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Fix an unsubscribe race in EventLoopWorker #3868

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Apr 20, 2016
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12 changes: 10 additions & 2 deletions src/main/java/rx/internal/schedulers/CachedThreadScheduler.java
Original file line number Diff line number Diff line change
Expand Up @@ -204,13 +204,21 @@ public Subscription schedule(Action0 action) {
}

@Override
public Subscription schedule(Action0 action, long delayTime, TimeUnit unit) {
public Subscription schedule(final Action0 action, long delayTime, TimeUnit unit) {
if (innerSubscription.isUnsubscribed()) {
// don't schedule, we are unsubscribed
return Subscriptions.unsubscribed();
}

ScheduledAction s = threadWorker.scheduleActual(action, delayTime, unit);
ScheduledAction s = threadWorker.scheduleActual(new Action0() {
@Override
public void call() {
if (isUnsubscribed()) {
return;
}
action.call();
}
}, delayTime, unit);
innerSubscription.add(s);
s.addParent(innerSubscription);
return s;
Expand Down
27 changes: 22 additions & 5 deletions src/main/java/rx/internal/schedulers/EventLoopsScheduler.java
Original file line number Diff line number Diff line change
Expand Up @@ -156,20 +156,37 @@ public boolean isUnsubscribed() {
}

@Override
public Subscription schedule(Action0 action) {
public Subscription schedule(final Action0 action) {
if (isUnsubscribed()) {
return Subscriptions.unsubscribed();
}

return poolWorker.scheduleActual(action, 0, null, serial);
return poolWorker.scheduleActual(new Action0() {
@Override
public void call() {
if (isUnsubscribed()) {
return;
}
action.call();
}
}, 0, null, serial);
}

@Override
public Subscription schedule(Action0 action, long delayTime, TimeUnit unit) {
public Subscription schedule(final Action0 action, long delayTime, TimeUnit unit) {
if (isUnsubscribed()) {
return Subscriptions.unsubscribed();
}

return poolWorker.scheduleActual(action, delayTime, unit, timed);
return poolWorker.scheduleActual(new Action0() {
@Override
public void call() {
if (isUnsubscribed()) {
return;
}
action.call();
}
}, delayTime, unit, timed);
}
}

Expand All @@ -178,4 +195,4 @@ static final class PoolWorker extends NewThreadWorker {
super(threadFactory);
}
}
}
}
31 changes: 31 additions & 0 deletions src/test/java/rx/schedulers/AbstractSchedulerConcurrencyTests.java
Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,8 @@
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;

import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
Expand Down Expand Up @@ -423,4 +425,33 @@ public void call(Integer t) {
assertEquals(5, count.get());
}

@Test
public void workerUnderConcurrentUnsubscribeShouldNotAllowLaterTasksToRunDueToUnsubscriptionRace() {
Scheduler scheduler = getScheduler();
for (int i = 0; i < 1000; i++) {
Worker worker = scheduler.createWorker();
final Queue<Integer> q = new ConcurrentLinkedQueue<Integer>();
Action0 action1 = new Action0() {

@Override
public void call() {
q.add(1);
}
};
Action0 action2 = new Action0() {

@Override
public void call() {
q.add(2);
}
};
worker.schedule(action1);
worker.schedule(action2);
worker.unsubscribe();
if (q.size() == 1 && q.poll() == 2) {
//expect a queue of 1,2 or 1. If queue is just 2 then we have a problem!
fail("wrong order on loop " + i);
}
}
}
}
30 changes: 0 additions & 30 deletions src/test/java/rx/schedulers/ExecutorSchedulerTest.java
Original file line number Diff line number Diff line change
Expand Up @@ -18,11 +18,9 @@
import static org.junit.Assert.*;

import java.lang.management.*;
import java.util.Queue;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicInteger;

import org.junit.Assert;
import org.junit.Test;

import rx.*;
Expand Down Expand Up @@ -277,32 +275,4 @@ public void call() {

assertFalse(w.tasks.hasSubscriptions());
}

@Test
public void workerUnderConcurrentUnsubscribeShouldNotAllowLaterTasksToRunDueToUnsubscriptionRace() {
Scheduler scheduler = Schedulers.from(Executors.newFixedThreadPool(1));
for (int i = 0; i< 1000; i++) {
Worker worker = scheduler.createWorker();
final Queue<Integer> q = new ConcurrentLinkedQueue<Integer>();
Action0 action1 = new Action0() {

@Override
public void call() {
q.add(1);
}};
Action0 action2 = new Action0() {

@Override
public void call() {
q.add(2);
}};
worker.schedule(action1);
worker.schedule(action2);
worker.unsubscribe();
if (q.size()==1 && q.poll() == 2) {
//expect a queue of 1,2 or 1. If queue is just 2 then we have a problem!
Assert.fail("wrong order on loop " + i);
}
}
}
}