001    package org.apache.jcs.utils.access;
002    
003    /*
004     * Licensed to the Apache Software Foundation (ASF) under one
005     * or more contributor license agreements.  See the NOTICE file
006     * distributed with this work for additional information
007     * regarding copyright ownership.  The ASF licenses this file
008     * to you under the Apache License, Version 2.0 (the
009     * "License"); you may not use this file except in compliance
010     * with the License.  You may obtain a copy of the License at
011     *
012     *   http://www.apache.org/licenses/LICENSE-2.0
013     *
014     * Unless required by applicable law or agreed to in writing,
015     * software distributed under the License is distributed on an
016     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017     * KIND, either express or implied.  See the License for the
018     * specific language governing permissions and limitations
019     * under the License.
020     */
021    
022    /**
023     * Interface for doing a piece of work which is expected to be cached. This is
024     * ment to be used in conjunction with JCSWorker.
025     * <p>
026     * Implement doWork() to return the work being done. isFinished() should return
027     * false until setFinished(true) is called, after which time it should return
028     * true.
029     * <p>
030     * @author tsavo
031     */
032    public interface JCSWorkerHelper
033    {
034        /**
035         * Tells us weather or not the work has been completed. This will be called
036         * automatically by JCSWorker. You should not call it yourself.
037         * <p>
038         * @return True if the work has allready been done, otherwise false.
039         */
040        public boolean isFinished();
041    
042        /**
043         * Sets weather or not the work has been done.
044         * <p>
045         * @param isFinished
046         *            True if the work has allready been done, otherwise false.
047         */
048        public void setFinished( boolean isFinished );
049    
050        /**
051         * The method to implement to do the work that should be cached. JCSWorker
052         * will call this itself! You should not call this directly.
053         * <p>
054         * @return The result of doing the work to be cached.
055         * @throws Exception
056         *             If anything goes wrong while doing the work, an Exception
057         *             should be thrown.
058         */
059        public Object doWork()
060            throws Exception;
061    }