/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
* an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
**********************************************************************************************************************/
package eu.stratosphere.nephele.util;
import java.util.concurrent.atomic.AtomicReference;
/**
* Auxiliary class which provides atomic operations on enumerations. Internally, the class uses an
* {@link AtomicReference} object to guarantee the atomicity.
* <p>
* This class is thread-safe.
*
*/
public final class AtomicEnum<T extends Enum<T>> {
/**
* The atomic reference which provides the atomicity internally.
*/
private final AtomicReference<T> ref;
/**
* Constructs a new atomic enumeration object.
*
* @param initialValue
* the initial value of the enumeration
*/
public AtomicEnum(final T initialValue) {
this.ref = new AtomicReference<T>(initialValue);
}
/**
* Sets to the given value.
*
* @param newValue
* the new value
*/
public void set(final T newValue) {
this.ref.set(newValue);
}
/**
* Gets the current value.
*
* @return the current value.
*/
public T get() {
return this.ref.get();
}
/**
* Sets the given value and returns the old value.
*
* @param newValue
* the new value
* @return the previous value
*/
public T getAndSet(final T newValue) {
return this.ref.getAndSet(newValue);
}
/**
* Atomically set the value to the given updated value if the current value == the expected value.
*
* @param expect
* the expected value
* @param update
* the new value
* @return <code>true</code> if successful, <code>false</code> otherwise
*/
public boolean compareAndSet(final T expect, final T update) {
return this.ref.compareAndSet(expect, update);
}
}