/*
* @(#)$Id$
*
* Copyright 2006-2008 Makoto YUI
*
* 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.
*
* Contributors:
* Makoto YUI - initial implementation
*/
package xbird.util.concurrent.counter;
import java.util.concurrent.atomic.AtomicInteger;
import xbird.util.hashes.HashUtils;
/**
*
* <DIV lang="en"></DIV>
* <DIV lang="ja"></DIV>
*
* @author Makoto YUI (yuin405+xbird@gmail.com)
*/
public final class StripeAtomicIntCounter implements ICounter {
private static final long serialVersionUID = -1886936728047307997L;
private final AtomicInteger[] _cnts;
private final int _size;
private final int _mask;
private volatile int _fuzzy_sum_cache;
private volatile long _fuzzy_time;
public StripeAtomicIntCounter(int nstripe) {
assert (nstripe > 0) : nstripe;
final int power2 = HashUtils.nextPowerOfTwo(nstripe);
this._size = power2;
this._mask = power2 - 1;
this._cnts = new AtomicInteger[power2];
for(int i = 0; i < power2; i++) {
_cnts[i] = new AtomicInteger();
}
}
public StripeAtomicIntCounter(int nstripe, int initValue) {
assert (nstripe > 0) : nstripe;
final int power2 = HashUtils.nextPowerOfTwo(nstripe);
this._size = power2;
this._mask = power2 - 1;
this._cnts = new AtomicInteger[power2];
_cnts[0] = new AtomicInteger(initValue);
for(int i = 1; i < power2; i++) {
_cnts[i] = new AtomicInteger();
}
}
public int get() {
final AtomicInteger[] cnts = _cnts;
int sum = 0;
for(int i = 0; i < _size; i++) {
sum += cnts[i].get();
}
return sum;
}
public int estimateGet() {
if(_size < 64) {
return get();
}
final long millis = System.currentTimeMillis();
if(_fuzzy_time != millis) {
_fuzzy_sum_cache = get();
_fuzzy_time = millis; // Indicate freshness of cached value
}
return _fuzzy_sum_cache;
}
public void add(final int x) {
int idx = HashUtils.hash(Thread.currentThread(), _size - 1);
_cnts[idx].addAndGet(x);
}
public void add2(final int x) {
int hash = HashUtils.hash(Thread.currentThread());
int idx = hash & _mask;
_cnts[idx].addAndGet(x);
}
public int getAndAdd(final int x) {
int l = get();
add(x);
return l;
}
public int addAndGet(final int x) {
add(x);
return get();
}
public int incrementAndGet() {
return addAndGet(1);
}
public int decrementAndGet() {
return addAndGet(-1);
}
public int getAndIncrement() {
return getAndAdd(1);
}
public int getAndDecrement() {
return getAndAdd(-1);
}
}