org.apache.commons.cache.Cache.java Source code

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Here is the source code for org.apache.commons.cache.Cache.java

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/*
 * Copyright 2001-2004 The Apache Software Foundation
 *
 * 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.apache.commons.cache;

import java.io.Serializable;

/**
 * A {@link Cache} defines an API for storing and later
 * retrieving {@link Object}s based upon key values.
 * <p>
 * A {@link Cache} supports an event subscription/publication
 * system.
 *
 * @version $Id: Cache.java 155435 2005-02-26 13:17:27Z dirkv $
 * @author Rodney Waldhoff
 */
public interface Cache extends Serializable {
    /**
     * Store the specified <i>val</i> under the specified
     * <i>key</i>.
     *
     * @param key the key used to later obtain the <i>val</i> from me,
     *            which MUST NOT be <tt>null</tt>.
     * @param val the val to store, which MUST NOT be <tt>null</tt>.
     * @param expiry the timestamp at which the given <i>val</i> becomes stale, or <tt>null</tt>.
     * @param cost the implemenation dependent cost of generating the <i>val</i>, or <tt>null</tt>.
     * @return <tt>true</tt> if the <i>val</i> was stored, <tt>false</tt> otherwise.
     */
    public boolean store(Serializable key, Serializable val, Long expiry, Long cost);

    /**
     * Store the specified <i>val</i> under the specified
     * <i>key</i> and the specified <i>group</i>.
     *
     * @param key the key used to later obtain the <i>val</i> from me,
     *            which MUST NOT be <tt>null</tt>.
     * @param group a meta-key which can be used to clear the object later
     * @param val the val to store, which MUST NOT be <tt>null</tt>.
     * @param expiry the timestamp at which the given <i>val</i> becomes stale, or <tt>null</tt>.
     * @param cost the implemenation dependent cost of generating the <i>val</i>, or <tt>null</tt>.
     * @return <tt>true</tt> if the <i>val</i> was stored, <tt>false</tt> otherwise.
     */
    public boolean store(Serializable key, Serializable val, Long expiry, Long cost, Serializable group);

    /**
     * Obtain the value previously {@link #store stored} under
     * the given <i>key</i>.
     *
     * @param key the key which MUST NOT be <tt>null</tt>.
     * @return the previously {@link #store stored} value, or <tt>null</tt>.
     */
    public Serializable retrieve(Serializable key);

    public Serializable[] getKeysForGroup(Serializable group);

    /**
     * Returns <tt>true</tt> if I have a value associated with
     * the given <i>key</i>, <tt>false</tt> otherwise.
     *
     * @param key the key which MUST NOT be <tt>null</tt>.
     * @return <tt>true</tt> if I have a value associated with
     *         the given <i>key</i>, <tt>false</tt> otherwise.
     */
    public boolean contains(Serializable key);

    /**
     * Remove any value previously {@link #store stored} under
     * the given <i>key</i>.
     *
     * @param key the key which MUST NOT be <tt>null</tt>.
     */
    public void clear(Serializable key);

    /**
     * Remove any value previously {@link #store stored} under
     * the given <i>group</i>.
     *
     * @param group the group which MUST NOT be <tt>null</tt>.
     */
    public void clearGroup(Serializable group);

    /**
     * Remove all values previously {@link #store stored}.
     */
    public void clear();

    /**
     * Add the given {@link StorageListener} to my
     * set of {@link StorageListener}s.
     * @link obs the observer to add
     */
    public abstract void registerStorageListener(StorageListener obs);

    /**
     * Remove the given {@link StorageListener} from my
     * set of {@link StorageListener}s.
     * @link obs the observer to remove
     */
    public abstract void unregisterStorageListener(StorageListener obs);

    /**
     * Clear my set of {@link StorageListener}s.
     */
    public abstract void unregisterStorageListeners();

    /**
     * Add the given {@link RetrievalListener} to my
     * set of {@link RetrievalListener}s.
     * @link obs the observer to add
     */
    public abstract void registerRetrievalListener(RetrievalListener obs);

    /**
     * Remove the given {@link RetrievalListener} from my
     * set of {@link RetrievalListener}s.
     * @link obs the observer to remove
     */
    public abstract void unregisterRetrievalListener(RetrievalListener obs);

    /**
     * Clear my set of {@link RetrievalListener}s.
     */
    public abstract void unregisterRetrievalListeners();

    public abstract long getStat(CacheStat stat) throws UnsupportedOperationException;
}