1 package org.sonatype.aether;
2
3 /*******************************************************************************
4 * Copyright (c) 2010-2011 Sonatype, Inc.
5 * All rights reserved. This program and the accompanying materials
6 * are made available under the terms of the Eclipse Public License v1.0
7 * which accompanies this distribution, and is available at
8 * http://www.eclipse.org/legal/epl-v10.html
9 *******************************************************************************/
10
11 /**
12 * A container for data that is specific to a repository system session. Both components within the repository system
13 * and clients of the system may use this storage to associate arbitrary data with a session. Unlike a cache, this
14 * session data is not subject to purging. For this same reason, session data should also not be abused as a cache (i.e.
15 * for storing values that can be re-calculated) to avoid memory exhaustion. <strong>Note:</strong> Actual
16 * implementations must be thread-safe.
17 *
18 * @author Benjamin Bentmann
19 * @see RepositorySystemSession#getData()
20 */
21 public interface SessionData
22 {
23
24 /**
25 * Associates the specified session data with the given key.
26 *
27 * @param key The key under which to store the session data, must not be {@code null}.
28 * @param value The data to associate with the key, may be {@code null} to remove the mapping.
29 */
30 void set( Object key, Object value );
31
32 /**
33 * Associates the specified session data with the given key if the key is currently mapped to the given value. This
34 * method provides an atomic compare-and-update of some key's value.
35 *
36 * @param key The key under which to store the session data, must not be {@code null}.
37 * @param oldValue The expected data currently associated with the key, may be {@code null}.
38 * @param newValue The data to associate with the key, may be {@code null} to remove the mapping.
39 * @return {@code true} if the key mapping was updated to the specified value, {@code false} if the current key
40 * mapping didn't match the expected value and was not updated.
41 */
42 boolean set( Object key, Object oldValue, Object newValue );
43
44 /**
45 * Gets the session data associated with the specified key.
46 *
47 * @param key The key for which to retrieve the session data, must not be {@code null}.
48 * @return The session data associated with the key or {@code null} if none.
49 */
50 Object get( Object key );
51
52 }