io.druid.client.cache.HybridCache.java Source code

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Here is the source code for io.druid.client.cache.HybridCache.java

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/*
 * Licensed to Metamarkets Group Inc. (Metamarkets) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  Metamarkets licenses this file
 * to you 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 io.druid.client.cache;

import com.google.common.collect.Maps;
import com.google.common.collect.Sets;
import com.metamx.emitter.service.ServiceEmitter;

import java.util.Map;
import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;

public class HybridCache implements Cache {
    private final Cache level1;
    private final Cache level2;

    private final AtomicLong hitCount = new AtomicLong(0);
    private final AtomicLong missCount = new AtomicLong(0);

    public HybridCache(Cache level1, Cache level2) {
        this.level1 = level1;
        this.level2 = level2;
    }

    @Override
    public byte[] get(NamedKey key) {
        byte[] res = level1.get(key);
        if (res == null) {
            res = level2.get(key);
            if (res != null) {
                level1.put(key, res);
                hitCount.incrementAndGet();
                return res;
            }
            missCount.incrementAndGet();
        }
        if (res != null) {
            hitCount.incrementAndGet();
        }
        return res;
    }

    @Override
    public void put(NamedKey key, byte[] value) {
        level1.put(key, value);
        level2.put(key, value);
    }

    @Override
    public Map<NamedKey, byte[]> getBulk(Iterable<NamedKey> keys) {
        Set<NamedKey> remaining = Sets.newHashSet(keys);
        Map<NamedKey, byte[]> res = level1.getBulk(keys);
        hitCount.addAndGet(res.size());

        remaining = Sets.difference(remaining, res.keySet());

        if (!remaining.isEmpty()) {
            Map<NamedKey, byte[]> res2 = level2.getBulk(remaining);
            for (Map.Entry<NamedKey, byte[]> entry : res2.entrySet()) {
                level1.put(entry.getKey(), entry.getValue());
            }

            int size = res2.size();
            hitCount.addAndGet(size);
            missCount.addAndGet(remaining.size() - size);

            if (size != 0) {
                res = Maps.newHashMap(res);
                res.putAll(res2);
            }
        }
        return res;
    }

    @Override
    public void close(String namespace) {
        level1.close(namespace);
        level2.close(namespace);
    }

    @Override
    public CacheStats getStats() {
        CacheStats stats1 = level1.getStats();
        CacheStats stats2 = level2.getStats();
        return new CacheStats(hitCount.get(), missCount.get(), stats1.getNumEntries() + stats2.getNumEntries(),
                stats1.getSizeInBytes() + stats2.getSizeInBytes(),
                stats1.getNumEvictions() + stats2.getNumEvictions(),
                stats1.getNumTimeouts() + stats2.getNumTimeouts(), stats1.getNumErrors() + stats2.getNumErrors());
    }

    @Override
    public boolean isLocal() {
        return level1.isLocal() && level2.isLocal();
    }

    @Override
    public void doMonitor(ServiceEmitter emitter) {
        level1.doMonitor(emitter);
        level2.doMonitor(emitter);
    }
}