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io.reactivex.rxjava3.internal.operators.flowable.FlowableGroupBy Maven / Gradle / Ivy
/*
* Copyright (c) 2016-present, RxJava Contributors.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is
* distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
* the License for the specific language governing permissions and limitations under the License.
*/
package io.reactivex.rxjava3.internal.operators.flowable;
import java.util.*;
import java.util.concurrent.*;
import java.util.concurrent.atomic.*;
import org.reactivestreams.*;
import io.reactivex.rxjava3.annotations.Nullable;
import io.reactivex.rxjava3.core.*;
import io.reactivex.rxjava3.exceptions.*;
import io.reactivex.rxjava3.flowables.GroupedFlowable;
import io.reactivex.rxjava3.functions.*;
import io.reactivex.rxjava3.internal.subscriptions.*;
import io.reactivex.rxjava3.internal.util.*;
import io.reactivex.rxjava3.operators.SpscLinkedArrayQueue;
import io.reactivex.rxjava3.plugins.RxJavaPlugins;
public final class FlowableGroupBy extends AbstractFlowableWithUpstream> {
final Function keySelector;
final Function valueSelector;
final int bufferSize;
final boolean delayError;
final Function, ? extends Map> mapFactory;
public FlowableGroupBy(Flowable source, Function keySelector, Function valueSelector,
int bufferSize, boolean delayError, Function, ? extends Map> mapFactory) {
super(source);
this.keySelector = keySelector;
this.valueSelector = valueSelector;
this.bufferSize = bufferSize;
this.delayError = delayError;
this.mapFactory = mapFactory;
}
@Override
@SuppressWarnings({ "unchecked", "rawtypes" })
protected void subscribeActual(Subscriber> s) {
final Map> groups;
final Queue> evictedGroups;
try {
if (mapFactory == null) {
evictedGroups = null;
groups = new ConcurrentHashMap<>();
} else {
evictedGroups = new ConcurrentLinkedQueue<>();
Consumer evictionAction = (Consumer) new EvictionAction<>(evictedGroups);
groups = (Map) mapFactory.apply(evictionAction);
}
} catch (Throwable e) {
Exceptions.throwIfFatal(e);
s.onSubscribe(EmptyComponent.INSTANCE);
s.onError(e);
return;
}
GroupBySubscriber subscriber =
new GroupBySubscriber<>(s, keySelector, valueSelector, bufferSize, delayError, groups, evictedGroups);
source.subscribe(subscriber);
}
public static final class GroupBySubscriber
extends AtomicLong
implements FlowableSubscriber, Subscription {
private static final long serialVersionUID = -3688291656102519502L;
final Subscriber> downstream;
final Function keySelector;
final Function valueSelector;
final int bufferSize;
final int limit;
final boolean delayError;
final Map> groups;
final Queue> evictedGroups;
static final Object NULL_KEY = new Object();
Subscription upstream;
final AtomicBoolean cancelled = new AtomicBoolean();
long emittedGroups;
final AtomicInteger groupCount = new AtomicInteger(1);
final AtomicLong groupConsumed = new AtomicLong();
boolean done;
public GroupBySubscriber(Subscriber> actual, Function keySelector,
Function valueSelector, int bufferSize, boolean delayError,
Map> groups, Queue> evictedGroups) {
this.downstream = actual;
this.keySelector = keySelector;
this.valueSelector = valueSelector;
this.bufferSize = bufferSize;
this.limit = bufferSize - (bufferSize >> 2);
this.delayError = delayError;
this.groups = groups;
this.evictedGroups = evictedGroups;
}
@Override
public void onSubscribe(Subscription s) {
if (SubscriptionHelper.validate(this.upstream, s)) {
this.upstream = s;
downstream.onSubscribe(this);
s.request(bufferSize);
}
}
@Override
public void onNext(T t) {
if (done) {
return;
}
K key;
try {
key = keySelector.apply(t);
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
upstream.cancel();
onError(ex);
return;
}
boolean newGroup = false;
Object mapKey = key != null ? key : NULL_KEY;
GroupedUnicast group = groups.get(mapKey);
if (group == null) {
// if the main has been cancelled, stop creating groups
// and skip this value
if (cancelled.get()) {
return;
}
group = GroupedUnicast.createWith(key, bufferSize, this, delayError);
groups.put(mapKey, group);
groupCount.getAndIncrement();
newGroup = true;
}
V v;
try {
v = ExceptionHelper.nullCheck(valueSelector.apply(t), "The valueSelector returned a null value.");
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
upstream.cancel();
if (newGroup) {
if (emittedGroups != get()) {
downstream.onNext(group);
} else {
MissingBackpressureException mbe = groupHangWarning(emittedGroups);
mbe.initCause(ex);
onError(mbe);
return;
}
}
onError(ex);
return;
}
group.onNext(v);
completeEvictions();
if (newGroup) {
if (emittedGroups != get()) {
emittedGroups++;
downstream.onNext(group);
if (group.state.tryAbandon()) {
cancel(key);
group.onComplete();
requestGroup(1);
}
} else {
upstream.cancel();
onError(groupHangWarning(emittedGroups));
}
}
}
static MissingBackpressureException groupHangWarning(long n) {
return new MissingBackpressureException("Unable to emit a new group (#" + n + ") due to lack of requests. Please make sure the downstream can always accept a new group as well as each group is consumed in order for the whole operator to be able to proceed.");
}
@Override
public void onError(Throwable t) {
if (done) {
RxJavaPlugins.onError(t);
return;
}
done = true;
for (GroupedUnicast g : groups.values()) {
g.onError(t);
}
groups.clear();
completeEvictions();
downstream.onError(t);
}
@Override
public void onComplete() {
if (!done) {
for (GroupedUnicast g : groups.values()) {
g.onComplete();
}
groups.clear();
completeEvictions();
done = true;
downstream.onComplete();
}
}
@Override
public void request(long n) {
if (SubscriptionHelper.validate(n)) {
BackpressureHelper.add(this, n);
}
}
@Override
public void cancel() {
// cancelling the main source means we don't want any more groups
// but running groups still require new values
if (cancelled.compareAndSet(false, true)) {
completeEvictions();
if (groupCount.decrementAndGet() == 0) {
upstream.cancel();
}
}
}
private void completeEvictions() {
if (evictedGroups != null) {
int count = 0;
GroupedUnicast evictedGroup;
while ((evictedGroup = evictedGroups.poll()) != null) {
if (evictedGroup.state.tryComplete()) {
count++;
}
}
if (count != 0) {
groupCount.addAndGet(-count);
}
}
}
public void cancel(K key) {
Object mapKey = key != null ? key : NULL_KEY;
if (groups.remove(mapKey) != null) {
if (groupCount.decrementAndGet() == 0) {
upstream.cancel();
}
}
}
void requestGroup(long n) {
// lots of atomics, save local
AtomicLong groupConsumed = this.groupConsumed;
int limit = this.limit;
// Concurrent groups can request at once, a CAS loop is needed
for (;;) {
long currentConsumed = groupConsumed.get();
long newConsumed = BackpressureHelper.addCap(currentConsumed, n);
// Accumulate the consumed amounts and atomically update the total
if (groupConsumed.compareAndSet(currentConsumed, newConsumed)) {
// if successful, let's see if the prefetch limit has been surpassed
for (;;) {
if (newConsumed < limit) {
// no further actions to be taken
return;
}
// Yes, remove one limit from total consumed
long newConsumedAfterLimit = newConsumed - limit;
// Only one thread should subtract
if (groupConsumed.compareAndSet(newConsumed, newConsumedAfterLimit)) {
// Then request up to limit
upstream.request(limit);
}
// We don't quit but loop to see if we are still above the prefetch limit
newConsumed = groupConsumed.get();
}
}
}
}
}
static final class EvictionAction implements Consumer> {
final Queue> evictedGroups;
EvictionAction(Queue> evictedGroups) {
this.evictedGroups = evictedGroups;
}
@Override
public void accept(GroupedUnicast value) {
evictedGroups.offer(value);
}
}
static final class GroupedUnicast extends GroupedFlowable {
final State state;
public static GroupedUnicast createWith(K key, int bufferSize, GroupBySubscriber parent, boolean delayError) {
State state = new State<>(bufferSize, parent, key, delayError);
return new GroupedUnicast<>(key, state);
}
protected GroupedUnicast(K key, State state) {
super(key);
this.state = state;
}
@Override
protected void subscribeActual(Subscriber s) {
state.subscribe(s);
}
public void onNext(T t) {
state.onNext(t);
}
public void onError(Throwable e) {
state.onError(e);
}
public void onComplete() {
state.onComplete();
}
}
static final class State extends BasicIntQueueSubscription implements Publisher {
private static final long serialVersionUID = -3852313036005250360L;
final K key;
final SpscLinkedArrayQueue queue;
final GroupBySubscriber parent;
final boolean delayError;
final AtomicLong requested = new AtomicLong();
volatile boolean done;
Throwable error;
final AtomicBoolean cancelled = new AtomicBoolean();
final AtomicReference> actual = new AtomicReference<>();
boolean outputFused;
int produced;
final AtomicInteger once = new AtomicInteger();
static final int FRESH = 0;
static final int HAS_SUBSCRIBER = 1;
static final int ABANDONED = 2;
static final int ABANDONED_HAS_SUBSCRIBER = ABANDONED | HAS_SUBSCRIBER;
final AtomicBoolean evictOnce = new AtomicBoolean();
State(int bufferSize, GroupBySubscriber parent, K key, boolean delayError) {
this.queue = new SpscLinkedArrayQueue<>(bufferSize);
this.parent = parent;
this.key = key;
this.delayError = delayError;
}
@Override
public void request(long n) {
if (SubscriptionHelper.validate(n)) {
BackpressureHelper.add(requested, n);
drain();
}
}
@Override
public void cancel() {
if (cancelled.compareAndSet(false, true)) {
cancelParent();
drain();
}
}
@Override
public void subscribe(Subscriber subscriber) {
for (;;) {
int s = once.get();
if ((s & HAS_SUBSCRIBER) != 0) {
break;
}
int u = s | HAS_SUBSCRIBER;
if (once.compareAndSet(s, u)) {
subscriber.onSubscribe(this);
actual.lazySet(subscriber);
if (cancelled.get()) {
actual.lazySet(null);
} else {
drain();
}
return;
}
}
EmptySubscription.error(new IllegalStateException("Only one Subscriber allowed!"), subscriber);
}
public void onNext(T t) {
queue.offer(t);
drain();
}
public void onError(Throwable e) {
error = e;
done = true;
drain();
}
public void onComplete() {
done = true;
drain();
}
boolean tryComplete() {
boolean canEvict = evictOnce.compareAndSet(false, true);
done = true;
drain();
return canEvict;
}
void cancelParent() {
if ((once.get() & ABANDONED) == 0) {
if (evictOnce.compareAndSet(false, true)) {
parent.cancel(key);
}
}
}
boolean tryAbandon() {
return once.get() == FRESH && once.compareAndSet(FRESH, ABANDONED);
}
void drain() {
if (getAndIncrement() != 0) {
return;
}
if (outputFused) {
drainFused();
} else {
drainNormal();
}
}
void drainFused() {
int missed = 1;
final SpscLinkedArrayQueue q = this.queue;
Subscriber a = this.actual.get();
for (;;) {
if (a != null) {
if (cancelled.get()) {
return;
}
boolean d = done;
if (d && !delayError) {
Throwable ex = error;
if (ex != null) {
q.clear();
a.onError(ex);
return;
}
}
a.onNext(null);
if (d) {
Throwable ex = error;
if (ex != null) {
a.onError(ex);
} else {
a.onComplete();
}
return;
}
}
missed = addAndGet(-missed);
if (missed == 0) {
return;
}
if (a == null) {
a = this.actual.get();
}
}
}
void drainNormal() {
int missed = 1;
final SpscLinkedArrayQueue q = queue;
final boolean delayError = this.delayError;
Subscriber a = actual.get();
final AtomicBoolean cancelled = this.cancelled;
outer:
for (;;) {
if (cancelled.get()) {
cleanupQueue(0, false);
} else {
if (a != null) {
long r = requested.get();
long e = 0;
while (e != r) {
boolean d = done;
T v = q.poll();
boolean empty = v == null;
if (checkTerminated(d, empty, a, delayError, e, !empty)) {
continue outer;
}
if (empty) {
break;
}
a.onNext(v);
e++;
}
if (e == r && checkTerminated(done, q.isEmpty(), a, delayError, e, false)) {
continue outer;
}
if (e != 0L) {
BackpressureHelper.produced(requested, e);
// replenish based on this batch run
requestParent(e);
}
}
}
missed = addAndGet(-missed);
if (missed == 0) {
break;
}
if (a == null) {
a = actual.get();
}
}
}
void requestParent(long e) {
if ((once.get() & ABANDONED) == 0) {
parent.requestGroup(e);
}
}
void cleanupQueue(long emitted, boolean polled) {
// if this group is canceled, all accumulated emissions and
// remaining items in the queue should be requested
// so that other groups can proceed
while (queue.poll() != null) {
emitted++;
}
replenishParent(emitted, polled);
}
void replenishParent(long emitted, boolean polled) {
if (polled) {
emitted++;
}
if (emitted != 0L) {
requestParent(emitted);
}
}
boolean checkTerminated(boolean d, boolean empty, Subscriber a,
boolean delayError, long emitted, boolean polled) {
if (cancelled.get()) {
cleanupQueue(emitted, polled);
return true;
}
if (d) {
if (delayError) {
if (empty) {
cancelled.lazySet(true);
Throwable e = error;
if (e != null) {
a.onError(e);
} else {
a.onComplete();
// completion doesn't mean the parent has completed
// because of evicted groups
replenishParent(emitted, polled);
}
return true;
}
} else {
Throwable e = error;
if (e != null) {
queue.clear();
cancelled.lazySet(true);
a.onError(e);
return true;
} else
if (empty) {
cancelled.lazySet(true);
a.onComplete();
// completion doesn't mean the parent has completed
// because of evicted groups
replenishParent(emitted, polled);
return true;
}
}
}
return false;
}
@Override
public int requestFusion(int mode) {
// FIXME fusion mode causes hangs
/*
if ((mode & ASYNC) != 0) {
outputFused = true;
return ASYNC;
}
*/
return NONE;
}
void tryReplenish() {
int p = produced;
if (p != 0) {
produced = 0;
requestParent(p);
}
}
@Nullable
@Override
public T poll() {
T v = queue.poll();
if (v != null) {
produced++;
return v;
}
tryReplenish();
return null;
}
@Override
public boolean isEmpty() {
if (queue.isEmpty()) {
tryReplenish();
return true;
}
tryReplenish();
return false;
}
@Override
public void clear() {
SpscLinkedArrayQueue q = queue;
// queue.clear() would drop submitted items and not replenish, possibly hanging other groups
while (q.poll() != null) {
produced++;
}
tryReplenish();
}
}
}
