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/*
* 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/licenses/publicdomain
*/
package scala.actors.threadpool;
/**
* An {@code int} value that may be updated atomically. See the
* {@link edu.emory.mathcs.backport.java.util.concurrent.atomic} package specification for
* description of the properties of atomic variables. An
* {@code AtomicInteger} is used in applications such as atomically
* incremented counters, and cannot be used as a replacement for an
* {@link java.lang.Integer}. However, this class does extend
* {@code Number} to allow uniform access by tools and utilities that
* deal with numerically-based classes.
*
* @since 1.5
* @author Doug Lea
*/
public class AtomicInteger extends Number implements java.io.Serializable {
private static final long serialVersionUID = 6214790243416807050L;
private volatile int value;
/**
* Creates a new AtomicInteger with the given initial value.
*
* @param initialValue the initial value
*/
public AtomicInteger(int initialValue) {
value = initialValue;
}
/**
* Creates a new AtomicInteger with initial value {@code 0}.
*/
public AtomicInteger() {
}
/**
* Gets the current value.
*
* @return the current value
*/
public final int get() {
return value;
}
/**
* Sets to the given value.
*
* @param newValue the new value
*/
public final synchronized void set(int newValue) {
value = newValue;
}
/**
* Eventually sets to the given value.
*
* @param newValue the new value
* @since 1.6
*/
public final synchronized void lazySet(int newValue) {
value = newValue;
}
/**
* Atomically sets to the given value and returns the old value.
*
* @param newValue the new value
* @return the previous value
*/
public final synchronized int getAndSet(int newValue) {
int old = value;
value = newValue;
return old;
}
/**
* Atomically sets the value to the given updated value
* if the current value {@code ==} the expected value.
*
* @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.
*/
public final synchronized boolean compareAndSet(int expect, int update) {
if (value == expect) {
value = update;
return true;
}
else {
return false;
}
}
/**
* Atomically sets the value to the given updated value
* if the current value {@code ==} the expected value.
*
* May fail spuriously
* and does not provide ordering guarantees, so is only rarely an
* appropriate alternative to {@code compareAndSet}.
*
* @param expect the expected value
* @param update the new value
* @return true if successful.
*/
public final synchronized boolean weakCompareAndSet(int expect, int update) {
if (value == expect) {
value = update;
return true;
}
else {
return false;
}
}
/**
* Atomically increments by one the current value.
*
* @return the previous value
*/
public final synchronized int getAndIncrement() {
return value++;
}
/**
* Atomically decrements by one the current value.
*
* @return the previous value
*/
public final synchronized int getAndDecrement() {
return value--;
}
/**
* Atomically adds the given value to the current value.
*
* @param delta the value to add
* @return the previous value
*/
public final synchronized int getAndAdd(int delta) {
int old = value;
value += delta;
return old;
}
/**
* Atomically increments by one the current value.
*
* @return the updated value
*/
public final synchronized int incrementAndGet() {
return ++value;
}
/**
* Atomically decrements by one the current value.
*
* @return the updated value
*/
public final synchronized int decrementAndGet() {
return --value;
}
/**
* Atomically adds the given value to the current value.
*
* @param delta the value to add
* @return the updated value
*/
public final synchronized int addAndGet(int delta) {
return value += delta;
}
/**
* Returns the String representation of the current value.
* @return the String representation of the current value.
*/
public String toString() {
return Integer.toString(get());
}
public int intValue() {
return get();
}
public long longValue() {
return (long)get();
}
public float floatValue() {
return (float)get();
}
public double doubleValue() {
return (double)get();
}
}