985: Add Ability to track whether state changed; Add Config for Rende…

…r on State Change Only

.github/workflows/kotlin.yml

@@ -188,6 +188,34 @@ jobs :
         with :
           report_paths : '**/build/test-results/test/TEST-*.xml'
 
+  jvm-stateChange-runtime-test :
+    name : Render On State Change Only Runtime JVM Tests
+    runs-on : ubuntu-latest
+    timeout-minutes : 20
+    steps :
+      - uses : actions/checkout@v3
+      - uses : gradle/wrapper-validation-action@v1
+      - name : set up JDK 11
+        uses : actions/setup-java@v3
+        with :
+          distribution : 'zulu'
+          java-version : 11
+
+      ## Actual task
+      - uses : gradle/gradle-build-action@v2
+        name : Check with Gradle
+        with :
+          arguments : |
+            jvmTest --continue -Pworkflow.runtime=stateChange
+          cache-read-only : false
+
+      # Report as Github Pull Request Check.
+      - name : Publish Test Report
+        uses : mikepenz/action-junit-report@v3
+        if : always() # always run even if the previous step fails
+        with :
+          report_paths : '**/build/test-results/test/TEST-*.xml'
+
   ios-tests :
     name : iOS Tests
     runs-on : macos-latest
@@ -280,7 +308,6 @@ jobs :
           profile : Galaxy Nexus
           api-level : ${{ matrix.api-level }}
           arch : x86_64
-          # Skip the benchmarks as this is running on emulators
           script : ./gradlew :benchmarks:performance-poetry:complex-poetry:connectedCheck --continue
 
       - name : Upload results
@@ -384,6 +411,54 @@ jobs :
           name : instrumentation-test-results-${{ matrix.api-level }}
           path : ./**/build/reports/androidTests/connected/**
 
+  stateChange-runtime-instrumentation-tests :
+    name : Render on State Change Only Instrumentation tests
+    runs-on : macos-latest
+    timeout-minutes : 45
+    strategy :
+      # Allow tests to continue on other devices if they fail on one device.
+      fail-fast : false
+      matrix :
+        api-level :
+          - 29
+      # Unclear that older versions actually honor command to disable animation.
+      # Newer versions are reputed to be too slow: https://github.com/ReactiveCircus/android-emulator-runner/issues/222
+    steps :
+      - uses : actions/checkout@v3
+      - name : set up JDK 11
+        uses : actions/setup-java@v3
+        with :
+          distribution : 'zulu'
+          java-version : 11
+
+      ## Build before running tests, using cache.
+      - uses : gradle/gradle-build-action@v2
+        name : Build instrumented tests
+        with :
+          # Unfortunately I don't think we can key this cache based on our project property so
+          # we clean and rebuild.
+          arguments : |
+            clean assembleDebugAndroidTest -Pworkflow.runtime=stateChange
+          cache-read-only : false
+
+      ## Actual task
+      - name : Instrumentation Tests
+        uses : reactivecircus/android-emulator-runner@v2
+        with :
+          # @ychescale9 suspects Galaxy Nexus is the fastest one
+          profile : Galaxy Nexus
+          api-level : ${{ matrix.api-level }}
+          arch : x86_64
+          # Skip the benchmarks as this is running on emulators
+          script : ./gradlew connectedCheck -x :benchmarks:dungeon-benchmark:connectedCheck -x :benchmarks:performance-poetry:complex-benchmark:connectedCheck -x :benchmarks:performance-poetry:complex-poetry:connectedCheck -Pworkflow.runtime=stateChange
+
+      - name : Upload results
+        if : ${{ always() }}
+        uses : actions/upload-artifact@v3
+        with :
+          name : instrumentation-test-results-${{ matrix.api-level }}
+          path : ./**/build/reports/androidTests/connected/**
+
   upload-to-mobiledev :
     name : mobile.dev | Build & Upload
     runs-on : ubuntu-latest

gradle.properties

@@ -8,7 +8,7 @@ android.useAndroidX=true
 systemProp.org.gradle.internal.publish.checksums.insecure=true
 
 GROUP=com.squareup.workflow1
-VERSION_NAME=1.10.0-beta06-SNAPSHOT
+VERSION_NAME=1.10.0-beta06-state2-SNAPSHOT
 
 POM_DESCRIPTION=Square Workflow
 

samples/dungeon/timemachine/src/test/java/com/squareup/sample/timemachine/TimeMachineWorkflowTest.kt

@@ -25,7 +25,12 @@ class TimeMachineWorkflowTest {
     val delegateWorkflow = Workflow.stateful<String, Nothing, DelegateRendering>(
       initialState = "initial",
       render = { renderState ->
-        DelegateRendering(renderState, setState = eventHandler { s -> state = s })
+        DelegateRendering(
+          renderState,
+          setState = eventHandler { s ->
+            state = s
+          }
+        )
       }
     )
     val clock = TestTimeSource()

workflow-config/config-android/src/main/java/com/squareup/workflow1/config/AndroidRuntimeConfigTools.kt

@@ -2,6 +2,7 @@ package com.squareup.workflow1.config
 
 import com.squareup.workflow1.RuntimeConfig
 import com.squareup.workflow1.RuntimeConfig.ConflateStaleRenderings
+import com.squareup.workflow1.RuntimeConfig.RenderOnStateChangeOnly
 import com.squareup.workflow1.RuntimeConfig.RenderPerAction
 import com.squareup.workflow1.WorkflowExperimentalRuntime
 
@@ -18,6 +19,8 @@ public class AndroidRuntimeConfigTools {
      * this function, and then pass that to the call to [renderWorkflowIn] as the [RuntimeConfig].
      *
      * Current options are:
+     * "stateChange" : [RenderOnStateChangeOnly] Only re-render when the state of some WorkflowNode
+     *      has changed.
      * "conflate" : [ConflateStaleRenderings] Process all queued actions before passing rendering
      *      to the UI layer.
      * "baseline" : [RenderPerAction] Original Workflow Runtime. Note that this doesn't need to
@@ -26,6 +29,7 @@ public class AndroidRuntimeConfigTools {
     @WorkflowExperimentalRuntime
     public fun getAppWorkflowRuntimeConfig(): RuntimeConfig {
       return when (BuildConfig.WORKFLOW_RUNTIME) {
+        "stateChange" -> RenderOnStateChangeOnly
         "conflate" -> ConflateStaleRenderings
         else -> RenderPerAction
       }

workflow-config/config-jvm/src/main/java/com/squareup/workflow1/config/JvmTestRuntimeConfigTools.kt

@@ -2,6 +2,7 @@ package com.squareup.workflow1.config
 
 import com.squareup.workflow1.RuntimeConfig
 import com.squareup.workflow1.RuntimeConfig.ConflateStaleRenderings
+import com.squareup.workflow1.RuntimeConfig.RenderOnStateChangeOnly
 import com.squareup.workflow1.RuntimeConfig.RenderPerAction
 import com.squareup.workflow1.WorkflowExperimentalRuntime
 
@@ -17,6 +18,8 @@ public class JvmTestRuntimeConfigTools {
      * [RuntimeConfig].
      *
      * Current options are:
+     * "stateChange" : [RenderOnStateChangeOnly] Only re-render when the state of some WorkflowNode
+     *      has changed.
      * "conflate" : [ConflateStaleRenderings] Process all queued actions before passing rendering
      *      to the UI layer.
      * "baseline" : [RenderPerAction] Original Workflow Runtime. Note that this doesn't need to
@@ -26,6 +29,7 @@ public class JvmTestRuntimeConfigTools {
     public fun getTestRuntimeConfig(): RuntimeConfig {
       val runtimeConfig = System.getProperty("workflow.runtime", "baseline")
       return when (runtimeConfig) {
+        "stateChange" -> RenderOnStateChangeOnly
         "conflate" -> ConflateStaleRenderings
         else -> RenderPerAction
       }

workflow-core/api/workflow-core.api

@@ -1,3 +1,17 @@
+public final class com/squareup/workflow1/ActionApplied : com/squareup/workflow1/ActionProcessingResult {
+	public fun <init> (Lcom/squareup/workflow1/WorkflowOutput;Z)V
+	public synthetic fun <init> (Lcom/squareup/workflow1/WorkflowOutput;ZILkotlin/jvm/internal/DefaultConstructorMarker;)V
+	public final fun component1 ()Lcom/squareup/workflow1/WorkflowOutput;
+	public final fun component2 ()Z
+	public final fun copy (Lcom/squareup/workflow1/WorkflowOutput;Z)Lcom/squareup/workflow1/ActionApplied;
+	public static synthetic fun copy$default (Lcom/squareup/workflow1/ActionApplied;Lcom/squareup/workflow1/WorkflowOutput;ZILjava/lang/Object;)Lcom/squareup/workflow1/ActionApplied;
+	public fun equals (Ljava/lang/Object;)Z
+	public final fun getOutput ()Lcom/squareup/workflow1/WorkflowOutput;
+	public final fun getStateChanged ()Z
+	public fun hashCode ()I
+	public fun toString ()Ljava/lang/String;
+}
+
 public abstract interface class com/squareup/workflow1/ActionProcessingResult {
 }
 
@@ -217,6 +231,7 @@ public final class com/squareup/workflow1/WorkflowAction$Companion {
 
 public final class com/squareup/workflow1/WorkflowAction$Updater {
 	public fun <init> (Lcom/squareup/workflow1/WorkflowAction;Ljava/lang/Object;Ljava/lang/Object;)V
+	public final fun forceRerender ()V
 	public final fun getProps ()Ljava/lang/Object;
 	public final fun getState ()Ljava/lang/Object;
 	public final fun setOutput (Ljava/lang/Object;)V
@@ -271,7 +286,7 @@ public final class com/squareup/workflow1/WorkflowIdentifierType$Unsnapshottable
 	public fun toString ()Ljava/lang/String;
 }
 
-public final class com/squareup/workflow1/WorkflowOutput : com/squareup/workflow1/ActionProcessingResult {
+public final class com/squareup/workflow1/WorkflowOutput {
 	public fun <init> (Ljava/lang/Object;)V
 	public fun equals (Ljava/lang/Object;)Z
 	public final fun getValue ()Ljava/lang/Object;

workflow-core/src/commonMain/kotlin/com/squareup/workflow1/WorkflowAction.kt

@@ -22,15 +22,25 @@ public abstract class WorkflowAction<in PropsT, StateT, out OutputT> {
     public val props: @UnsafeVariance PropsT,
     public var state: StateT
   ) {
-    internal var maybeOutput: WorkflowOutput<@UnsafeVariance OutputT>? = null
+    internal val startingState = state
+    internal var forcedRerender: Boolean = false
+    internal var outputOrNull: WorkflowOutput<@UnsafeVariance OutputT>? = null
       private set
 
     /**
      * Sets the value the workflow will emit as output when this action is applied.
      * If this method is not called, there will be no output.
      */
     public fun setOutput(output: @UnsafeVariance OutputT) {
-      this.maybeOutput = WorkflowOutput(output)
+      this.outputOrNull = WorkflowOutput(output)
+    }
+
+    /**
+     * The action will cause the Workflow to re-render regardless of whether or not state has
+     * changed, for all [RuntimeConfig]s.
+     */
+    public fun forceRerender() {
+      forcedRerender = true
     }
   }
 
@@ -105,24 +115,24 @@ public fun <PropsT, StateT, OutputT> action(
 public fun <PropsT, StateT, OutputT> WorkflowAction<PropsT, StateT, OutputT>.applyTo(
   props: PropsT,
   state: StateT
-): Pair<StateT, WorkflowOutput<OutputT>?> {
+): Pair<StateT, ActionApplied<OutputT>> {
   val updater = Updater(props, state)
   updater.apply()
-  return Pair(updater.state, updater.maybeOutput)
+  return Pair(
+    updater.state,
+    ActionApplied(
+      output = updater.outputOrNull,
+      stateChanged = updater.forcedRerender || updater.state != updater.startingState,
+    )
+  )
 }
 
 /**
- * Only [WorkflowOutput] needs the generic OutputT so we do not include it in the root
- * interface here.
+ * Box around a potentially nullable [OutputT]
  */
-public sealed interface ActionProcessingResult
-
-public object PropsUpdated : ActionProcessingResult
-
-public object ActionsExhausted : ActionProcessingResult
-
-/** Wrapper around a potentially-nullable [OutputT] value. */
-public class WorkflowOutput<out OutputT>(public val value: OutputT) : ActionProcessingResult {
+public class WorkflowOutput<out OutputT>(
+  public val value: OutputT
+) {
   override fun toString(): String = "WorkflowOutput($value)"
 
   override fun equals(other: Any?): Boolean = when {
@@ -133,3 +143,28 @@ public class WorkflowOutput<out OutputT>(public val value: OutputT) : ActionProc
 
   override fun hashCode(): Int = value.hashCode()
 }
+
+/**
+ * An [ActionProcessingResult] is any possible outcome after the runtime does a loop of processing.
+ *
+ * Only [ActionApplied] needs the generic OutputT so we do not include it in the root
+ * interface here.
+ */
+public sealed interface ActionProcessingResult
+
+public object PropsUpdated : ActionProcessingResult
+
+public object ActionsExhausted : ActionProcessingResult
+
+/**
+ * Result of applying an action.
+ *
+ * @param output: the potentially null [WorkflowOutput]. If null, then no output was set by the
+ *   action. Otherwise it is a [WorkflowOutput] around the output value of type [OutputT],
+ *   which could be null.
+ * @param stateChanged: whether or not the action changed the state.
+ */
+public data class ActionApplied<out OutputT>(
+  public val output: WorkflowOutput<OutputT>?,
+  public val stateChanged: Boolean = false,
+) : ActionProcessingResult

workflow-core/src/commonTest/kotlin/com/squareup/workflow1/SinkTest.kt

@@ -21,7 +21,6 @@ import kotlin.test.fail
 
 @OptIn(
   ExperimentalCoroutinesApi::class,
-  ExperimentalStdlibApi::class,
 )
 internal class SinkTest {
 
@@ -42,9 +41,9 @@ internal class SinkTest {
     assertEquals(1, sink.actions.size)
     sink.actions.removeFirst()
       .let { action ->
-        val (newState, output) = action.applyTo("props", "state")
+        val (newState, result) = action.applyTo("props", "state")
         assertEquals("props state 1", newState)
-        assertEquals("output: 1", output?.value)
+        assertEquals("output: 1", result.output!!.value)
       }
     assertTrue(sink.actions.isEmpty())
 
@@ -53,9 +52,9 @@ internal class SinkTest {
     assertEquals(1, sink.actions.size)
     sink.actions.removeFirst()
       .let { action ->
-        val (newState, output) = action.applyTo("props", "state")
+        val (newState, result) = action.applyTo("props", "state")
         assertEquals("props state 2", newState)
-        assertEquals("output: 2", output?.value)
+        assertEquals("output: 2", result.output!!.value)
       }
 
     collector.cancel()
@@ -95,16 +94,16 @@ internal class SinkTest {
           assertEquals(3, counter.getAndIncrement())
         }
         .applyTo(Unit, Unit)
-        .let { (_, output) ->
+        .let { (_, result) ->
           assertEquals(6, counter.getAndIncrement())
-          assertEquals("a", output?.value)
+          assertEquals("a", result.output!!.value)
         }
 
       sentActions.removeFirst()
         .applyTo(Unit, Unit)
-        .let { (_, output) ->
+        .let { (_, result) ->
           assertEquals(7, counter.getAndIncrement())
-          assertEquals("b", output?.value)
+          assertEquals("b", result.output!!.value)
         }
 
       collectJob.cancel()
@@ -125,10 +124,10 @@ internal class SinkTest {
       advanceUntilIdle()
 
       val enqueuedAction = sink.actions.removeFirst()
-      val (newState, output) = enqueuedAction.applyTo("props", "state")
+      val (newState, result) = enqueuedAction.applyTo("props", "state")
       assertEquals(1, applications)
       assertEquals("props state applied", newState)
-      assertEquals("output", output?.value)
+      assertEquals("output", result.output!!.value)
     }
   }
 
@@ -171,11 +170,11 @@ internal class SinkTest {
       val enqueuedAction = sink.actions.removeFirst()
       sendJob.cancel()
       advanceUntilIdle()
-      val (newState, output) = enqueuedAction.applyTo("unused props", "state")
+      val (newState, result) = enqueuedAction.applyTo("unused props", "state")
 
       assertFalse(applied)
       assertEquals("state", newState)
-      assertNull(output)
+      assertNull(result.output)
     }
 
   private class RecordingSink : Sink<WorkflowAction<String, String, String>> {