001    // Copyright 2008, 2011 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5;
016    
017    /**
018     * An optional interface implemented by objects that are persisted in the {@link org.apache.tapestry5.services.Session}.
019     * At the end of each request, any objects read from the session are re-stored into the session, to ensure that
020     * in-memory changes are flushed to other persistent session stores (e.g. RDBMS, servers in a cluster, etc). Objects
021     * that implement this interface are expected to track when they are dirty (have pending changes), so that the save
022     * back into the session can be avoided when not necessary.
023     * <p>
024     * This method is accessed concurrently.
025     *
026     * @see org.apache.tapestry5.annotations.ImmutableSessionPersistedObject
027     * @see org.apache.tapestry5.services.SessionPersistedObjectAnalyzer
028     * @since 5.1.1.0
029     */
030    public interface OptimizedSessionPersistedObject
031    {
032        /**
033         * @return true if the object has in-memory changes since the last time this method was called.
034         */
035        boolean checkAndResetDirtyMarker();
036    }