com.isotrol.impe3.pms.core.support.LoaderCaches.java Source code

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Here is the source code for com.isotrol.impe3.pms.core.support.LoaderCaches.java

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/**
 * This file is part of Port@l
 * Port@l 3.0 - Portal Engine and Management System
 * Copyright (C) 2010  Isotrol, SA.  http://www.isotrol.com
 *
 * Port@l is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Port@l 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Port@l.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.isotrol.impe3.pms.core.support;

import java.util.concurrent.TimeUnit;

import com.google.common.base.Function;
import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;

/**
 * Loaders cache support methods.
 * @author Andres Rodriguez
 */
public final class LoaderCaches {
    /** Collection maximum size. */
    private static final long COLLECTION_SIZE = 32L;
    /** Collection expiration. */
    private static final long COLLECTION_HOURS = 1L;
    /** Instance maximum size. */
    private static final long INSTANCE_SIZE = 4096L;
    /** Instance expiration. */
    private static final long INSTANCE_HOURS = 24L;

    /** Not instantiable. */
    private LoaderCaches() {
        throw new AssertionError();
    }

    private static CacheBuilder<Object, Object> builder(long maximumSize, long hours) {
        return CacheBuilder.newBuilder().maximumSize(maximumSize).softValues().expireAfterAccess(hours * 3600L,
                TimeUnit.SECONDS);
    }

    private static CacheBuilder<Object, Object> builder() {
        return builder(COLLECTION_SIZE, COLLECTION_HOURS);
    }

    public static <K, V> Cache<K, V> create(long maximumSize, long hours) {
        return builder(maximumSize, hours).build();
    }

    public static <K, V> Cache<K, V> collection() {
        return create(COLLECTION_SIZE, COLLECTION_HOURS);
    }

    public static <K, V> Cache<K, V> instance() {
        return create(INSTANCE_SIZE, INSTANCE_HOURS);
    }

    public static <K, V> LoadingCache<K, V> create(long maximumSize, long hours, CacheLoader<? super K, V> loader) {
        return builder(maximumSize, hours).build(loader);
    }

    public static <K, V> LoadingCache<K, V> collection(CacheLoader<? super K, V> loader) {
        return create(COLLECTION_SIZE, COLLECTION_HOURS, loader);
    }

    public static <K, V> LoadingCache<K, V> create(long maximumSize, long hours, Function<? super K, V> computer) {
        return builder().build(CacheLoader.from(computer));
    }

    public static <K, V> LoadingCache<K, V> collection(Function<? super K, V> computer) {
        return create(COLLECTION_SIZE, COLLECTION_HOURS, computer);
    }
}