com.nesscomputing.cache.NonEvictingJvmCacheProvider.java Source code

Introduction

Here is the source code for com.nesscomputing.cache.NonEvictingJvmCacheProvider.java

Source

/**
 * Copyright (C) 2012 Ness Computing, Inc.
 *
 * 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.nesscomputing.cache;

import java.util.Collection;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentMap;

import javax.annotation.Nullable;

import com.google.common.collect.Maps;
import com.google.inject.Singleton;

import com.nesscomputing.logging.Log;

/** An in JVM cache that does not evict its keys due to memory pressure.
 *
 * Note: once ehcache 2.5 is released this can be implemented as a subclass of JvmCacheProvider with pinning in ehcache.
 *
 * @author christopher
 *
 */
@Singleton
public class NonEvictingJvmCacheProvider implements InternalCacheProvider {
    private final static Log LOG = Log.findLog();
    private final ConcurrentMap<Map.Entry<String, String>, byte[]> map = Maps.newConcurrentMap();

    @Override
    public void set(String namespace, Collection<CacheStore<byte[]>> stores,
            @Nullable CacheStatistics cacheStatistics) {
        for (CacheStore<byte[]> entry : stores) {
            LOG.trace("%s setting %s:%s", this, namespace, entry.getKey());
            Entry<String, String> key = Maps.immutableEntry(namespace, entry.getKey());
            byte[] value = entry.getData();
            if (value != null) {
                map.put(key, value);
            } else {
                map.remove(key);
            }
        }
    }

    @Override
    public Map<String, byte[]> get(String namespace, Collection<String> keys,
            @Nullable CacheStatistics cacheStatistics) {
        Map<String, byte[]> ret = Maps.newHashMap();
        for (String key : keys) {
            byte[] data = map.get(Maps.immutableEntry(namespace, key));
            LOG.trace("%s getting %s:%s=%s", this, namespace, key, data);
            if (data != null) {
                ret.put(key, data);
            }
        }
        return ret;
    }

    @Override
    public void clear(String namespace, Collection<String> keys, @Nullable CacheStatistics cacheStatistics) {
        for (String key : keys) {
            LOG.trace("%s clearing %s:%s", this, namespace, key);
            map.remove(Maps.immutableEntry(namespace, key));
        }
    }

    @Override
    public Map<String, Boolean> add(String namespace, Collection<CacheStore<byte[]>> stores,
            @Nullable CacheStatistics cacheStatistics) {
        final Map<String, Boolean> result = Maps.newHashMap();

        for (CacheStore<byte[]> entry : stores) {
            LOG.trace("%s setting %s:%s", this, namespace, entry.getKey());
            Entry<String, String> key = Maps.immutableEntry(namespace, entry.getKey());
            byte[] data = entry.getData();
            byte[] old;
            if (data != null) {
                old = map.putIfAbsent(key, data);
            } else {
                old = null;
            }
            result.put(entry.getKey(), old == null);
        }
        return result;
    }
}