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