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.extra;
import jsr166e.LongAdder;
import java.util.concurrent.ConcurrentHashMap;
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;

    /** 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, LongAdder> map;

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

    /**
     * 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) {
            LongAdder r = new LongAdder();
            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) {
        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:	1.1
Committed:	Sun Jul 31 14:20:01 2011 UTC (12 years, 9 months ago) by dl
Branch:	MAIN
Log Message:	Rename classes
#	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 jsr166e.extra;
8			import jsr166e.LongAdder;
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 adders, that may be useful in computing frequency
16			* counts and histograms, or may be used a form of multiset. A {@link
17			* LongAdder} is associated with each key. Keys are added to the table
18			* implicitly upon any attempt to update, or may be added explicitly
19			* using method {@link #install}.
20			*
21			* <p><em>jsr166e note: This class is targeted to be placed in
22			* java.util.concurrent.atomic<em>
23			*
24			* @author Doug Lea
25			*/
26			public class LongAdderTable<K> implements Serializable {
27			/** Relies on default serialization */
28			private static final long serialVersionUID = 7249369246863182397L;
29
30			/** Concurrency parameter for map -- we assume high contention */
31			private static final int MAP_SEGMENTS =
32			Math.max(16, Runtime.getRuntime().availableProcessors());
33
34			/** The underlying map */
35			private final ConcurrentHashMap<K, LongAdder> map;
36
37			/**
38			* Creates a new empty table.
39			*/
40			public LongAdderTable() {
41			map = new ConcurrentHashMap<K, LongAdder>(16, 0.75f, MAP_SEGMENTS);
42			}
43
44			/**
45			* If the given key does not already exist in the table, inserts
46			* the key with initial sum of zero; in either case returning the
47			* adder associated with this key.
48			*
49			* @param key the key
50			* @return the adder associated with the key
51			*/
52			public LongAdder install(K key) {
53			LongAdder a = map.get(key);
54			if (a == null) {
55			LongAdder r = new LongAdder();
56			if ((a = map.putIfAbsent(key, r)) == null)
57			a = r;
58			}
59			return a;
60			}
61
62			/**
63			* Adds the given value to the sum associated with the given
64			* key. If the key does not already exist in the table, it is
65			* inserted.
66			*
67			* @param key the key
68			* @param x the value to add
69			*/
70			public void add(K key, long x) {
71			LongAdder a = map.get(key);
72			if (a == null) {
73			LongAdder r = new LongAdder();
74			if ((a = map.putIfAbsent(key, r)) == null)
75			a = r;
76			}
77			a.add(x);
78			}
79
80			/**
81			* Increments the sum associated with the given key. If the key
82			* does not already exist in the table, it is inserted.
83			*
84			* @param key the key
85			*/
86			public void increment(K key) { add(key, 1L); }
87
88			/**
89			* Decrements the sum associated with the given key. If the key
90			* does not already exist in the table, it is inserted.
91			*
92			* @param key the key
93			*/
94			public void decrement(K key) { add(key, -1L); }
95
96			/**
97			* Returns the sum associated with the given key, or zero if the
98			* key does not currently exist in the table.
99			*
100			* @param key the key
101			* @return the sum associated with the key, or zero if the key is
102			* not in the table
103			*/
104			public long sum(K key) {
105			LongAdder a = map.get(key);
106			return a == null ? 0L : a.sum();
107			}
108
109			/**
110			* Resets the sum associated with the given key to zero if the key
111			* exists in the table. This method does <em>NOT</em> add or
112			* remove the key from the table (see {@link #remove}).
113			*
114			* @param key the key
115			*/
116			public void reset(K key) {
117			LongAdder a = map.get(key);
118			if (a != null)
119			a.reset();
120			}
121
122			/**
123			* Resets the sum associated with the given key to zero if the key
124			* exists in the table. This method does <em>NOT</em> add or
125			* remove the key from the table (see {@link #remove}).
126			*
127			* @param key the key
128			* @return the previous sum, or zero if the key is not
129			* in the table
130			*/
131			public long sumThenReset(K key) {
132			LongAdder a = map.get(key);
133			return a == null ? 0L : a.sumThenReset();
134			}
135
136			/**
137			* Returns the sum totalled across all keys.
138			*
139			* @return the sum totalled across all keys.
140			*/
141			public long sumAll() {
142			long sum = 0L;
143			for (LongAdder a : map.values())
144			sum += a.sum();
145			return sum;
146			}
147
148			/**
149			* Resets the sum associated with each key to zero.
150			*/
151			public void resetAll() {
152			for (LongAdder a : map.values())
153			a.reset();
154			}
155
156			/**
157			* Totals, then resets, the sums associated with all keys.
158			*
159			* @return the sum totalled across all keys.
160			*/
161			public long sumThenResetAll() {
162			long sum = 0L;
163			for (LongAdder a : map.values())
164			sum += a.sumThenReset();
165			return sum;
166			}
167
168			/**
169			* Removes the given key from the table.
170			*
171			* @param key the key
172			*/
173			public void remove(K key) { map.remove(key); }
174
175			/**
176			* Removes all keys from the table.
177			*/
178			public void removeAll() { map.clear(); }
179
180			/**
181			* Returns the current set of keys.
182			*
183			* @return the current set of keys
184			*/
185			public Set<K> keySet() {
186			return map.keySet();
187			}
188
189			/**
190			* Returns the current set of key-value mappings.
191			*
192			* @return the current set of key-value mappings
193			*/
194			public Set<Map.Entry<K,LongAdder>> entrySet() {
195			return map.entrySet();
196			}
197
198			}