monix.execution.atomic.AtomicBoolean.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 monix.execution.internal.atomic.{BoxedInt, Factory}
/** Atomic references wrapping `Boolean` values.
*
* Note that the equality test in `compareAndSet` is value based,
* since `Boolean` is a primitive.
*/
final class AtomicBoolean private (private[this] val ref: BoxedInt) extends Atomic[Boolean] {
def get(): Boolean =
ref.volatileGet() == 1
def set(update: Boolean): Unit =
ref.volatileSet(if (update) 1 else 0)
/** Convenience method that expects the current value to be not the provided value.
* Equivalent to `compareAndSet(!update, update)`.
*/
def flip(update: Boolean): Boolean =
ref.compareAndSet(if (update) 0 else 1, if (update) 1 else 0)
def compareAndSet(expect: Boolean, update: Boolean): Boolean =
ref.compareAndSet(if (expect) 1 else 0, if (update) 1 else 0)
def getAndSet(update: Boolean): Boolean =
ref.getAndSet(if (update) 1 else 0) == 1
def lazySet(update: Boolean): Unit =
ref.lazySet(if (update) 1 else 0)
override def toString: String =
s"AtomicBoolean($get)"
}
/** @define createDesc Constructs an [[AtomicBoolean]] 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 AtomicBoolean {
/** Builds an [[AtomicBoolean]] reference.
*
* @param initialValue is the initial value with which to initialize the atomic
*/
def apply(initialValue: Boolean): AtomicBoolean =
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: Boolean, padding: PaddingStrategy): AtomicBoolean =
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: Boolean, padding: PaddingStrategy, allowPlatformIntrinsics: Boolean): AtomicBoolean = {
new AtomicBoolean(
Factory.newBoxedInt(
if (initialValue) 1 else 0,
boxStrategyToPaddingStrategy(padding),
true, // allowUnsafe
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: Boolean, padding: PaddingStrategy): AtomicBoolean = {
new AtomicBoolean(
Factory.newBoxedInt(
if (initialValue) 1 else 0,
boxStrategyToPaddingStrategy(padding),
false, // allowUnsafe
false // allowJava8Intrinsics
))
}
}