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1.x: reduce Subscriber's creation overhead #3479

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38770db
1.x: reduce Subscriber's creation overhead
akarnokd Oct 28, 2015
1c0d45b
Updated perf.
akarnokd Oct 29, 2015
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92 changes: 63 additions & 29 deletions src/main/java/rx/Subscriber.java
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Original file line number Diff line number Diff line change
Expand Up @@ -33,15 +33,25 @@
public abstract class Subscriber<T> implements Observer<T>, Subscription {

// represents requested not set yet
private static final Long NOT_SET = Long.MIN_VALUE;
private static final long NOT_SET = Long.MIN_VALUE;

private final SubscriptionList subscriptions;
// private final SubscriptionList subscriptions;
private final Subscriber<?> subscriber;
/* protected by `this` */
private Producer producer;
/* protected by `this` */
private long requested = NOT_SET; // default to not set

SubscriptionList subscriptions;
static final SubscriptionList UNSUBSCRIBED;

final boolean sharedSubscriptions;

static {
UNSUBSCRIBED = new SubscriptionList();
UNSUBSCRIBED.unsubscribe();
}

protected Subscriber() {
this(null, false);
}
Expand Down Expand Up @@ -78,7 +88,7 @@ protected Subscriber(Subscriber<?> subscriber) {
*/
protected Subscriber(Subscriber<?> subscriber, boolean shareSubscriptions) {
this.subscriber = subscriber;
this.subscriptions = shareSubscriptions && subscriber != null ? subscriber.subscriptions : new SubscriptionList();
this.sharedSubscriptions = shareSubscriptions && subscriber != null;
}

/**
Expand All @@ -90,12 +100,37 @@ protected Subscriber(Subscriber<?> subscriber, boolean shareSubscriptions) {
* the {@code Subscription} to add
*/
public final void add(Subscription s) {
subscriptions.add(s);
if (sharedSubscriptions) {
subscriber.add(s);
return;
}
SubscriptionList sl;
synchronized (this) {
sl = subscriptions;
if (sl == null) {
sl = new SubscriptionList();
subscriptions = sl;
}
}
sl.add(s);
}

@Override
public final void unsubscribe() {
subscriptions.unsubscribe();
if (sharedSubscriptions) {
subscriber.unsubscribe();
return;
}
SubscriptionList sl;
synchronized (this) {
sl = subscriptions;
if (sl == null) {
subscriptions = UNSUBSCRIBED;
return;
}
}

sl.unsubscribe();
}

/**
Expand All @@ -105,7 +140,11 @@ public final void unsubscribe() {
*/
@Override
public final boolean isUnsubscribed() {
return subscriptions.isUnsubscribed();
if (sharedSubscriptions) {
return subscriber.isUnsubscribed();
}
SubscriptionList sl = subscriptions;
return sl != null && sl.isUnsubscribed();
}

/**
Expand Down Expand Up @@ -144,33 +183,27 @@ protected final void request(long n) {

// if producer is set then we will request from it
// otherwise we increase the requested count by n
Producer producerToRequestFrom = null;
Producer producerToRequestFrom;
synchronized (this) {
if (producer != null) {
producerToRequestFrom = producer;
} else {
addToRequested(n);
producerToRequestFrom = producer;
if (producerToRequestFrom == null) {
long r = requested;
if (r == NOT_SET) {
requested = n;
} else {
long u = r + n;
if (u < 0L) {
u = Long.MAX_VALUE;
}
requested = u;
}
return;
}
}
// after releasing lock (we should not make requests holding a lock)
producerToRequestFrom.request(n);
}

private void addToRequested(long n) {
if (requested == NOT_SET) {
requested = n;
} else {
final long total = requested + n;
// check if overflow occurred
if (total < 0) {
requested = Long.MAX_VALUE;
} else {
requested = total;
}
}
}

/**
* If other subscriber is set (by calling constructor
* {@link #Subscriber(Subscriber)} or
Expand All @@ -189,10 +222,11 @@ private void addToRequested(long n) {
public void setProducer(Producer p) {
long toRequest;
boolean passToSubscriber = false;
final Subscriber<?> child = subscriber;
synchronized (this) {
toRequest = requested;
producer = p;
if (subscriber != null) {
if (child != null) {
// middle operator ... we pass thru unless a request has been made
if (toRequest == NOT_SET) {
// we pass-thru to the next producer as nothing has been requested
Expand All @@ -202,13 +236,13 @@ public void setProducer(Producer p) {
}
// do after releasing lock
if (passToSubscriber) {
subscriber.setProducer(producer);
child.setProducer(p);
} else {
// we execute the request with whatever has been requested (or Long.MAX_VALUE)
if (toRequest == NOT_SET) {
producer.request(Long.MAX_VALUE);
p.request(Long.MAX_VALUE);
} else {
producer.request(toRequest);
p.request(toRequest);
}
}
}
Expand Down
85 changes: 72 additions & 13 deletions src/perf/java/rx/SubscribingPerf.java
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,8 @@
import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.infra.Blackhole;

import rx.functions.Func1;

/**
* Benchmark the cost of subscription and initial request management.
* <p>
Expand All @@ -38,64 +40,121 @@ public class SubscribingPerf {

@Benchmark
public void justDirect(Blackhole bh) {
just.subscribe(new DirectSubscriber<Integer>(Long.MAX_VALUE, bh));
DirectSubscriber<Integer> subscriber = new DirectSubscriber<Integer>(Long.MAX_VALUE, bh);
bh.consume(subscriber);
just.subscribe(subscriber);
}

@Benchmark
public void justStarted(Blackhole bh) {
just.subscribe(new StartedSubscriber<Integer>(Long.MAX_VALUE, bh));
StartedSubscriber<Integer> subscriber = new StartedSubscriber<Integer>(Long.MAX_VALUE, bh);
bh.consume(subscriber);
just.subscribe(subscriber);
}

@Benchmark
public void justUsual(Blackhole bh) {
just.subscribe(new UsualSubscriber<Integer>(Long.MAX_VALUE, bh));
UsualSubscriber<Integer> subscriber = new UsualSubscriber<Integer>(Long.MAX_VALUE, bh);
bh.consume(subscriber);
just.subscribe(subscriber);
}

@Benchmark
public void rangeDirect(Blackhole bh) {
range.subscribe(new DirectSubscriber<Integer>(Long.MAX_VALUE, bh));
DirectSubscriber<Integer> subscriber = new DirectSubscriber<Integer>(Long.MAX_VALUE, bh);
bh.consume(subscriber);
range.subscribe(subscriber);
}

@Benchmark
public void rangeStarted(Blackhole bh) {
range.subscribe(new DirectSubscriber<Integer>(Long.MAX_VALUE, bh));
StartedSubscriber<Integer> subscriber = new StartedSubscriber<Integer>(Long.MAX_VALUE, bh);
bh.consume(subscriber);
range.subscribe(subscriber);
}

@Benchmark
public void rangeUsual(Blackhole bh) {
range.subscribe(new UsualSubscriber<Integer>(Long.MAX_VALUE, bh));
UsualSubscriber<Integer> subscriber = new UsualSubscriber<Integer>(Long.MAX_VALUE, bh);
bh.consume(subscriber);
range.subscribe(subscriber);
}

@Benchmark
public void justDirectUnsafe(Blackhole bh) {
just.unsafeSubscribe(new DirectSubscriber<Integer>(Long.MAX_VALUE, bh));
DirectSubscriber<Integer> subscriber = new DirectSubscriber<Integer>(Long.MAX_VALUE, bh);
bh.consume(subscriber);
just.unsafeSubscribe(subscriber);
}

@Benchmark
public void justStartedUnsafe(Blackhole bh) {
just.unsafeSubscribe(new StartedSubscriber<Integer>(Long.MAX_VALUE, bh));
StartedSubscriber<Integer> subscriber = new StartedSubscriber<Integer>(Long.MAX_VALUE, bh);
bh.consume(subscriber);
just.unsafeSubscribe(subscriber);
}

@Benchmark
public void justUsualUnsafe(Blackhole bh) {
just.unsafeSubscribe(new UsualSubscriber<Integer>(Long.MAX_VALUE, bh));
UsualSubscriber<Integer> subscriber = new UsualSubscriber<Integer>(Long.MAX_VALUE, bh);
bh.consume(subscriber);
just.unsafeSubscribe(subscriber);
}

@Benchmark
public void rangeDirectUnsafe(Blackhole bh) {
range.unsafeSubscribe(new DirectSubscriber<Integer>(Long.MAX_VALUE, bh));
DirectSubscriber<Integer> subscriber = new DirectSubscriber<Integer>(Long.MAX_VALUE, bh);
bh.consume(subscriber);
range.unsafeSubscribe(subscriber);
}

@Benchmark
public void rangeStartedUnsafe(Blackhole bh) {
range.unsafeSubscribe(new DirectSubscriber<Integer>(Long.MAX_VALUE, bh));
StartedSubscriber<Integer> subscriber = new StartedSubscriber<Integer>(Long.MAX_VALUE, bh);
bh.consume(subscriber);
range.unsafeSubscribe(subscriber);
}

@Benchmark
public void rangeUsualUnsafe(Blackhole bh) {
range.unsafeSubscribe(new UsualSubscriber<Integer>(Long.MAX_VALUE, bh));
UsualSubscriber<Integer> subscriber = new UsualSubscriber<Integer>(Long.MAX_VALUE, bh);
bh.consume(subscriber);
range.unsafeSubscribe(subscriber);
}

@State(Scope.Thread)
public static class Chain {
@Param({"10", "1000", "1000000"})
public int times;

@Param({"1", "2", "3", "4", "5"})
public int maps;

Observable<Integer> source;

@Setup
public void setup() {
Observable<Integer> o = Observable.range(1, times);

for (int i = 0; i < maps; i++) {
o = o.map(new Func1<Integer, Integer>() {
@Override
public Integer call(Integer v) {
return v + 1;
}
});
}

source = o;
}

@Benchmark
public void mapped(Chain c, Blackhole bh) {
DirectSubscriber<Integer> subscriber = new DirectSubscriber<Integer>(Long.MAX_VALUE, bh);
bh.consume(subscriber);
c.source.subscribe(subscriber);
}
}

static final class DirectSubscriber<T> extends Subscriber<T> {
final long r;
Expand Down Expand Up @@ -179,4 +238,4 @@ public void onCompleted() {

}
}
}
}