119 lines
3.4 KiB
Java
119 lines
3.4 KiB
Java
/*
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* Copyright (C) 2010 The Guava Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.common.cache;
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import com.google.caliper.AfterExperiment;
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import com.google.caliper.BeforeExperiment;
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import com.google.caliper.Benchmark;
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import com.google.caliper.Param;
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import com.google.common.primitives.Ints;
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import java.util.Random;
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import java.util.concurrent.atomic.AtomicLong;
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/**
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* Single-threaded benchmark for {@link LoadingCache}.
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*
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* @author Charles Fry
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*/
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public class LoadingCacheSingleThreadBenchmark {
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@Param({"1000", "2000"})
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int maximumSize;
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@Param("5000")
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int distinctKeys;
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@Param("4")
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int segments;
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// 1 means uniform likelihood of keys; higher means some keys are more popular
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// tweak this to control hit rate
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@Param("2.5")
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double concentration;
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Random random = new Random();
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LoadingCache<Integer, Integer> cache;
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int max;
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static AtomicLong requests = new AtomicLong(0);
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static AtomicLong misses = new AtomicLong(0);
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@BeforeExperiment
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void setUp() {
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// random integers will be generated in this range, then raised to the
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// power of (1/concentration) and floor()ed
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max = Ints.checkedCast((long) Math.pow(distinctKeys, concentration));
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cache =
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CacheBuilder.newBuilder()
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.concurrencyLevel(segments)
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.maximumSize(maximumSize)
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.build(
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new CacheLoader<Integer, Integer>() {
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@Override
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public Integer load(Integer from) {
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return (int) misses.incrementAndGet();
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}
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});
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// To start, fill up the cache.
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// Each miss both increments the counter and causes the map to grow by one,
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// so until evictions begin, the size of the map is the greatest return
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// value seen so far
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while (cache.getUnchecked(nextRandomKey()) < maximumSize) {}
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requests.set(0);
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misses.set(0);
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}
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@Benchmark
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int time(int reps) {
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int dummy = 0;
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for (int i = 0; i < reps; i++) {
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dummy += cache.getUnchecked(nextRandomKey());
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}
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requests.addAndGet(reps);
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return dummy;
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}
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private int nextRandomKey() {
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int a = random.nextInt(max);
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/*
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* For example, if concentration=2.0, the following takes the square root of
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* the uniformly-distributed random integer, then truncates any fractional
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* part, so higher integers would appear (in this case linearly) more often
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* than lower ones.
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*/
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return (int) Math.pow(a, 1.0 / concentration);
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}
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@AfterExperiment
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void tearDown() {
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double req = requests.get();
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double hit = req - misses.get();
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// Currently, this is going into /dev/null, but I'll fix that
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System.out.println("hit rate: " + hit / req);
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}
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// for proper distributions later:
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// import JSci.maths.statistics.ProbabilityDistribution;
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// int key = (int) dist.inverse(random.nextDouble());
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}
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