CachedStoreFactory.java

/*
 * Distributed as part of mchange-commons-java 0.2.11
 *
 * Copyright (C) 2015 Machinery For Change, Inc.
 *
 * Author: Steve Waldman <swaldman@mchange.com>
 *
 * This library is free software; you can redistribute it and/or modify
 * it under the terms of EITHER:
 *
 *     1) The GNU Lesser General Public License (LGPL), version 2.1, as 
 *        published by the Free Software Foundation
 *
 * OR
 *
 *     2) The Eclipse Public License (EPL), version 1.0
 *
 * You may choose which license to accept if you wish to redistribute
 * or modify this work. You may offer derivatives of this work
 * under the license you have chosen, or you may provide the same
 * choice of license which you have been offered here.
 *
 * This software 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.
 *
 * You should have received copies of both LGPL v2.1 and EPL v1.0
 * along with this software; see the files LICENSE-EPL and LICENSE-LGPL.
 * If not, the text of these licenses are currently available at
 *
 * LGPL v2.1: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
 *  EPL v1.0: http://www.eclipse.org/org/documents/epl-v10.php 
 * 
 */

package com.mchange.v1.cachedstore;

import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.lang.reflect.InvocationHandler;

/**
 * Unless otherwise noted, implementations are to be presumed
 * NOT thread safe!!! use the synchronized
 * wrappers defined in CachedStoreUtils for multithreaded situations!
 *
 * @see CachedStoreUtils#synchronizedCachedStore
 * @see CachedStoreUtils#synchronizedTweakableCachedStore
 */
public final class CachedStoreFactory
{
    public static TweakableCachedStore createNoCleanupCachedStore(CachedStore.Manager manager)
    { return new NoCleanupCachedStore( manager ); }

    /**
     *  Better to use createSynchronousCleanupSoftKeyCachedStore to prevent the build of 
     *  cleaned SoftReferences, unless the universe of potential cacheables is small.
     */
    public static TweakableCachedStore createSoftValueCachedStore(CachedStore.Manager manager)
    { return new SoftReferenceCachedStore( manager ); }

    public static TweakableCachedStore createSynchronousCleanupSoftKeyCachedStore(CachedStore.Manager manager)
    { 
	final ManualCleanupSoftKeyCachedStore inner = new ManualCleanupSoftKeyCachedStore( manager ); 
	InvocationHandler handler = new InvocationHandler()
	    {
		public Object invoke(Object proxy, Method m, Object[] args) 
		    throws Throwable
		{
		    inner.vacuum();
		    return m.invoke( inner, args ); 
		}
	    };
	return (TweakableCachedStore) Proxy.newProxyInstance( CachedStoreFactory.class.getClassLoader(),
							      new Class[] { TweakableCachedStore.class },
							      handler );
    }

    /**
     *  Always reads directly from manager, as if values are always dirty.
     */
    public static TweakableCachedStore createNoCacheCachedStore( CachedStore.Manager mgr )
    { return new NoCacheCachedStore( mgr ); }

    /**
     * creates a WritableCachedStore implementation that uses soft keys and synchronous
     * cleanup for its read cache.
     */
    public static WritableCachedStore createDefaultWritableCachedStore(WritableCachedStore.Manager manager)
    {
	TweakableCachedStore readOnlyCache = createSynchronousCleanupSoftKeyCachedStore( manager );
	return new SimpleWritableCachedStore( readOnlyCache, manager );
    }

    public static WritableCachedStore cacheWritesOnlyWritableCachedStore( WritableCachedStore.Manager mgr )
    { 
	TweakableCachedStore readOnlyCache = createNoCacheCachedStore( mgr );
	return new SimpleWritableCachedStore( readOnlyCache, mgr );
    }

    /**
     *  Always reads directly from manager, as if values are always dirty. Always
     *  writes to back-end storage. Effectively Autoflushing, since every write
     *  is flushed.
     *
     *  @see Autoflushing 
     */
    public static WritableCachedStore createNoCacheWritableCachedStore( WritableCachedStore.Manager mgr )
    { return new NoCacheWritableCachedStore( mgr ); }
}