src/jsr166e/LongAdderTable.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;
import jsr166e.LongAdder;
import java.util.Map;
import java.util.Set;
import java.io.Serializable;

/**
 * A keyed table of adders, that may be useful in computing frequency
 * counts and histograms, or may be used a form of multiset.  A {@link
 * LongAdder} is associated with each key. Keys are added to the table
 * implicitly upon any attempt to update, or may be added explicitly
 * using method {@link #install}.
 *
 * <p><em>jsr166e note: This class is targeted to be placed in
 * java.util.concurrent.atomic<em>
 *
 * @author Doug Lea
 */
public class LongAdderTable<K> implements Serializable {
    /** Relies on default serialization */
    private static final long serialVersionUID = 7249369246863182397L;

    /** The underlying map */
    private final ConcurrentHashMapV8<K, LongAdder> map;

    static final class CreateAdder
        implements ConcurrentHashMapV8.MappingFunction<Object, LongAdder> {
        public LongAdder map(Object unused) { return new LongAdder(); }
    }

    private static final CreateAdder createAdder = new CreateAdder();

    /**
     * Creates a new empty table.
     */
    public LongAdderTable() {
        map = new ConcurrentHashMapV8<K, LongAdder>();
    }

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

    /**
     * Resets the sum associated with each key to zero.
     */
    public void resetAll() {
        for (LongAdder 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 (LongAdder 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); }

    /**
     * Removes all keys from the table.
     */
    public void removeAll() { map.clear(); }

    /**
     * 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,LongAdder>> entrySet() {
        return map.entrySet();
    }

}
Revision:	1.4
Committed:	Tue Aug 30 07:16:56 2011 UTC (12 years, 8 months ago) by jsr166
Branch:	MAIN
Changes since 1.3:	+1 -1 lines
Log Message:	whitespace
#	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;
8	import jsr166e.LongAdder;
9	import java.util.Map;
10	import java.util.Set;
11	import java.io.Serializable;
12
13	/**
14	* A keyed table of adders, that may be useful in computing frequency
15	* counts and histograms, or may be used a form of multiset. A {@link
16	* LongAdder} is associated with each key. Keys are added to the table
17	* implicitly upon any attempt to update, or may be added explicitly
18	* using method {@link #install}.
19	*
20	* <p><em>jsr166e note: This class is targeted to be placed in
21	* java.util.concurrent.atomic<em>
22	*
23	* @author Doug Lea
24	*/
25	public class LongAdderTable<K> implements Serializable {
26	/** Relies on default serialization */
27	private static final long serialVersionUID = 7249369246863182397L;
28
29	/** The underlying map */
30	private final ConcurrentHashMapV8<K, LongAdder> map;
31
32	static final class CreateAdder
33	implements ConcurrentHashMapV8.MappingFunction<Object, LongAdder> {
34	public LongAdder map(Object unused) { return new LongAdder(); }
35	}
36
37	private static final CreateAdder createAdder = new CreateAdder();
38
39	/**
40	* Creates a new empty table.
41	*/
42	public LongAdderTable() {
43	map = new ConcurrentHashMapV8<K, LongAdder>();
44	}
45
46	/**
47	* If the given key does not already exist in the table, inserts
48	* the key with initial sum of zero; in either case returning the
49	* adder associated with this key.
50	*
51	* @param key the key
52	* @return the adder associated with the key
53	*/
54	public LongAdder install(K key) {
55	LongAdder a = map.get(key);
56	if (a == null) {
57	LongAdder r = new LongAdder();
58	if ((a = map.putIfAbsent(key, r)) == null)
59	a = r;
60	}
61	return a;
62	}
63
64	/**
65	* Adds the given value to the sum associated with the given
66	* key. If the key does not already exist in the table, it is
67	* inserted.
68	*
69	* @param key the key
70	* @param x the value to add
71	*/
72	public void add(K key, long x) {
73	LongAdder a = map.get(key);
74	if (a == null)
75	a = map.computeIfAbsent(key, createAdder);
76	a.add(x);
77	}
78
79	/**
80	* Increments the sum associated with the given key. If the key
81	* does not already exist in the table, it is inserted.
82	*
83	* @param key the key
84	*/
85	public void increment(K key) { add(key, 1L); }
86
87	/**
88	* Decrements the sum associated with the given key. If the key
89	* does not already exist in the table, it is inserted.
90	*
91	* @param key the key
92	*/
93	public void decrement(K key) { add(key, -1L); }
94
95	/**
96	* Returns the sum associated with the given key, or zero if the
97	* key does not currently exist in the table.
98	*
99	* @param key the key
100	* @return the sum associated with the key, or zero if the key is
101	* not in the table
102	*/
103	public long sum(K key) {
104	LongAdder a = map.get(key);
105	return a == null ? 0L : a.sum();
106	}
107
108	/**
109	* Resets the sum associated with the given key to zero if the key
110	* exists in the table. This method does <em>NOT</em> add or
111	* remove the key from the table (see {@link #remove}).
112	*
113	* @param key the key
114	*/
115	public void reset(K key) {
116	LongAdder a = map.get(key);
117	if (a != null)
118	a.reset();
119	}
120
121	/**
122	* Resets the sum associated with the given key to zero if the key
123	* exists in the table. This method does <em>NOT</em> add or
124	* remove the key from the table (see {@link #remove}).
125	*
126	* @param key the key
127	* @return the previous sum, or zero if the key is not
128	* in the table
129	*/
130	public long sumThenReset(K key) {
131	LongAdder a = map.get(key);
132	return a == null ? 0L : a.sumThenReset();
133	}
134
135	/**
136	* Returns the sum totalled across all keys.
137	*
138	* @return the sum totalled across all keys.
139	*/
140	public long sumAll() {
141	long sum = 0L;
142	for (LongAdder a : map.values())
143	sum += a.sum();
144	return sum;
145	}
146
147	/**
148	* Resets the sum associated with each key to zero.
149	*/
150	public void resetAll() {
151	for (LongAdder a : map.values())
152	a.reset();
153	}
154
155	/**
156	* Totals, then resets, the sums associated with all keys.
157	*
158	* @return the sum totalled across all keys.
159	*/
160	public long sumThenResetAll() {
161	long sum = 0L;
162	for (LongAdder a : map.values())
163	sum += a.sumThenReset();
164	return sum;
165	}
166
167	/**
168	* Removes the given key from the table.
169	*
170	* @param key the key
171	*/
172	public void remove(K key) { map.remove(key); }
173
174	/**
175	* Removes all keys from the table.
176	*/
177	public void removeAll() { map.clear(); }
178
179	/**
180	* Returns the current set of keys.
181	*
182	* @return the current set of keys
183	*/
184	public Set<K> keySet() {
185	return map.keySet();
186	}
187
188	/**
189	* Returns the current set of key-value mappings.
190	*
191	* @return the current set of key-value mappings
192	*/
193	public Set<Map.Entry<K,LongAdder>> entrySet() {
194	return map.entrySet();
195	}
196
197	}