org.apache.activemq.artemis.shaded.io.netty.util.internal.shaded.org.jctools.queues.BaseMpscLinkedArrayQueue 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.apache.activemq.artemis.shaded.io.netty.util.internal.shaded.org.jctools.queues;
import org.apache.activemq.artemis.shaded.io.netty.util.internal.shaded.org.jctools.queues.IndexedQueueSizeUtil.IndexedQueue;
import org.apache.activemq.artemis.shaded.io.netty.util.internal.shaded.org.jctools.util.PortableJvmInfo;
import org.apache.activemq.artemis.shaded.io.netty.util.internal.shaded.org.jctools.util.Pow2;
import org.apache.activemq.artemis.shaded.io.netty.util.internal.shaded.org.jctools.util.RangeUtil;
import java.util.AbstractQueue;
import java.util.Iterator;
import java.util.NoSuchElementException;
import static org.apache.activemq.artemis.shaded.io.netty.util.internal.shaded.org.jctools.queues.LinkedArrayQueueUtil.length;
import static org.apache.activemq.artemis.shaded.io.netty.util.internal.shaded.org.jctools.queues.LinkedArrayQueueUtil.modifiedCalcCircularRefElementOffset;
import static org.apache.activemq.artemis.shaded.io.netty.util.internal.shaded.org.jctools.util.UnsafeAccess.UNSAFE;
import static org.apache.activemq.artemis.shaded.io.netty.util.internal.shaded.org.jctools.util.UnsafeAccess.fieldOffset;
import static org.apache.activemq.artemis.shaded.io.netty.util.internal.shaded.org.jctools.util.UnsafeRefArrayAccess.*;
abstract class BaseMpscLinkedArrayQueuePad1 extends AbstractQueue implements IndexedQueue
{
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
}
// $gen:ordered-fields
abstract class BaseMpscLinkedArrayQueueProducerFields extends BaseMpscLinkedArrayQueuePad1
{
private final static long P_INDEX_OFFSET = fieldOffset(BaseMpscLinkedArrayQueueProducerFields.class, "producerIndex");
private volatile long producerIndex;
@Override
public final long lvProducerIndex()
{
return producerIndex;
}
final void soProducerIndex(long newValue)
{
UNSAFE.putOrderedLong(this, P_INDEX_OFFSET, newValue);
}
final boolean casProducerIndex(long expect, long newValue)
{
return UNSAFE.compareAndSwapLong(this, P_INDEX_OFFSET, expect, newValue);
}
}
abstract class BaseMpscLinkedArrayQueuePad2 extends BaseMpscLinkedArrayQueueProducerFields
{
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
}
// $gen:ordered-fields
abstract class BaseMpscLinkedArrayQueueConsumerFields extends BaseMpscLinkedArrayQueuePad2
{
private final static long C_INDEX_OFFSET = fieldOffset(BaseMpscLinkedArrayQueueConsumerFields.class,"consumerIndex");
private volatile long consumerIndex;
protected long consumerMask;
protected E[] consumerBuffer;
@Override
public final long lvConsumerIndex()
{
return consumerIndex;
}
final long lpConsumerIndex()
{
return UNSAFE.getLong(this, C_INDEX_OFFSET);
}
final void soConsumerIndex(long newValue)
{
UNSAFE.putOrderedLong(this, C_INDEX_OFFSET, newValue);
}
}
abstract class BaseMpscLinkedArrayQueuePad3 extends BaseMpscLinkedArrayQueueConsumerFields
{
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
}
// $gen:ordered-fields
abstract class BaseMpscLinkedArrayQueueColdProducerFields extends BaseMpscLinkedArrayQueuePad3
{
private final static long P_LIMIT_OFFSET = fieldOffset(BaseMpscLinkedArrayQueueColdProducerFields.class,"producerLimit");
private volatile long producerLimit;
protected long producerMask;
protected E[] producerBuffer;
final long lvProducerLimit()
{
return producerLimit;
}
final boolean casProducerLimit(long expect, long newValue)
{
return UNSAFE.compareAndSwapLong(this, P_LIMIT_OFFSET, expect, newValue);
}
final void soProducerLimit(long newValue)
{
UNSAFE.putOrderedLong(this, P_LIMIT_OFFSET, newValue);
}
}
/**
* An MPSC array queue which starts at initialCapacity and grows to maxCapacity in linked chunks
* of the initial size. The queue grows only when the current buffer is full and elements are not copied on
* resize, instead a link to the new buffer is stored in the old buffer for the consumer to follow.
*/
abstract class BaseMpscLinkedArrayQueue extends BaseMpscLinkedArrayQueueColdProducerFields
implements MessagePassingQueue, QueueProgressIndicators
{
// No post padding here, subclasses must add
private static final Object JUMP = new Object();
private static final Object BUFFER_CONSUMED = new Object();
private static final int CONTINUE_TO_P_INDEX_CAS = 0;
private static final int RETRY = 1;
private static final int QUEUE_FULL = 2;
private static final int QUEUE_RESIZE = 3;
/**
* @param initialCapacity the queue initial capacity. If chunk size is fixed this will be the chunk size.
* Must be 2 or more.
*/
public BaseMpscLinkedArrayQueue(final int initialCapacity)
{
RangeUtil.checkGreaterThanOrEqual(initialCapacity, 2, "initialCapacity");
int p2capacity = Pow2.roundToPowerOfTwo(initialCapacity);
// leave lower bit of mask clear
long mask = (p2capacity - 1) << 1;
// need extra element to point at next array
E[] buffer = allocateRefArray(p2capacity + 1);
producerBuffer = buffer;
producerMask = mask;
consumerBuffer = buffer;
consumerMask = mask;
soProducerLimit(mask); // we know it's all empty to start with
}
@Override
public int size()
{
// NOTE: because indices are on even numbers we cannot use the size util.
/*
* It is possible for a thread to be interrupted or reschedule between the read of the producer and
* consumer indices, therefore protection is required to ensure size is within valid range. In the
* event of concurrent polls/offers to this method the size is OVER estimated as we read consumer
* index BEFORE the producer index.
*/
long after = lvConsumerIndex();
long size;
while (true)
{
final long before = after;
final long currentProducerIndex = lvProducerIndex();
after = lvConsumerIndex();
if (before == after)
{
size = ((currentProducerIndex - after) >> 1);
break;
}
}
// Long overflow is impossible, so size is always positive. Integer overflow is possible for the unbounded
// indexed queues.
if (size > Integer.MAX_VALUE)
{
return Integer.MAX_VALUE;
}
else
{
return (int) size;
}
}
@Override
public boolean isEmpty()
{
// Order matters!
// Loading consumer before producer allows for producer increments after consumer index is read.
// This ensures this method is conservative in it's estimate. Note that as this is an MPMC there is
// nothing we can do to make this an exact method.
return (this.lvConsumerIndex() == this.lvProducerIndex());
}
@Override
public String toString()
{
return this.getClass().getName();
}
@Override
public boolean offer(final E e)
{
if (null == e)
{
throw new NullPointerException();
}
long mask;
E[] buffer;
long pIndex;
while (true)
{
long producerLimit = lvProducerLimit();
pIndex = lvProducerIndex();
// lower bit is indicative of resize, if we see it we spin until it's cleared
if ((pIndex & 1) == 1)
{
continue;
}
// pIndex is even (lower bit is 0) -> actual index is (pIndex >> 1)
// mask/buffer may get changed by resizing -> only use for array access after successful CAS.
mask = this.producerMask;
buffer = this.producerBuffer;
// a successful CAS ties the ordering, lv(pIndex) - [mask/buffer] -> cas(pIndex)
// assumption behind this optimization is that queue is almost always empty or near empty
if (producerLimit <= pIndex)
{
int result = offerSlowPath(mask, pIndex, producerLimit);
switch (result)
{
case CONTINUE_TO_P_INDEX_CAS:
break;
case RETRY:
continue;
case QUEUE_FULL:
return false;
case QUEUE_RESIZE:
resize(mask, buffer, pIndex, e, null);
return true;
}
}
if (casProducerIndex(pIndex, pIndex + 2))
{
break;
}
}
// INDEX visible before ELEMENT
final long offset = modifiedCalcCircularRefElementOffset(pIndex, mask);
soRefElement(buffer, offset, e); // release element e
return true;
}
/**
* {@inheritDoc}
*
* This implementation is correct for single consumer thread use only.
*/
@SuppressWarnings("unchecked")
@Override
public E poll()
{
final E[] buffer = consumerBuffer;
final long index = lpConsumerIndex();
final long mask = consumerMask;
final long offset = modifiedCalcCircularRefElementOffset(index, mask);
Object e = lvRefElement(buffer, offset);
if (e == null)
{
if (index != lvProducerIndex())
{
// poll() == null iff queue is empty, null element is not strong enough indicator, so we must
// check the producer index. If the queue is indeed not empty we spin until element is
// visible.
do
{
e = lvRefElement(buffer, offset);
}
while (e == null);
}
else
{
return null;
}
}
if (e == JUMP)
{
final E[] nextBuffer = nextBuffer(buffer, mask);
return newBufferPoll(nextBuffer, index);
}
soRefElement(buffer, offset, null); // release element null
soConsumerIndex(index + 2); // release cIndex
return (E) e;
}
/**
* {@inheritDoc}
*
* This implementation is correct for single consumer thread use only.
*/
@SuppressWarnings("unchecked")
@Override
public E peek()
{
final E[] buffer = consumerBuffer;
final long index = lpConsumerIndex();
final long mask = consumerMask;
final long offset = modifiedCalcCircularRefElementOffset(index, mask);
Object e = lvRefElement(buffer, offset);
if (e == null && index != lvProducerIndex())
{
// peek() == null iff queue is empty, null element is not strong enough indicator, so we must
// check the producer index. If the queue is indeed not empty we spin until element is visible.
do
{
e = lvRefElement(buffer, offset);
}
while (e == null);
}
if (e == JUMP)
{
return newBufferPeek(nextBuffer(buffer, mask), index);
}
return (E) e;
}
/**
* We do not inline resize into this method because we do not resize on fill.
*/
private int offerSlowPath(long mask, long pIndex, long producerLimit)
{
final long cIndex = lvConsumerIndex();
long bufferCapacity = getCurrentBufferCapacity(mask);
if (cIndex + bufferCapacity > pIndex)
{
if (!casProducerLimit(producerLimit, cIndex + bufferCapacity))
{
// retry from top
return RETRY;
}
else
{
// continue to pIndex CAS
return CONTINUE_TO_P_INDEX_CAS;
}
}
// full and cannot grow
else if (availableInQueue(pIndex, cIndex) <= 0)
{
// offer should return false;
return QUEUE_FULL;
}
// grab index for resize -> set lower bit
else if (casProducerIndex(pIndex, pIndex + 1))
{
// trigger a resize
return QUEUE_RESIZE;
}
else
{
// failed resize attempt, retry from top
return RETRY;
}
}
/**
* @return available elements in queue * 2
*/
protected abstract long availableInQueue(long pIndex, long cIndex);
@SuppressWarnings("unchecked")
private E[] nextBuffer(final E[] buffer, final long mask)
{
final long offset = nextArrayOffset(mask);
final E[] nextBuffer = (E[]) lvRefElement(buffer, offset);
consumerBuffer = nextBuffer;
consumerMask = (length(nextBuffer) - 2) << 1;
soRefElement(buffer, offset, BUFFER_CONSUMED);
return nextBuffer;
}
private static long nextArrayOffset(long mask)
{
return modifiedCalcCircularRefElementOffset(mask + 2, Long.MAX_VALUE);
}
private E newBufferPoll(E[] nextBuffer, long index)
{
final long offset = modifiedCalcCircularRefElementOffset(index, consumerMask);
final E n = lvRefElement(nextBuffer, offset);
if (n == null)
{
throw new IllegalStateException("new buffer must have at least one element");
}
soRefElement(nextBuffer, offset, null);
soConsumerIndex(index + 2);
return n;
}
private E newBufferPeek(E[] nextBuffer, long index)
{
final long offset = modifiedCalcCircularRefElementOffset(index, consumerMask);
final E n = lvRefElement(nextBuffer, offset);
if (null == n)
{
throw new IllegalStateException("new buffer must have at least one element");
}
return n;
}
@Override
public long currentProducerIndex()
{
return lvProducerIndex() / 2;
}
@Override
public long currentConsumerIndex()
{
return lvConsumerIndex() / 2;
}
@Override
public abstract int capacity();
@Override
public boolean relaxedOffer(E e)
{
return offer(e);
}
@SuppressWarnings("unchecked")
@Override
public E relaxedPoll()
{
final E[] buffer = consumerBuffer;
final long index = lpConsumerIndex();
final long mask = consumerMask;
final long offset = modifiedCalcCircularRefElementOffset(index, mask);
Object e = lvRefElement(buffer, offset);
if (e == null)
{
return null;
}
if (e == JUMP)
{
final E[] nextBuffer = nextBuffer(buffer, mask);
return newBufferPoll(nextBuffer, index);
}
soRefElement(buffer, offset, null);
soConsumerIndex(index + 2);
return (E) e;
}
@SuppressWarnings("unchecked")
@Override
public E relaxedPeek()
{
final E[] buffer = consumerBuffer;
final long index = lpConsumerIndex();
final long mask = consumerMask;
final long offset = modifiedCalcCircularRefElementOffset(index, mask);
Object e = lvRefElement(buffer, offset);
if (e == JUMP)
{
return newBufferPeek(nextBuffer(buffer, mask), index);
}
return (E) e;
}
@Override
public int fill(Supplier s)
{
long result = 0;// result is a long because we want to have a safepoint check at regular intervals
final int capacity = capacity();
do
{
final int filled = fill(s, PortableJvmInfo.RECOMENDED_OFFER_BATCH);
if (filled == 0)
{
return (int) result;
}
result += filled;
}
while (result <= capacity);
return (int) result;
}
@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;
long mask;
E[] buffer;
long pIndex;
int claimedSlots;
while (true)
{
long producerLimit = lvProducerLimit();
pIndex = lvProducerIndex();
// lower bit is indicative of resize, if we see it we spin until it's cleared
if ((pIndex & 1) == 1)
{
continue;
}
// pIndex is even (lower bit is 0) -> actual index is (pIndex >> 1)
// NOTE: mask/buffer may get changed by resizing -> only use for array access after successful CAS.
// Only by virtue offloading them between the lvProducerIndex and a successful casProducerIndex are they
// safe to use.
mask = this.producerMask;
buffer = this.producerBuffer;
// a successful CAS ties the ordering, lv(pIndex) -> [mask/buffer] -> cas(pIndex)
// we want 'limit' slots, but will settle for whatever is visible to 'producerLimit'
long batchIndex = Math.min(producerLimit, pIndex + 2l * limit); // -> producerLimit >= batchIndex
if (pIndex >= producerLimit)
{
int result = offerSlowPath(mask, pIndex, producerLimit);
switch (result)
{
case CONTINUE_TO_P_INDEX_CAS:
// offer slow path verifies only one slot ahead, we cannot rely on indication here
case RETRY:
continue;
case QUEUE_FULL:
return 0;
case QUEUE_RESIZE:
resize(mask, buffer, pIndex, null, s);
return 1;
}
}
// claim limit slots at once
if (casProducerIndex(pIndex, batchIndex))
{
claimedSlots = (int) ((batchIndex - pIndex) / 2);
break;
}
}
for (int i = 0; i < claimedSlots; i++)
{
final long offset = modifiedCalcCircularRefElementOffset(pIndex + 2l * i, mask);
soRefElement(buffer, offset, s.get());
}
return claimedSlots;
}
@Override
public void fill(Supplier s, WaitStrategy wait, ExitCondition exit)
{
MessagePassingQueueUtil.fill(this, s, wait, exit);
}
@Override
public int drain(Consumer c)
{
return drain(c, capacity());
}
@Override
public int drain(Consumer c, int limit)
{
return MessagePassingQueueUtil.drain(this, c, limit);
}
@Override
public void drain(Consumer c, WaitStrategy wait, ExitCondition exit)
{
MessagePassingQueueUtil.drain(this, c, wait, exit);
}
/**
* Get an iterator for this queue. This method is thread safe.
*
* The iterator provides a best-effort snapshot of the elements in the queue.
* The returned iterator is not guaranteed to return elements in queue order,
* and races with the consumer thread may cause gaps in the sequence of returned elements.
* Like {link #relaxedPoll}, the iterator may not immediately return newly inserted elements.
*
* @return The iterator.
*/
@Override
public Iterator iterator() {
return new WeakIterator(consumerBuffer, lvConsumerIndex(), lvProducerIndex());
}
private static class WeakIterator implements Iterator
{
private final long pIndex;
private long nextIndex;
private E nextElement;
private E[] currentBuffer;
private int mask;
WeakIterator(E[] currentBuffer, long cIndex, long pIndex)
{
this.pIndex = pIndex >> 1;
this.nextIndex = cIndex >> 1;
setBuffer(currentBuffer);
nextElement = getNext();
}
@Override
public void remove() {
throw new UnsupportedOperationException("remove");
}
@Override
public boolean hasNext()
{
return nextElement != null;
}
@Override
public E next()
{
final E e = nextElement;
if (e == null)
{
throw new NoSuchElementException();
}
nextElement = getNext();
return e;
}
private void setBuffer(E[] buffer)
{
this.currentBuffer = buffer;
this.mask = length(buffer) - 2;
}
private E getNext()
{
while (nextIndex < pIndex)
{
long index = nextIndex++;
E e = lvRefElement(currentBuffer, calcCircularRefElementOffset(index, mask));
// skip removed/not yet visible elements
if (e == null)
{
continue;
}
// not null && not JUMP -> found next element
if (e != JUMP)
{
return e;
}
// need to jump to the next buffer
int nextBufferIndex = mask + 1;
Object nextBuffer = lvRefElement(currentBuffer,
calcRefElementOffset(nextBufferIndex));
if (nextBuffer == BUFFER_CONSUMED || nextBuffer == null)
{
// Consumer may have passed us, or the next buffer is not visible yet: drop out early
return null;
}
setBuffer((E[]) nextBuffer);
// now with the new array retry the load, it can't be a JUMP, but we need to repeat same index
e = lvRefElement(currentBuffer, calcCircularRefElementOffset(index, mask));
// skip removed/not yet visible elements
if (e == null)
{
continue;
}
else
{
return e;
}
}
return null;
}
}
private void resize(long oldMask, E[] oldBuffer, long pIndex, E e, Supplier s)
{
assert (e != null && s == null) || (e == null || s != null);
int newBufferLength = getNextBufferSize(oldBuffer);
final E[] newBuffer;
try
{
newBuffer = allocateRefArray(newBufferLength);
}
catch (OutOfMemoryError oom)
{
assert lvProducerIndex() == pIndex + 1;
soProducerIndex(pIndex);
throw oom;
}
producerBuffer = newBuffer;
final int newMask = (newBufferLength - 2) << 1;
producerMask = newMask;
final long offsetInOld = modifiedCalcCircularRefElementOffset(pIndex, oldMask);
final long offsetInNew = modifiedCalcCircularRefElementOffset(pIndex, newMask);
soRefElement(newBuffer, offsetInNew, e == null ? s.get() : e);// element in new array
soRefElement(oldBuffer, nextArrayOffset(oldMask), newBuffer);// buffer linked
// ASSERT code
final long cIndex = lvConsumerIndex();
final long availableInQueue = availableInQueue(pIndex, cIndex);
RangeUtil.checkPositive(availableInQueue, "availableInQueue");
// Invalidate racing CASs
// We never set the limit beyond the bounds of a buffer
soProducerLimit(pIndex + Math.min(newMask, availableInQueue));
// make resize visible to the other producers
soProducerIndex(pIndex + 2);
// INDEX visible before ELEMENT, consistent with consumer expectation
// make resize visible to consumer
soRefElement(oldBuffer, offsetInOld, JUMP);
}
/**
* @return next buffer size(inclusive of next array pointer)
*/
protected abstract int getNextBufferSize(E[] buffer);
/**
* @return current buffer capacity for elements (excluding next pointer and jump entry) * 2
*/
protected abstract long getCurrentBufferCapacity(long mask);
}