badoo · CherryPerry · Aug 4, 2022 · Jul 15, 2022 · Jul 15, 2022 · Jul 15, 2022
diff --git a/mvicore-android/build.gradle b/mvicore-android/build.gradle
@@ -41,6 +41,7 @@ dependencies {
 
     implementation deps('io.reactivex.rxjava2:rxjava')
     implementation deps('io.reactivex.rxjava2:rxkotlin')
+    implementation deps('io.reactivex.rxjava2:rxandroid')
 
     testImplementation deps('junit:junit')
     testImplementation deps('org.jetbrains.kotlin:kotlin-test-junit')

diff --git a/mvicore-android/src/main/java/com/badoo/mvicore/android/AndroidMainThreadFeatureScheduler.kt b/mvicore-android/src/main/java/com/badoo/mvicore/android/AndroidMainThreadFeatureScheduler.kt
@@ -0,0 +1,21 @@
+package com.badoo.mvicore.android
+
+import android.os.Looper
+import com.badoo.mvicore.feature.FeatureScheduler
+import io.reactivex.Scheduler
+import io.reactivex.android.schedulers.AndroidSchedulers
+
+/**
+ * A feature scheduler that ensures that MVICore feature only manipulates state on the Android
+ * main thread.
+ *
+ * It also uses the 'isOnFeatureThread' field to avoid observing on the main thread if it is already
+ * the current thread.
+ */
+object AndroidMainThreadFeatureScheduler: FeatureScheduler {
+    override val scheduler: Scheduler
+        get() = AndroidSchedulers.mainThread()
+
+    override val isOnFeatureThread: Boolean
+        get() = Looper.myLooper() == Looper.getMainLooper()
+}
diff --git a/mvicore-demo/mvicore-demo-feature2/build.gradle b/mvicore-demo/mvicore-demo-feature2/build.gradle
@@ -43,5 +43,6 @@ dependencies {
     implementation deps('io.reactivex.rxjava2:rxandroid')
 
     implementation project(":mvicore")
+    implementation project(":mvicore-android")
     implementation project(':mvicore-demo:mvicore-demo-catapi')
 }
diff --git a/mvicore-demo/mvicore-demo-feature2/src/main/java/com/badoo/feature2/Feature2.kt b/mvicore-demo/mvicore-demo-feature2/src/main/java/com/badoo/feature2/Feature2.kt
@@ -11,6 +11,7 @@ import com.badoo.feature2.Feature2.News
 import com.badoo.feature2.Feature2.State
 import com.badoo.feature2.Feature2.Wish
 import com.badoo.feature2.Feature2.Wish.LoadNewImage
+import com.badoo.mvicore.android.AndroidMainThreadFeatureScheduler
 import com.badoo.mvicore.element.Actor
 import com.badoo.mvicore.element.Bootstrapper
 import com.badoo.mvicore.element.NewsPublisher
@@ -19,7 +20,6 @@ import com.badoo.mvicore.element.TimeCapsule
 import com.badoo.mvicore.feature.ActorReducerFeature
 import io.reactivex.Observable
 import io.reactivex.Observable.just
-import io.reactivex.android.schedulers.AndroidSchedulers
 import kotlinx.android.parcel.Parcelize
 
 class Feature2(
@@ -29,7 +29,8 @@ class Feature2(
     bootstrapper = BootStrapperImpl(),
     actor = ActorImpl(),
     reducer = ReducerImpl(),
-    newsPublisher = NewsPublisherImpl()
+    newsPublisher = NewsPublisherImpl(),
+    featureScheduler = AndroidMainThreadFeatureScheduler
 ) {
     init {
         timeCapsule?.register(Feature2::class.java) { state.copy(
@@ -74,7 +75,6 @@ class Feature2(
         fun loadRandomImage(): Observable<Response> {
             return service.getRandomImage()
                 .randomlyThrowAnException()
-                .observeOn(AndroidSchedulers.mainThread())
         }
     }
 

diff --git a/mvicore/src/main/java/com/badoo/mvicore/extension/Rx.kt b/mvicore/src/main/java/com/badoo/mvicore/extension/Rx.kt
@@ -4,15 +4,8 @@ import io.reactivex.Observable
 import io.reactivex.Observer
 import io.reactivex.Scheduler
 import io.reactivex.functions.Consumer
-import io.reactivex.subjects.Subject
 
 fun <T> Observer<T>.asConsumer() = Consumer<T> { onNext(it) }
 
-internal fun <T> Observable<T>.observeOnNullable(scheduler: Scheduler?): Observable<T> =
-    if (scheduler != null) observeOn(scheduler) else this
-
 internal fun <T> Observable<T>.subscribeOnNullable(scheduler: Scheduler?): Observable<T> =
     if (scheduler != null) subscribeOn(scheduler) else this
-
-internal fun <T> Subject<T>.serializeIfNotNull(param: Any?): Subject<T> =
-    if (param != null) toSerialized() else this
diff --git a/mvicore/src/main/java/com/badoo/mvicore/feature/ActorReducerFeature.kt b/mvicore/src/main/java/com/badoo/mvicore/feature/ActorReducerFeature.kt
@@ -5,19 +5,33 @@ import com.badoo.mvicore.element.Bootstrapper
 import com.badoo.mvicore.element.NewsPublisher
 import com.badoo.mvicore.element.Reducer
 
+/**
+ * An implementation of a single threaded feature.
+ *
+ * Please be aware of the following threading behaviours based on whether a 'featureScheduler' is provided.
+ *
+ * No 'featureScheduler' provided:
+ * The feature must execute on the thread that created the class. If the bootstrapper/actor observables
+ * change to a different thread it is your responsibility to switch back to the feature's original
+ * thread via observeOn, otherwise an exception will be thrown.
+ *
+ * 'featureScheduler' provided (this must be single threaded):
+ * The feature does not have to execute on the thread that created the class. It automatically
+ * switches to the feature scheduler thread when necessary.
+ */
 open class ActorReducerFeature<Wish : Any, in Effect : Any, State : Any, News : Any>(
     initialState: State,
     bootstrapper: Bootstrapper<Wish>? = null,
     actor: Actor<State, Wish, Effect>,
     reducer: Reducer<State, Effect>,
     newsPublisher: NewsPublisher<Wish, Effect, State, News>? = null,
-    schedulers: FeatureSchedulers? = null
+    featureScheduler: FeatureScheduler? = null
 ) : BaseFeature<Wish, Wish, Effect, State, News>(
     initialState = initialState,
     bootstrapper = bootstrapper,
     wishToAction = { wish -> wish },
     actor = actor,
     reducer = reducer,
     newsPublisher = newsPublisher,
-    schedulers = schedulers
+    featureScheduler = featureScheduler
 )
diff --git a/mvicore/src/main/java/com/badoo/mvicore/feature/AsyncFeatureSchedulers.kt b/mvicore/src/main/java/com/badoo/mvicore/feature/AsyncFeatureSchedulers.kt
@@ -0,0 +1,12 @@
+package com.badoo.mvicore.feature
+
+import io.reactivex.Scheduler
+
+/**
+ * A set of [Scheduler]s that change the threading behaviour of [BaseAsyncFeature]
+ */
+class AsyncFeatureSchedulers(
+    /** Should be single-threaded. */
+    val featureScheduler: Scheduler,
+    val observationScheduler: Scheduler
+)