Atomically replaces the contents of the instance and calls the callback with the old value or calls the callback with the new value if the instance holds the terminal value. - Java java.util.concurrent.atomic

Java examples for java.util.concurrent.atomic:AtomicReferenceFieldUpdater

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Description

Atomically replaces the contents of the instance and calls the callback with the old value or calls the callback with the new value if the instance holds the terminal value.

Demo Code

/**/*  www .  jav a  2 s . c o m*/
 * Copyright 2015 David Karnok and Netflix, Inc.
 * 
 * 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 com.java2s;
import java.util.concurrent.atomic.*;
import java.util.function.*;

public class Main {
    /**
     * Atomically replaces the contents of the instance and calls the callback with the old value
     * or calls the callback with the new value if the instance holds the terminal value.
     * @param updater
     * @param instance
     * @param newValue
     * @param terminalValue
     * @param onTerminate
     * @return false if the instance holds the terminal value
     * @see #update(AtomicReferenceFieldUpdater, Object, Object, Object, Consumer)
     */
    public static <T, U> boolean set(
            AtomicReferenceFieldUpdater<T, U> updater, T instance,
            U newValue, U terminalValue, Consumer<? super U> onTerminate) {
        for (;;) {
            U a = updater.get(instance);
            if (a == terminalValue) {
                if (newValue != null) {
                    onTerminate.accept(newValue);
                }
                return false;
            }
            if (updater.compareAndSet(instance, a, newValue)) {
                if (a != null) {
                    onTerminate.accept(a);
                }
                return true;
            }
        }
    }

    /**
     * Atomically replaces the contents of the instance and calls the callback with the old value
     * or calls the callback with the new value if the instance holds the terminal value.
     * @param instance
     * @param newValue
     * @param terminalValue
     * @param onTerminate
     * @return false if the instance holds the terminal value
     * @see #update(AtomicReference, Object, Object, Consumer)
     */
    public static <T, U> boolean set(AtomicReference<U> instance,
            U newValue, U terminalValue, Consumer<? super U> onTerminate) {
        for (;;) {
            U a = instance.get();
            if (a == terminalValue) {
                if (newValue != null) {
                    onTerminate.accept(newValue);
                }
                return false;
            }
            if (instance.compareAndSet(a, newValue)) {
                if (a != null) {
                    onTerminate.accept(a);
                }
                return true;
            }
        }
    }
}

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