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
#	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	dl	1.2	package jsr166e;
8	dl	1.1	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	dl	1.3	/** The underlying map */
30			private final ConcurrentHashMapV8<K, LongAdder> map;
31
32	jsr166	1.4	static final class CreateAdder
33	dl	1.3	implements ConcurrentHashMapV8.MappingFunction<Object, LongAdder> {
34			public LongAdder map(Object unused) { return new LongAdder(); }
35			}
36	dl	1.1
37	dl	1.3	private static final CreateAdder createAdder = new CreateAdder();
38	dl	1.1
39			/**
40			* Creates a new empty table.
41			*/
42			public LongAdderTable() {
43	dl	1.3	map = new ConcurrentHashMapV8<K, LongAdder>();
44	dl	1.1	}
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	dl	1.3	if (a == null)
75			a = map.computeIfAbsent(key, createAdder);
76	dl	1.1	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			}