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rxjava2-backport developed by David Karnok
/**
* Copyright 2015 David Karnok and Netflix, Inc.
*
* 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 hu.akarnokd.rxjava2.internal.subscribers;
import java.util.Queue;
import java.util.concurrent.atomic.*;
import org.reactivestreams.Subscriber;
import hu.akarnokd.rxjava2.disposables.Disposable;
import hu.akarnokd.rxjava2.internal.subscriptions.SubscriptionHelper;
import hu.akarnokd.rxjava2.internal.util.*;
/**
* Abstract base class for subscribers that hold another subscriber, a queue
* and requires queue-drain behavior.
*
* @param the source type to which this subscriber will be subscribed
* @param the value type in the queue
* @param the value type the child subscriber accepts
*/
public abstract class QueueDrainSubscriber extends QueueDrainSubscriberPad4 implements Subscriber, QueueDrain {
protected final Subscriber actual;
protected final Queue queue;
protected volatile boolean cancelled;
protected volatile boolean done;
protected Throwable error;
public QueueDrainSubscriber(Subscriber actual, Queue queue) {
this.actual = actual;
this.queue = queue;
}
@Override
public final boolean cancelled() {
return cancelled;
}
@Override
public final boolean done() {
return done;
}
@Override
public final boolean enter() {
return WIP.getAndIncrement(this) == 0;
}
public final boolean fastEnter() {
return wip == 0 && WIP.compareAndSet(this, 0, 1);
}
protected final void fastpathEmit(U value, boolean delayError) {
final Subscriber s = actual;
final Queue q = queue;
if (wip == 0 && WIP.compareAndSet(this, 0, 1)) {
long r = requested;
if (r != 0L) {
if (accept(s, value)) {
if (r != Long.MAX_VALUE) {
produced(1);
}
}
if (leave(-1) == 0) {
return;
}
}
q.offer(value);
} else {
q.offer(value);
if (!enter()) {
return;
}
}
QueueDrainHelper.drainLoop(q, s, delayError, this);
}
protected final void fastpathEmitMax(U value, boolean delayError, Disposable dispose) {
final Subscriber s = actual;
final Queue q = queue;
if (wip == 0 && WIP.compareAndSet(this, 0, 1)) {
long r = requested;
if (r != 0L) {
if (accept(s, value)) {
if (r != Long.MAX_VALUE) {
produced(1);
}
}
if (leave(-1) == 0) {
return;
}
} else {
dispose.dispose();
s.onError(new IllegalStateException("Could not emit buffer due to lack of requests"));
return;
}
} else {
q.offer(value);
if (!enter()) {
return;
}
}
QueueDrainHelper.drainMaxLoop(q, s, delayError, dispose, this);
}
protected final void fastpathOrderedEmitMax(U value, boolean delayError, Disposable dispose) {
final Subscriber s = actual;
final Queue q = queue;
if (wip == 0 && WIP.compareAndSet(this, 0, 1)) {
long r = requested;
if (r != 0L) {
if (q.isEmpty()) {
if (accept(s, value)) {
if (r != Long.MAX_VALUE) {
produced(1);
}
}
if (leave(-1) == 0) {
return;
}
} else {
q.offer(value);
}
} else {
cancelled = true;
dispose.dispose();
s.onError(new IllegalStateException("Could not emit buffer due to lack of requests"));
return;
}
} else {
q.offer(value);
if (!enter()) {
return;
}
}
QueueDrainHelper.drainMaxLoop(q, s, delayError, dispose, this);
}
/**
* Makes sure the fast-path emits in order.
* @param value
* @param delayError
*/
protected final void fastpathOrderedEmit(U value, boolean delayError) {
final Subscriber s = actual;
final Queue q = queue;
if (wip == 0 && WIP.compareAndSet(this, 0, 1)) {
if (q.isEmpty()) {
long r = requested;
if (r != 0L) {
if (accept(s, value)) {
if (r != Long.MAX_VALUE) {
produced(1);
}
}
if (leave(-1) == 0) {
return;
}
}
}
q.offer(value);
} else {
q.offer(value);
if (!enter()) {
return;
}
}
QueueDrainHelper.drainLoop(q, s, delayError, this);
}
@Override
public final Throwable error() {
return error;
}
@Override
public final int leave(int m) {
return WIP.addAndGet(this, m);
}
@Override
public final long requested() {
return requested;
}
@Override
public final long produced(long n) {
return REQUESTED.addAndGet(this, -n);
}
public final void requested(long n) {
if (SubscriptionHelper.validateRequest(n)) {
return;
}
BackpressureHelper.add(REQUESTED, this, n);
}
public void drain(boolean delayError) {
if (enter()) {
QueueDrainHelper.drainLoop(queue, actual, delayError, this);
}
}
}
// -------------------------------------------------------------------
// Padding superclasses
//-------------------------------------------------------------------
/** Pads the header away from other fields. */
class QueueDrainSubscriberPad0 {
volatile long p1, p2, p3, p4, p5, p6, p7;
volatile long p8, p9, p10, p11, p12, p13, p14, p15;
}
/** The WIP counter. */
class QueueDrainSubscriberWip extends QueueDrainSubscriberPad0 {
volatile int wip;
static final AtomicIntegerFieldUpdater WIP =
AtomicIntegerFieldUpdater.newUpdater(QueueDrainSubscriberWip.class, "wip");
}
/** Pads away the wip from the other fields. */
class QueueDrainSubscriberPad2 extends QueueDrainSubscriberWip {
volatile long p1a, p2a, p3a, p4a, p5a, p6a, p7a;
volatile long p8a, p9a, p10a, p11a, p12a, p13a, p14a, p15a;
}
/** Contains the requested field. */
class QueueDrainSubscriberPad3 extends QueueDrainSubscriberPad2 {
volatile long requested;
static final AtomicLongFieldUpdater REQUESTED =
AtomicLongFieldUpdater.newUpdater(QueueDrainSubscriberPad3.class, "requested");
}
/** Pads away the requested from the other fields. */
class QueueDrainSubscriberPad4 extends QueueDrainSubscriberPad3 {
volatile long q1, q2, q3, q4, q5, q6, q7;
volatile long q8, q9, q10, q11, q12, q13, q14, q15;
}
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