com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.atomic.BaseMpscLinkedAtomicArrayQueue 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 com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.atomic;
import com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.IndexedQueueSizeUtil.IndexedQueue;
import com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.util.PortableJvmInfo;
import com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.util.Pow2;
import com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.util.RangeUtil;
import java.util.AbstractQueue;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.concurrent.atomic.AtomicLongFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceArray;
import com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.MessagePassingQueue;
import com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.MessagePassingQueue.Supplier;
import com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.MessagePassingQueueUtil;
import com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.QueueProgressIndicators;
import com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.IndexedQueueSizeUtil;
import static com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.atomic.AtomicQueueUtil.*;
/**
* NOTE: This class was automatically generated by com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicLinkedQueueGenerator
* which can found in the jctools-build module. The original source file is BaseMpscLinkedArrayQueue.java.
*/
abstract class BaseMpscLinkedAtomicArrayQueuePad1 extends AbstractQueue implements IndexedQueue {
// 8b
byte b000, b001, b002, b003, b004, b005, b006, b007;
// 16b
byte b010, b011, b012, b013, b014, b015, b016, b017;
// 24b
byte b020, b021, b022, b023, b024, b025, b026, b027;
// 32b
byte b030, b031, b032, b033, b034, b035, b036, b037;
// 40b
byte b040, b041, b042, b043, b044, b045, b046, b047;
// 48b
byte b050, b051, b052, b053, b054, b055, b056, b057;
// 56b
byte b060, b061, b062, b063, b064, b065, b066, b067;
// 64b
byte b070, b071, b072, b073, b074, b075, b076, b077;
// 72b
byte b100, b101, b102, b103, b104, b105, b106, b107;
// 80b
byte b110, b111, b112, b113, b114, b115, b116, b117;
// 88b
byte b120, b121, b122, b123, b124, b125, b126, b127;
// 96b
byte b130, b131, b132, b133, b134, b135, b136, b137;
// 104b
byte b140, b141, b142, b143, b144, b145, b146, b147;
// 112b
byte b150, b151, b152, b153, b154, b155, b156, b157;
// 120b
byte b160, b161, b162, b163, b164, b165, b166, b167;
// 128b
byte b170, b171, b172, b173, b174, b175, b176, b177;
}
/**
* NOTE: This class was automatically generated by com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicLinkedQueueGenerator
* which can found in the jctools-build module. The original source file is BaseMpscLinkedArrayQueue.java.
*/
abstract class BaseMpscLinkedAtomicArrayQueueProducerFields extends BaseMpscLinkedAtomicArrayQueuePad1 {
private static final AtomicLongFieldUpdater P_INDEX_UPDATER = AtomicLongFieldUpdater.newUpdater(BaseMpscLinkedAtomicArrayQueueProducerFields.class, "producerIndex");
private volatile long producerIndex;
@Override
public final long lvProducerIndex() {
return producerIndex;
}
final void soProducerIndex(long newValue) {
P_INDEX_UPDATER.lazySet(this, newValue);
}
final boolean casProducerIndex(long expect, long newValue) {
return P_INDEX_UPDATER.compareAndSet(this, expect, newValue);
}
}
/**
* NOTE: This class was automatically generated by com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicLinkedQueueGenerator
* which can found in the jctools-build module. The original source file is BaseMpscLinkedArrayQueue.java.
*/
abstract class BaseMpscLinkedAtomicArrayQueuePad2 extends BaseMpscLinkedAtomicArrayQueueProducerFields {
// 8b
byte b000, b001, b002, b003, b004, b005, b006, b007;
// 16b
byte b010, b011, b012, b013, b014, b015, b016, b017;
// 24b
byte b020, b021, b022, b023, b024, b025, b026, b027;
// 32b
byte b030, b031, b032, b033, b034, b035, b036, b037;
// 40b
byte b040, b041, b042, b043, b044, b045, b046, b047;
// 48b
byte b050, b051, b052, b053, b054, b055, b056, b057;
// 56b
byte b060, b061, b062, b063, b064, b065, b066, b067;
// 64b
byte b070, b071, b072, b073, b074, b075, b076, b077;
// 72b
byte b100, b101, b102, b103, b104, b105, b106, b107;
// 80b
byte b110, b111, b112, b113, b114, b115, b116, b117;
// 88b
byte b120, b121, b122, b123, b124, b125, b126, b127;
// 96b
byte b130, b131, b132, b133, b134, b135, b136, b137;
// 104b
byte b140, b141, b142, b143, b144, b145, b146, b147;
// 112b
byte b150, b151, b152, b153, b154, b155, b156, b157;
// 120b
byte b160, b161, b162, b163, b164, b165, b166, b167;
// 128b
byte b170, b171, b172, b173, b174, b175, b176, b177;
}
/**
* NOTE: This class was automatically generated by com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicLinkedQueueGenerator
* which can found in the jctools-build module. The original source file is BaseMpscLinkedArrayQueue.java.
*/
abstract class BaseMpscLinkedAtomicArrayQueueConsumerFields extends BaseMpscLinkedAtomicArrayQueuePad2 {
private static final AtomicLongFieldUpdater C_INDEX_UPDATER = AtomicLongFieldUpdater.newUpdater(BaseMpscLinkedAtomicArrayQueueConsumerFields.class, "consumerIndex");
private volatile long consumerIndex;
protected long consumerMask;
protected AtomicReferenceArray consumerBuffer;
@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 com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicLinkedQueueGenerator
* which can found in the jctools-build module. The original source file is BaseMpscLinkedArrayQueue.java.
*/
abstract class BaseMpscLinkedAtomicArrayQueuePad3 extends BaseMpscLinkedAtomicArrayQueueConsumerFields {
// 8b
byte b000, b001, b002, b003, b004, b005, b006, b007;
// 16b
byte b010, b011, b012, b013, b014, b015, b016, b017;
// 24b
byte b020, b021, b022, b023, b024, b025, b026, b027;
// 32b
byte b030, b031, b032, b033, b034, b035, b036, b037;
// 40b
byte b040, b041, b042, b043, b044, b045, b046, b047;
// 48b
byte b050, b051, b052, b053, b054, b055, b056, b057;
// 56b
byte b060, b061, b062, b063, b064, b065, b066, b067;
// 64b
byte b070, b071, b072, b073, b074, b075, b076, b077;
// 72b
byte b100, b101, b102, b103, b104, b105, b106, b107;
// 80b
byte b110, b111, b112, b113, b114, b115, b116, b117;
// 88b
byte b120, b121, b122, b123, b124, b125, b126, b127;
// 96b
byte b130, b131, b132, b133, b134, b135, b136, b137;
// 104b
byte b140, b141, b142, b143, b144, b145, b146, b147;
// 112b
byte b150, b151, b152, b153, b154, b155, b156, b157;
// 120b
byte b160, b161, b162, b163, b164, b165, b166, b167;
// 128b
byte b170, b171, b172, b173, b174, b175, b176, b177;
}
/**
* NOTE: This class was automatically generated by com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicLinkedQueueGenerator
* which can found in the jctools-build module. The original source file is BaseMpscLinkedArrayQueue.java.
*/
abstract class BaseMpscLinkedAtomicArrayQueueColdProducerFields extends BaseMpscLinkedAtomicArrayQueuePad3 {
private static final AtomicLongFieldUpdater P_LIMIT_UPDATER = AtomicLongFieldUpdater.newUpdater(BaseMpscLinkedAtomicArrayQueueColdProducerFields.class, "producerLimit");
private volatile long producerLimit;
protected long producerMask;
protected AtomicReferenceArray producerBuffer;
final long lvProducerLimit() {
return producerLimit;
}
final boolean casProducerLimit(long expect, long newValue) {
return P_LIMIT_UPDATER.compareAndSet(this, expect, newValue);
}
final void soProducerLimit(long newValue) {
P_LIMIT_UPDATER.lazySet(this, newValue);
}
}
/**
* NOTE: This class was automatically generated by com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicLinkedQueueGenerator
* which can found in the jctools-build module. The original source file is BaseMpscLinkedArrayQueue.java.
*
* 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 BaseMpscLinkedAtomicArrayQueue extends BaseMpscLinkedAtomicArrayQueueColdProducerFields 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 BaseMpscLinkedAtomicArrayQueue(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
AtomicReferenceArray buffer = allocateRefArray(p2capacity + 1);
producerBuffer = buffer;
producerMask = mask;
consumerBuffer = buffer;
consumerMask = mask;
// we know it's all empty to start with
soProducerLimit(mask);
}
@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;
}
}
// indexed queues.
if (size > Integer.MAX_VALUE) {
return Integer.MAX_VALUE;
} else {
return (int) size;
}
}
@Override
public boolean isEmpty() {
// 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;
AtomicReferenceArray 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;
// 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 int offset = modifiedCalcCircularRefElementOffset(pIndex, mask);
// release element e
soRefElement(buffer, offset, e);
return true;
}
/**
* {@inheritDoc}
*
* This implementation is correct for single consumer thread use only.
*/
@SuppressWarnings("unchecked")
@Override
public E poll() {
final AtomicReferenceArray buffer = consumerBuffer;
final long index = lpConsumerIndex();
final long mask = consumerMask;
final int offset = modifiedCalcCircularRefElementOffset(index, mask);
Object e = lvRefElement(buffer, offset);
if (e == null) {
if (index != lvProducerIndex()) {
// visible.
do {
e = lvRefElement(buffer, offset);
} while (e == null);
} else {
return null;
}
}
if (e == JUMP) {
final AtomicReferenceArray nextBuffer = nextBuffer(buffer, mask);
return newBufferPoll(nextBuffer, index);
}
// release element null
soRefElement(buffer, offset, null);
// release cIndex
soConsumerIndex(index + 2);
return (E) e;
}
/**
* {@inheritDoc}
*
* This implementation is correct for single consumer thread use only.
*/
@SuppressWarnings("unchecked")
@Override
public E peek() {
final AtomicReferenceArray buffer = consumerBuffer;
final long index = lpConsumerIndex();
final long mask = consumerMask;
final int offset = modifiedCalcCircularRefElementOffset(index, mask);
Object e = lvRefElement(buffer, offset);
if (e == null && index != lvProducerIndex()) {
// 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;
}
} else // full and cannot grow
if (availableInQueue(pIndex, cIndex) <= 0) {
// offer should return false;
return QUEUE_FULL;
} else // grab index for resize -> set lower bit
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 AtomicReferenceArray nextBuffer(final AtomicReferenceArray buffer, final long mask) {
final int offset = nextArrayOffset(mask);
final AtomicReferenceArray nextBuffer = (AtomicReferenceArray) lvRefElement(buffer, offset);
consumerBuffer = nextBuffer;
consumerMask = (length(nextBuffer) - 2) << 1;
soRefElement(buffer, offset, BUFFER_CONSUMED);
return nextBuffer;
}
private static int nextArrayOffset(long mask) {
return modifiedCalcCircularRefElementOffset(mask + 2, Long.MAX_VALUE);
}
private E newBufferPoll(AtomicReferenceArray nextBuffer, long index) {
final int 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(AtomicReferenceArray nextBuffer, long index) {
final int 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 AtomicReferenceArray buffer = consumerBuffer;
final long index = lpConsumerIndex();
final long mask = consumerMask;
final int offset = modifiedCalcCircularRefElementOffset(index, mask);
Object e = lvRefElement(buffer, offset);
if (e == null) {
return null;
}
if (e == JUMP) {
final AtomicReferenceArray 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 AtomicReferenceArray buffer = consumerBuffer;
final long index = lpConsumerIndex();
final long mask = consumerMask;
final int 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) {
// result is a long because we want to have a safepoint check at regular intervals
long result = 0;
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;
AtomicReferenceArray 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'
// -> producerLimit >= batchIndex
long batchIndex = Math.min(producerLimit, pIndex + 2l * limit);
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 int 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());
}
/**
* NOTE: This class was automatically generated by com.datastax.oss.driver.shaded.netty.util.internal.shaded.org.jctools.queues.atomic.JavaParsingAtomicLinkedQueueGenerator
* which can found in the jctools-build module. The original source file is BaseMpscLinkedArrayQueue.java.
*/
private static class WeakIterator implements Iterator {
private final long pIndex;
private long nextIndex;
private E nextElement;
private AtomicReferenceArray currentBuffer;
private int mask;
WeakIterator(AtomicReferenceArray 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(AtomicReferenceArray 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((AtomicReferenceArray) 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, AtomicReferenceArray oldBuffer, long pIndex, E e, Supplier s) {
assert (e != null && s == null) || (e == null || s != null);
int newBufferLength = getNextBufferSize(oldBuffer);
final AtomicReferenceArray 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 int offsetInOld = modifiedCalcCircularRefElementOffset(pIndex, oldMask);
final int offsetInNew = modifiedCalcCircularRefElementOffset(pIndex, newMask);
// element in new array
soRefElement(newBuffer, offsetInNew, e == null ? s.get() : e);
// buffer linked
soRefElement(oldBuffer, nextArrayOffset(oldMask), newBuffer);
// 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(AtomicReferenceArray buffer);
/**
* @return current buffer capacity for elements (excluding next pointer and jump entry) * 2
*/
protected abstract long getCurrentBufferCapacity(long mask);
}