    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.services;
    016
    017    import org.apache.tapestry5.ioc.annotations.UsesMappedConfiguration;
    018
    019    /**
    020     * Analyzes a session-persisted object, specifically to see if it is dirty or not.
    021     * <p/>
    022     * This service is provided to support applications which store mutable session attributes where the
    023     * session is replicated to a slower medium (e.g. RDMBS, Cluster, etc) this can help alleviate excessive writes
    024     * to the session store while ensuring changes are propagated.
    025     * <p/>
    026     * The service implementation uses a mapped configuration to form a
    027     * {@linkplain org.apache.tapestry5.ioc.services.StrategyBuilder strategy} based on object type. The service may be
    028     * injected using the {@link org.apache.tapestry5.ioc.annotations.Primary} marker annotation.
    029     *
    030     * @see org.apache.tapestry5.annotations.ImmutableSessionPersistedObject
    031     * @see org.apache.tapestry5.OptimizedSessionPersistedObject
    032     * @since 5.1.0.0
    033     */
    034    @UsesMappedConfiguration(key = Class.class, value = SessionPersistedObjectAnalyzer.class)
    035    public interface SessionPersistedObjectAnalyzer<T>
    036    {
    037        /**
    038         * Atomically check and reset the dirty state of the session persisted object.
    039         * <p/>
    040         * The implementer should take consideration for the fact that session attributes are accessed concurrently. A
    041         * naive check/set algorithm may allow changes to go un-noticed.
    042         *
    043         * @param sessionPersistedObject the session attribute (never null)
    044         * @return true if the object needs to be re-stored into the session
    045         * @since 5.3
    046         */
    047        boolean checkAndResetDirtyState(T sessionPersistedObject);
    048
    049    }