/*
* Copyright 2015 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.cache.simulator.admission;
import com.clearspring.analytics.stream.frequency.CountMin64TinyLfu;
import com.github.benmanes.caffeine.cache.simulator.BasicSettings;
import com.github.benmanes.caffeine.cache.simulator.admission.countmin4.AdaptiveResetCountMin4;
import com.github.benmanes.caffeine.cache.simulator.admission.countmin4.IncrementalResetCountMin4;
import com.github.benmanes.caffeine.cache.simulator.admission.countmin4.PeriodicResetCountMin4;
import com.github.benmanes.caffeine.cache.simulator.admission.perfect.PerfectFrequency;
import com.github.benmanes.caffeine.cache.simulator.admission.table.RandomRemovalFrequencyTable;
import com.github.benmanes.caffeine.cache.simulator.admission.tinycache.TinyCacheAdapter;
import com.github.benmanes.caffeine.cache.simulator.policy.PolicyStats;
import com.typesafe.config.Config;
/**
* Admits new entries based on the estimated frequency of its historic use.
*
* @author ben.manes@gmail.com (Ben Manes)
*/
public final class TinyLfu implements Admittor {
private final PolicyStats policyStats;
private final Frequency sketch;
public TinyLfu(Config config, PolicyStats policyStats) {
this.policyStats = policyStats;
this.sketch = makeSketch(config);
}
private Frequency makeSketch(Config config) {
BasicSettings settings = new BasicSettings(config);
String type = settings.tinyLfu().sketch();
if (type.equalsIgnoreCase("count-min-4")) {
String reset = settings.tinyLfu().countMin4().reset();
if (reset.equalsIgnoreCase("periodic")) {
return new PeriodicResetCountMin4(config);
} else if (reset.equalsIgnoreCase("incremental")) {
return new IncrementalResetCountMin4(config);
} else if (reset.equalsIgnoreCase("adaptive")) {
return new AdaptiveResetCountMin4(config);
}
} else if (type.equalsIgnoreCase("count-min-64")) {
return new CountMin64TinyLfu(config);
} else if (type.equalsIgnoreCase("random-table")) {
return new RandomRemovalFrequencyTable(config);
} else if (type.equalsIgnoreCase("tiny-table")) {
return new TinyCacheAdapter(config);
} else if (type.equalsIgnoreCase("perfect-table")) {
return new PerfectFrequency(config);
}
throw new IllegalStateException("Unknown sketch type: " + type);
}
public int frequency(long key) {
return sketch.frequency(key);
}
@Override
public void record(long key) {
sketch.increment(key);
}
@Override
public boolean admit(long candidateKey, long victimKey) {
sketch.reportMiss();
long candidateFreq = sketch.frequency(candidateKey);
long victimFreq = sketch.frequency(victimKey);
if (candidateFreq > victimFreq) {
policyStats.recordAdmission();
return true;
}
policyStats.recordRejection();
return false;
}
}