Implementation of Reactive Extensions, supporting multiple platforms, schedulers, and interoperability with coroutines and RxJava. Offers `Observable`, `Maybe`, `Single`, `Completable`, various subjects, and sophisticated subscription management through `DisposableScope`.
Kotlin multiplatform implementation of Reactive Extensions.
Should you have any questions or feedback welcome to the Kotlin Slack channel: #reaktive
There are a number of modules published to Maven Central:
kotlin {
sourceSets {
commonMain {
dependencies {
implementation 'com.badoo.reaktive:reaktive:<version>'
implementation 'com.badoo.reaktive:reaktive-annotations:<version>'
implementation 'com.badoo.reaktive:coroutines-interop:<version>' // For interop with coroutines
implementation 'com.badoo.reaktive:rxjava2-interop:<version>' // For interop with RxJava v2
implementation 'com.badoo.reaktive:rxjava3-interop:<version>' // For interop with RxJava v3
}
}
commonTest {
dependencies {
implementation 'com.badoo.reaktive:reaktive-testing:<version>'
}
}
}
}
Since version 2.x, Reaktive only works with the new memory model.
This functionality is provided by the coroutines-interop module. Please mind some known problems with multi-threaded coroutines on Kotlin/Native.
val flow: Flow<Int> = observableOf(1, 2, 3).asFlow()
val observable: Observable<Int> = flowOf(1, 2, 3).asObservable()
fun doSomething() {
singleFromCoroutine { getSomething() }
.subscribe { println(it) }
}
suspend fun getSomething(): String {
delay(1.seconds)
return "something"
}
val defaultScheduler = Dispatchers.Default.asScheduler()
val computationDispatcher = computationScheduler.asCoroutineDispatcher()
Reaktive provides an easy way to manage subscriptions: DisposableScope.
Take a look at the following examples:
val scope =
disposableScope {
observable.subscribeScoped(...) // Subscription will be disposed when the scope is disposed
doOnDispose {
// Will be called when the scope is disposed
}
someDisposable.scope() // `someDisposable` will be disposed when the scope is disposed
}
// At some point later
scope.dispose()
Please see the corresponding documentation page: Reaktive and Swift interoperability.
Reaktive provides Plugin API, something similar to RxJava plugins. The Plugin API provides a way to decorate Reaktive sources. A plugin should implement the ReaktivePlugin interface, and can be registered using the registerReaktivePlugin function and unregistered using the unregisterReaktivePlugin function.
reaktive - the main Reaktive library (multiplatform)reaktive-annotations - collection of annotations (mutiplatform)reaktive-testing - testing utilities (multiplatform)utils - some utilities like Clock, AtomicReference, Lock, etc. (multiplatform)coroutines-interop - Kotlin coroutines interoperability helpers (multiplatform)rxjava2-interop - RxJava v2 interoperability helpers (JVM and Android)rxjava3-interop - RxJava v3 interoperability helpers (JVM and Android)computationScheduler - fixed thread pool equal to a number of coresioScheduler - unbound thread pool with caching policynewThreadScheduler - creates a new thread for each unit of worksingleScheduler - executes tasks on a single shared background threadtrampolineScheduler - queues tasks and executes them on one of the participating threadsmainScheduler - executes tasks on main threadObservable, Maybe, Single, CompletablePublishSubject, BehaviorSubject, ReplaySubject, UnicastSubjectsuspend functions to/from Single, Maybe and CompletableFlow to/from ObservableCoroutineContext to SchedulerScheduler to CoroutineDispatcherThe old (strict) Kotlin Native memory model and concurrency are very special. In general shared mutable state between threads is not allowed. Since Reaktive supports multithreading in Kotlin Native, please read the following documents before using it:
Object detachment is relatively difficult to achieve and is very error-prone when the objects are created from outside and are not fully managed by the library. This is why Reaktive prefers frozen state. Here are some hints:
subscribeOn freezes both its upstream source and downstream observer,
all the Disposables (upstream's and downstream's) are frozen as well,
all the values (including errors) are not frozen by the operatorobserveOn freezes only its downstream observer and all the values (including errors) passed through it, plus all the Disposables,
upstream source is not frozen by the operatordebounce, timer, delay, etc.) behave same as observeOn in most of the casesSometimes freezing is not acceptable, e.g. we might want to load some data in background and then update the UI. Obviously UI can not be frozen. With Reaktive it is possible to achieve such a behaviour in two ways:
Use threadLocal operator:
val values = mutableListOf<Any>()
var isFinished = false
observable<Any> { emitter ->
// Background job
}
.subscribeOn(ioScheduler)
.observeOn(mainScheduler)
.threadLocal()
.doOnBeforeNext { values += it } // Callback is not frozen, we can update the mutable list
.doOnBeforeFinally { isFinished = true } // Callback is not frozen, we can change the flag
.subscribe()
Set isThreadLocal flag to true in subscribe operator:
val values = mutableListOf<Any>()
var isComplete = false
observable<Any> { emitter ->
// Background job
}
.subscribeOn(ioScheduler)
.observeOn(mainScheduler)
.subscribe(
isThreadLocal = true,
onNext = { values += it }, // Callback is not frozen, we can update the mutable list
onComplete = { isComplete = true } // Callback is not frozen, we can change the flag
)
In both cases subscription (subscribe call) must be performed on the Main thread.
class MyPresenter(
private val view: MyView,
private val longRunningAction: Completable
) : DisposableScope by DisposableScope() {
init {
doOnDispose {
// Will be called when the presenter is disposed
}
}
fun load() {
view.showProgressBar()
// Subscription will be disposed when the presenter is disposed
longRunningAction.subscribeScoped(onComplete = view::hideProgressBar)
}
}
class MyActivity : AppCompatActivity(), DisposableScope by DisposableScope() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
MyPresenter(...).scope()
}
override fun onDestroy() {
dispose()
super.onDestroy()
}
}
object MyPlugin : ReaktivePlugin {
override fun <T> onAssembleObservable(observable: Observable<T>): Observable<T> =
object : Observable<T> {
private val traceException = TraceException()
override fun subscribe(observer: ObservableObserver<T>) {
observable.subscribe(
object : ObservableObserver<T> by observer {
override fun onError(error: Throwable) {
observer.onError(error, traceException)
}
}
)
}
}
override fun <T> onAssembleSingle(single: Single<T>): Single<T> =
TODO("Similar to onAssembleSingle")
override fun <T> onAssembleMaybe(maybe: Maybe<T>): Maybe<T> =
TODO("Similar to onAssembleSingle")
override fun onAssembleCompletable(completable: Completable): Completable =
TODO("Similar to onAssembleSingle")
private fun ErrorCallback.onError(error: Throwable, traceException: TraceException) {
if (error.suppressedExceptions.lastOrNull() !is TraceException) {
error.addSuppressed(traceException)
}
onError(error)
}
private class TraceException : Exception()
}
Surfaced from shared tags and platforms — no rankings paid for.