coroutine-flow-support: Add example to show how to safely collect flo…

…w. (EO)

dependencies.gradle

@@ -24,7 +24,8 @@ ext {
                             ktx: "androidx.core:core-ktx:1.6.0"
                     ],
                     activity        : [
-                            compose : "androidx.activity:activity-compose:1.3.1"
+                            compose : "androidx.activity:activity-compose:1.3.1",
+                            ktx     : "androidx.activity:activity-ktx:1.3.1"
                     ],
                     compose         : [
                             foundation  : "androidx.compose.foundation:foundation:$composeVersion",
@@ -70,6 +71,8 @@ ext {
             rxjava               : "io.reactivex.rxjava3:rxjava:3.1.1",
             rxandroid            : "io.reactivex.rxjava3:rxandroid:3.0.0",
             rxrelays             : "com.jakewharton.rxrelay3:rxrelay:3.0.1",
-            truth                : "com.google.truth:truth:$truthVersion"
+            truth                : "com.google.truth:truth:$truthVersion",
+            cororutinesTest      : "org.jetbrains.kotlinx:kotlinx-coroutines-test:$kotlinCoroutinesVersion"
+
     ]
 }

formula-android/src/main/java/com/instacart/formula/android/FeatureView.kt

@@ -1,7 +1,6 @@
 package com.instacart.formula.android
 
 import android.view.View
-import androidx.lifecycle.LifecycleObserver
 import com.instacart.formula.Cancelable
 import io.reactivex.rxjava3.core.Observable
 
@@ -15,7 +14,7 @@ import io.reactivex.rxjava3.core.Observable
  *
  * @param view The root Android view.
  * @param bind A bind function connects state observable to the view rendering.
- * @param lifecycleObserver Optional lifecycle callbacks if you need to know the Fragment state.
+ * @param lifecycleCallbacks Optional lifecycle callbacks if you need to know the Fragment state.
  */
 class FeatureView<RenderModel>(
     val view: View,

formula-coroutines/src/main/java/com/instacart/formula/coroutines/FlowStream.kt

@@ -7,6 +7,7 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.collect
 import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.runBlocking
 
 /**
@@ -73,7 +74,9 @@ interface FlowStream<Message> : Stream<Message> {
     val scope: CoroutineScope
 
     override fun start(send: (Message) -> Unit): Cancelable? {
-        val job = flow().launchIn(scope)
+        val job = flow()
+            .onEach { send(it) }
+            .launchIn(scope)
         return Cancelable(job::cancel)
     }
 }

samples/stopwatch-coroutines/.gitignore

@@ -0,0 +1 @@
+/build

samples/stopwatch-coroutines/build.gradle

@@ -0,0 +1,55 @@
+apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply plugin: "kotlin-parcelize"
+
+android {
+    compileSdkVersion constants.compileSdk
+    defaultConfig {
+        applicationId "com.instacart.formula.stopwatch.coroutines"
+        minSdkVersion constants.minSdk
+        targetSdkVersion constants.targetSdk
+        versionCode 1
+        versionName "1.0"
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+
+    testOptions {
+        unitTests {
+            includeAndroidResources = true
+        }
+    }
+}
+
+tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+}
+
+dependencies {
+    implementation project(":formula-coroutines")
+
+    implementation libraries.kotlin
+    implementation libraries.androidx.appcompat
+    implementation libraries.androidx.lifecycle.runtimektx
+    implementation libraries.androidx.activity.ktx
+
+    testImplementation libraries.junit
+    testImplementation "com.google.truth:truth:$truthVersion"
+
+    testImplementation libraries.androidx.test.rules
+    testImplementation libraries.androidx.test.runner
+    testImplementation libraries.cororutinesTest
+}

samples/stopwatch-coroutines/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

samples/stopwatch-coroutines/src/main/AndroidManifest.xml

@@ -0,0 +1,18 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+        package="com.instacart.formula.stopwatch">
+
+    <application android:allowBackup="true"
+        android:label="@string/app_name"
+        android:icon="@mipmap/ic_launcher"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/AppTheme">
+
+        <activity android:name=".StopwatchActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+</manifest>

samples/stopwatch-coroutines/src/main/java/com/instacart/formula/stopwatch/StopWatchViewModel.kt

@@ -0,0 +1,16 @@
+package com.instacart.formula.stopwatch
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.instacart.formula.coroutines.toFlow
+import kotlinx.coroutines.flow.*
+
+class StopWatchViewModel(private val formula: StopwatchFormula = StopwatchFormula()) : ViewModel() {
+
+    val rendererStream by lazy {
+        formula.toFlow() //Let's imagine this flow uses a really expensive resource (i.e. Connectivity monitoring)
+            //Cannot use .stateIn() since we do not have initial StopwatchRenderModel
+            .shareIn(viewModelScope, SharingStarted.WhileSubscribed(), 0)
+            .distinctUntilChanged()
+    }
+}

samples/stopwatch-coroutines/src/main/java/com/instacart/formula/stopwatch/StopwatchActivity.kt

@@ -0,0 +1,36 @@
+package com.instacart.formula.stopwatch
+
+import android.os.Bundle
+import androidx.activity.viewModels
+import androidx.fragment.app.FragmentActivity
+import androidx.lifecycle.Lifecycle
+import androidx.lifecycle.lifecycleScope
+import androidx.lifecycle.repeatOnLifecycle
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.launch
+
+class StopwatchActivity : FragmentActivity() {
+
+    private val counterViewModel by viewModels<StopWatchViewModel>()
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.stopwatch_activity)
+
+        val renderView = StopwatchRenderView(findViewById(R.id.activity_content))
+
+        val renderModels = counterViewModel.rendererStream
+
+        renderModels.safeCollect { renderView.render(it) }
+    }
+
+    fun <T> Flow<T>.safeCollect(block: (T) -> Unit) = lifecycleScope.launch {
+        repeatOnLifecycle(Lifecycle.State.STARTED) {
+            this@safeCollect.collect {
+                block(it)
+            }
+        }
+    }
+
+}

samples/stopwatch-coroutines/src/main/java/com/instacart/formula/stopwatch/StopwatchAnalytics.kt

@@ -0,0 +1,5 @@
+package com.instacart.formula.stopwatch
+
+class StopwatchAnalytics {
+    fun trackClick() = Unit
+}

samples/stopwatch-coroutines/src/main/java/com/instacart/formula/stopwatch/StopwatchFormula.kt

@@ -0,0 +1,82 @@
+package com.instacart.formula.stopwatch
+
+import com.instacart.formula.Evaluation
+import com.instacart.formula.Formula
+import com.instacart.formula.FormulaContext
+import com.instacart.formula.coroutines.FlowStream
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.MainScope
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.flow.onEach
+import java.util.concurrent.TimeUnit
+
+class StopwatchFormula(private val scope: CoroutineScope = MainScope()) : Formula<Unit, StopwatchFormula.State, StopwatchRenderModel> {
+
+    data class State(
+        val timePassedInMillis: Long,
+        val isRunning: Boolean
+    )
+
+    private val analytics = StopwatchAnalytics()
+
+    override fun initialState(input: Unit): State = State(
+        timePassedInMillis = 0,
+        isRunning = true
+    )
+
+    override fun evaluate(
+        input: Unit,
+        state: State,
+        context: FormulaContext<State>
+    ): Evaluation<StopwatchRenderModel> {
+        return Evaluation(
+            output = StopwatchRenderModel(
+                timePassed = formatTimePassed(state.timePassedInMillis),
+            ),
+            updates = context.updates {
+                if (state.isRunning) {
+                    val incrementTimePassed = FlowStream.fromFlow(scope) {
+
+                        flow {
+                            while(true) {
+                                emit(Unit)
+                                delay(1)
+                            }
+                        }
+                    }
+
+                    incrementTimePassed.onEvent {
+                        transition(state.copy(timePassedInMillis = state.timePassedInMillis + 1))
+                    }
+                }
+            }
+        )
+    }
+
+    private fun formatTimePassed(timePassedInMillis: Long): String {
+        return buildString {
+            val minutesPassed = TimeUnit.MILLISECONDS.toMinutes(timePassedInMillis)
+            if (minutesPassed > 0) {
+                append(minutesPassed)
+                append('m')
+                append(' ')
+            }
+
+            val secondsPassed = TimeUnit.MILLISECONDS.toSeconds(timePassedInMillis) % 60
+            append(secondsPassed)
+            append('s')
+            append(' ')
+
+            // Always show millis as two digits
+            val millisPassed = (timePassedInMillis % 1000) / 10
+            if (millisPassed < 10) {
+                append('0')
+            }
+            append(millisPassed)
+        }
+    }
+
+}

samples/stopwatch-coroutines/src/main/java/com/instacart/formula/stopwatch/StopwatchRenderModels.kt

@@ -0,0 +1,6 @@
+package com.instacart.formula.stopwatch
+
+data class StopwatchRenderModel(
+    val timePassed: String
+)
+

samples/stopwatch-coroutines/src/main/java/com/instacart/formula/stopwatch/StopwatchRenderView.kt

@@ -0,0 +1,16 @@
+package com.instacart.formula.stopwatch
+
+import android.view.ViewGroup
+import android.widget.Button
+import android.widget.TextView
+import com.instacart.formula.Renderer
+import com.instacart.formula.RenderView
+
+class StopwatchRenderView(root: ViewGroup) : RenderView<StopwatchRenderModel> {
+    private val timePassed: TextView = root.findViewById(R.id.time_passed_text_view)
+
+    override val render: Renderer<StopwatchRenderModel> = Renderer { model ->
+
+        timePassed.text = model.timePassed
+    }
+}

samples/stopwatch-coroutines/src/main/res/drawable-v24/ic_launcher_foreground.xml

@@ -0,0 +1,34 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:aapt="http://schemas.android.com/aapt"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportHeight="108"
+    android:viewportWidth="108">
+    <path
+        android:fillType="evenOdd"
+        android:pathData="M32,64C32,64 38.39,52.99 44.13,50.95C51.37,48.37 70.14,49.57 70.14,49.57L108.26,87.69L108,109.01L75.97,107.97L32,64Z"
+        android:strokeColor="#00000000"
+        android:strokeWidth="1">
+        <aapt:attr name="android:fillColor">
+            <gradient
+                android:endX="78.5885"
+                android:endY="90.9159"
+                android:startX="48.7653"
+                android:startY="61.0927"
+                android:type="linear">
+                <item
+                    android:color="#44000000"
+                    android:offset="0.0" />
+                <item
+                    android:color="#00000000"
+                    android:offset="1.0" />
+            </gradient>
+        </aapt:attr>
+    </path>
+    <path
+        android:fillColor="#FFFFFF"
+        android:fillType="nonZero"
+        android:pathData="M66.94,46.02L66.94,46.02C72.44,50.07 76,56.61 76,64L32,64C32,56.61 35.56,50.11 40.98,46.06L36.18,41.19C35.45,40.45 35.45,39.3 36.18,38.56C36.91,37.81 38.05,37.81 38.78,38.56L44.25,44.05C47.18,42.57 50.48,41.71 54,41.71C57.48,41.71 60.78,42.57 63.68,44.05L69.11,38.56C69.84,37.81 70.98,37.81 71.71,38.56C72.44,39.3 72.44,40.45 71.71,41.19L66.94,46.02ZM62.94,56.92C64.08,56.92 65,56.01 65,54.88C65,53.76 64.08,52.85 62.94,52.85C61.8,52.85 60.88,53.76 60.88,54.88C60.88,56.01 61.8,56.92 62.94,56.92ZM45.06,56.92C46.2,56.92 47.13,56.01 47.13,54.88C47.13,53.76 46.2,52.85 45.06,52.85C43.92,52.85 43,53.76 43,54.88C43,56.01 43.92,56.92 45.06,56.92Z"
+        android:strokeColor="#00000000"
+        android:strokeWidth="1" />
+</vector>