Move main thread scheduler to FragmentFlowStore.

instacart · Jan 26, 2024 · 2cc53c3 · 2cc53c3
1 parent 25f6b12
commit 2cc53c3
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Showing 5 changed files with 51 additions and 21 deletions.
diff --git a/formula-android/src/main/java/com/instacart/formula/android/FragmentFlowStore.kt b/formula-android/src/main/java/com/instacart/formula/android/FragmentFlowStore.kt
@@ -5,6 +5,7 @@ import com.instacart.formula.Formula
 import com.instacart.formula.Snapshot
 import com.instacart.formula.android.internal.Binding
 import com.instacart.formula.android.events.FragmentLifecycleEvent
+import com.instacart.formula.android.internal.FeatureObservableAction
 import com.instacart.formula.rxjava3.RxAction
 import com.instacart.formula.rxjava3.toObservable
 import com.jakewharton.rxrelay3.PublishRelay
@@ -122,14 +123,18 @@ class FragmentFlowStore @PublishedApi internal constructor(
                     val fragmentId = entry.key
                     val feature = (entry.value as? FeatureEvent.Init)?.feature
                     if (feature != null) {
-                        RxAction.fromObservable(feature) {
-                            feature.state.onErrorResumeNext {
-                                input.onScreenError(fragmentId.key, it)
-                                Observable.empty()
+                        val action = FeatureObservableAction(
+                            fragmentEnvironment = input,
+                            fragmentId = fragmentId,
+                            feature = feature,
+                        )
+                        action.onEvent {
+                            if (state.activeIds.contains(fragmentId)) {
+                                val keyState = FragmentState(fragmentId.key, it)
+                                transition(state.copy(states = state.states.plus(fragmentId to keyState)))
+                            } else {
+                                none()
                             }
-                        }.onEvent {
-                            val keyState = FragmentState(fragmentId.key, it)
-                            transition(state.copy(states = state.states.plus(fragmentId to keyState)))
                         }
                     }
                 }

diff --git a/formula-android/src/main/java/com/instacart/formula/android/internal/ActivityManager.kt b/formula-android/src/main/java/com/instacart/formula/android/internal/ActivityManager.kt
@@ -6,7 +6,6 @@ import com.instacart.formula.android.events.ActivityResult
 import com.instacart.formula.android.FragmentEnvironment
 import com.instacart.formula.android.ActivityStore
 import com.instacart.formula.android.FormulaFragment
-import com.instacart.formula.android.FragmentFlowState
 import com.instacart.formula.android.ViewFactory
 import io.reactivex.rxjava3.disposables.CompositeDisposable
 import io.reactivex.rxjava3.disposables.Disposable
@@ -20,24 +19,18 @@ internal class ActivityManager<Activity : FragmentActivity>(
     private val store: ActivityStore<Activity>
 ) {
 
-    private val fragmentState = store
-        .contracts
-        .state(environment)
-        .doOnNext(delegate.fragmentFlowStateRelay::accept)
-        .replay(1)
-
     internal val stateSubscription: Disposable
     private var uiSubscription: Disposable? = null
     private var fragmentRenderView: FragmentFlowRenderView? = null
 
     init {
         stateSubscription = if (store.streams != null) {
             val disposables = CompositeDisposable()
-            disposables.add(fragmentState.connect())
+            disposables.add(subscribeToFragmentStateChanges())
             disposables.add(store.streams.invoke(StreamConfiguratorIml(delegate)))
             disposables
         } else {
-            fragmentState.connect()
+            subscribeToFragmentStateChanges()
         }
     }
 
@@ -63,12 +56,10 @@ internal class ActivityManager<Activity : FragmentActivity>(
         delegate.onLifecycleStateChanged(Lifecycle.State.CREATED)
         val renderView = fragmentRenderView ?: throw callOnPreCreateException(activity)
 
-        val updateScheduler = AndroidUpdateScheduler<FragmentFlowState> {
+        uiSubscription = delegate.fragmentFlowState().subscribe {
             renderView.render(it)
             store.onRenderFragmentState?.invoke(activity, it)
         }
-
-        uiSubscription = fragmentState.subscribe(updateScheduler::emitUpdate)
     }
 
     fun onActivityStarted(activity: Activity) {
@@ -115,6 +106,13 @@ internal class ActivityManager<Activity : FragmentActivity>(
         return fragmentRenderView?.viewFactory(fragment)
     }
 
+    private fun subscribeToFragmentStateChanges(): Disposable {
+        return store
+            .contracts
+            .state(environment)
+            .subscribe(delegate.fragmentFlowStateRelay::accept)
+    }
+
     private fun callOnPreCreateException(activity: FragmentActivity): IllegalStateException {
         return IllegalStateException("please call onPreCreate before calling Activity.super.onCreate(): ${activity::class.java.simpleName}")
     }

diff --git a/formula-android/src/main/java/com/instacart/formula/android/internal/FeatureBinding.kt b/formula-android/src/main/java/com/instacart/formula/android/internal/FeatureBinding.kt
@@ -32,7 +32,6 @@ internal class FeatureBinding<in Component, in Dependencies, in Key : FragmentKe
                         if (binds(key)) {
                             Action.onData(fragmentId).onEvent {
                                 transition {
-                                    // TODO: should this happen on the main thread? It needs to be available to main thread
                                     try {
                                         val dependencies = toDependencies(input.component)
                                         val feature = input.environment.fragmentDelegate.initializeFeature(

diff --git a/...a-android/src/main/java/com/instacart/formula/android/internal/FeatureObservableAction.kt b/...a-android/src/main/java/com/instacart/formula/android/internal/FeatureObservableAction.kt
@@ -0,0 +1,29 @@
+package com.instacart.formula.android.internal
+
+import com.instacart.formula.Action
+import com.instacart.formula.Cancelable
+import com.instacart.formula.android.Feature
+import com.instacart.formula.android.FragmentEnvironment
+import com.instacart.formula.android.FragmentId
+import io.reactivex.rxjava3.core.Observable
+
+class FeatureObservableAction(
+    private val fragmentEnvironment: FragmentEnvironment,
+    private val fragmentId: FragmentId,
+    private val feature: Feature<*>,
+) : Action<Any> {
+
+    override fun key(): Any = fragmentId
+
+    override fun start(send: (Any) -> Unit): Cancelable {
+        val observable = feature.state.onErrorResumeNext {
+            fragmentEnvironment.onScreenError(fragmentId.key, it)
+            Observable.empty()
+        }
+
+        // We ensure all feature state updates come on the main thread.
+        val androidUpdateScheduler = AndroidUpdateScheduler(send)
+        val disposable = observable.subscribe(androidUpdateScheduler::emitUpdate)
+        return Cancelable(disposable::dispose)
+    }
+}
diff --git a/...la-android/src/main/java/com/instacart/formula/android/internal/FragmentFlowRenderView.kt b/...la-android/src/main/java/com/instacart/formula/android/internal/FragmentFlowRenderView.kt
@@ -42,7 +42,6 @@ internal class FragmentFlowRenderView(
 
     private val featureProvider = object : FeatureProvider {
         override fun getFeature(id: FragmentId): FeatureEvent? {
-            // TODO: should we initialize feature if it's missing
             return fragmentState?.features?.get(id)
         }
     }