co.elastic.apm.agent.shaded.jctools.queues.BaseSpscLinkedArrayQueue 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 co.elastic.apm.agent.shaded.jctools.queues;
import co.elastic.apm.agent.shaded.jctools.queues.IndexedQueueSizeUtil.IndexedQueue;
import co.elastic.apm.agent.shaded.jctools.util.PortableJvmInfo;
import java.lang.reflect.Field;
import java.util.AbstractQueue;
import java.util.Iterator;
import static co.elastic.apm.agent.shaded.jctools.queues.CircularArrayOffsetCalculator.calcElementOffset;
import static co.elastic.apm.agent.shaded.jctools.queues.LinkedArrayQueueUtil.length;
import static co.elastic.apm.agent.shaded.jctools.queues.LinkedArrayQueueUtil.nextArrayOffset;
import static co.elastic.apm.agent.shaded.jctools.util.UnsafeAccess.UNSAFE;
import static co.elastic.apm.agent.shaded.jctools.util.UnsafeAccess.fieldOffset;
import static co.elastic.apm.agent.shaded.jctools.util.UnsafeRefArrayAccess.lvElement;
import static co.elastic.apm.agent.shaded.jctools.util.UnsafeRefArrayAccess.soElement;
abstract class BaseSpscLinkedArrayQueuePrePad extends AbstractQueue implements IndexedQueue
{
long p0, p1, p2, p3, p4, p5, p6, p7;
long p10, p11, p12, p13, p14, p15;
// p16, p17; drop 2 longs, the cold fields act as buffer
}
abstract class BaseSpscLinkedArrayQueueConsumerColdFields extends BaseSpscLinkedArrayQueuePrePad
{
protected long consumerMask;
protected E[] consumerBuffer;
}
// $gen:ordered-fields
abstract class BaseSpscLinkedArrayQueueConsumerField extends BaseSpscLinkedArrayQueueConsumerColdFields
{
private final static long C_INDEX_OFFSET = fieldOffset(BaseSpscLinkedArrayQueueConsumerField.class, "consumerIndex");
protected long consumerIndex;
final void soConsumerIndex(long newValue)
{
UNSAFE.putOrderedLong(this, C_INDEX_OFFSET, newValue);
}
@Override
public final long lvConsumerIndex()
{
return UNSAFE.getLongVolatile(this, C_INDEX_OFFSET);
}
}
abstract class BaseSpscLinkedArrayQueueL2Pad extends BaseSpscLinkedArrayQueueConsumerField
{
long p0, p1, p2, p3, p4, p5, p6, p7;
long p10, p11, p12, p13, p14, p15, p16, p17;
}
// $gen:ordered-fields
abstract class BaseSpscLinkedArrayQueueProducerFields extends BaseSpscLinkedArrayQueueL2Pad
{
private final static long P_INDEX_OFFSET = fieldOffset(BaseSpscLinkedArrayQueueProducerFields.class,"producerIndex");
protected long producerIndex;
final void soProducerIndex(long newValue)
{
UNSAFE.putOrderedLong(this, P_INDEX_OFFSET, newValue);
}
@Override
public final long lvProducerIndex()
{
return UNSAFE.getLongVolatile(this, P_INDEX_OFFSET);
}
}
abstract class BaseSpscLinkedArrayQueueProducerColdFields extends BaseSpscLinkedArrayQueueProducerFields
{
protected long producerBufferLimit;
protected long producerMask; // fixed for chunked and unbounded
protected E[] producerBuffer;
}
abstract class BaseSpscLinkedArrayQueue extends BaseSpscLinkedArrayQueueProducerColdFields
implements MessagePassingQueue, QueueProgressIndicators
{
private static final Object JUMP = new Object();
@Override
public final Iterator iterator()
{
throw new UnsupportedOperationException();
}
@Override
public final int size()
{
return IndexedQueueSizeUtil.size(this);
}
@Override
public final boolean isEmpty()
{
return IndexedQueueSizeUtil.isEmpty(this);
}
@Override
public String toString()
{
return this.getClass().getName();
}
@Override
public long currentProducerIndex()
{
return lvProducerIndex();
}
@Override
public long currentConsumerIndex()
{
return lvConsumerIndex();
}
protected final void soNext(E[] curr, E[] next)
{
long offset = nextArrayOffset(curr);
soElement(curr, offset, next);
}
@SuppressWarnings("unchecked")
protected final E[] lvNextArrayAndUnlink(E[] curr)
{
final long offset = nextArrayOffset(curr);
final E[] nextBuffer = (E[]) lvElement(curr, offset);
// prevent GC nepotism
soElement(curr, offset, null);
return nextBuffer;
}
@Override
public boolean relaxedOffer(E e)
{
return offer(e);
}
@Override
public E relaxedPoll()
{
return poll();
}
@Override
public E relaxedPeek()
{
return peek();
}
@Override
public int drain(Consumer c)
{
return MessagePassingQueueUtil.drain(this, c);
}
@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 drain(Consumer c, int limit)
{
return MessagePassingQueueUtil.drain(this, c, limit);
}
@Override
public int fill(Supplier s, int limit)
{
for (int i = 0; i < limit; i++)
{
// local load of field to avoid repeated loads after volatile reads
final E[] buffer = producerBuffer;
final long index = producerIndex;
final long mask = producerMask;
final long offset = calcElementOffset(index, mask);
// expected hot path
if (index < producerBufferLimit)
{
writeToQueue(buffer, s.get(), index, offset);
}
else
{
if (!offerColdPath(buffer, mask, index, offset, null, s))
{
return i;
}
}
}
return limit;
}
@Override
public void drain(Consumer c, WaitStrategy wait, ExitCondition exit)
{
MessagePassingQueueUtil.drain(this, c, wait, exit);
}
@Override
public void fill(Supplier s, WaitStrategy wait, ExitCondition exit)
{
while (exit.keepRunning())
{
while (fill(s, PortableJvmInfo.RECOMENDED_OFFER_BATCH) != 0 && exit.keepRunning())
{
continue;
}
int idleCounter = 0;
while (exit.keepRunning() && fill(s, PortableJvmInfo.RECOMENDED_OFFER_BATCH) == 0)
{
idleCounter = wait.idle(idleCounter);
}
}
}
/**
* {@inheritDoc}
*
* This implementation is correct for single producer thread use only.
*/
@Override
public boolean offer(final E e)
{
// Objects.requireNonNull(e);
if (null == e)
{
throw new NullPointerException();
}
// local load of field to avoid repeated loads after volatile reads
final E[] buffer = producerBuffer;
final long index = producerIndex;
final long mask = producerMask;
final long offset = calcElementOffset(index, mask);
// expected hot path
if (index < producerBufferLimit)
{
writeToQueue(buffer, e, index, offset);
return true;
}
return offerColdPath(buffer, mask, index, offset, e, null);
}
abstract boolean offerColdPath(
E[] buffer,
long mask,
long pIndex,
long offset,
E v,
Supplier s);
/**
* {@inheritDoc}
*
* This implementation is correct for single consumer thread use only.
*/
@SuppressWarnings("unchecked")
@Override
public E poll()
{
// local load of field to avoid repeated loads after volatile reads
final E[] buffer = consumerBuffer;
final long index = consumerIndex;
final long mask = consumerMask;
final long offset = calcElementOffset(index, mask);
final Object e = lvElement(buffer, offset);// LoadLoad
boolean isNextBuffer = e == JUMP;
if (null != e && !isNextBuffer)
{
soConsumerIndex(index + 1);// this ensures correctness on 32bit platforms
soElement(buffer, offset, null);
return (E) e;
}
else if (isNextBuffer)
{
return newBufferPoll(buffer, index);
}
return null;
}
/**
* {@inheritDoc}
*
* This implementation is correct for single consumer thread use only.
*/
@SuppressWarnings("unchecked")
@Override
public E peek()
{
final E[] buffer = consumerBuffer;
final long index = consumerIndex;
final long mask = consumerMask;
final long offset = calcElementOffset(index, mask);
final Object e = lvElement(buffer, offset);// LoadLoad
if (e == JUMP)
{
return newBufferPeek(buffer, index);
}
return (E) e;
}
final void linkOldToNew(
final long currIndex,
final E[] oldBuffer, final long offset,
final E[] newBuffer, final long offsetInNew,
final E e)
{
soElement(newBuffer, offsetInNew, e);// StoreStore
// link to next buffer and add next indicator as element of old buffer
soNext(oldBuffer, newBuffer);
soElement(oldBuffer, offset, JUMP);
// index is visible after elements (isEmpty/poll ordering)
soProducerIndex(currIndex + 1);// this ensures atomic write of long on 32bit platforms
}
final void writeToQueue(final E[] buffer, final E e, final long index, final long offset)
{
soElement(buffer, offset, e);// StoreStore
soProducerIndex(index + 1);// this ensures atomic write of long on 32bit platforms
}
private E newBufferPeek(final E[] buffer, final long index)
{
E[] nextBuffer = lvNextArrayAndUnlink(buffer);
consumerBuffer = nextBuffer;
final long mask = length(nextBuffer) - 2;
consumerMask = mask;
final long offset = calcElementOffset(index, mask);
return lvElement(nextBuffer, offset);// LoadLoad
}
private E newBufferPoll(final E[] buffer, final long index)
{
E[] nextBuffer = lvNextArrayAndUnlink(buffer);
consumerBuffer = nextBuffer;
final long mask = length(nextBuffer) - 2;
consumerMask = mask;
final long offset = calcElementOffset(index, mask);
final E n = lvElement(nextBuffer, offset);// LoadLoad
if (null == n)
{
throw new IllegalStateException("new buffer must have at least one element");
}
else
{
soConsumerIndex(index + 1);// this ensures correctness on 32bit platforms
soElement(nextBuffer, offset, null);// StoreStore
return n;
}
}
}