com.github.benmanes.caffeine.cache.simulator.policy.sketch.tinycache.WindowTinyCachePolicy.java Source code

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Here is the source code for com.github.benmanes.caffeine.cache.simulator.policy.sketch.tinycache.WindowTinyCachePolicy.java

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/*
 * Copyright 2015 Gilga Einziger. 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.policy.sketch.tinycache;

import java.util.Set;

import com.github.benmanes.caffeine.cache.simulator.BasicSettings;
import com.github.benmanes.caffeine.cache.simulator.admission.tinycache.TinyCache;
import com.github.benmanes.caffeine.cache.simulator.admission.tinycache.TinyCacheWithGhostCache;
import com.github.benmanes.caffeine.cache.simulator.policy.Policy;
import com.github.benmanes.caffeine.cache.simulator.policy.PolicyStats;
import com.google.common.collect.ImmutableSet;
import com.typesafe.config.Config;

/**
 * @author gilga1983@gmail.com (Gil Einziger)
 */
public final class WindowTinyCachePolicy implements Policy {
    private final TinyCache window;
    private final PolicyStats policyStats;
    private final TinyCacheWithGhostCache tinyCache;

    public WindowTinyCachePolicy(Config config) {
        BasicSettings settings = new BasicSettings(config);
        this.policyStats = new PolicyStats("sketch.WindowTinyCache");
        int maxSize = settings.maximumSize();
        if (maxSize <= 64) {
            window = null;
        } else {
            maxSize -= 64;
            window = new TinyCache(1, 64, 0);
        }
        tinyCache = new TinyCacheWithGhostCache((int) Math.ceil(maxSize / 64.0), 64, settings.randomSeed());
    }

    /** Returns all variations of this policy based on the configuration parameters. */
    public static Set<Policy> policies(Config config) {
        return ImmutableSet.of(new WindowTinyCachePolicy(config));
    }

    @Override
    public void record(long key) {
        if (tinyCache.contains(key) || ((window != null) && window.contains(key))) {
            tinyCache.recordItem(key);
            policyStats.recordHit();
        } else {
            boolean evicted = tinyCache.addItem(key);
            if (!evicted && (window != null)) {
                evicted = window.addItem(key);
            }
            tinyCache.recordItem(key);
            policyStats.recordMiss();
            if (evicted) {
                policyStats.recordEviction();
            }
        }
    }

    @Override
    public PolicyStats stats() {
        return policyStats;
    }
}