nl.tue.gale.common.cache.Caches.java Source code

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Here is the source code for nl.tue.gale.common.cache.Caches.java

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/*
    
   This file is part of GALE (Generic Adaptation Language and Engine).
    
GALE is free software: you can redistribute it and/or modify it under the 
terms of the GNU Lesser General Public License as published by the Free 
Software Foundation, either version 3 of the License, or (at your option) 
any later version.
    
GALE is distributed in the hope that it will be useful, but WITHOUT ANY 
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for 
more details.
    
You should have received a copy of the GNU Lesser General Public License
along with GALE. If not, see <http://www.gnu.org/licenses/>.
    
 */
/**
 * Caches.java
 * Last modified: $Date$
 * In revision:   $Revision$
 * Modified by:   $Author$
 *
 * Copyright (c) 2008-2011 Eindhoven University of Technology.
 * All Rights Reserved.
 *
 * This software is proprietary information of the Eindhoven University
 * of Technology. It may be used according to the GNU LGPL license.
 */
package nl.tue.gale.common.cache;

import java.util.concurrent.TimeUnit;

import nl.tue.gale.common.uri.URI;

import com.google.common.base.Function;
import com.google.common.collect.MapMaker;

public final class Caches {
    private Caches() {
        throw new AssertionError();
    }

    public static <T> Cache<T> newFixedCache(int maxSize) {
        Cache<T> result = new ComputingMapCache<T>(new MapMaker().maximumSize(maxSize).<URI, T>makeMap(), null,
                null);
        return result;
    }

    public static <T> Cache<T> newCache(int maxSize) {
        Cache<T> result = new ComputingMapCache<T>(
                new MapMaker().maximumSize(maxSize).softValues().<URI, T>makeMap(), null, null);
        return result;
    }

    private static abstract class DelayedCacheFunction<T> implements Function<URI, T> {
        protected ComputingMapCache<T> cache = null;
    }

    public static <T> Cache<T> newCache(int maxSize, final CacheResolver<T> resolver, final T nullValue) {
        if (resolver == null)
            return newCache(maxSize);
        final DelayedCacheFunction<T> function = new DelayedCacheFunction<T>() {
            @Override
            public T apply(URI uri) {
                T result = resolver.get(uri, cache).get(uri);
                if (result == null)
                    return nullValue;
                return result;
            }
        };
        ComputingMapCache<T> result = new ComputingMapCache<T>(
                new MapMaker().maximumSize(maxSize).softValues().<URI, T>makeComputingMap(function), resolver,
                nullValue);
        function.cache = result;
        return result;
    }

    public static <T> Cache<T> newVolatileCache(int maxSize, long duration, TimeUnit unit) {
        Cache<T> result = new ComputingMapCache<T>(
                new MapMaker().maximumSize(maxSize).softValues().expireAfterWrite(duration, unit).<URI, T>makeMap(),
                null, null);
        return result;
    }

    public static <T> Cache<T> newVolatileCache(int maxSize, final CacheResolver<T> resolver, final T nullValue,
            long duration, TimeUnit unit) {
        if (resolver == null)
            return newVolatileCache(maxSize, duration, unit);
        final DelayedCacheFunction<T> function = new DelayedCacheFunction<T>() {
            @Override
            public T apply(URI uri) {
                T result = resolver.get(uri, cache).get(uri);
                if (result == null)
                    return nullValue;
                return result;
            }
        };
        ComputingMapCache<T> result = new ComputingMapCache<T>(new MapMaker().maximumSize(maxSize).softValues()
                .expireAfterWrite(duration, unit).<URI, T>makeComputingMap(function), resolver, nullValue);
        function.cache = result;
        return result;
    }
}