    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
    015package org.apache.tapestry5.services;
    016
    017import 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)
    035public 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}