    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.ioc;
    014
    015import org.apache.tapestry5.ioc.annotations.EagerLoad;
    016import org.apache.tapestry5.services.UpdateListenerHub;
    017
    018/**
    019 * Optional interface that may be implemented by a service implementation (or even
    020 * a {@linkplain ObjectLocator#proxy(Class, Class) proxy} to give the service implementation
    021 * more control over its lifecyle.
    022 *
    023 * @since 5.2.2
    024 */
    025public interface ReloadAware
    026{
    027    /**
    028     * Invoked when Tapestry {@linkplain UpdateListenerHub#fireCheckForUpdates() notices
    029     * that the implementation class has changed}. The existing instance is notified, so that
    030     * it can cleanly shutdown now, before being re-instantiated. This is necessary when the
    031     * service implementation retains some form of external resources.
    032     *
    033     * In addition, the implementation may request an immediate reload. Normally, reloading of the service is deferred
    034     * until a method of the proxy object is invoked (this causes the normal just-in-time instantiation of the
    035     * implementation). When this method returns true, the implementation is re-created immediately. This is most often
    036     * the case for services that are {@linkplain EagerLoad eagerly loaded} in the first place.
    037     *
    038     * @return true if the service should be reloaded immediately, false if reload should be deferred
    039     */
    040    boolean shutdownImplementationForReload();
    041}