/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
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*/
/*
* This file is available under and governed by the GNU General Public
* License version 2 only, as published by the Free Software Foundation.
* However, the following notice accompanied the original version of this
* file:
*
* 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.lang.invoke.MethodHandles;
import java.lang.invoke.VarHandle;
import java.util.function.LongBinaryOperator;
import java.util.function.LongUnaryOperator;
/**
* A {@code long} array in which elements may be updated atomically.
* See the {@link VarHandle} specification for descriptions of the
* properties of atomic accesses.
* @since 1.5
* @author Doug Lea
*/
public class AtomicLongArray implements java.io.Serializable {
private static final long serialVersionUID = -2308431214976778248L;
private static final VarHandle AA
= MethodHandles.arrayElementVarHandle(long[].class);
private final long[] array;
/**
* 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;
}
/**
* Returns the current value of the element at index {@code i},
* with memory effects as specified by {@link VarHandle#getVolatile}.
*
* @param i the index
* @return the current value
*/
public final long get(int i) {
return (long)AA.getVolatile(array, i);
}
/**
* Sets the element at index {@code i} to {@code newValue},
* with memory effects as specified by {@link VarHandle#setVolatile}.
*
* @param i the index
* @param newValue the new value
*/
public final void set(int i, long newValue) {
AA.setVolatile(array, i, newValue);
}
/**
* Sets the element at index {@code i} to {@code newValue},
* with memory effects as specified by {@link VarHandle#setRelease}.
*
* @param i the index
* @param newValue the new value
* @since 1.6
*/
public final void lazySet(int i, long newValue) {
AA.setRelease(array, i, newValue);
}
/**
* Atomically sets the element at index {@code i} to {@code
* newValue} and returns the old value,
* with memory effects as specified by {@link VarHandle#getAndSet}.
*
* @param i the index
* @param newValue the new value
* @return the previous value
*/
public final long getAndSet(int i, long newValue) {
return (long)AA.getAndSet(array, i, newValue);
}
/**
* Atomically sets the element at index {@code i} to {@code newValue}
* if the element's current value {@code == expectedValue},
* with memory effects as specified by {@link VarHandle#compareAndSet}.
*
* @param i the index
* @param expectedValue the expected value
* @param newValue 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 expectedValue, long newValue) {
return AA.compareAndSet(array, i, expectedValue, newValue);
}
/**
* Possibly atomically sets the element at index {@code i} to
* {@code newValue} if the element's current value {@code == expectedValue},
* with memory effects as specified by {@link VarHandle#weakCompareAndSetPlain}.
*
* @deprecated This method has plain memory effects but the method
* name implies volatile memory effects (see methods such as
* {@link #compareAndExchange} and {@link #compareAndSet}). To avoid
* confusion over plain or volatile memory effects it is recommended that
* the method {@link #weakCompareAndSetPlain} be used instead.
*
* @param i the index
* @param expectedValue the expected value
* @param newValue the new value
* @return {@code true} if successful
* @see #weakCompareAndSetPlain
*/
@Deprecated(since="9")
public final boolean weakCompareAndSet(int i, long expectedValue, long newValue) {
return AA.weakCompareAndSetPlain(array, i, expectedValue, newValue);
}
/**
* Possibly atomically sets the element at index {@code i} to
* {@code newValue} if the element's current value {@code == expectedValue},
* with memory effects as specified by {@link VarHandle#weakCompareAndSetPlain}.
*
* @param i the index
* @param expectedValue the expected value
* @param newValue the new value
* @return {@code true} if successful
* @since 9
*/
public final boolean weakCompareAndSetPlain(int i, long expectedValue, long newValue) {
return AA.weakCompareAndSetPlain(array, i, expectedValue, newValue);
}
/**
* Atomically increments the value of the element at index {@code i},
* with memory effects as specified by {@link VarHandle#getAndAdd}.
*
* <p>Equivalent to {@code getAndAdd(i, 1)}.
*
* @param i the index
* @return the previous value
*/
public final long getAndIncrement(int i) {
return (long)AA.getAndAdd(array, i, 1L);
}
/**
* Atomically decrements the value of the element at index {@code i},
* with memory effects as specified by {@link VarHandle#getAndAdd}.
*
* <p>Equivalent to {@code getAndAdd(i, -1)}.
*
* @param i the index
* @return the previous value
*/
public final long getAndDecrement(int i) {
return (long)AA.getAndAdd(array, i, -1L);
}
/**
* Atomically adds the given value to the element at index {@code i},
* with memory effects as specified by {@link VarHandle#getAndAdd}.
*
* @param i the index
* @param delta the value to add
* @return the previous value
*/
public final long getAndAdd(int i, long delta) {
return (long)AA.getAndAdd(array, i, delta);
}
/**
* Atomically increments the value of the element at index {@code i},
* with memory effects as specified by {@link VarHandle#getAndAdd}.
*
* <p>Equivalent to {@code addAndGet(i, 1)}.
*
* @param i the index
* @return the updated value
*/
public final long incrementAndGet(int i) {
return (long)AA.getAndAdd(array, i, 1L) + 1L;
}
/**
* Atomically decrements the value of the element at index {@code i},
* with memory effects as specified by {@link VarHandle#getAndAdd}.
*
* <p>Equivalent to {@code addAndGet(i, -1)}.
*
* @param i the index
* @return the updated value
*/
public final long decrementAndGet(int i) {
return (long)AA.getAndAdd(array, i, -1L) - 1L;
}
/**
* Atomically adds the given value to the element at index {@code i},
* with memory effects as specified by {@link VarHandle#getAndAdd}.
*
* @param i the index
* @param delta the value to add
* @return the updated value
*/
public long addAndGet(int i, long delta) {
return (long)AA.getAndAdd(array, 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 prev = get(i), next = 0L;
for (boolean haveNext = false;;) {
if (!haveNext)
next = updateFunction.applyAsLong(prev);
if (weakCompareAndSetVolatile(i, prev, next))
return prev;
haveNext = (prev == (prev = get(i)));
}
}
/**
* 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 prev = get(i), next = 0L;
for (boolean haveNext = false;;) {
if (!haveNext)
next = updateFunction.applyAsLong(prev);
if (weakCompareAndSetVolatile(i, prev, next))
return next;
haveNext = (prev == (prev = get(i)));
}
}
/**
* 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 of the element 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 prev = get(i), next = 0L;
for (boolean haveNext = false;;) {
if (!haveNext)
next = accumulatorFunction.applyAsLong(prev, x);
if (weakCompareAndSetVolatile(i, prev, next))
return prev;
haveNext = (prev == (prev = get(i)));
}
}
/**
* 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 of the element 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 prev = get(i), next = 0L;
for (boolean haveNext = false;;) {
if (!haveNext)
next = accumulatorFunction.applyAsLong(prev, x);
if (weakCompareAndSetVolatile(i, prev, next))
return next;
haveNext = (prev == (prev = get(i)));
}
}
/**
* 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(get(i));
if (i == iMax)
return b.append(']').toString();
b.append(',').append(' ');
}
}
// jdk9
/**
* Returns the current value of the element at index {@code i},
* with memory semantics of reading as if the variable was declared
* non-{@code volatile}.
*
* @param i the index
* @return the value
* @since 9
*/
public final long getPlain(int i) {
return (long)AA.get(array, i);
}
/**
* Sets the element at index {@code i} to {@code newValue},
* with memory semantics of setting as if the variable was
* declared non-{@code volatile} and non-{@code final}.
*
* @param i the index
* @param newValue the new value
* @since 9
*/
public final void setPlain(int i, long newValue) {
AA.set(array, i, newValue);
}
/**
* Returns the current value of the element at index {@code i},
* with memory effects as specified by {@link VarHandle#getOpaque}.
*
* @param i the index
* @return the value
* @since 9
*/
public final long getOpaque(int i) {
return (long)AA.getOpaque(array, i);
}
/**
* Sets the element at index {@code i} to {@code newValue},
* with memory effects as specified by {@link VarHandle#setOpaque}.
*
* @param i the index
* @param newValue the new value
* @since 9
*/
public final void setOpaque(int i, long newValue) {
AA.setOpaque(array, i, newValue);
}
/**
* Returns the current value of the element at index {@code i},
* with memory effects as specified by {@link VarHandle#getAcquire}.
*
* @param i the index
* @return the value
* @since 9
*/
public final long getAcquire(int i) {
return (long)AA.getAcquire(array, i);
}
/**
* Sets the element at index {@code i} to {@code newValue},
* with memory effects as specified by {@link VarHandle#setRelease}.
*
* @param i the index
* @param newValue the new value
* @since 9
*/
public final void setRelease(int i, long newValue) {
AA.setRelease(array, i, newValue);
}
/**
* Atomically sets the element at index {@code i} to {@code newValue}
* if the element's current value, referred to as the <em>witness
* value</em>, {@code == expectedValue},
* with memory effects as specified by
* {@link VarHandle#compareAndExchange}.
*
* @param i the index
* @param expectedValue the expected value
* @param newValue the new value
* @return the witness value, which will be the same as the
* expected value if successful
* @since 9
*/
public final long compareAndExchange(int i, long expectedValue, long newValue) {
return (long)AA.compareAndExchange(array, i, expectedValue, newValue);
}
/**
* Atomically sets the element at index {@code i} to {@code newValue}
* if the element's current value, referred to as the <em>witness
* value</em>, {@code == expectedValue},
* with memory effects as specified by
* {@link VarHandle#compareAndExchangeAcquire}.
*
* @param i the index
* @param expectedValue the expected value
* @param newValue the new value
* @return the witness value, which will be the same as the
* expected value if successful
* @since 9
*/
public final long compareAndExchangeAcquire(int i, long expectedValue, long newValue) {
return (long)AA.compareAndExchangeAcquire(array, i, expectedValue, newValue);
}
/**
* Atomically sets the element at index {@code i} to {@code newValue}
* if the element's current value, referred to as the <em>witness
* value</em>, {@code == expectedValue},
* with memory effects as specified by
* {@link VarHandle#compareAndExchangeRelease}.
*
* @param i the index
* @param expectedValue the expected value
* @param newValue the new value
* @return the witness value, which will be the same as the
* expected value if successful
* @since 9
*/
public final long compareAndExchangeRelease(int i, long expectedValue, long newValue) {
return (long)AA.compareAndExchangeRelease(array, i, expectedValue, newValue);
}
/**
* Possibly atomically sets the element at index {@code i} to
* {@code newValue} if the element's current value {@code == expectedValue},
* with memory effects as specified by
* {@link VarHandle#weakCompareAndSet}.
*
* @param i the index
* @param expectedValue the expected value
* @param newValue the new value
* @return {@code true} if successful
* @since 9
*/
public final boolean weakCompareAndSetVolatile(int i, long expectedValue, long newValue) {
return AA.weakCompareAndSet(array, i, expectedValue, newValue);
}
/**
* Possibly atomically sets the element at index {@code i} to
* {@code newValue} if the element's current value {@code == expectedValue},
* with memory effects as specified by
* {@link VarHandle#weakCompareAndSetAcquire}.
*
* @param i the index
* @param expectedValue the expected value
* @param newValue the new value
* @return {@code true} if successful
* @since 9
*/
public final boolean weakCompareAndSetAcquire(int i, long expectedValue, long newValue) {
return AA.weakCompareAndSetAcquire(array, i, expectedValue, newValue);
}
/**
* Possibly atomically sets the element at index {@code i} to
* {@code newValue} if the element's current value {@code == expectedValue},
* with memory effects as specified by
* {@link VarHandle#weakCompareAndSetRelease}.
*
* @param i the index
* @param expectedValue the expected value
* @param newValue the new value
* @return {@code true} if successful
* @since 9
*/
public final boolean weakCompareAndSetRelease(int i, long expectedValue, long newValue) {
return AA.weakCompareAndSetRelease(array, i, expectedValue, newValue);
}
}