io.netty.util.internal.shaded.org.jctools.queues.atomic.MpscAtomicArrayQueue Maven / Gradle / Ivy
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/*
* 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.netty.util.internal.shaded.org.jctools.queues.atomic;
import java.util.concurrent.atomic.AtomicLongFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceArray;
import java.util.concurrent.atomic.AtomicLongArray;
import io.netty.util.internal.shaded.org.jctools.queues.MessagePassingQueueUtil;
import static io.netty.util.internal.shaded.org.jctools.queues.atomic.AtomicQueueUtil.*;
/**
* NOTE: This class was automatically generated by io.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicArrayQueueGenerator
* which can found in the jctools-build module. The original source file is MpscArrayQueue.java.
*/
abstract class MpscAtomicArrayQueueL1Pad extends AtomicReferenceArrayQueue {
long p00, p01, p02, p03, p04, p05, p06, p07;
long p10, p11, p12, p13, p14, p15, p16;
MpscAtomicArrayQueueL1Pad(int capacity) {
super(capacity);
}
}
/**
* NOTE: This class was automatically generated by io.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicArrayQueueGenerator
* which can found in the jctools-build module. The original source file is MpscArrayQueue.java.
*/
abstract class MpscAtomicArrayQueueProducerIndexField extends MpscAtomicArrayQueueL1Pad {
private static final AtomicLongFieldUpdater P_INDEX_UPDATER = AtomicLongFieldUpdater.newUpdater(MpscAtomicArrayQueueProducerIndexField.class, "producerIndex");
private volatile long producerIndex;
MpscAtomicArrayQueueProducerIndexField(int capacity) {
super(capacity);
}
@Override
public final long lvProducerIndex() {
return producerIndex;
}
final boolean casProducerIndex(long expect, long newValue) {
return P_INDEX_UPDATER.compareAndSet(this, expect, newValue);
}
}
/**
* NOTE: This class was automatically generated by io.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicArrayQueueGenerator
* which can found in the jctools-build module. The original source file is MpscArrayQueue.java.
*/
abstract class MpscAtomicArrayQueueMidPad extends MpscAtomicArrayQueueProducerIndexField {
long p01, p02, p03, p04, p05, p06, p07;
long p10, p11, p12, p13, p14, p15, p16, p17;
MpscAtomicArrayQueueMidPad(int capacity) {
super(capacity);
}
}
/**
* NOTE: This class was automatically generated by io.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicArrayQueueGenerator
* which can found in the jctools-build module. The original source file is MpscArrayQueue.java.
*/
abstract class MpscAtomicArrayQueueProducerLimitField extends MpscAtomicArrayQueueMidPad {
private static final AtomicLongFieldUpdater P_LIMIT_UPDATER = AtomicLongFieldUpdater.newUpdater(MpscAtomicArrayQueueProducerLimitField.class, "producerLimit");
// First unavailable index the producer may claim up to before rereading the consumer index
private volatile long producerLimit;
MpscAtomicArrayQueueProducerLimitField(int capacity) {
super(capacity);
this.producerLimit = capacity;
}
final long lvProducerLimit() {
return producerLimit;
}
final void soProducerLimit(long newValue) {
P_LIMIT_UPDATER.lazySet(this, newValue);
}
}
/**
* NOTE: This class was automatically generated by io.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicArrayQueueGenerator
* which can found in the jctools-build module. The original source file is MpscArrayQueue.java.
*/
abstract class MpscAtomicArrayQueueL2Pad extends MpscAtomicArrayQueueProducerLimitField {
long p00, p01, p02, p03, p04, p05, p06, p07;
long p10, p11, p12, p13, p14, p15, p16;
MpscAtomicArrayQueueL2Pad(int capacity) {
super(capacity);
}
}
/**
* NOTE: This class was automatically generated by io.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicArrayQueueGenerator
* which can found in the jctools-build module. The original source file is MpscArrayQueue.java.
*/
abstract class MpscAtomicArrayQueueConsumerIndexField extends MpscAtomicArrayQueueL2Pad {
private static final AtomicLongFieldUpdater C_INDEX_UPDATER = AtomicLongFieldUpdater.newUpdater(MpscAtomicArrayQueueConsumerIndexField.class, "consumerIndex");
private volatile long consumerIndex;
MpscAtomicArrayQueueConsumerIndexField(int capacity) {
super(capacity);
}
@Override
public final long lvConsumerIndex() {
return consumerIndex;
}
final long lpConsumerIndex() {
return consumerIndex;
}
final void soConsumerIndex(long newValue) {
C_INDEX_UPDATER.lazySet(this, newValue);
}
}
/**
* NOTE: This class was automatically generated by io.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicArrayQueueGenerator
* which can found in the jctools-build module. The original source file is MpscArrayQueue.java.
*/
abstract class MpscAtomicArrayQueueL3Pad extends MpscAtomicArrayQueueConsumerIndexField {
long p01, p02, p03, p04, p05, p06, p07;
long p10, p11, p12, p13, p14, p15, p16, p17;
MpscAtomicArrayQueueL3Pad(int capacity) {
super(capacity);
}
}
/**
* NOTE: This class was automatically generated by io.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicArrayQueueGenerator
* which can found in the jctools-build module. The original source file is MpscArrayQueue.java.
*
* A Multi-Producer-Single-Consumer queue based on a {@link io.netty.util.internal.shaded.org.jctools.queues.ConcurrentCircularArrayQueue}. This
* implies that any thread may call the offer method, but only a single thread may call poll/peek for correctness to
* maintained.
* This implementation follows patterns documented on the package level for False Sharing protection.
* This implementation is using the Fast Flow
* method for polling from the queue (with minor change to correctly publish the index) and an extension of
* the Leslie Lamport concurrent queue algorithm (originated by Martin Thompson) on the producer side.
*/
public class MpscAtomicArrayQueue extends MpscAtomicArrayQueueL3Pad {
public MpscAtomicArrayQueue(final int capacity) {
super(capacity);
}
/**
* {@link #offer}} if {@link #size()} is less than threshold.
*
* @param e the object to offer onto the queue, not null
* @param threshold the maximum allowable size
* @return true if the offer is successful, false if queue size exceeds threshold
* @since 1.0.1
*/
public boolean offerIfBelowThreshold(final E e, int threshold) {
if (null == e) {
throw new NullPointerException();
}
final int mask = this.mask;
final long capacity = mask + 1;
long producerLimit = lvProducerLimit();
long pIndex;
do {
pIndex = lvProducerIndex();
long available = producerLimit - pIndex;
long size = capacity - available;
if (size >= threshold) {
final long cIndex = lvConsumerIndex();
size = pIndex - cIndex;
if (size >= threshold) {
// the size exceeds threshold
return false;
} else {
// update producer limit to the next index that we must recheck the consumer index
producerLimit = cIndex + capacity;
// this is racy, but the race is benign
soProducerLimit(producerLimit);
}
}
} while (!casProducerIndex(pIndex, pIndex + 1));
/*
* NOTE: the new producer index value is made visible BEFORE the element in the array. If we relied on
* the index visibility to poll() we would need to handle the case where the element is not visible.
*/
// Won CAS, move on to storing
final int offset = calcCircularRefElementOffset(pIndex, mask);
soRefElement(buffer, offset, e);
// AWESOME :)
return true;
}
/**
* {@inheritDoc}
*
* IMPLEMENTATION NOTES:
* Lock free offer using a single CAS. As class name suggests access is permitted to many threads
* concurrently.
*
* @see java.util.Queue#offer
* @see io.netty.util.internal.shaded.org.jctools.queues.MessagePassingQueue#offer
*/
@Override
public boolean offer(final E e) {
if (null == e) {
throw new NullPointerException();
}
// use a cached view on consumer index (potentially updated in loop)
final int mask = this.mask;
long producerLimit = lvProducerLimit();
long pIndex;
do {
pIndex = lvProducerIndex();
if (pIndex >= producerLimit) {
final long cIndex = lvConsumerIndex();
producerLimit = cIndex + mask + 1;
if (pIndex >= producerLimit) {
// FULL :(
return false;
} else {
// update producer limit to the next index that we must recheck the consumer index
// this is racy, but the race is benign
soProducerLimit(producerLimit);
}
}
} while (!casProducerIndex(pIndex, pIndex + 1));
/*
* NOTE: the new producer index value is made visible BEFORE the element in the array. If we relied on
* the index visibility to poll() we would need to handle the case where the element is not visible.
*/
// Won CAS, move on to storing
final int offset = calcCircularRefElementOffset(pIndex, mask);
soRefElement(buffer, offset, e);
// AWESOME :)
return true;
}
/**
* A wait free alternative to offer which fails on CAS failure.
*
* @param e new element, not null
* @return 1 if next element cannot be filled, -1 if CAS failed, 0 if successful
*/
public final int failFastOffer(final E e) {
if (null == e) {
throw new NullPointerException();
}
final int mask = this.mask;
final long capacity = mask + 1;
final long pIndex = lvProducerIndex();
long producerLimit = lvProducerLimit();
if (pIndex >= producerLimit) {
final long cIndex = lvConsumerIndex();
producerLimit = cIndex + capacity;
if (pIndex >= producerLimit) {
// FULL :(
return 1;
} else {
// update producer limit to the next index that we must recheck the consumer index
soProducerLimit(producerLimit);
}
}
// look Ma, no loop!
if (!casProducerIndex(pIndex, pIndex + 1)) {
// CAS FAIL :(
return -1;
}
// Won CAS, move on to storing
final int offset = calcCircularRefElementOffset(pIndex, mask);
soRefElement(buffer, offset, e);
// AWESOME :)
return 0;
}
/**
* {@inheritDoc}
*
* IMPLEMENTATION NOTES:
* Lock free poll using ordered loads/stores. As class name suggests access is limited to a single thread.
*
* @see java.util.Queue#poll
* @see io.netty.util.internal.shaded.org.jctools.queues.MessagePassingQueue#poll
*/
@Override
public E poll() {
final long cIndex = lpConsumerIndex();
final int offset = calcCircularRefElementOffset(cIndex, mask);
// Copy field to avoid re-reading after volatile load
final AtomicReferenceArray buffer = this.buffer;
// If we can't see the next available element we can't poll
E e = lvRefElement(buffer, offset);
if (null == e) {
/*
* NOTE: Queue may not actually be empty in the case of a producer (P1) being interrupted after
* winning the CAS on offer but before storing the element in the queue. Other producers may go on
* to fill up the queue after this element.
*/
if (cIndex != lvProducerIndex()) {
do {
e = lvRefElement(buffer, offset);
} while (e == null);
} else {
return null;
}
}
soRefElement(buffer, offset, null);
soConsumerIndex(cIndex + 1);
return e;
}
/**
* {@inheritDoc}
*
* IMPLEMENTATION NOTES:
* Lock free peek using ordered loads. As class name suggests access is limited to a single thread.
*
* @see java.util.Queue#poll
* @see io.netty.util.internal.shaded.org.jctools.queues.MessagePassingQueue#poll
*/
@Override
public E peek() {
// Copy field to avoid re-reading after volatile load
final AtomicReferenceArray buffer = this.buffer;
final long cIndex = lpConsumerIndex();
final int offset = calcCircularRefElementOffset(cIndex, mask);
E e = lvRefElement(buffer, offset);
if (null == e) {
/*
* NOTE: Queue may not actually be empty in the case of a producer (P1) being interrupted after
* winning the CAS on offer but before storing the element in the queue. Other producers may go on
* to fill up the queue after this element.
*/
if (cIndex != lvProducerIndex()) {
do {
e = lvRefElement(buffer, offset);
} while (e == null);
} else {
return null;
}
}
return e;
}
@Override
public boolean relaxedOffer(E e) {
return offer(e);
}
@Override
public E relaxedPoll() {
final AtomicReferenceArray buffer = this.buffer;
final long cIndex = lpConsumerIndex();
final int offset = calcCircularRefElementOffset(cIndex, mask);
// If we can't see the next available element we can't poll
E e = lvRefElement(buffer, offset);
if (null == e) {
return null;
}
soRefElement(buffer, offset, null);
soConsumerIndex(cIndex + 1);
return e;
}
@Override
public E relaxedPeek() {
final AtomicReferenceArray buffer = this.buffer;
final int mask = this.mask;
final long cIndex = lpConsumerIndex();
return lvRefElement(buffer, calcCircularRefElementOffset(cIndex, mask));
}
@Override
public int drain(final Consumer c, final int limit) {
if (null == c)
throw new IllegalArgumentException("c is null");
if (limit < 0)
throw new IllegalArgumentException("limit is negative: " + limit);
if (limit == 0)
return 0;
final AtomicReferenceArray buffer = this.buffer;
final int mask = this.mask;
final long cIndex = lpConsumerIndex();
for (int i = 0; i < limit; i++) {
final long index = cIndex + i;
final int offset = calcCircularRefElementOffset(index, mask);
final E e = lvRefElement(buffer, offset);
if (null == e) {
return i;
}
soRefElement(buffer, offset, null);
// ordered store -> atomic and ordered for size()
soConsumerIndex(index + 1);
c.accept(e);
}
return limit;
}
@Override
public int fill(Supplier s, int limit) {
if (null == s)
throw new IllegalArgumentException("supplier is null");
if (limit < 0)
throw new IllegalArgumentException("limit is negative:" + limit);
if (limit == 0)
return 0;
final int mask = this.mask;
final long capacity = mask + 1;
long producerLimit = lvProducerLimit();
long pIndex;
int actualLimit = 0;
do {
pIndex = lvProducerIndex();
long available = producerLimit - pIndex;
if (available <= 0) {
final long cIndex = lvConsumerIndex();
producerLimit = cIndex + capacity;
available = producerLimit - pIndex;
if (available <= 0) {
// FULL :(
return 0;
} else {
// update producer limit to the next index that we must recheck the consumer index
soProducerLimit(producerLimit);
}
}
actualLimit = Math.min((int) available, limit);
} while (!casProducerIndex(pIndex, pIndex + actualLimit));
// right, now we claimed a few slots and can fill them with goodness
final AtomicReferenceArray buffer = this.buffer;
for (int i = 0; i < actualLimit; i++) {
// Won CAS, move on to storing
final int offset = calcCircularRefElementOffset(pIndex + i, mask);
soRefElement(buffer, offset, s.get());
}
return actualLimit;
}
@Override
public int drain(Consumer c) {
return drain(c, capacity());
}
@Override
public int fill(Supplier s) {
return MessagePassingQueueUtil.fillBounded(this, s);
}
@Override
public void drain(Consumer c, WaitStrategy w, ExitCondition exit) {
MessagePassingQueueUtil.drain(this, c, w, exit);
}
@Override
public void fill(Supplier s, WaitStrategy wait, ExitCondition exit) {
MessagePassingQueueUtil.fill(this, s, wait, exit);
}
/**
* @deprecated This was renamed to failFastOffer please migrate
*/
@Deprecated
public int weakOffer(E e) {
return this.failFastOffer(e);
}
}