1 /*******************************************************************************
2 * Copyright (c) 2010, 2014 Sonatype, Inc.
3 * All rights reserved. This program and the accompanying materials
4 * are made available under the terms of the Eclipse Public License v1.0
5 * which accompanies this distribution, and is available at
6 * http://www.eclipse.org/legal/epl-v10.html
7 *
8 * Contributors:
9 * Sonatype, Inc. - initial API and implementation
10 *******************************************************************************/
11 package org.eclipse.aether;
12
13 /**
14 * A container for data that is specific to a repository system session. Both components within the repository system
15 * and clients of the system may use this storage to associate arbitrary data with a session.
16 * <p>
17 * Unlike a cache, this session data is not subject to purging. For this same reason, session data should also not be
18 * abused as a cache (i.e. for storing values that can be re-calculated) to avoid memory exhaustion.
19 * <p>
20 * <strong>Note:</strong> Actual implementations must be thread-safe.
21 *
22 * @see RepositorySystemSession#getData()
23 * @noimplement This interface is not intended to be implemented by clients.
24 * @noextend This interface is not intended to be extended by clients.
25 */
26 public interface SessionData
27 {
28
29 /**
30 * Associates the specified session data with the given key.
31 *
32 * @param key The key under which to store the session data, must not be {@code null}.
33 * @param value The data to associate with the key, may be {@code null} to remove the mapping.
34 */
35 void set( Object key, Object value );
36
37 /**
38 * Associates the specified session data with the given key if the key is currently mapped to the given value. This
39 * method provides an atomic compare-and-update of some key's value.
40 *
41 * @param key The key under which to store the session data, must not be {@code null}.
42 * @param oldValue The expected data currently associated with the key, may be {@code null}.
43 * @param newValue The data to associate with the key, may be {@code null} to remove the mapping.
44 * @return {@code true} if the key mapping was successfully updated from the old value to the new value,
45 * {@code false} if the current key mapping didn't match the expected value and was not updated.
46 */
47 boolean set( Object key, Object oldValue, Object newValue );
48
49 /**
50 * Gets the session data associated with the specified key.
51 *
52 * @param key The key for which to retrieve the session data, must not be {@code null}.
53 * @return The session data associated with the key or {@code null} if none.
54 */
55 Object get( Object key );
56
57 }