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}