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3.x: Fix Flowable.concatMap backpressure w/ scalars #7089

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Merged
merged 1 commit into from
Oct 5, 2020
Merged

3.x: Fix Flowable.concatMap backpressure w/ scalars #7089

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18 changes: 10 additions & 8 deletions src/main/java/io/reactivex/rxjava3/internal/operators/flowable/FlowableConcatMap.java
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@
package io.reactivex.rxjava3.internal.operators.flowable;

import java.util.Objects;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.*;

import org.reactivestreams.*;

Expand Down Expand Up @@ -308,7 +308,7 @@ void drain() {
continue;
} else {
active = true;
inner.setSubscription(new WeakScalarSubscription<>(vr, inner));
inner.setSubscription(new SimpleScalarSubscription<>(vr, inner));
}

} else {
Expand All @@ -325,20 +325,22 @@ void drain() {
}
}

static final class WeakScalarSubscription<T> implements Subscription {
static final class SimpleScalarSubscription<T>
extends AtomicBoolean
implements Subscription {
private static final long serialVersionUID = -7606889335172043256L;

final Subscriber<? super T> downstream;
final T value;
boolean once;

WeakScalarSubscription(T value, Subscriber<? super T> downstream) {
SimpleScalarSubscription(T value, Subscriber<? super T> downstream) {
this.value = value;
this.downstream = downstream;
}

@Override
public void request(long n) {
if (n > 0 && !once) {
once = true;
if (n > 0L && compareAndSet(false, true)) {
Subscriber<? super T> a = downstream;
a.onNext(value);
a.onComplete();
Expand Down Expand Up @@ -507,7 +509,7 @@ void drain() {
continue;
} else {
active = true;
inner.setSubscription(new WeakScalarSubscription<>(vr, inner));
inner.setSubscription(new SimpleScalarSubscription<>(vr, inner));
}
} else {
active = true;
Expand Down
4 changes: 2 additions & 2 deletions ...ain/java/io/reactivex/rxjava3/internal/operators/flowable/FlowableConcatMapScheduler.java
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Original file line number Diff line number Diff line change
Expand Up @@ -345,7 +345,7 @@ public void run() {
continue;
} else {
active = true;
inner.setSubscription(new WeakScalarSubscription<>(vr, inner));
inner.setSubscription(new SimpleScalarSubscription<>(vr, inner));
}

} else {
Expand Down Expand Up @@ -528,7 +528,7 @@ public void run() {
continue;
} else {
active = true;
inner.setSubscription(new WeakScalarSubscription<>(vr, inner));
inner.setSubscription(new SimpleScalarSubscription<>(vr, inner));
}
} else {
active = true;
Expand Down
50 changes: 50 additions & 0 deletions ...java/io/reactivex/rxjava3/internal/operators/flowable/FlowableConcatMapSchedulerTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,56 @@ public Publisher<? extends Object> apply(String v)
.assertResult("RxSingleScheduler");
}

@Test
public void innerScalarRequestRace() {
Flowable<Integer> just = Flowable.just(1);
int n = 1000;
for (int i = 0; i < TestHelper.RACE_DEFAULT_LOOPS; i++) {
PublishProcessor<Flowable<Integer>> source = PublishProcessor.create();

TestSubscriber<Integer> ts = source
.concatMap(v -> v, n + 1, ImmediateThinScheduler.INSTANCE)
.test(1L);

TestHelper.race(() -> {
for (int j = 0; j < n; j++) {
source.onNext(just);
}
}, () -> {
for (int j = 0; j < n; j++) {
ts.request(1);
}
});

ts.assertValueCount(n);
}
}

@Test
public void innerScalarRequestRaceDelayError() {
Flowable<Integer> just = Flowable.just(1);
int n = 1000;
for (int i = 0; i < TestHelper.RACE_DEFAULT_LOOPS; i++) {
PublishProcessor<Flowable<Integer>> source = PublishProcessor.create();

TestSubscriber<Integer> ts = source
.concatMapDelayError(v -> v, true, n + 1, ImmediateThinScheduler.INSTANCE)
.test(1L);

TestHelper.race(() -> {
for (int j = 0; j < n; j++) {
source.onNext(just);
}
}, () -> {
for (int j = 0; j < n; j++) {
ts.request(1);
}
});

ts.assertValueCount(n);
}
}

@Test
public void boundaryFusionDelayError() {
Flowable.range(1, 10000)
Expand Down
58 changes: 54 additions & 4 deletions src/test/java/io/reactivex/rxjava3/internal/operators/flowable/FlowableConcatMapTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -24,18 +24,18 @@
import io.reactivex.rxjava3.core.*;
import io.reactivex.rxjava3.exceptions.*;
import io.reactivex.rxjava3.functions.*;
import io.reactivex.rxjava3.internal.operators.flowable.FlowableConcatMap.WeakScalarSubscription;
import io.reactivex.rxjava3.processors.UnicastProcessor;
import io.reactivex.rxjava3.internal.operators.flowable.FlowableConcatMap.SimpleScalarSubscription;
import io.reactivex.rxjava3.processors.*;
import io.reactivex.rxjava3.schedulers.Schedulers;
import io.reactivex.rxjava3.subscribers.TestSubscriber;
import io.reactivex.rxjava3.testsupport.TestHelper;

public class FlowableConcatMapTest extends RxJavaTest {

@Test
public void weakSubscriptionRequest() {
public void simpleSubscriptionRequest() {
TestSubscriber<Integer> ts = new TestSubscriber<>(0);
WeakScalarSubscription<Integer> ws = new WeakScalarSubscription<>(1, ts);
SimpleScalarSubscription<Integer> ws = new SimpleScalarSubscription<>(1, ts);
ts.onSubscribe(ws);

ws.request(0);
Expand Down Expand Up @@ -79,6 +79,56 @@ public Publisher<? extends Object> apply(String v)
.assertResult("RxSingleScheduler");
}

@Test
public void innerScalarRequestRace() {
Flowable<Integer> just = Flowable.just(1);
int n = 1000;
for (int i = 0; i < TestHelper.RACE_DEFAULT_LOOPS; i++) {
PublishProcessor<Flowable<Integer>> source = PublishProcessor.create();

TestSubscriber<Integer> ts = source
.concatMap(v -> v, n + 1)
.test(1L);

TestHelper.race(() -> {
for (int j = 0; j < n; j++) {
source.onNext(just);
}
}, () -> {
for (int j = 0; j < n; j++) {
ts.request(1);
}
});

ts.assertValueCount(n);
}
}

@Test
public void innerScalarRequestRaceDelayError() {
Flowable<Integer> just = Flowable.just(1);
int n = 1000;
for (int i = 0; i < TestHelper.RACE_DEFAULT_LOOPS; i++) {
PublishProcessor<Flowable<Integer>> source = PublishProcessor.create();

TestSubscriber<Integer> ts = source
.concatMapDelayError(v -> v, true, n + 1)
.test(1L);

TestHelper.race(() -> {
for (int j = 0; j < n; j++) {
source.onNext(just);
}
}, () -> {
for (int j = 0; j < n; j++) {
ts.request(1);
}
});

ts.assertValueCount(n);
}
}

@Test
public void boundaryFusionDelayError() {
Flowable.range(1, 10000)
Expand Down