts on interrupt or timeout.
*
* @param timed true if use timed waits
* @param nanos time to wait, if timed
* @return state upon completion
*/
private int awaitDone(boolean timed, long nanos)
throws InterruptedException {
final long deadline = timed ? System.nanoTime() + nanos : 0L;
WaitNode q = null;
boolean queued = false;
for (;;) {
if (Thread.interrupted()) {
removeWaiter(q);
throw new InterruptedException();
}
}
boolean innerCancel(boolean mayInterruptIfRunning) {
for (;;) {
int s = getState();
if (ranOrCancelled(s))
return false;
if (compareAndSetState(s, CANCELLED))
break;
int s = state;
if (s > COMPLETING) {
if (q != null)
q.thread = null;
return s;
}
if (mayInterruptIfRunning) {
Thread r = runner;
if (r != null)
r.interrupt();
else if (s == COMPLETING) // cannot time out yet
Thread.yield();
else if (q == null)
q = new WaitNode();
else if (!queued)
queued = UNSAFE.compareAndSwapObject(this, waitersOffset,
q.next = waiters, q);
else if (timed) {
nanos = deadline - System.nanoTime();
if (nanos <= 0L) {
removeWaiter(q);
return state;
}
LockSupport.parkNanos(this, nanos);
}
releaseShared(0);
done();
return true;
else
LockSupport.park(this);
}
}
void innerRun() {
if (!compareAndSetState(READY, RUNNING))
return;
runner = Thread.currentThread();
if (getState() == RUNNING) { // recheck after setting thread
V result;
try {
result = callable.call();
} catch (Throwable ex) {
setException(ex);
return;
/**
* Tries to unlink a timed-out or interrupted wait node to avoid
* accumulating garbage. Internal nodes are simply unspliced
* without CAS since it is harmless if they are traversed anyway
* by releasers. To avoid effects of unsplicing from already
* removed nodes, the list is retraversed in case of an apparent
* race. This is slow when there are a lot of nodes, but we don't
* expect lists to be long enough to outweigh higher-overhead
* schemes.
*/
private void removeWaiter(WaitNode node) {
if (node != null) {
node.thread = null;
retry:
for (;;) { // restart on removeWaiter race
for (WaitNode pred = null, q = waiters, s; q != null; q = s) {
s = q.next;
if (q.thread != null)
pred = q;
else if (pred != null) {
pred.next = s;
if (pred.thread == null) // check for race
continue retry;
}
else if (!UNSAFE.compareAndSwapObject(this, waitersOffset,
q, s))
continue retry;
}
set(result);
} else {
releaseShared(0); // cancel
break;
}
}
}
boolean innerRunAndReset() {
if (!compareAndSetState(READY, RUNNING))
return false;
try {
runner = Thread.currentThread();
if (getState() == RUNNING)
callable.call(); // don't set result
runner = null;
return compareAndSetState(RUNNING, READY);
} catch (Throwable ex) {
setException(ex);
return false;
}
// Unsafe mechanics
private static final sun.misc.Unsafe UNSAFE;
private static final long stateOffset;
private static final long runnerOffset;
private static final long waitersOffset;
static {
try {
UNSAFE = sun.misc.Unsafe.getUnsafe();
Class<?> k = FutureTask.class;
stateOffset = UNSAFE.objectFieldOffset
(k.getDeclaredField("state"));
runnerOffset = UNSAFE.objectFieldOffset
(k.getDeclaredField("runner"));
waitersOffset = UNSAFE.objectFieldOffset
(k.getDeclaredField("waiters"));
} catch (Exception e) {
throw new Error(e);
}
}
}
test/java/util/concurrent/FutureTask/DoneTimedGetLoops.java 0 → 100644
浏览文件 @ 0aac167d
/*
* Copyright (c) 2012 Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* Written by Martin Buchholz with assistance from members of JCP JSR-166
* Expert Group and released to the public domain, as explained at
* http://creativecommons.org/publicdomain/zero/1.0/
*/
/*
* @test
* @run main DoneTimedGetLoops 300
* @summary isDone returning true guarantees that subsequent timed get
* will never throw TimeoutException.
*/
import java.util.*;
import java.util.concurrent.*;
import java.util.concurrent.atomic.*;
@SuppressWarnings({"unchecked", "rawtypes", "deprecation"})
public class DoneTimedGetLoops {
final long testDurationMillisDefault = 10L * 1000L;
final long testDurationMillis;
static class PublicFutureTask extends FutureTask<Boolean> {
final static Runnable noop = new Runnable() { public void run() {} };
PublicFutureTask() { super(noop, null); }
public void set(Boolean v) { super.set(v); }
public void setException(Throwable t) { super.setException(t); }
}
DoneTimedGetLoops(String[] args) {
testDurationMillis = (args.length > 0) ?
Long.valueOf(args[0]) : testDurationMillisDefault;
}
void test(String[] args) throws Throwable {
final long testDurationNanos = testDurationMillis * 1000L * 1000L;
final long quittingTimeNanos = System.nanoTime() + testDurationNanos;
final long timeoutMillis = 10L * 1000L;
final AtomicReference<PublicFutureTask> normalRef
= new AtomicReference<PublicFutureTask>();
final AtomicReference<PublicFutureTask> abnormalRef
= new AtomicReference<PublicFutureTask>();
final Throwable throwable = new Throwable();
abstract class CheckedThread extends Thread {
CheckedThread(String name) {
super(name);
setDaemon(true);
start();
}
/** Polls for quitting time. */
protected boolean quittingTime() {
return System.nanoTime() - quittingTimeNanos > 0;
}
/** Polls occasionally for quitting time. */
protected boolean quittingTime(long i) {
return (i % 1024) == 0 && quittingTime();
}
abstract protected void realRun() throws Exception;
public void run() {
try { realRun(); } catch (Throwable t) { unexpected(t); }
}
}
Thread setter = new CheckedThread("setter") {
protected void realRun() {
while (! quittingTime()) {
PublicFutureTask future = new PublicFutureTask();
normalRef.set(future);
future.set(Boolean.TRUE);
}}};
Thread setterException = new CheckedThread("setterException") {
protected void realRun() {
while (! quittingTime()) {
PublicFutureTask future = new PublicFutureTask();
abnormalRef.set(future);
future.setException(throwable);
}}};
Thread doneTimedGetNormal = new CheckedThread("doneTimedGetNormal") {
protected void realRun() throws Exception {
while (! quittingTime()) {
PublicFutureTask future = normalRef.get();
if (future != null) {
while (!future.isDone())
;
check(future.get(0L, TimeUnit.HOURS) == Boolean.TRUE);
}}}};
Thread doneTimedGetAbnormal = new CheckedThread("doneTimedGetAbnormal") {
protected void realRun() throws Exception {
while (! quittingTime()) {
PublicFutureTask future = abnormalRef.get();
if (future != null) {
while (!future.isDone())
;
try { future.get(0L, TimeUnit.HOURS); fail(); }
catch (ExecutionException t) {
check(t.getCause() == throwable);
}
}}}};
for (Thread thread : new Thread[] {
setter,
setterException,
doneTimedGetNormal,
doneTimedGetAbnormal }) {
thread.join(timeoutMillis + testDurationMillis);
if (thread.isAlive()) {
System.err.printf("Hung thread: %s%n", thread.getName());
failed++;
for (StackTraceElement e : thread.getStackTrace())
System.err.println(e);
// Kludge alert
thread.stop();
thread.join(timeoutMillis);
}
}
}
//--------------------- Infrastructure ---------------------------
volatile int passed = 0, failed = 0;
void pass() {passed++;}
void fail() {failed++; Thread.dumpStack();}
void fail(String msg) {System.err.println(msg); fail();}
void unexpected(Throwable t) {failed++; t.printStackTrace();}
void check(boolean cond) {if (cond) pass(); else fail();}
void equal(Object x, Object y) {
if (x == null ? y == null : x.equals(y)) pass();
else fail(x + " not equal to " + y);}
public static void main(String[] args) throws Throwable {
new DoneTimedGetLoops(args).instanceMain(args);}
public void instanceMain(String[] args) throws Throwable {
try {test(args);} catch (Throwable t) {unexpected(t);}
System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
if (failed > 0) throw new AssertionError("Some tests failed");}
}
test/java/util/concurrent/FutureTask/ExplicitSet.java 0 → 100644
浏览文件 @ 0aac167d
/*
* Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* @test
* @bug 7132378
* @summary Race in FutureTask if used with explicit set ( not Runnable )
* @author Chris Hegarty
*/
import java.util.concurrent.Callable;
import java.util.concurrent.FutureTask;
public class ExplicitSet {
static void realMain(String[] args) throws Throwable {
for (int i = 1; i <= 10000; i++) {
//System.out.print(".");
test();
}
}
static void test() throws Throwable {
final SettableTask task = new SettableTask();
Thread thread = new Thread() { public void run() {
try {
check(task.get() != null);
} catch (Exception e) { unexpected(e); }
}};
thread.start();
task.set(Boolean.TRUE);
thread.join(5000);
}
static class SettableTask extends FutureTask<Boolean> {
SettableTask() {
super(new Callable<Boolean>() {
public Boolean call() {
fail ("The task should never be run!");
return null;
};
});
}
@Override
public void set(Boolean b) {
super.set(b);
}
}
//--------------------- Infrastructure ---------------------------
static volatile int passed = 0, failed = 0;
static void pass() {passed++;}
static void fail() {failed++; Thread.dumpStack();}
static void fail(String msg) {System.out.println(msg); fail();}
static void unexpected(Throwable t) {failed++; t.printStackTrace();}
static void check(boolean cond) {if (cond) pass(); else fail();}
static void equal(Object x, Object y) {
if (x == null ? y == null : x.equals(y)) pass();
else fail(x + " not equal to " + y);}
public static void main(String[] args) throws Throwable {
try {realMain(args);} catch (Throwable t) {unexpected(t);}
System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
if (failed > 0) throw new AssertionError("Some tests failed");}
}
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