/*
* Copyright 2014 Ben Manes. All Rights Reserved.
*
* 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 com.github.benmanes.caffeine;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ThreadLocalRandom;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import com.google.common.collect.ForwardingMap;
/**
* Demonstrates that inheritance is ~8% faster than delegation.
*
* @author ben.manes@gmail.com (Ben Manes)
*/
@State(Scope.Benchmark)
public class DelegationBenchmark {
private static final int SIZE = (2 << 14);
private static final int MASK = SIZE - 1;
final Map<Integer, Integer> inherit = new InheritMap();
final Map<Integer, Integer> delegate = new DelgateMap();
@Setup
public void setup() {
for (int i = 0; i < SIZE; i++) {
inherit.put(i, i);
delegate.put(i, i);
}
}
@State(Scope.Thread)
public static class ThreadState {
int index = ThreadLocalRandom.current().nextInt();
}
@Benchmark
public Integer inherit_get(ThreadState threadState) {
return inherit.get(threadState.index++ & MASK);
}
@Benchmark
public Integer delegate_get(ThreadState threadState) {
return delegate.get(threadState.index++ & MASK);
}
static final class InheritMap extends ConcurrentHashMap<Integer, Integer> {
private static final long serialVersionUID = 1L;
@Override
public Integer get(Object key) {
Integer value = super.get(key);
return (value == null) ? null : (value - 1);
}
}
static final class DelgateMap extends ForwardingMap<Integer, Integer> {
final Map<Integer, Integer> delegate = new ConcurrentHashMap<>();
@Override
public Integer get(Object key) {
Integer value = delegate.get(key);
return (value == null) ? null : (value - 1);
}
@Override
protected Map<Integer, Integer> delegate() {
return delegate;
}
}
}