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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 org.jctools.queues.unpadded;

import org.jctools.queues.IndexedQueueSizeUtil.IndexedQueue;
import org.jctools.util.PortableJvmInfo;
import org.jctools.util.Pow2;
import org.jctools.util.RangeUtil;
import java.util.AbstractQueue;
import java.util.Iterator;
import java.util.NoSuchElementException;
import static org.jctools.queues.LinkedArrayQueueUtil.length;
import static org.jctools.queues.LinkedArrayQueueUtil.modifiedCalcCircularRefElementOffset;
import static org.jctools.util.UnsafeAccess.UNSAFE;
import static org.jctools.util.UnsafeAccess.fieldOffset;
import static org.jctools.util.UnsafeRefArrayAccess.*;
import org.jctools.queues.*;

/**
 * NOTE: This class was automatically generated by org.jctools.queues.unpadded.JavaParsingUnpaddedQueueGenerator
 * which can found in the jctools-build module. The original source file is BaseMpscLinkedArrayQueue.java.
 */
abstract class BaseMpscLinkedUnpaddedArrayQueuePad1 extends AbstractQueue implements IndexedQueue {
}

/**
 * NOTE: This class was automatically generated by org.jctools.queues.unpadded.JavaParsingUnpaddedQueueGenerator
 * which can found in the jctools-build module. The original source file is BaseMpscLinkedArrayQueue.java.
 */
abstract class BaseMpscLinkedUnpaddedArrayQueueProducerFields extends BaseMpscLinkedUnpaddedArrayQueuePad1 {

    private final static long P_INDEX_OFFSET = fieldOffset(BaseMpscLinkedUnpaddedArrayQueueProducerFields.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);
    }
}

/**
 * NOTE: This class was automatically generated by org.jctools.queues.unpadded.JavaParsingUnpaddedQueueGenerator
 * which can found in the jctools-build module. The original source file is BaseMpscLinkedArrayQueue.java.
 */
abstract class BaseMpscLinkedUnpaddedArrayQueuePad2 extends BaseMpscLinkedUnpaddedArrayQueueProducerFields {
}

/**
 * NOTE: This class was automatically generated by org.jctools.queues.unpadded.JavaParsingUnpaddedQueueGenerator
 * which can found in the jctools-build module. The original source file is BaseMpscLinkedArrayQueue.java.
 */
abstract class BaseMpscLinkedUnpaddedArrayQueueConsumerFields extends BaseMpscLinkedUnpaddedArrayQueuePad2 {

    private final static long C_INDEX_OFFSET = fieldOffset(BaseMpscLinkedUnpaddedArrayQueueConsumerFields.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);
    }
}

/**
 * NOTE: This class was automatically generated by org.jctools.queues.unpadded.JavaParsingUnpaddedQueueGenerator
 * which can found in the jctools-build module. The original source file is BaseMpscLinkedArrayQueue.java.
 */
abstract class BaseMpscLinkedUnpaddedArrayQueuePad3 extends BaseMpscLinkedUnpaddedArrayQueueConsumerFields {
}

/**
 * NOTE: This class was automatically generated by org.jctools.queues.unpadded.JavaParsingUnpaddedQueueGenerator
 * which can found in the jctools-build module. The original source file is BaseMpscLinkedArrayQueue.java.
 */
abstract class BaseMpscLinkedUnpaddedArrayQueueColdProducerFields extends BaseMpscLinkedUnpaddedArrayQueuePad3 {

    private final static long P_LIMIT_OFFSET = fieldOffset(BaseMpscLinkedUnpaddedArrayQueueColdProducerFields.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);
    }
}

/**
 * NOTE: This class was automatically generated by org.jctools.queues.unpadded.JavaParsingUnpaddedQueueGenerator
 * 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 BaseMpscLinkedUnpaddedArrayQueue extends BaseMpscLinkedUnpaddedArrayQueueColdProducerFields 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 BaseMpscLinkedUnpaddedArrayQueue(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;
        // we know it's all empty to start with
        soProducerLimit(mask);
    }

    @Override
    public int size() {
        return IndexedQueueSizeUtil.size(this, IndexedQueueSizeUtil.IGNORE_PARITY_DIVISOR);
    }

    @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 ((lvConsumerIndex() - lvProducerIndex()) / 2 == 0);
    }

    @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);
        // 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 E[] buffer = consumerBuffer; final long cIndex = lpConsumerIndex(); final long mask = consumerMask; final long offset = modifiedCalcCircularRefElementOffset(cIndex, mask); Object e = lvRefElement(buffer, offset); if (e == null) { long pIndex = lvProducerIndex(); // isEmpty? if ((cIndex - pIndex) / 2 == 0) { return null; } // poll() == null iff queue is empty, null element is not strong enough indicator, so we must // spin until element is visible. do { e = lvRefElement(buffer, offset); } while (e == null); } if (e == JUMP) { final E[] nextBuffer = nextBuffer(buffer, mask); return newBufferPoll(nextBuffer, cIndex); } // release element null soRefElement(buffer, offset, null); // release cIndex soConsumerIndex(cIndex + 2); 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 cIndex = lpConsumerIndex(); final long mask = consumerMask; final long offset = modifiedCalcCircularRefElementOffset(cIndex, mask); Object e = lvRefElement(buffer, offset); if (e == null) { long pIndex = lvProducerIndex(); // isEmpty? if ((cIndex - pIndex) / 2 == 0) { return null; } // peek() == null iff queue is empty, null element is not strong enough indicator, so we must // spin until element is visible. do { e = lvRefElement(buffer, offset); } while (e == null); } if (e == JUMP) { return newBufferPeek(nextBuffer(buffer, mask), cIndex); } 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 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 cIndex) { final long offset = modifiedCalcCircularRefElementOffset(cIndex, 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(cIndex + 2); return n; } private E newBufferPeek(E[] nextBuffer, long cIndex) { final long offset = modifiedCalcCircularRefElementOffset(cIndex, 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 cIndex = lpConsumerIndex(); final long mask = consumerMask; final long offset = modifiedCalcCircularRefElementOffset(cIndex, mask); Object e = lvRefElement(buffer, offset); if (e == null) { return null; } if (e == JUMP) { final E[] nextBuffer = nextBuffer(buffer, mask); return newBufferPoll(nextBuffer, cIndex); } soRefElement(buffer, offset, null); soConsumerIndex(cIndex + 2); return (E) e; } @SuppressWarnings("unchecked") @Override public E relaxedPeek() { final E[] buffer = consumerBuffer; final long cIndex = lpConsumerIndex(); final long mask = consumerMask; final long offset = modifiedCalcCircularRefElementOffset(cIndex, mask); Object e = lvRefElement(buffer, offset); if (e == JUMP) { return newBufferPeek(nextBuffer(buffer, mask), cIndex); } 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; 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' // -> 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 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); // 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(E[] buffer); /** * @return current buffer capacity for elements (excluding next pointer and jump entry) * 2 */ protected abstract long getCurrentBufferCapacity(long mask); }





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