    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.ioc.Invokable;
    016import org.apache.tapestry5.ioc.ObjectCreator;
    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 * <p/>
    023 * Due to <a href="https://issues.apache.org/jira/browse/TAPESTRY-2141">TAPESTRY-2141<a> (and the underlying JDK 1.5 bug
    024 * <a href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5025230">5025230</a>), this service has expanded to
    025 * manage per-thread data (not just end-of-request listeners).
    026 */
    027public interface PerthreadManager
    028{
    029    /**
    030     * Adds a listener to the hub. All listeners are discarded at the {@link #cleanup()}.
    031     *
    032     * @param listener
    033     *         to add
    034     * @deprecated Deprecated in 5.4, use {@link #addThreadCleanupCallback(Runnable)} instead.
    035     */
    036    void addThreadCleanupListener(ThreadCleanupListener listener);
    037
    038    /**
    039     * Adds a callback to be invoked when {@link #cleanup()} is invoked; callbacks are then removed.
    040     *
    041     * @param callback
    042     * @since 5.4
    043     */
    044    void addThreadCleanupCallback(Runnable callback);
    045
    046    /**
    047     * Immediately performs a cleanup of the thread, invoking all callback, then discarding all per-thread data
    048     * stored by the manager (including the list of callbacks).
    049     */
    050    void cleanup();
    051
    052    /**
    053     * Creates a value using a unique internal key.
    054     *
    055     * @since 5.2.0
    056     */
    057    <T> PerThreadValue<T> createValue();
    058
    059    /**
    060     * Return {@link org.apache.tapestry5.ioc.ObjectCreator}, which for each thread,
    061     * the first call will use the delegate {@link org.apache.tapestry5.ioc.ObjectCreator} to create
    062     * an instance, and later calls will reuse the same per-thread instance. The instance is stored in the
    063     * {@link org.apache.tapestry5.ioc.services.PerthreadManager} and will be released at the end of the request.
    064     *
    065     * @since 5.4
    066     */
    067    <T> ObjectCreator<T> createValue(ObjectCreator<T> delegate);
    068
    069    /**
    070     * Invokes {@link Runnable#run()}, providing a try...finally to {@linkplain #cleanup() cleanup} after.
    071     *
    072     * @since 5.2.0
    073     */
    074    void run(Runnable runnable);
    075
    076    /**
    077     * Returns the result from the invocation, providing a try...finally to {@linkplain #cleanup() cleanup} after.
    078     */
    079    <T> T invoke(Invokable<T> invokable);
    080}