java.util.concurrent.atomic.AtomicIntegerArray
jdk1.6类 java.util.concurrent.atomic.AtomicIntegerArray
java.util.concurrent.atomic.AtomicIntegerArray
- public AtomicIntegerArray(int length)
- _private long rawIndex(int i)_
- public AtomicIntegerArray(int length)
- public AtomicIntegerArray(int[] array)
- public final int length()
- public final int get(int i)
- public final void set(int i, int newValue)
- public final void lazySet(int i, int newValue)
- public final int getAndSet(int i, int newValue)
- public final boolean compareAndSet(int i, int expect, int update)
- public final boolean weakCompareAndSet(int i, int expect, int update)
- public final int getAndIncrement(int i)
- public final int getAndDecrement(int i)
- public final int getAndAdd(int i, int delta)
- public final int incrementAndGet(int i)
- public final int decrementAndGet(int i)
- public final int addAndGet(int i, int delta)
- public String toString()
/*
* %W% %E%
*
* Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.util.concurrent.atomic;
import sun.misc.Unsafe;
import java.util.*;
/**
* An {@code int} 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
*/
/**
* 可以用原子方式更新其元素的 int 数组。有关原子变量属性的描述，
* 请参阅 java.util.concurrent.atomic 包规范。
*/
public class AtomicIntegerArray implements java.io.Serializable {
private static final long serialVersionUID = 2862133569453604235L;
// setup to use Unsafe.compareAndSwapInt for updates
private static final Unsafe unsafe = Unsafe.getUnsafe();
private static final int base = unsafe.arrayBaseOffset(int[].class);
private static final int scale = unsafe.arrayIndexScale(int[].class);
private final int[] array;
private long rawIndex(int i) {
if (i < 0 || i >= array.length)
throw new IndexOutOfBoundsException("index " + i);
return base + (long) i * scale;
}
/**
* Creates a new AtomicIntegerArray of given length.
*
* @param length the length of the array
*/
/**
* 创建给定长度的新 AtomicIntegerArray。
* @param length 该数组的长度
* @return
*/
public AtomicIntegerArray(int length) {
array = new int[length];
// must perform at least one volatile write to conform to JMM
if (length > 0)
unsafe.putIntVolatile(array, rawIndex(0), 0);
}
/**
* Creates a new AtomicIntegerArray 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
*/
/**
* 创建与给定数组具有相同长度的新 AtomicIntegerArray，并从给定数组复制其所有元素。
* @param array 从中复制元素的数组
* @return [description]
*/
public AtomicIntegerArray(int[] array) {
if (array == null)
throw new NullPointerException();
int length = array.length;
this.array = new int[length];
if (length > 0) {
int last = length-1;
for (int i = 0; i < last; ++i)
this.array[i] = array[i];
// Do the last write as volatile
unsafe.putIntVolatile(this.array, rawIndex(last), array[last]);
}
}
/**
* Returns the length of the array.
*
* @return the length of the array
*/
/**
* 返回该数组的长度。
* @return 该数组的长度
*/
public final int length() {
return array.length;
}
/**
* Gets the current value at position {@code i}.
*
* @param i the index
* @return the current value
*/
/**
* 获取位置 i 的当前值。
* @param i 索引
* @return 当前值
*/
public final int get(int i) {
return unsafe.getIntVolatile(array, rawIndex(i));
}
/**
* Sets the element at position {@code i} to the given value.
*
* @param i the index
* @param newValue the new value
*/
/**
* 将位置 i 的元素设置为给定值。
* @param i 索引
* @param newValue 新值
*/
public final void set(int i, int newValue) {
unsafe.putIntVolatile(array, rawIndex(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
*/
/**
* 最后将位置 i 的元素设置为给定值。
* @param i 索引
* @param newValue 新值
*/
public final void lazySet(int i, int newValue) {
unsafe.putOrderedInt(array, rawIndex(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
*/
/**
* 将位置 i 的元素以原子方式设置为给定值，并返回旧值。
* @param i 索引
* @param newValue 薪值
* @return 以前的值
*/
public final int getAndSet(int i, int newValue) {
while (true) {
int current = get(i);
if (compareAndSet(i, current, newValue))
return current;
}
}
/**
* 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 true if successful. False return indicates that
* the actual value was not equal to the expected value.
*/
/**
* 如果当前值 == 预期值，则以原子方式将位置 i 的元素设置为给定的更新值。
* @param i 索引
* @param expect 预期值
* @param update 薪值
* @return 如果成功，则返回 true。返回 false 指示实际值与预期值不相等。
*/
public final boolean compareAndSet(int i, int expect, int update) {
return unsafe.compareAndSwapInt(array, rawIndex(i),
expect, update);
}
/**
* Atomically sets the element at position {@code i} to the given
* updated value if the current value {@code ==} the expected value.
*
* <p>May <a href="package-summary.html#Spurious">fail spuriously</a>
* and does not provide ordering guarantees, 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 true if successful.
*/
/**
* 如果当前值 == 预期值，则以原子方式将位置 i 的元素设置为给定的更新值。
* 可能意外失败并且不提供排序保证，所以只是在很少的情况下才对
* compareAndSet 进行适当地选择。
* @param i 索引
* @param expect 预期值
* @param update 薪值
* @return 如果成功，则返回 true。
*/
public final boolean weakCompareAndSet(int i, int expect, int update) {
return compareAndSet(i, expect, update);
}
/**
* Atomically increments by one the element at index {@code i}.
*
* @param i the index
* @return the previous value
*/
/**
* 以原子方式将索引 i 的元素加 1。
* @param i 索引
* @return 以前的值
*/
public final int getAndIncrement(int i) {
while (true) {
int current = get(i);
int next = current + 1;
if (compareAndSet(i, current, next))
return current;
}
}
/**
* Atomically decrements by one the element at index {@code i}.
*
* @param i the index
* @return the previous value
*/
/**
* 以原子方式将索引 i 的元素减 1。
* @param i 索引
* @return 以前的值
*/
public final int getAndDecrement(int i) {
while (true) {
int current = get(i);
int next = current - 1;
if (compareAndSet(i, current, next))
return current;
}
}
/**
* 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
*/
/**
* 以原子方式将给定值与索引 i 的元素相加。
* @param i 索引
* @param delta 要加上的值
* @return 以前的值
*/
public final int getAndAdd(int i, int delta) {
while (true) {
int current = get(i);
int next = current + delta;
if (compareAndSet(i, current, next))
return current;
}
}
/**
* Atomically increments by one the element at index {@code i}.
*
* @param i the index
* @return the updated value
*/
/**
* 以原子方式将索引 i 的元素加 1。
* @param i 索引
* @return 更新的值
*/
public final int incrementAndGet(int i) {
while (true) {
int current = get(i);
int next = current + 1;
if (compareAndSet(i, current, next))
return next;
}
}
/**
* Atomically decrements by one the element at index {@code i}.
*
* @param i the index
* @return the updated value
*/
/**
* 以原子方式将索引 i 的元素减 1。
* @param i 索引
* @return 更新的值
*/
public final int decrementAndGet(int i) {
while (true) {
int current = get(i);
int next = current - 1;
if (compareAndSet(i, current, next))
return next;
}
}
/**
* 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
*/
/**
* 以原子方式将给定值与索引 i 的元素相加。
* @param i 索引
* @param delta 要加上的值
* @return 更新的值
*/
public final int addAndGet(int i, int delta) {
while (true) {
int current = get(i);
int next = current + delta;
if (compareAndSet(i, current, next))
return next;
}
}
/**
* Returns the String representation of the current values of array.
* @return the String representation of the current values of array.
*/
/**
* 返回数组当前值的字符串表示形式。
* @return 数组当前值的字符串表示形式。
*/
public String toString() {
if (array.length > 0) // force volatile read
get(0);
return Arrays.toString(array);
}
}