/*
* 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.Pow2;
import org.jctools.util.RangeUtil;
/**
* An MPSC array queue which starts at <i>initialCapacity</i> and grows to <i>maxCapacity</i> 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.<br>
*
* @param <E>
*/
public class MpscGrowableArrayQueue<E> extends MpscChunkedArrayQueue<E>
implements MessagePassingQueue<E>, QueueProgressIndicators {
public MpscGrowableArrayQueue(int maxCapacity) {
super(Math.max(2, Pow2.roundToPowerOfTwo(maxCapacity / 8)), maxCapacity);
}
/**
* @param initialCapacity the queue initial capacity. If chunk size is fixed this will be the chunk size.
* Must be 2 or more.
* @param maxCapacity the maximum capacity will be rounded up to the closest power of 2 and will be the
* upper limit of number of elements in this queue. Must be 4 or more and round up to a larger
* power of 2 than initialCapacity.
*/
public MpscGrowableArrayQueue(int initialCapacity, int maxCapacity) {
super(initialCapacity, maxCapacity);
}
@Override
protected int getNextBufferSize(E[] buffer) {
final long maxSize = maxQueueCapacity / 2;
RangeUtil.checkLessThanOrEqual(buffer.length, maxSize, "buffer.length");
final int newSize = 2 * (buffer.length - 1);
return newSize + 1;
}
@Override
protected long getCurrentBufferCapacity(long mask) {
return (mask + 2 == maxQueueCapacity) ? maxQueueCapacity : mask;
}
}