jsr166e/extra/StripedAdderTable.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 jsr166e.extra;
import jsr166e.StripedAdder;
import java.util.concurrent.ConcurrentHashMap;
import java.util.Map;
import java.util.Set;
import java.io.Serializable;

/**
 * A keyed table of scalable adders, that may be useful in computing
 * frequency counts and histograms, or may be used a form of multiset.
 * A {@link StripedAdder} is associated with each key. Keys may be
 * added to the table explicitly ({@link #install}, and are also added
 * implicitly upon any attempt to update.
 *
 * @author Doug Lea
 */
public class StripedAdderTable<K> implements Serializable {
    /** Relies on default serialization */
    private static final long serialVersionUID = 7249369246863182397L;

    /** Concurrency parameter for map -- we assume high contention */
    private static final int MAP_SEGMENTS =
        Math.max(16, Runtime.getRuntime().availableProcessors());

    /** The underlying map */
    private final ConcurrentHashMap<K, StripedAdder> map;

    /**
     * Creates a new empty table.
     */
    public StripedAdderTable() {
        map = new ConcurrentHashMap<K, StripedAdder>(16, 0.75f, MAP_SEGMENTS);
    }

    /**
     * If the given key does not already exist in the table, adds the
     * key with initial sum of zero; in either case returning the
     * adder associated with this key.
     *
     * @param key the key
     * @return the counter associated with the key
     */
    public StripedAdder install(K key) {
        StripedAdder a = map.get(key);
        if (a == null) {
            StripedAdder r = new StripedAdder();
            if ((a = map.putIfAbsent(key, r)) == null)
                a = r;
        }
        return a;
    }

    /**
     * Adds the given value to the sum associated with the given
     * key.  If the key does not already exist in the table, it is
     * inserted.
     *
     * @param key the key
     * @param x the value to add
     */
    public void add(K key, long x) {
        StripedAdder a = map.get(key);
        if (a == null) {
            StripedAdder r = new StripedAdder();
            if ((a = map.putIfAbsent(key, r)) == null)
                a = r;
        }
        a.add(x);
    }

    /**
     * Increments the sum associated with the given key.  If the key
     * does not already exist in the table, it is inserted.
     *
     * @param key the key
     */
    public void increment(K key) { add(key, 1L); }

    /**
     * Decrements the sum associated with the given key.  If the key
     * does not already exist in the table, it is inserted.
     *
     * @param key the key
     */
    public void decrement(K key) { add(key, -1L); }

    /**
     * Returns the sum associated with the given key, or zero if the
     * key does not currently exist in the table.
     *
     * @param key the key
     * @return the sum associated with the key, or zero if the key is
     * not in the table
     */
    public long sum(K key) {
        StripedAdder a = map.get(key);
        return a == null ? 0L : a.sum();
    }

    /**
     * Resets the sum associated with the given key to zero if the key
     * exists in the table.  This method does <em>NOT</em> add or
     * remove the key from the table (see {@link #remove}).
     *
     * @param key the key
     */
    public void reset(K key) {
        StripedAdder a = map.get(key);
        if (a != null)
            a.reset();
    }

    /**
     * Resets the sum associated with the given key to zero if the key
     * exists in the table.  This method does <em>NOT</em> add or
     * remove the key from the table (see {@link #remove}).
     *
     * @param key the key
     * @return the previous sum, or zero if the key is not
     * in the table
     */
    public long sumThenReset(K key) {
        StripedAdder a = map.get(key);
        return a == null ? 0L : a.sumThenReset();
    }

    /**
     * Returns the sum totalled across all keys.
     *
     * @return the sum totalled across all keys.
     */
    public long sumAll() {
        long sum = 0L;
        for (StripedAdder a : map.values())
            sum += a.sum();
        return sum;
    }

    /**
     * Resets the sum associated with each key to zero.
     */
    public void resetAll() {
        for (StripedAdder a : map.values())
            a.reset();
    }

    /**
     * Totals, then resets, the sums associated with all keys.
     *
     * @return the sum totalled across all keys.
     */
    public long sumThenResetAll() {
        long sum = 0L;
        for (StripedAdder a : map.values())
            sum += a.sumThenReset();
        return sum;
    }

    /**
     * Removes the given key from the table.
     *
     * @param key the key
     */
    public void remove(K key) { map.remove(key); }

    /**
     * Returns the current set of keys.
     *
     * @return the current set of keys
     */
    public Set<K> keySet() {
        return map.keySet();
    }

    /**
     * Returns the current set of key-value mappings.
     *
     * @return the current set of key-value mappings
     */
    public Set<Map.Entry<K,StripedAdder>> entrySet() {
        return map.entrySet();
    }

}
Revision:	1.3
Committed:	Sun Jul 31 14:20:06 2011 UTC (12 years, 10 months ago) by dl
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.2:	+0 -0 lines
State:	*FILE REMOVED*
Log Message:	Rename classes
#	Content
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 jsr166e.extra;
8	import jsr166e.StripedAdder;
9	import java.util.concurrent.ConcurrentHashMap;
10	import java.util.Map;
11	import java.util.Set;
12	import java.io.Serializable;
13
14	/**
15	* A keyed table of scalable adders, that may be useful in computing
16	* frequency counts and histograms, or may be used a form of multiset.
17	* A {@link StripedAdder} is associated with each key. Keys may be
18	* added to the table explicitly ({@link #install}, and are also added
19	* implicitly upon any attempt to update.
20	*
21	* @author Doug Lea
22	*/
23	public class StripedAdderTable<K> implements Serializable {
24	/** Relies on default serialization */
25	private static final long serialVersionUID = 7249369246863182397L;
26
27	/** Concurrency parameter for map -- we assume high contention */
28	private static final int MAP_SEGMENTS =
29	Math.max(16, Runtime.getRuntime().availableProcessors());
30
31	/** The underlying map */
32	private final ConcurrentHashMap<K, StripedAdder> map;
33
34	/**
35	* Creates a new empty table.
36	*/
37	public StripedAdderTable() {
38	map = new ConcurrentHashMap<K, StripedAdder>(16, 0.75f, MAP_SEGMENTS);
39	}
40
41	/**
42	* If the given key does not already exist in the table, adds the
43	* key with initial sum of zero; in either case returning the
44	* adder associated with this key.
45	*
46	* @param key the key
47	* @return the counter associated with the key
48	*/
49	public StripedAdder install(K key) {
50	StripedAdder a = map.get(key);
51	if (a == null) {
52	StripedAdder r = new StripedAdder();
53	if ((a = map.putIfAbsent(key, r)) == null)
54	a = r;
55	}
56	return a;
57	}
58
59	/**
60	* Adds the given value to the sum associated with the given
61	* key. If the key does not already exist in the table, it is
62	* inserted.
63	*
64	* @param key the key
65	* @param x the value to add
66	*/
67	public void add(K key, long x) {
68	StripedAdder a = map.get(key);
69	if (a == null) {
70	StripedAdder r = new StripedAdder();
71	if ((a = map.putIfAbsent(key, r)) == null)
72	a = r;
73	}
74	a.add(x);
75	}
76
77	/**
78	* Increments the sum associated with the given key. If the key
79	* does not already exist in the table, it is inserted.
80	*
81	* @param key the key
82	*/
83	public void increment(K key) { add(key, 1L); }
84
85	/**
86	* Decrements the sum associated with the given key. If the key
87	* does not already exist in the table, it is inserted.
88	*
89	* @param key the key
90	*/
91	public void decrement(K key) { add(key, -1L); }
92
93	/**
94	* Returns the sum associated with the given key, or zero if the
95	* key does not currently exist in the table.
96	*
97	* @param key the key
98	* @return the sum associated with the key, or zero if the key is
99	* not in the table
100	*/
101	public long sum(K key) {
102	StripedAdder a = map.get(key);
103	return a == null ? 0L : a.sum();
104	}
105
106	/**
107	* Resets the sum associated with the given key to zero if the key
108	* exists in the table. This method does <em>NOT</em> add or
109	* remove the key from the table (see {@link #remove}).
110	*
111	* @param key the key
112	*/
113	public void reset(K key) {
114	StripedAdder a = map.get(key);
115	if (a != null)
116	a.reset();
117	}
118
119	/**
120	* Resets the sum associated with the given key to zero if the key
121	* exists in the table. This method does <em>NOT</em> add or
122	* remove the key from the table (see {@link #remove}).
123	*
124	* @param key the key
125	* @return the previous sum, or zero if the key is not
126	* in the table
127	*/
128	public long sumThenReset(K key) {
129	StripedAdder a = map.get(key);
130	return a == null ? 0L : a.sumThenReset();
131	}
132
133	/**
134	* Returns the sum totalled across all keys.
135	*
136	* @return the sum totalled across all keys.
137	*/
138	public long sumAll() {
139	long sum = 0L;
140	for (StripedAdder a : map.values())
141	sum += a.sum();
142	return sum;
143	}
144
145	/**
146	* Resets the sum associated with each key to zero.
147	*/
148	public void resetAll() {
149	for (StripedAdder a : map.values())
150	a.reset();
151	}
152
153	/**
154	* Totals, then resets, the sums associated with all keys.
155	*
156	* @return the sum totalled across all keys.
157	*/
158	public long sumThenResetAll() {
159	long sum = 0L;
160	for (StripedAdder a : map.values())
161	sum += a.sumThenReset();
162	return sum;
163	}
164
165	/**
166	* Removes the given key from the table.
167	*
168	* @param key the key
169	*/
170	public void remove(K key) { map.remove(key); }
171
172	/**
173	* Returns the current set of keys.
174	*
175	* @return the current set of keys
176	*/
177	public Set<K> keySet() {
178	return map.keySet();
179	}
180
181	/**
182	* Returns the current set of key-value mappings.
183	*
184	* @return the current set of key-value mappings
185	*/
186	public Set<Map.Entry<K,StripedAdder>> entrySet() {
187	return map.entrySet();
188	}
189
190	}