monix.execution.atomic.AtomicDouble.scala Maven / Gradle / Ivy
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/*
* Copyright (c) 2014-2019 by The Monix Project Developers.
* See the project homepage at: https://monix.io
*
* 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 monix.execution.atomic
import monix.execution.atomic.PaddingStrategy.NoPadding
import scala.annotation.tailrec
import java.lang.Double.{doubleToLongBits, longBitsToDouble}
import monix.execution.internal.atomic.{BoxedLong, Factory}
/** Atomic references wrapping `Double` values.
*
* Note that the equality test in `compareAndSet` is value based,
* since `Double` is a primitive.
*/
final class AtomicDouble private (val ref: BoxedLong) extends AtomicNumber[Double] {
def get(): Double = longBitsToDouble(ref.volatileGet())
def set(update: Double): Unit = ref.volatileSet(doubleToLongBits(update))
def lazySet(update: Double): Unit = ref.lazySet(doubleToLongBits(update))
def compareAndSet(expect: Double, update: Double): Boolean = {
val expectLong = doubleToLongBits(expect)
val updateLong = doubleToLongBits(update)
ref.compareAndSet(expectLong, updateLong)
}
def getAndSet(update: Double): Double = {
longBitsToDouble(ref.getAndSet(doubleToLongBits(update)))
}
@tailrec
def increment(v: Int = 1): Unit = {
val current = get
val update = incrementOp(current, v)
if (!compareAndSet(current, update))
increment(v)
}
@tailrec
def add(v: Double): Unit = {
val current = get
val update = plusOp(current, v)
if (!compareAndSet(current, update))
add(v)
}
@tailrec
def incrementAndGet(v: Int = 1): Double = {
val current = get
val update = incrementOp(current, v)
if (!compareAndSet(current, update))
incrementAndGet(v)
else
update
}
@tailrec
def addAndGet(v: Double): Double = {
val current = get
val update = plusOp(current, v)
if (!compareAndSet(current, update))
addAndGet(v)
else
update
}
@tailrec
def getAndIncrement(v: Int = 1): Double = {
val current = get
val update = incrementOp(current, v)
if (!compareAndSet(current, update))
getAndIncrement(v)
else
current
}
@tailrec
def getAndAdd(v: Double): Double = {
val current = get
val update = plusOp(current, v)
if (!compareAndSet(current, update))
getAndAdd(v)
else
current
}
@tailrec
def subtract(v: Double): Unit = {
val current = get
val update = minusOp(current, v)
if (!compareAndSet(current, update))
subtract(v)
}
@tailrec
def subtractAndGet(v: Double): Double = {
val current = get
val update = minusOp(current, v)
if (!compareAndSet(current, update))
subtractAndGet(v)
else
update
}
@tailrec
def getAndSubtract(v: Double): Double = {
val current = get
val update = minusOp(current, v)
if (!compareAndSet(current, update))
getAndSubtract(v)
else
current
}
def decrement(v: Int = 1): Unit = increment(-v)
def decrementAndGet(v: Int = 1): Double = incrementAndGet(-v)
def getAndDecrement(v: Int = 1): Double = getAndIncrement(-v)
private[this] def plusOp(a: Double, b: Double): Double = a + b
private[this] def minusOp(a: Double, b: Double): Double = a - b
private[this] def incrementOp(a: Double, b: Int): Double = a + b
}
/** @define createDesc Constructs an [[AtomicDouble]] reference, allowing
* for fine-tuning of the created instance.
*
* A [[PaddingStrategy]] can be provided in order to counter
* the "false sharing" problem.
*
* Note that for ''Scala.js'' we aren't applying any padding,
* as it doesn't make much sense, since Javascript execution
* is single threaded, but this builder is provided for
* syntax compatibility anyway across the JVM and Javascript
* and we never know how Javascript engines will evolve.
*/
object AtomicDouble {
/** Builds an [[AtomicDouble]] reference.
*
* @param initialValue is the initial value with which to initialize the atomic
*/
def apply(initialValue: Double): AtomicDouble =
withPadding(initialValue, NoPadding)
/** $createDesc
*
* @param initialValue is the initial value with which to initialize the atomic
* @param padding is the [[PaddingStrategy]] to apply
*/
def withPadding(initialValue: Double, padding: PaddingStrategy): AtomicDouble =
create(initialValue, padding, allowPlatformIntrinsics = true)
/** $createDesc
*
* Also this builder on top Java 8 also allows for turning off the
* Java 8 intrinsics, thus forcing usage of CAS-loops for
* `getAndSet` and for `getAndAdd`.
*
* @param initialValue is the initial value with which to initialize the atomic
* @param padding is the [[PaddingStrategy]] to apply
* @param allowPlatformIntrinsics is a boolean parameter that specifies whether
* the instance is allowed to use the Java 8 optimized operations
* for `getAndSet` and for `getAndAdd`
*/
def create(initialValue: Double, padding: PaddingStrategy, allowPlatformIntrinsics: Boolean): AtomicDouble = {
new AtomicDouble(
Factory.newBoxedLong(
doubleToLongBits(initialValue),
boxStrategyToPaddingStrategy(padding),
true, // allowIntrinsics
allowPlatformIntrinsics
))
}
/** $createDesc
*
* This builder guarantees to construct a safe atomic reference that
* does not make use of `sun.misc.Unsafe`. On top of platforms that
* don't support it, notably some versions of Android or on top of
* the upcoming Java 9, this might be desirable.
*
* NOTE that explicit usage of this builder is not usually necessary
* because [[create]] can auto-detect whether the underlying platform
* supports `sun.misc.Unsafe` and if it does, then its usage is
* recommended, because the "safe" atomic instances have overhead.
*
* @param initialValue is the initial value with which to initialize the atomic
* @param padding is the [[PaddingStrategy]] to apply
*/
def safe(initialValue: Double, padding: PaddingStrategy): AtomicDouble = {
new AtomicDouble(
Factory.newBoxedLong(
doubleToLongBits(initialValue),
boxStrategyToPaddingStrategy(padding),
false, // allowUnsafe
false // allowJava8Intrinsics
))
}
}