Ship skipping null state updates

Summary: The experiment results are neutral, there are no regressions or other issues. We can ship skipping state updates when the old and new value is null.

Reviewed By: apowolny

Differential Revision: D60572677

fbshipit-source-id: dbc3898e90e1bdcc57f58449b7baa4e3a69f05f9

litho-core/src/main/java/com/facebook/litho/TreeState.kt

@@ -19,7 +19,6 @@ package com.facebook.litho
 import android.util.Pair
 import androidx.annotation.VisibleForTesting
 import com.facebook.litho.Component.RenderData
-import com.facebook.litho.config.ComponentsConfiguration
 import com.facebook.litho.internal.HookKey
 import com.facebook.rendercore.annotations.UIState
 
@@ -245,9 +244,7 @@ class TreeState {
   ): Boolean {
     val stateHandler = getStateHandler(isNestedTree)
     val committedState = stateHandler.getStateContainer(globalKey) as KStateContainer?
-    if (committedState != null &&
-        (ComponentsConfiguration.enableSkipNullStateUpdates ||
-            committedState.states.getOrNull(hookStateIndex) != null)) {
+    if (committedState != null) {
       val committedStateWithUpdatesApplied =
           stateHandler.getStateContainerWithHookUpdates(globalKey)
       if (committedStateWithUpdatesApplied != null) {

litho-core/src/main/java/com/facebook/litho/config/ComponentsConfiguration.kt

@@ -301,11 +301,6 @@ internal constructor(
      * NaN or Infinity.
      */
     @JvmField var enableLoggingForInvalidAspectRatio: Boolean = false
-    /**
-     * This flag is used to enable a change where a state update is skipped if the current and new
-     * state value are null.
-     */
-    @JvmField var enableSkipNullStateUpdates: Boolean = false
     /** This flag is used to enable a fix for the ANR issue with sticky header RecyclerView. */
     @JvmField var enableFixForStickyHeader: Boolean = false
 

litho-core/src/test/kotlin/com/facebook/litho/KStateTest.kt

@@ -19,7 +19,6 @@ package com.facebook.litho
 import android.view.View
 import com.facebook.litho.SizeSpec.EXACTLY
 import com.facebook.litho.accessibility.contentDescription
-import com.facebook.litho.config.ComponentsConfiguration
 import com.facebook.litho.core.height
 import com.facebook.litho.core.width
 import com.facebook.litho.kotlin.widget.Text
@@ -604,12 +603,7 @@ class KStateTest {
 
     lithoViewRule.act(testLithoView) { clickOnTag("test_view") }
 
-    // TODO clean up when experiment concluded
-    if (ComponentsConfiguration.enableSkipNullStateUpdates) {
-      assertThat(renderCount.get()).isEqualTo(1)
-    } else {
-      assertThat(renderCount.get()).isEqualTo(2)
-    }
+    assertThat(renderCount.get()).isEqualTo(1)
   }
 
   private class CountDownLatchComponent(