org.arbeitspferde.friesian.ConfigurableMapMakerCache.java Source code

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Here is the source code for org.arbeitspferde.friesian.ConfigurableMapMakerCache.java

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/* Copyright 2012 Google, 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 org.arbeitspferde.friesian;

import com.google.common.base.Preconditions;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheBuilderSpec;

import java.util.concurrent.ConcurrentMap;
import java.util.logging.Logger;

import javax.annotation.Nullable;

/**
 * Build an in-memory cache subject to {@link CacheBuilderSpec} definitions.
 *
 * @param <T> The type of objects that this cache can hold.
 */
public class ConfigurableMapMakerCache<T> implements Cache<T> {
    private static final Logger log = Logger.getLogger(ConfigurableMapMakerCache.class.getCanonicalName());
    private final ConcurrentMap<Integer, T> backingMap;

    public ConfigurableMapMakerCache(final CacheBuilderSpec specification) throws IllegalArgumentException {
        Preconditions.checkNotNull(specification, "specification may not be null.");
        Preconditions.checkArgument(!specification.toParsableString().isEmpty(), "specification may not be empty.");

        backingMap = CacheBuilder.from(specification).<Integer, T>build().asMap();

        log.info(String.format("Created map with %s specification.", specification));
    }

    @Override
    public int getCacheSize() {
        return backingMap.size();
    }

    @Override
    public void update(final int index, final T data) throws IndexOutOfBoundsException {
        Preconditions.checkArgument(index >= 0, "index must be zero or greater.");
        Preconditions.checkNotNull(data, "data may not be null.");

        backingMap.put(index, data);
    }

    @Override
    @Nullable
    public T get(final int index) {
        Preconditions.checkArgument(index >= 0, "index must be zero or greater.");

        return backingMap.get(index);
    }
}