/*
* Quasar: lightweight threads and actors for the JVM.
* Copyright (c) 2013-2014, Parallel Universe Software Co. All rights reserved.
*
* This program and the accompanying materials are dual-licensed under
* either the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation
*
* or (per the licensee's choosing)
*
* under the terms of the GNU Lesser General Public License version 3.0
* as published by the Free Software Foundation.
*/
package co.paralleluniverse.strands.queues;
/**
*
* @author pron
*/
abstract class CircularWordBuffer<E> extends CircularBuffer<E> {
private final int[] array;
public CircularWordBuffer(int size, boolean singleProducer) {
super(size, singleProducer);
this.array = new int[capacity];
}
void enqRaw(int elem) {
long index = preEnq();
orderedSet((int) index & mask, elem); // must be orderedSet so as to not be re-ordered with tail bump in postEnq
postEnq();
}
abstract class WordConsumer extends Consumer {
private int value;
@Override
protected void grabValue(int index) {
value = array[index];
}
@Override
protected void clearValue() {
}
int getRawValue() {
return value;
}
}
//////////////////////////
private static final int base;
private static final int shift;
static {
try {
base = UNSAFE.arrayBaseOffset(int[].class);
int scale = UNSAFE.arrayIndexScale(int[].class);
if ((scale & (scale - 1)) != 0)
throw new Error("data type scale not a power of two");
shift = 31 - Integer.numberOfLeadingZeros(scale);
} catch (Exception ex) {
throw new Error(ex);
}
}
private static long byteOffset(int i) {
return ((long) i << shift) + base;
}
private void orderedSet(int i, int value) {
UNSAFE.putOrderedInt(array, byteOffset(i), value);
}
}