A small toolkit of classes that support compare-and-swap semantics for safe mutation of variables.
A small toolkit of classes that support compare-and-swap semantics for safe mutation of variables.
On top of the JVM, this means dealing with lock-free thread-safe programming. Also works on top of Javascript,
with Scala.js (for good reasons, as Atomic references are still useful in non-multi-threaded environments).
The backbone of Atomic references is this method:
def compareAndSet(expect: T, update: T): Boolean
This method atomically sets a variable to the update value if it currently holds
the expect value, reporting true on success or false on failure. The classes in this package
also contain methods to get and unconditionally set values. They also support weak operations,
defined in WeakAtomic[T], such as (e.g. weakCompareAndSet, lazySet) or operations that
block the current thread through spin-locking, until a condition happens (e.g. waitForCompareAndSet),
methods exposed by BlockingAtomic[T].
Building a reference is easy with the provided constructor, which will automatically return the
most specific type needed (in the following sample, that's an AtomicDouble, inheriting from AtomicNumber[T]):
val atomicNumber = Atomic(12.2)
atomicNumber.incrementAndGet()
// => 13.2
In comparison with java.util.concurrent.AtomicReference, these references implement common interfaces
that you can use generically (i.e. Atomic[T], AtomicNumber[T]).
And also provide useful helpers for atomically mutating of values
(i.e. transform, transformAndGet, getAndTransform, etc...) or of numbers of any kind
(incrementAndGet, getAndAdd, etc...).
A small toolkit of classes that support compare-and-swap semantics for safe mutation of variables.
On top of the JVM, this means dealing with lock-free thread-safe programming. Also works on top of Javascript, with Scala.js (for good reasons, as Atomic references are still useful in non-multi-threaded environments).
The backbone of Atomic references is this method:
This method atomically sets a variable to the
updatevalue if it currently holds theexpectvalue, reportingtrueon success orfalseon failure. The classes in this package also contain methods to get and unconditionally set values. They also support weak operations, defined inWeakAtomic[T], such as (e.g.weakCompareAndSet,lazySet) or operations that block the current thread through spin-locking, until a condition happens (e.g.waitForCompareAndSet), methods exposed byBlockingAtomic[T].Building a reference is easy with the provided constructor, which will automatically return the most specific type needed (in the following sample, that's an
AtomicDouble, inheriting fromAtomicNumber[T]):In comparison with
java.util.concurrent.AtomicReference, these references implement common interfaces that you can use generically (i.e.Atomic[T],AtomicNumber[T]). And also provide useful helpers for atomically mutating of values (i.e.transform,transformAndGet,getAndTransform, etc...) or of numbers of any kind (incrementAndGet,getAndAdd, etc...).