org.jctools.queues.SpscArrayQueue Maven / Gradle / Ivy
/*
* 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 org.jctools.queues;
import org.jctools.util.SpscLookAheadUtil;
import static org.jctools.util.UnsafeAccess.UNSAFE;
import static org.jctools.util.UnsafeAccess.fieldOffset;
import static org.jctools.util.UnsafeRefArrayAccess.*;
abstract class SpscArrayQueueColdField extends ConcurrentCircularArrayQueue
{
final int lookAheadStep;
SpscArrayQueueColdField(int capacity)
{
super(capacity);
int actualCapacity = capacity();
lookAheadStep = SpscLookAheadUtil.computeLookAheadStep(actualCapacity);
}
}
abstract class SpscArrayQueueL1Pad extends SpscArrayQueueColdField
{
byte b000,b001,b002,b003,b004,b005,b006,b007;// 8b
byte b010,b011,b012,b013,b014,b015,b016,b017;// 16b
byte b020,b021,b022,b023,b024,b025,b026,b027;// 24b
byte b030,b031,b032,b033,b034,b035,b036,b037;// 32b
byte b040,b041,b042,b043,b044,b045,b046,b047;// 40b
byte b050,b051,b052,b053,b054,b055,b056,b057;// 48b
byte b060,b061,b062,b063,b064,b065,b066,b067;// 56b
byte b070,b071,b072,b073,b074,b075,b076,b077;// 64b
byte b100,b101,b102,b103,b104,b105,b106,b107;// 72b
byte b110,b111,b112,b113,b114,b115,b116,b117;// 80b
byte b120,b121,b122,b123,b124,b125,b126,b127;// 88b
byte b130,b131,b132,b133,b134,b135,b136,b137;// 96b
byte b140,b141,b142,b143,b144,b145,b146,b147;//104b
byte b150,b151,b152,b153,b154,b155,b156,b157;//112b
byte b160,b161,b162,b163,b164,b165,b166,b167;//120b
byte b170,b171,b172,b173,b174,b175,b176,b177;//128b
SpscArrayQueueL1Pad(int capacity)
{
super(capacity);
}
}
// $gen:ordered-fields
abstract class SpscArrayQueueProducerIndexFields extends SpscArrayQueueL1Pad
{
private final static long P_INDEX_OFFSET = fieldOffset(SpscArrayQueueProducerIndexFields.class, "producerIndex");
private volatile long producerIndex;
protected long producerLimit;
SpscArrayQueueProducerIndexFields(int capacity)
{
super(capacity);
}
@Override
public final long lvProducerIndex()
{
return producerIndex;
}
final long lpProducerIndex()
{
return UNSAFE.getLong(this, P_INDEX_OFFSET);
}
final void soProducerIndex(final long newValue)
{
UNSAFE.putOrderedLong(this, P_INDEX_OFFSET, newValue);
}
}
abstract class SpscArrayQueueL2Pad extends SpscArrayQueueProducerIndexFields
{
byte b000,b001,b002,b003,b004,b005,b006,b007;// 8b
byte b010,b011,b012,b013,b014,b015,b016,b017;// 16b
byte b020,b021,b022,b023,b024,b025,b026,b027;// 24b
byte b030,b031,b032,b033,b034,b035,b036,b037;// 32b
byte b040,b041,b042,b043,b044,b045,b046,b047;// 40b
byte b050,b051,b052,b053,b054,b055,b056,b057;// 48b
byte b060,b061,b062,b063,b064,b065,b066,b067;// 56b
byte b070,b071,b072,b073,b074,b075,b076,b077;// 64b
byte b100,b101,b102,b103,b104,b105,b106,b107;// 72b
byte b110,b111,b112,b113,b114,b115,b116,b117;// 80b
byte b120,b121,b122,b123,b124,b125,b126,b127;// 88b
byte b130,b131,b132,b133,b134,b135,b136,b137;// 96b
byte b140,b141,b142,b143,b144,b145,b146,b147;//104b
byte b150,b151,b152,b153,b154,b155,b156,b157;//112b
byte b160,b161,b162,b163,b164,b165,b166,b167;//120b
byte b170,b171,b172,b173,b174,b175,b176,b177;//128b
SpscArrayQueueL2Pad(int capacity)
{
super(capacity);
}
}
//$gen:ordered-fields
abstract class SpscArrayQueueConsumerIndexField extends SpscArrayQueueL2Pad
{
private final static long C_INDEX_OFFSET = fieldOffset(SpscArrayQueueConsumerIndexField.class, "consumerIndex");
private volatile long consumerIndex;
SpscArrayQueueConsumerIndexField(int capacity)
{
super(capacity);
}
public final long lvConsumerIndex()
{
return UNSAFE.getLongVolatile(this, C_INDEX_OFFSET);
}
final long lpConsumerIndex()
{
return UNSAFE.getLong(this, C_INDEX_OFFSET);
}
final void soConsumerIndex(final long newValue)
{
UNSAFE.putOrderedLong(this, C_INDEX_OFFSET, newValue);
}
}
abstract class SpscArrayQueueL3Pad extends SpscArrayQueueConsumerIndexField
{
byte b000,b001,b002,b003,b004,b005,b006,b007;// 8b
byte b010,b011,b012,b013,b014,b015,b016,b017;// 16b
byte b020,b021,b022,b023,b024,b025,b026,b027;// 24b
byte b030,b031,b032,b033,b034,b035,b036,b037;// 32b
byte b040,b041,b042,b043,b044,b045,b046,b047;// 40b
byte b050,b051,b052,b053,b054,b055,b056,b057;// 48b
byte b060,b061,b062,b063,b064,b065,b066,b067;// 56b
byte b070,b071,b072,b073,b074,b075,b076,b077;// 64b
byte b100,b101,b102,b103,b104,b105,b106,b107;// 72b
byte b110,b111,b112,b113,b114,b115,b116,b117;// 80b
byte b120,b121,b122,b123,b124,b125,b126,b127;// 88b
byte b130,b131,b132,b133,b134,b135,b136,b137;// 96b
byte b140,b141,b142,b143,b144,b145,b146,b147;//104b
byte b150,b151,b152,b153,b154,b155,b156,b157;//112b
byte b160,b161,b162,b163,b164,b165,b166,b167;//120b
byte b170,b171,b172,b173,b174,b175,b176,b177;//128b
SpscArrayQueueL3Pad(int capacity)
{
super(capacity);
}
}
/**
* A Single-Producer-Single-Consumer queue backed by a pre-allocated buffer.
*
* This implementation is a mashup of the Fast Flow
* algorithm with an optimization of the offer method taken from the BQueue algorithm (a variation on Fast
* Flow), and adjusted to comply with Queue.offer semantics with regards to capacity.
* For convenience the relevant papers are available in the `resources` folder:
*
* 2010 - Pisa - SPSC Queues on Shared Cache Multi-Core Systems.pdf
* 2012 - Junchang- BQueue- Efficient and Practical Queuing.pdf
*
* This implementation is wait free.
*/
public class SpscArrayQueue extends SpscArrayQueueL3Pad
{
public SpscArrayQueue(final int capacity)
{
super(Math.max(capacity, 4));
}
/**
* {@inheritDoc}
*
* This implementation is correct for single producer thread use only.
*/
@Override
public boolean offer(final E e)
{
if (null == e)
{
throw new NullPointerException();
}
// local load of field to avoid repeated loads after volatile reads
final E[] buffer = this.buffer;
final long mask = this.mask;
final long producerIndex = this.lpProducerIndex();
if (producerIndex >= producerLimit &&
!offerSlowPath(buffer, mask, producerIndex))
{
return false;
}
final long offset = calcCircularRefElementOffset(producerIndex, mask);
soRefElement(buffer, offset, e);
soProducerIndex(producerIndex + 1); // ordered store -> atomic and ordered for size()
return true;
}
private boolean offerSlowPath(final E[] buffer, final long mask, final long producerIndex)
{
final int lookAheadStep = this.lookAheadStep;
if (null == lvRefElement(buffer,
calcCircularRefElementOffset(producerIndex + lookAheadStep, mask)))
{
producerLimit = producerIndex + lookAheadStep;
}
else
{
final long offset = calcCircularRefElementOffset(producerIndex, mask);
if (null != lvRefElement(buffer, offset))
{
return false;
}
}
return true;
}
/**
* {@inheritDoc}
*
* This implementation is correct for single consumer thread use only.
*/
@Override
public E poll()
{
final long consumerIndex = this.lpConsumerIndex();
final long offset = calcCircularRefElementOffset(consumerIndex, mask);
// local load of field to avoid repeated loads after volatile reads
final E[] buffer = this.buffer;
final E e = lvRefElement(buffer, offset);
if (null == e)
{
return null;
}
soRefElement(buffer, offset, null);
soConsumerIndex(consumerIndex + 1); // ordered store -> atomic and ordered for size()
return e;
}
/**
* {@inheritDoc}
*
* This implementation is correct for single consumer thread use only.
*/
@Override
public E peek()
{
return lvRefElement(buffer, calcCircularRefElementOffset(lpConsumerIndex(), mask));
}
@Override
public boolean relaxedOffer(final E message)
{
return offer(message);
}
@Override
public E relaxedPoll()
{
return poll();
}
@Override
public E relaxedPeek()
{
return peek();
}
@Override
public int drain(final Consumer c)
{
return drain(c, capacity());
}
@Override
public int fill(final Supplier s)
{
return fill(s, capacity());
}
@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 E[] buffer = this.buffer;
final long mask = this.mask;
final long consumerIndex = this.lpConsumerIndex();
for (int i = 0; i < limit; i++)
{
final long index = consumerIndex + i;
final long offset = calcCircularRefElementOffset(index, mask);
final E e = lvRefElement(buffer, offset);
if (null == e)
{
return i;
}
soRefElement(buffer, offset, null);
soConsumerIndex(index + 1); // ordered store -> atomic and ordered for size()
c.accept(e);
}
return limit;
}
@Override
public int fill(final Supplier s, final 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 E[] buffer = this.buffer;
final long mask = this.mask;
final int lookAheadStep = this.lookAheadStep;
final long producerIndex = this.lpProducerIndex();
for (int i = 0; i < limit; i++)
{
final long index = producerIndex + i;
final long lookAheadElementOffset =
calcCircularRefElementOffset(index + lookAheadStep, mask);
if (null == lvRefElement(buffer, lookAheadElementOffset))
{
int lookAheadLimit = Math.min(lookAheadStep, limit - i);
for (int j = 0; j < lookAheadLimit; j++)
{
final long offset = calcCircularRefElementOffset(index + j, mask);
soRefElement(buffer, offset, s.get());
soProducerIndex(index + j + 1); // ordered store -> atomic and ordered for size()
}
i += lookAheadLimit - 1;
}
else
{
final long offset = calcCircularRefElementOffset(index, mask);
if (null != lvRefElement(buffer, offset))
{
return i;
}
soRefElement(buffer, offset, s.get());
soProducerIndex(index + 1); // ordered store -> atomic and ordered for size()
}
}
return limit;
}
@Override
public void drain(final Consumer c, final WaitStrategy w, final ExitCondition exit)
{
if (null == c)
throw new IllegalArgumentException("c is null");
if (null == w)
throw new IllegalArgumentException("wait is null");
if (null == exit)
throw new IllegalArgumentException("exit condition is null");
final E[] buffer = this.buffer;
final long mask = this.mask;
long consumerIndex = this.lpConsumerIndex();
int counter = 0;
while (exit.keepRunning())
{
for (int i = 0; i < 4096; i++)
{
final long offset = calcCircularRefElementOffset(consumerIndex, mask);
final E e = lvRefElement(buffer, offset);
if (null == e)
{
counter = w.idle(counter);
continue;
}
consumerIndex++;
counter = 0;
soRefElement(buffer, offset, null);
soConsumerIndex(consumerIndex); // ordered store -> atomic and ordered for size()
c.accept(e);
}
}
}
@Override
public void fill(final Supplier s, final WaitStrategy w, final ExitCondition e)
{
if (null == w)
throw new IllegalArgumentException("waiter is null");
if (null == e)
throw new IllegalArgumentException("exit condition is null");
if (null == s)
throw new IllegalArgumentException("supplier is null");
final E[] buffer = this.buffer;
final long mask = this.mask;
final int lookAheadStep = this.lookAheadStep;
long producerIndex = this.lpProducerIndex();
int counter = 0;
while (e.keepRunning())
{
final long lookAheadElementOffset =
calcCircularRefElementOffset(producerIndex + lookAheadStep, mask);
if (null == lvRefElement(buffer, lookAheadElementOffset))
{
for (int j = 0; j < lookAheadStep; j++)
{
final long offset = calcCircularRefElementOffset(producerIndex, mask);
producerIndex++;
soRefElement(buffer, offset, s.get());
soProducerIndex(producerIndex); // ordered store -> atomic and ordered for size()
}
}
else
{
final long offset = calcCircularRefElementOffset(producerIndex, mask);
if (null != lvRefElement(buffer, offset))
{
counter = w.idle(counter);
continue;
}
producerIndex++;
counter = 0;
soRefElement(buffer, offset, s.get());
soProducerIndex(producerIndex); // ordered store -> atomic and ordered for size()
}
}
}
}