util/concurrent/ConcurrentMap.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 */

package java.util.concurrent;
import java.util.Map;

/**
 * A {@link java.util.Map} providing additional atomic
 * <tt>putIfAbsent</tt>, <tt>remove</tt>, and <tt>replace</tt> methods.
 *
 * <p>Memory consistency effects: As with other concurrent
 * collections, actions in a thread prior to placing an object into a
 * {@code ConcurrentMap} as a key or value
 * <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a>
 * actions subsequent to the access or removal of that object from
 * the {@code ConcurrentMap} in another thread.
 *
 * <p>This interface is a member of the
 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
 * Java Collections Framework</a>.
 *
 * @since 1.5
 * @author Doug Lea
 * @param <K> the type of keys maintained by this map
 * @param <V> the type of mapped values
 */
public interface ConcurrentMap<K, V> extends Map<K, V> {
    /**
     * If the specified key is not already associated
     * with a value, associate it with the given value.
     * This is equivalent to
     *  <pre> {@code
     * if (!map.containsKey(key))
     *   return map.put(key, value);
     * else
     *   return map.get(key);}</pre>
     *
     * except that the action is performed atomically.
     *
     * @param key key with which the specified value is to be associated
     * @param value value to be associated with the specified key
     * @return the previous value associated with the specified key, or
     *         <tt>null</tt> if there was no mapping for the key.
     *         (A <tt>null</tt> return can also indicate that the map
     *         previously associated <tt>null</tt> with the key,
     *         if the implementation supports null values.)
     * @throws UnsupportedOperationException if the <tt>put</tt> operation
     *         is not supported by this map
     * @throws ClassCastException if the class of the specified key or value
     *         prevents it from being stored in this map
     * @throws NullPointerException if the specified key or value is null,
     *         and this map does not permit null keys or values
     * @throws IllegalArgumentException if some property of the specified key
     *         or value prevents it from being stored in this map
     */
    V putIfAbsent(K key, V value);

    /**
     * Removes the entry for a key only if currently mapped to a given value.
     * This is equivalent to
     *  <pre> {@code
     * if (map.containsKey(key) && map.get(key).equals(value)) {
     *   map.remove(key);
     *   return true;
     * } else
     *   return false;}</pre>
     *
     * except that the action is performed atomically.
     *
     * @param key key with which the specified value is associated
     * @param value value expected to be associated with the specified key
     * @return <tt>true</tt> if the value was removed
     * @throws UnsupportedOperationException if the <tt>remove</tt> operation
     *         is not supported by this map
     * @throws ClassCastException if the key or value is of an inappropriate
     *         type for this map
     *         (<a href="../Collection.html#optional-restrictions">optional</a>)
     * @throws NullPointerException if the specified key or value is null,
     *         and this map does not permit null keys or values
     *         (<a href="../Collection.html#optional-restrictions">optional</a>)
     */
    boolean remove(Object key, Object value);

    /**
     * Replaces the entry for a key only if currently mapped to a given value.
     * This is equivalent to
     *  <pre> {@code
     * if (map.containsKey(key) && map.get(key).equals(oldValue)) {
     *   map.put(key, newValue);
     *   return true;
     * } else
     *   return false;}</pre>
     *
     * except that the action is performed atomically.
     *
     * @param key key with which the specified value is associated
     * @param oldValue value expected to be associated with the specified key
     * @param newValue value to be associated with the specified key
     * @return <tt>true</tt> if the value was replaced
     * @throws UnsupportedOperationException if the <tt>put</tt> operation
     *         is not supported by this map
     * @throws ClassCastException if the class of a specified key or value
     *         prevents it from being stored in this map
     * @throws NullPointerException if a specified key or value is null,
     *         and this map does not permit null keys or values
     * @throws IllegalArgumentException if some property of a specified key
     *         or value prevents it from being stored in this map
     */
    boolean replace(K key, V oldValue, V newValue);

    /**
     * Replaces the entry for a key only if currently mapped to some value.
     * This is equivalent to
     *  <pre> {@code
     * if (map.containsKey(key)) {
     *   return map.put(key, value);
     * } else
     *   return null;}</pre>
     *
     * except that the action is performed atomically.
     *
     * @param key key with which the specified value is associated
     * @param value value to be associated with the specified key
     * @return the previous value associated with the specified key, or
     *         <tt>null</tt> if there was no mapping for the key.
     *         (A <tt>null</tt> return can also indicate that the map
     *         previously associated <tt>null</tt> with the key,
     *         if the implementation supports null values.)
     * @throws UnsupportedOperationException if the <tt>put</tt> operation
     *         is not supported by this map
     * @throws ClassCastException if the class of the specified key or value
     *         prevents it from being stored in this map
     * @throws NullPointerException if the specified key or value is null,
     *         and this map does not permit null keys or values
     * @throws IllegalArgumentException if some property of the specified key
     *         or value prevents it from being stored in this map
     */
    V replace(K key, V value);
}
Revision:	1.1
Committed:	Sun Dec 16 20:55:15 2012 UTC (11 years, 5 months ago) by dl
Branch:	MAIN
Log Message:	Create src/jdk7 package
#	User	Rev	Content
1	dl	1.1	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3			* Expert Group and released to the public domain, as explained at
4			* http://creativecommons.org/publicdomain/zero/1.0/
5			*/
6
7			package java.util.concurrent;
8			import java.util.Map;
9
10			/**
11			* A {@link java.util.Map} providing additional atomic
12			* <tt>putIfAbsent</tt>, <tt>remove</tt>, and <tt>replace</tt> methods.
13			*
14			* <p>Memory consistency effects: As with other concurrent
15			* collections, actions in a thread prior to placing an object into a
16			* {@code ConcurrentMap} as a key or value
17			* <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a>
18			* actions subsequent to the access or removal of that object from
19			* the {@code ConcurrentMap} in another thread.
20			*
21			* <p>This interface is a member of the
22			* <a href="{@docRoot}/../technotes/guides/collections/index.html">
23			* Java Collections Framework</a>.
24			*
25			* @since 1.5
26			* @author Doug Lea
27			* @param <K> the type of keys maintained by this map
28			* @param <V> the type of mapped values
29			*/
30			public interface ConcurrentMap<K, V> extends Map<K, V> {
31			/**
32			* If the specified key is not already associated
33			* with a value, associate it with the given value.
34			* This is equivalent to
35			* <pre> {@code
36			* if (!map.containsKey(key))
37			* return map.put(key, value);
38			* else
39			* return map.get(key);}</pre>
40			*
41			* except that the action is performed atomically.
42			*
43			* @param key key with which the specified value is to be associated
44			* @param value value to be associated with the specified key
45			* @return the previous value associated with the specified key, or
46			* <tt>null</tt> if there was no mapping for the key.
47			* (A <tt>null</tt> return can also indicate that the map
48			* previously associated <tt>null</tt> with the key,
49			* if the implementation supports null values.)
50			* @throws UnsupportedOperationException if the <tt>put</tt> operation
51			* is not supported by this map
52			* @throws ClassCastException if the class of the specified key or value
53			* prevents it from being stored in this map
54			* @throws NullPointerException if the specified key or value is null,
55			* and this map does not permit null keys or values
56			* @throws IllegalArgumentException if some property of the specified key
57			* or value prevents it from being stored in this map
58			*/
59			V putIfAbsent(K key, V value);
60
61			/**
62			* Removes the entry for a key only if currently mapped to a given value.
63			* This is equivalent to
64			* <pre> {@code
65			* if (map.containsKey(key) && map.get(key).equals(value)) {
66			* map.remove(key);
67			* return true;
68			* } else
69			* return false;}</pre>
70			*
71			* except that the action is performed atomically.
72			*
73			* @param key key with which the specified value is associated
74			* @param value value expected to be associated with the specified key
75			* @return <tt>true</tt> if the value was removed
76			* @throws UnsupportedOperationException if the <tt>remove</tt> operation
77			* is not supported by this map
78			* @throws ClassCastException if the key or value is of an inappropriate
79			* type for this map
80			* (<a href="../Collection.html#optional-restrictions">optional</a>)
81			* @throws NullPointerException if the specified key or value is null,
82			* and this map does not permit null keys or values
83			* (<a href="../Collection.html#optional-restrictions">optional</a>)
84			*/
85			boolean remove(Object key, Object value);
86
87			/**
88			* Replaces the entry for a key only if currently mapped to a given value.
89			* This is equivalent to
90			* <pre> {@code
91			* if (map.containsKey(key) && map.get(key).equals(oldValue)) {
92			* map.put(key, newValue);
93			* return true;
94			* } else
95			* return false;}</pre>
96			*
97			* except that the action is performed atomically.
98			*
99			* @param key key with which the specified value is associated
100			* @param oldValue value expected to be associated with the specified key
101			* @param newValue value to be associated with the specified key
102			* @return <tt>true</tt> if the value was replaced
103			* @throws UnsupportedOperationException if the <tt>put</tt> operation
104			* is not supported by this map
105			* @throws ClassCastException if the class of a specified key or value
106			* prevents it from being stored in this map
107			* @throws NullPointerException if a specified key or value is null,
108			* and this map does not permit null keys or values
109			* @throws IllegalArgumentException if some property of a specified key
110			* or value prevents it from being stored in this map
111			*/
112			boolean replace(K key, V oldValue, V newValue);
113
114			/**
115			* Replaces the entry for a key only if currently mapped to some value.
116			* This is equivalent to
117			* <pre> {@code
118			* if (map.containsKey(key)) {
119			* return map.put(key, value);
120			* } else
121			* return null;}</pre>
122			*
123			* except that the action is performed atomically.
124			*
125			* @param key key with which the specified value is associated
126			* @param value value to be associated with the specified key
127			* @return the previous value associated with the specified key, or
128			* <tt>null</tt> if there was no mapping for the key.
129			* (A <tt>null</tt> return can also indicate that the map
130			* previously associated <tt>null</tt> with the key,
131			* if the implementation supports null values.)
132			* @throws UnsupportedOperationException if the <tt>put</tt> operation
133			* is not supported by this map
134			* @throws ClassCastException if the class of the specified key or value
135			* prevents it from being stored in this map
136			* @throws NullPointerException if the specified key or value is null,
137			* and this map does not permit null keys or values
138			* @throws IllegalArgumentException if some property of the specified key
139			* or value prevents it from being stored in this map
140			*/
141			V replace(K key, V value);
142			}