concurrent/atomic/AtomicLongArray.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.atomic;

import java.util.function.LongBinaryOperator;
import java.util.function.LongUnaryOperator;

/**
 * A {@code long} array in which elements may be updated atomically.
 * See the {@link java.util.concurrent.atomic} package specification
 * for description of the properties of atomic variables.
 * @since 1.5
 * @author Doug Lea
 */
public class AtomicLongArray implements java.io.Serializable {
    private static final long serialVersionUID = -2308431214976778248L;

    private static final sun.misc.Unsafe U = sun.misc.Unsafe.getUnsafe();
    private static final int ABASE;
    private static final int ASHIFT;
    private final long[] array;

    static {
        ABASE = U.arrayBaseOffset(long[].class);
        int scale = U.arrayIndexScale(long[].class);
        if ((scale & (scale - 1)) != 0)
            throw new Error("array index scale not a power of two");
        ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
    }

    private long checkedByteOffset(int i) {
        if (i < 0 || i >= array.length)
            throw new IndexOutOfBoundsException("index " + i);

        return byteOffset(i);
    }

    private static long byteOffset(int i) {
        return ((long) i << ASHIFT) + ABASE;
    }

    /**
     * Creates a new AtomicLongArray of the given length, with all
     * elements initially zero.
     *
     * @param length the length of the array
     */
    public AtomicLongArray(int length) {
        array = new long[length];
    }

    /**
     * Creates a new AtomicLongArray with the same length as, and
     * all elements copied from, the given array.
     *
     * @param array the array to copy elements from
     * @throws NullPointerException if array is null
     */
    public AtomicLongArray(long[] array) {
        // Visibility guaranteed by final field guarantees
        this.array = array.clone();
    }

    /**
     * Returns the length of the array.
     *
     * @return the length of the array
     */
    public final int length() {
        return array.length;
    }

    /**
     * Gets the current value at position {@code i}.
     *
     * @param i the index
     * @return the current value
     */
    public final long get(int i) {
        return getRaw(checkedByteOffset(i));
    }

    private long getRaw(long offset) {
        return U.getLongVolatile(array, offset);
    }

    /**
     * Sets the element at position {@code i} to the given value.
     *
     * @param i the index
     * @param newValue the new value
     */
    public final void set(int i, long newValue) {
        U.putLongVolatile(array, checkedByteOffset(i), newValue);
    }

    /**
     * Eventually sets the element at position {@code i} to the given value.
     *
     * @param i the index
     * @param newValue the new value
     * @since 1.6
     */
    public final void lazySet(int i, long newValue) {
        U.putOrderedLong(array, checkedByteOffset(i), newValue);
    }

    /**
     * Atomically sets the element at position {@code i} to the given value
     * and returns the old value.
     *
     * @param i the index
     * @param newValue the new value
     * @return the previous value
     */
    public final long getAndSet(int i, long newValue) {
        return U.getAndSetLong(array, checkedByteOffset(i), newValue);
    }

    /**
     * Atomically sets the element at position {@code i} to the given
     * updated value if the current value {@code ==} the expected value.
     *
     * @param i the index
     * @param expect the expected value
     * @param update the new value
     * @return {@code true} if successful. False return indicates that
     * the actual value was not equal to the expected value.
     */
    public final boolean compareAndSet(int i, long expect, long update) {
        return compareAndSetRaw(checkedByteOffset(i), expect, update);
    }

    private boolean compareAndSetRaw(long offset, long expect, long update) {
        return U.compareAndSwapLong(array, offset, expect, update);
    }

    /**
     * Atomically sets the element at position {@code i} to the given
     * updated value if the current value {@code ==} the expected value.
     *
     * <p><a href="package-summary.html#weakCompareAndSet">May fail
     * spuriously and does not provide ordering guarantees</a>, so is
     * only rarely an appropriate alternative to {@code compareAndSet}.
     *
     * @param i the index
     * @param expect the expected value
     * @param update the new value
     * @return {@code true} if successful
     */
    public final boolean weakCompareAndSet(int i, long expect, long update) {
        return compareAndSet(i, expect, update);
    }

    /**
     * Atomically increments by one the element at index {@code i}.
     *
     * @param i the index
     * @return the previous value
     */
    public final long getAndIncrement(int i) {
        return getAndAdd(i, 1);
    }

    /**
     * Atomically decrements by one the element at index {@code i}.
     *
     * @param i the index
     * @return the previous value
     */
    public final long getAndDecrement(int i) {
        return getAndAdd(i, -1);
    }

    /**
     * Atomically adds the given value to the element at index {@code i}.
     *
     * @param i the index
     * @param delta the value to add
     * @return the previous value
     */
    public final long getAndAdd(int i, long delta) {
        return U.getAndAddLong(array, checkedByteOffset(i), delta);
    }

    /**
     * Atomically increments by one the element at index {@code i}.
     *
     * @param i the index
     * @return the updated value
     */
    public final long incrementAndGet(int i) {
        return getAndAdd(i, 1) + 1;
    }

    /**
     * Atomically decrements by one the element at index {@code i}.
     *
     * @param i the index
     * @return the updated value
     */
    public final long decrementAndGet(int i) {
        return getAndAdd(i, -1) - 1;
    }

    /**
     * Atomically adds the given value to the element at index {@code i}.
     *
     * @param i the index
     * @param delta the value to add
     * @return the updated value
     */
    public long addAndGet(int i, long delta) {
        return getAndAdd(i, delta) + delta;
    }

    /**
     * Atomically updates the element at index {@code i} with the results
     * of applying the given function, returning the previous value. The
     * function should be side-effect-free, since it may be re-applied
     * when attempted updates fail due to contention among threads.
     *
     * @param i the index
     * @param updateFunction a side-effect-free function
     * @return the previous value
     * @since 1.8
     */
    public final long getAndUpdate(int i, LongUnaryOperator updateFunction) {
        long offset = checkedByteOffset(i);
        long prev, next;
        do {
            prev = getRaw(offset);
            next = updateFunction.applyAsLong(prev);
        } while (!compareAndSetRaw(offset, prev, next));
        return prev;
    }

    /**
     * Atomically updates the element at index {@code i} with the results
     * of applying the given function, returning the updated value. The
     * function should be side-effect-free, since it may be re-applied
     * when attempted updates fail due to contention among threads.
     *
     * @param i the index
     * @param updateFunction a side-effect-free function
     * @return the updated value
     * @since 1.8
     */
    public final long updateAndGet(int i, LongUnaryOperator updateFunction) {
        long offset = checkedByteOffset(i);
        long prev, next;
        do {
            prev = getRaw(offset);
            next = updateFunction.applyAsLong(prev);
        } while (!compareAndSetRaw(offset, prev, next));
        return next;
    }

    /**
     * Atomically updates the element at index {@code i} with the
     * results of applying the given function to the current and
     * given values, returning the previous value. The function should
     * be side-effect-free, since it may be re-applied when attempted
     * updates fail due to contention among threads.  The function is
     * applied with the current value at index {@code i} as its first
     * argument, and the given update as the second argument.
     *
     * @param i the index
     * @param x the update value
     * @param accumulatorFunction a side-effect-free function of two arguments
     * @return the previous value
     * @since 1.8
     */
    public final long getAndAccumulate(int i, long x,
                                      LongBinaryOperator accumulatorFunction) {
        long offset = checkedByteOffset(i);
        long prev, next;
        do {
            prev = getRaw(offset);
            next = accumulatorFunction.applyAsLong(prev, x);
        } while (!compareAndSetRaw(offset, prev, next));
        return prev;
    }

    /**
     * Atomically updates the element at index {@code i} with the
     * results of applying the given function to the current and
     * given values, returning the updated value. The function should
     * be side-effect-free, since it may be re-applied when attempted
     * updates fail due to contention among threads.  The function is
     * applied with the current value at index {@code i} as its first
     * argument, and the given update as the second argument.
     *
     * @param i the index
     * @param x the update value
     * @param accumulatorFunction a side-effect-free function of two arguments
     * @return the updated value
     * @since 1.8
     */
    public final long accumulateAndGet(int i, long x,
                                      LongBinaryOperator accumulatorFunction) {
        long offset = checkedByteOffset(i);
        long prev, next;
        do {
            prev = getRaw(offset);
            next = accumulatorFunction.applyAsLong(prev, x);
        } while (!compareAndSetRaw(offset, prev, next));
        return next;
    }

    /**
     * Returns the String representation of the current values of array.
     * @return the String representation of the current values of array
     */
    public String toString() {
        int iMax = array.length - 1;
        if (iMax == -1)
            return "[]";

        StringBuilder b = new StringBuilder();
        b.append('[');
        for (int i = 0; ; i++) {
            b.append(getRaw(byteOffset(i)));
            if (i == iMax)
                return b.append(']').toString();
            b.append(',').append(' ');
        }
    }

}
Revision:	1.1
Committed:	Sat Mar 26 06:22:51 2016 UTC (8 years, 2 months ago) by jsr166
Branch:	MAIN
CVS Tags:	HEAD
Log Message:	fork jdk8 maintenance branch for source and jtreg tests
#	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 java.util.concurrent.atomic;
8
9	import java.util.function.LongBinaryOperator;
10	import java.util.function.LongUnaryOperator;
11
12	/**
13	* A {@code long} array in which elements may be updated atomically.
14	* See the {@link java.util.concurrent.atomic} package specification
15	* for description of the properties of atomic variables.
16	* @since 1.5
17	* @author Doug Lea
18	*/
19	public class AtomicLongArray implements java.io.Serializable {
20	private static final long serialVersionUID = -2308431214976778248L;
21
22	private static final sun.misc.Unsafe U = sun.misc.Unsafe.getUnsafe();
23	private static final int ABASE;
24	private static final int ASHIFT;
25	private final long[] array;
26
27	static {
28	ABASE = U.arrayBaseOffset(long[].class);
29	int scale = U.arrayIndexScale(long[].class);
30	if ((scale & (scale - 1)) != 0)
31	throw new Error("array index scale not a power of two");
32	ASHIFT = 31 - Integer.numberOfLeadingZeros(scale);
33	}
34
35	private long checkedByteOffset(int i) {
36	if (i < 0 \|\| i >= array.length)
37	throw new IndexOutOfBoundsException("index " + i);
38
39	return byteOffset(i);
40	}
41
42	private static long byteOffset(int i) {
43	return ((long) i << ASHIFT) + ABASE;
44	}
45
46	/**
47	* Creates a new AtomicLongArray of the given length, with all
48	* elements initially zero.
49	*
50	* @param length the length of the array
51	*/
52	public AtomicLongArray(int length) {
53	array = new long[length];
54	}
55
56	/**
57	* Creates a new AtomicLongArray with the same length as, and
58	* all elements copied from, the given array.
59	*
60	* @param array the array to copy elements from
61	* @throws NullPointerException if array is null
62	*/
63	public AtomicLongArray(long[] array) {
64	// Visibility guaranteed by final field guarantees
65	this.array = array.clone();
66	}
67
68	/**
69	* Returns the length of the array.
70	*
71	* @return the length of the array
72	*/
73	public final int length() {
74	return array.length;
75	}
76
77	/**
78	* Gets the current value at position {@code i}.
79	*
80	* @param i the index
81	* @return the current value
82	*/
83	public final long get(int i) {
84	return getRaw(checkedByteOffset(i));
85	}
86
87	private long getRaw(long offset) {
88	return U.getLongVolatile(array, offset);
89	}
90
91	/**
92	* Sets the element at position {@code i} to the given value.
93	*
94	* @param i the index
95	* @param newValue the new value
96	*/
97	public final void set(int i, long newValue) {
98	U.putLongVolatile(array, checkedByteOffset(i), newValue);
99	}
100
101	/**
102	* Eventually sets the element at position {@code i} to the given value.
103	*
104	* @param i the index
105	* @param newValue the new value
106	* @since 1.6
107	*/
108	public final void lazySet(int i, long newValue) {
109	U.putOrderedLong(array, checkedByteOffset(i), newValue);
110	}
111
112	/**
113	* Atomically sets the element at position {@code i} to the given value
114	* and returns the old value.
115	*
116	* @param i the index
117	* @param newValue the new value
118	* @return the previous value
119	*/
120	public final long getAndSet(int i, long newValue) {
121	return U.getAndSetLong(array, checkedByteOffset(i), newValue);
122	}
123
124	/**
125	* Atomically sets the element at position {@code i} to the given
126	* updated value if the current value {@code ==} the expected value.
127	*
128	* @param i the index
129	* @param expect the expected value
130	* @param update the new value
131	* @return {@code true} if successful. False return indicates that
132	* the actual value was not equal to the expected value.
133	*/
134	public final boolean compareAndSet(int i, long expect, long update) {
135	return compareAndSetRaw(checkedByteOffset(i), expect, update);
136	}
137
138	private boolean compareAndSetRaw(long offset, long expect, long update) {
139	return U.compareAndSwapLong(array, offset, expect, update);
140	}
141
142	/**
143	* Atomically sets the element at position {@code i} to the given
144	* updated value if the current value {@code ==} the expected value.
145	*
146	* <p><a href="package-summary.html#weakCompareAndSet">May fail
147	* spuriously and does not provide ordering guarantees</a>, so is
148	* only rarely an appropriate alternative to {@code compareAndSet}.
149	*
150	* @param i the index
151	* @param expect the expected value
152	* @param update the new value
153	* @return {@code true} if successful
154	*/
155	public final boolean weakCompareAndSet(int i, long expect, long update) {
156	return compareAndSet(i, expect, update);
157	}
158
159	/**
160	* Atomically increments by one the element at index {@code i}.
161	*
162	* @param i the index
163	* @return the previous value
164	*/
165	public final long getAndIncrement(int i) {
166	return getAndAdd(i, 1);
167	}
168
169	/**
170	* Atomically decrements by one the element at index {@code i}.
171	*
172	* @param i the index
173	* @return the previous value
174	*/
175	public final long getAndDecrement(int i) {
176	return getAndAdd(i, -1);
177	}
178
179	/**
180	* Atomically adds the given value to the element at index {@code i}.
181	*
182	* @param i the index
183	* @param delta the value to add
184	* @return the previous value
185	*/
186	public final long getAndAdd(int i, long delta) {
187	return U.getAndAddLong(array, checkedByteOffset(i), delta);
188	}
189
190	/**
191	* Atomically increments by one the element at index {@code i}.
192	*
193	* @param i the index
194	* @return the updated value
195	*/
196	public final long incrementAndGet(int i) {
197	return getAndAdd(i, 1) + 1;
198	}
199
200	/**
201	* Atomically decrements by one the element at index {@code i}.
202	*
203	* @param i the index
204	* @return the updated value
205	*/
206	public final long decrementAndGet(int i) {
207	return getAndAdd(i, -1) - 1;
208	}
209
210	/**
211	* Atomically adds the given value to the element at index {@code i}.
212	*
213	* @param i the index
214	* @param delta the value to add
215	* @return the updated value
216	*/
217	public long addAndGet(int i, long delta) {
218	return getAndAdd(i, delta) + delta;
219	}
220
221	/**
222	* Atomically updates the element at index {@code i} with the results
223	* of applying the given function, returning the previous value. The
224	* function should be side-effect-free, since it may be re-applied
225	* when attempted updates fail due to contention among threads.
226	*
227	* @param i the index
228	* @param updateFunction a side-effect-free function
229	* @return the previous value
230	* @since 1.8
231	*/
232	public final long getAndUpdate(int i, LongUnaryOperator updateFunction) {
233	long offset = checkedByteOffset(i);
234	long prev, next;
235	do {
236	prev = getRaw(offset);
237	next = updateFunction.applyAsLong(prev);
238	} while (!compareAndSetRaw(offset, prev, next));
239	return prev;
240	}
241
242	/**
243	* Atomically updates the element at index {@code i} with the results
244	* of applying the given function, returning the updated value. The
245	* function should be side-effect-free, since it may be re-applied
246	* when attempted updates fail due to contention among threads.
247	*
248	* @param i the index
249	* @param updateFunction a side-effect-free function
250	* @return the updated value
251	* @since 1.8
252	*/
253	public final long updateAndGet(int i, LongUnaryOperator updateFunction) {
254	long offset = checkedByteOffset(i);
255	long prev, next;
256	do {
257	prev = getRaw(offset);
258	next = updateFunction.applyAsLong(prev);
259	} while (!compareAndSetRaw(offset, prev, next));
260	return next;
261	}
262
263	/**
264	* Atomically updates the element at index {@code i} with the
265	* results of applying the given function to the current and
266	* given values, returning the previous value. The function should
267	* be side-effect-free, since it may be re-applied when attempted
268	* updates fail due to contention among threads. The function is
269	* applied with the current value at index {@code i} as its first
270	* argument, and the given update as the second argument.
271	*
272	* @param i the index
273	* @param x the update value
274	* @param accumulatorFunction a side-effect-free function of two arguments
275	* @return the previous value
276	* @since 1.8
277	*/
278	public final long getAndAccumulate(int i, long x,
279	LongBinaryOperator accumulatorFunction) {
280	long offset = checkedByteOffset(i);
281	long prev, next;
282	do {
283	prev = getRaw(offset);
284	next = accumulatorFunction.applyAsLong(prev, x);
285	} while (!compareAndSetRaw(offset, prev, next));
286	return prev;
287	}
288
289	/**
290	* Atomically updates the element at index {@code i} with the
291	* results of applying the given function to the current and
292	* given values, returning the updated value. The function should
293	* be side-effect-free, since it may be re-applied when attempted
294	* updates fail due to contention among threads. The function is
295	* applied with the current value at index {@code i} as its first
296	* argument, and the given update as the second argument.
297	*
298	* @param i the index
299	* @param x the update value
300	* @param accumulatorFunction a side-effect-free function of two arguments
301	* @return the updated value
302	* @since 1.8
303	*/
304	public final long accumulateAndGet(int i, long x,
305	LongBinaryOperator accumulatorFunction) {
306	long offset = checkedByteOffset(i);
307	long prev, next;
308	do {
309	prev = getRaw(offset);
310	next = accumulatorFunction.applyAsLong(prev, x);
311	} while (!compareAndSetRaw(offset, prev, next));
312	return next;
313	}
314
315	/**
316	* Returns the String representation of the current values of array.
317	* @return the String representation of the current values of array
318	*/
319	public String toString() {
320	int iMax = array.length - 1;
321	if (iMax == -1)
322	return "[]";
323
324	StringBuilder b = new StringBuilder();
325	b.append('[');
326	for (int i = 0; ; i++) {
327	b.append(getRaw(byteOffset(i)));
328	if (i == iMax)
329	return b.append(']').toString();
330	b.append(',').append(' ');
331	}
332	}
333
334	}