Allow recursive calls to schedulerShouldRenderTransactions without deadlocks

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java

@@ -66,7 +66,6 @@
 import com.facebook.react.fabric.mounting.mountitems.MountItem;
 import com.facebook.react.fabric.mounting.mountitems.MountItemFactory;
 import com.facebook.react.interfaces.fabric.SurfaceHandler;
-import com.facebook.react.internal.featureflags.ReactNativeFeatureFlags;
 import com.facebook.react.internal.interop.InteropEventEmitter;
 import com.facebook.react.modules.core.ReactChoreographer;
 import com.facebook.react.modules.i18nmanager.I18nUtil;
@@ -214,14 +213,7 @@ public class FabricUIManager
         public void executeItems(Queue<MountItem> items) {
           // This executor can be technically accessed before the dispatcher is created,
           // but if that happens, something is terribly wrong
-          if (ReactNativeFeatureFlags.forceBatchingMountItemsOnAndroid()) {
-            for (MountItem mountItem : items) {
-              mMountItemDispatcher.addMountItem(mountItem);
-            }
-            mMountItemDispatcher.tryDispatchMountItems();
-          } else {
-            mMountItemDispatcher.dispatchMountItems(items);
-          }
+          mMountItemDispatcher.dispatchMountItems(items);
         }
       };
 

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlags.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<84f45a19bf93a62da7ce904a2682fc51>>
+ * @generated SignedSource<<4e30b8a42dfe7e041ecb30a386b54e50>>
  */
 
 /**
@@ -40,6 +40,12 @@ public object ReactNativeFeatureFlags {
   @JvmStatic
   public fun allowCollapsableChildren(): Boolean = accessor.allowCollapsableChildren()
 
+  /**
+   * Adds support for recursively processing commits that mount synchronously (Android only).
+   */
+  @JvmStatic
+  public fun allowRecursiveCommitsWithSynchronousMountOnAndroid(): Boolean = accessor.allowRecursiveCommitsWithSynchronousMountOnAndroid()
+
   /**
    * When enabled, the RuntimeScheduler processing the event loop will batch all rendering updates and dispatch them together at the end of each iteration of the loop.
    */

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxAccessor.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<2f84a5455d747e14324f7b79cbbdc763>>
+ * @generated SignedSource<<944fabed27a371ce2e1a86e367312c1f>>
  */
 
 /**
@@ -22,6 +22,7 @@ package com.facebook.react.internal.featureflags
 public class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAccessor {
   private var commonTestFlagCache: Boolean? = null
   private var allowCollapsableChildrenCache: Boolean? = null
+  private var allowRecursiveCommitsWithSynchronousMountOnAndroidCache: Boolean? = null
   private var batchRenderingUpdatesInEventLoopCache: Boolean? = null
   private var destroyFabricSurfacesInReactInstanceManagerCache: Boolean? = null
   private var enableBackgroundExecutorCache: Boolean? = null
@@ -59,6 +60,15 @@ public class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAccesso
     return cached
   }
 
+  override fun allowRecursiveCommitsWithSynchronousMountOnAndroid(): Boolean {
+    var cached = allowRecursiveCommitsWithSynchronousMountOnAndroidCache
+    if (cached == null) {
+      cached = ReactNativeFeatureFlagsCxxInterop.allowRecursiveCommitsWithSynchronousMountOnAndroid()
+      allowRecursiveCommitsWithSynchronousMountOnAndroidCache = cached
+    }
+    return cached
+  }
+
   override fun batchRenderingUpdatesInEventLoop(): Boolean {
     var cached = batchRenderingUpdatesInEventLoopCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxInterop.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<c82dca47362f4798dfcebda31b2fe2d6>>
+ * @generated SignedSource<<d2ccaef4c75979c26327963aeee0b0ad>>
  */
 
 /**
@@ -32,6 +32,8 @@ public object ReactNativeFeatureFlagsCxxInterop {
 
   @DoNotStrip @JvmStatic public external fun allowCollapsableChildren(): Boolean
 
+  @DoNotStrip @JvmStatic public external fun allowRecursiveCommitsWithSynchronousMountOnAndroid(): Boolean
+
   @DoNotStrip @JvmStatic public external fun batchRenderingUpdatesInEventLoop(): Boolean
 
   @DoNotStrip @JvmStatic public external fun destroyFabricSurfacesInReactInstanceManager(): Boolean

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsDefaults.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<1ea3b574063dca0256494361423ce63e>>
+ * @generated SignedSource<<c74b5434945f63cf42551b188b9f7a48>>
  */
 
 /**
@@ -27,6 +27,8 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
 
   override fun allowCollapsableChildren(): Boolean = true
 
+  override fun allowRecursiveCommitsWithSynchronousMountOnAndroid(): Boolean = false
+
   override fun batchRenderingUpdatesInEventLoop(): Boolean = false
 
   override fun destroyFabricSurfacesInReactInstanceManager(): Boolean = false

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsLocalAccessor.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<a66642e4f6027ab0f5280baa2169d901>>
+ * @generated SignedSource<<3b94757d58e6adb2bccf4ddfb86e2080>>
  */
 
 /**
@@ -26,6 +26,7 @@ public class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcces
 
   private var commonTestFlagCache: Boolean? = null
   private var allowCollapsableChildrenCache: Boolean? = null
+  private var allowRecursiveCommitsWithSynchronousMountOnAndroidCache: Boolean? = null
   private var batchRenderingUpdatesInEventLoopCache: Boolean? = null
   private var destroyFabricSurfacesInReactInstanceManagerCache: Boolean? = null
   private var enableBackgroundExecutorCache: Boolean? = null
@@ -65,6 +66,16 @@ public class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcces
     return cached
   }
 
+  override fun allowRecursiveCommitsWithSynchronousMountOnAndroid(): Boolean {
+    var cached = allowRecursiveCommitsWithSynchronousMountOnAndroidCache
+    if (cached == null) {
+      cached = currentProvider.allowRecursiveCommitsWithSynchronousMountOnAndroid()
+      accessedFeatureFlags.add("allowRecursiveCommitsWithSynchronousMountOnAndroid")
+      allowRecursiveCommitsWithSynchronousMountOnAndroidCache = cached
+    }
+    return cached
+  }
+
   override fun batchRenderingUpdatesInEventLoop(): Boolean {
     var cached = batchRenderingUpdatesInEventLoopCache
     if (cached == null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsProvider.kt

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<7a63b1fc14ccc86efb0929452755744d>>
+ * @generated SignedSource<<68ec2c046868a2cb1d2d88e4fdd9d993>>
  */
 
 /**
@@ -27,6 +27,8 @@ public interface ReactNativeFeatureFlagsProvider {
 
   @DoNotStrip public fun allowCollapsableChildren(): Boolean
 
+  @DoNotStrip public fun allowRecursiveCommitsWithSynchronousMountOnAndroid(): Boolean
+
   @DoNotStrip public fun batchRenderingUpdatesInEventLoop(): Boolean
 
   @DoNotStrip public fun destroyFabricSurfacesInReactInstanceManager(): Boolean

packages/react-native/ReactAndroid/src/main/jni/react/fabric/Binding.cpp

@@ -487,11 +487,28 @@ void Binding::schedulerShouldRenderTransactions(
     return;
   }
 
-  std::unique_lock<std::mutex> lock(pendingTransactionsMutex_);
-  for (auto& transaction : pendingTransactions_) {
-    mountingManager->executeMount(transaction);
+  if (ReactNativeFeatureFlags::
+          allowRecursiveCommitsWithSynchronousMountOnAndroid()) {
+    std::vector<MountingTransaction> pendingTransactions;
+
+    {
+      // Retain the lock to access the pending transactions but not to execute
+      // the mount operations because that method can call into this method
+      // again.
+      std::unique_lock<std::mutex> lock(pendingTransactionsMutex_);
+      pendingTransactions_.swap(pendingTransactions);
+    }
+
+    for (auto& transaction : pendingTransactions) {
+      mountingManager->executeMount(transaction);
+    }
+  } else {
+    std::unique_lock<std::mutex> lock(pendingTransactionsMutex_);
+    for (auto& transaction : pendingTransactions_) {
+      mountingManager->executeMount(transaction);
+    }
+    pendingTransactions_.clear();
   }
-  pendingTransactions_.clear();
 }
 
 void Binding::schedulerDidRequestPreliminaryViewAllocation(

packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<82d20aa409496b17df21a077088894a6>>
+ * @generated SignedSource<<318ea35c5b58c968d7026dbe547200e4>>
  */
 
 /**
@@ -51,6 +51,12 @@ class ReactNativeFeatureFlagsProviderHolder
     return method(javaProvider_);
   }
 
+  bool allowRecursiveCommitsWithSynchronousMountOnAndroid() override {
+    static const auto method =
+        getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("allowRecursiveCommitsWithSynchronousMountOnAndroid");
+    return method(javaProvider_);
+  }
+
   bool batchRenderingUpdatesInEventLoop() override {
     static const auto method =
         getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("batchRenderingUpdatesInEventLoop");
@@ -173,6 +179,11 @@ bool JReactNativeFeatureFlagsCxxInterop::allowCollapsableChildren(
   return ReactNativeFeatureFlags::allowCollapsableChildren();
 }
 
+bool JReactNativeFeatureFlagsCxxInterop::allowRecursiveCommitsWithSynchronousMountOnAndroid(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
+  return ReactNativeFeatureFlags::allowRecursiveCommitsWithSynchronousMountOnAndroid();
+}
+
 bool JReactNativeFeatureFlagsCxxInterop::batchRenderingUpdatesInEventLoop(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
   return ReactNativeFeatureFlags::batchRenderingUpdatesInEventLoop();
@@ -286,6 +297,9 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
       makeNativeMethod(
         "allowCollapsableChildren",
         JReactNativeFeatureFlagsCxxInterop::allowCollapsableChildren),
+      makeNativeMethod(
+        "allowRecursiveCommitsWithSynchronousMountOnAndroid",
+        JReactNativeFeatureFlagsCxxInterop::allowRecursiveCommitsWithSynchronousMountOnAndroid),
       makeNativeMethod(
         "batchRenderingUpdatesInEventLoop",
         JReactNativeFeatureFlagsCxxInterop::batchRenderingUpdatesInEventLoop),

packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<08463d4f487df81332c79c8e85b4dac8>>
+ * @generated SignedSource<<4d557dc4399d46888205165ee7ae4ab2>>
  */
 
 /**
@@ -36,6 +36,9 @@ class JReactNativeFeatureFlagsCxxInterop
   static bool allowCollapsableChildren(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 
+  static bool allowRecursiveCommitsWithSynchronousMountOnAndroid(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
+
   static bool batchRenderingUpdatesInEventLoop(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.cpp

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<c51ddd57ad10e748d6e2c5f444ea3765>>
+ * @generated SignedSource<<2a748a0a1b92cb0514fec83668ed8b0f>>
  */
 
 /**
@@ -29,6 +29,10 @@ bool ReactNativeFeatureFlags::allowCollapsableChildren() {
   return getAccessor().allowCollapsableChildren();
 }
 
+bool ReactNativeFeatureFlags::allowRecursiveCommitsWithSynchronousMountOnAndroid() {
+  return getAccessor().allowRecursiveCommitsWithSynchronousMountOnAndroid();
+}
+
 bool ReactNativeFeatureFlags::batchRenderingUpdatesInEventLoop() {
   return getAccessor().batchRenderingUpdatesInEventLoop();
 }

packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.h

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<705dba656bfb228227399bcda638c404>>
+ * @generated SignedSource<<a75464f590c4f55e64ad2e33cfc52989>>
  */
 
 /**
@@ -47,6 +47,11 @@ class ReactNativeFeatureFlags {
    */
   RN_EXPORT static bool allowCollapsableChildren();
 
+  /**
+   * Adds support for recursively processing commits that mount synchronously (Android only).
+   */
+  RN_EXPORT static bool allowRecursiveCommitsWithSynchronousMountOnAndroid();
+
   /**
    * When enabled, the RuntimeScheduler processing the event loop will batch all rendering updates and dispatch them together at the end of each iteration of the loop.
    */