    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.services;
    014
    015import org.apache.tapestry5.commons.ObjectCreator;
    016import org.apache.tapestry5.ioc.Invokable;
    017
    018/**
    019 * Manages per-thread data, and provides a way for listeners to know when such data should be cleaned up. Typically,
    020 * data is cleaned up at the end of the request (in a web application). Tapestry IoC has any number of objects that need
    021 * to know when this event occurs, so that they can clean up any per-thread/per-request state.
    022 */
    023public interface PerthreadManager
    024{
    025    /**
    026     * Adds a listener to the hub. All listeners are discarded at the {@link #cleanup()}.
    027     *
    028     * @param listener
    029     *         to add
    030     * @deprecated Deprecated in 5.4, use {@link #addThreadCleanupCallback(Runnable)} instead.
    031     */
    032    void addThreadCleanupListener(ThreadCleanupListener listener);
    033
    034    /**
    035     * Adds a callback to be invoked when {@link #cleanup()} is invoked; callbacks are then removed.
    036     *
    037     * @param callback
    038     * @since 5.4
    039     */
    040    void addThreadCleanupCallback(Runnable callback);
    041
    042    /**
    043     * Immediately performs a cleanup of the thread, invoking all callback, then discarding all per-thread data
    044     * stored by the manager (including the list of callbacks).
    045     */
    046    void cleanup();
    047
    048    /**
    049     * Creates a value using a unique internal key.
    050     *
    051     * @since 5.2.0
    052     */
    053    <T> PerThreadValue<T> createValue();
    054
    055    /**
    056     * Return {@link ObjectCreator}, which for each thread,
    057     * the first call will use the delegate {@link ObjectCreator} to create
    058     * an instance, and later calls will reuse the same per-thread instance. The instance is stored in the
    059     * {@link org.apache.tapestry5.ioc.services.PerthreadManager} and will be released at the end of the request.
    060     *
    061     * @since 5.4
    062     */
    063    <T> ObjectCreator<T> createValue(ObjectCreator<T> delegate);
    064
    065    /**
    066     * Invokes {@link Runnable#run()}, providing a try...finally to {@linkplain #cleanup() cleanup} after.
    067     *
    068     * @since 5.2.0
    069     */
    070    void run(Runnable runnable);
    071
    072    /**
    073     * Returns the result from the invocation, providing a try...finally to {@linkplain #cleanup() cleanup} after.
    074     */
    075    <T> T invoke(Invokable<T> invokable);
    076}