AtomicDouble.java

/**
 * Copyright 2015 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.netflix.spectator.impl;

import java.util.concurrent.atomic.AtomicLong;

/**
 * Wrapper around AtomicLong to make working with double values easier.
 *
 * <p><b>This class is an internal implementation detail only intended for use within spectator.
 * It is subject to change without notice.</b></p>
 */
public class AtomicDouble extends Number {

  private final AtomicLong value;

  /** Create an instance with an initial value of 0. */
  public AtomicDouble() {
    this(0.0);
  }

  /** Create an instance with an initial value of {@code init}. */
  public AtomicDouble(double init) {
    super();
    value = new AtomicLong(Double.doubleToLongBits(init));
  }

  /** Return the current value. */
  public double get() {
    return Double.longBitsToDouble(value.get());
  }

  /** Add {@code amount} to the value and return the new value. */
  public double addAndGet(double amount) {
    long v;
    double d;
    double n;
    long next;
    do {
      v = value.get();
      d = Double.longBitsToDouble(v);
      n = d + amount;
      next = Double.doubleToLongBits(n);
    } while (!value.compareAndSet(v, next));
    return n;
  }

  /** Add {@code amount} to the value and return the previous value. */
  public double getAndAdd(double amount) {
    long v;
    double d;
    double n;
    long next;
    do {
      v = value.get();
      d = Double.longBitsToDouble(v);
      n = d + amount;
      next = Double.doubleToLongBits(n);
    } while (!value.compareAndSet(v, next));
    return d;
  }

  /** Set the value to  {@code amount} and return the previous value. */
  public double getAndSet(double amount) {
    long v = value.getAndSet(Double.doubleToLongBits(amount));
    return Double.longBitsToDouble(v);
  }

  /**
   * Set the value to  {@code amount} if the current value is {@code expect}. Return true if the
   * value was updated.
   */
  public boolean compareAndSet(double expect, double update) {
    long e = Double.doubleToLongBits(expect);
    long u = Double.doubleToLongBits(update);
    return value.compareAndSet(e, u);
  }

  /** Set the current value to {@code amount}. */
  public void set(double amount) {
    value.set(Double.doubleToLongBits(amount));
  }

  @Override public int intValue() {
    return (int) get();
  }

  @Override public long longValue() {
    return (long) get();
  }

  @Override public float floatValue() {
    return (float) get();
  }

  @Override public double doubleValue() {
    return get();
  }
}