rx.internal.util.unsafe.ConcurrentSequencedCircularArrayQueue 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.
*
* Original License: https://github.com/JCTools/JCTools/blob/master/LICENSE
* Original location: https://github.com/JCTools/JCTools/blob/master/jctools-core/src/main/java/org/jctools/queues/ConcurrentSequencedCircularArrayQueue.java
*/
package rx.internal.util.unsafe;
import static rx.internal.util.unsafe.UnsafeAccess.UNSAFE;
import rx.internal.util.SuppressAnimalSniffer;
@SuppressAnimalSniffer
public abstract class ConcurrentSequencedCircularArrayQueue extends ConcurrentCircularArrayQueue {
private static final long ARRAY_BASE;
private static final int ELEMENT_SHIFT;
static {
final int scale = UnsafeAccess.UNSAFE.arrayIndexScale(long[].class);
if (8 == scale) {
ELEMENT_SHIFT = 3 + SPARSE_SHIFT;
} else {
throw new IllegalStateException("Unexpected long[] element size");
}
// Including the buffer pad in the array base offset
ARRAY_BASE = UnsafeAccess.UNSAFE.arrayBaseOffset(long[].class) + (BUFFER_PAD << (ELEMENT_SHIFT - SPARSE_SHIFT));
}
protected final long[] sequenceBuffer;
public ConcurrentSequencedCircularArrayQueue(int capacity) {
super(capacity);
int actualCapacity = (int) (this.mask + 1);
// pad data on either end with some empty slots.
sequenceBuffer = new long[(actualCapacity << SPARSE_SHIFT) + BUFFER_PAD * 2];
for (long i = 0; i < actualCapacity; i++) {
soSequence(sequenceBuffer, calcSequenceOffset(i), i);
}
}
protected final long calcSequenceOffset(long index) {
return ARRAY_BASE + ((index & mask) << ELEMENT_SHIFT);
}
protected final void soSequence(long[] buffer, long offset, long e) {
UNSAFE.putOrderedLong(buffer, offset, e);
}
protected final long lvSequence(long[] buffer, long offset) {
return UNSAFE.getLongVolatile(buffer, offset);
}
}
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