edu.emory.mathcs.backport.java.util.concurrent.atomic.AtomicBoolean Maven / Gradle / Ivy
Show all versions of virtdata-lib-curves4 Show documentation
/*
* 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 edu.emory.mathcs.backport.java.util.concurrent.atomic;
/**
* A {@code boolean} 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 AtomicBoolean} is used in applications such as atomically
* updated flags, and cannot be used as a replacement for a
* {@link java.lang.Boolean}.
*
* @since 1.5
* @author Doug Lea
*/
public class AtomicBoolean implements java.io.Serializable {
private static final long serialVersionUID = 4654671469794556979L;
private volatile int value;
/**
* Creates a new {@code AtomicBoolean} with the given initial value.
*
* @param initialValue the initial value
*/
public AtomicBoolean(boolean initialValue) {
value = initialValue ? 1 : 0;
}
/**
* Creates a new {@code AtomicBoolean} with initial value {@code false}.
*/
public AtomicBoolean() {
}
/**
* Returns the current value.
*
* @return the current value
*/
public final boolean get() {
return value != 0;
}
/**
* 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(boolean expect, boolean update) {
if (expect == (value != 0)) {
value = update ? 1 : 0;
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 synchronized boolean weakCompareAndSet(boolean expect, boolean update) {
if (expect == (value != 0)) {
value = update ? 1 : 0;
return true;
}
else {
return false;
}
}
/**
* Unconditionally sets to the given value.
*
* @param newValue the new value
*/
public final synchronized void set(boolean newValue) {
value = newValue ? 1 : 0;
}
/**
* Eventually sets to the given value.
*
* @param newValue the new value
* @since 1.6
*/
public final synchronized void lazySet(boolean newValue) {
value = newValue ? 1 : 0;
}
/**
* Atomically sets to the given value and returns the previous value.
*
* @param newValue the new value
* @return the previous value
*/
public final synchronized boolean getAndSet(boolean newValue) {
int old = value;
value = newValue ? 1 : 0;
return old != 0;
}
/**
* Returns the String representation of the current value.
* @return the String representation of the current value.
*/
public String toString() {
return Boolean.toString(get());
}
}