From 0925e9b8e7a8f9cabc144220b8494b8a54b0ad33 Mon Sep 17 00:00:00 2001
From: Christoph Purrer <chpurrer@meta.com>
Date: Thu, 4 Apr 2024 16:22:19 -0700
Subject: [PATCH] Add ReactRootViewTagGenerator (#43882)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/43882

Changelog: [Added] Add ReactRootViewTagGenerator

This copies over a modified version of the [react-native-windows](https://github.com/microsoft/react-native-windows/blob/main/vnext/Microsoft.ReactNative/Modules/ReactRootViewTagGenerator.h) implementation so it can be shared with other C based platforms

This also updates the outdated comment about the non existing ReactIOSTagHandles JS module.

Differential Revision: D55772580
---
 .../React/Modules/RCTUIManagerUtils.m         |  3 ++-
 .../uimanager/ReactRootViewTagGenerator.kt    |  2 +-
 .../core/ReactRootViewTagGenerator.cpp        | 22 +++++++++++++++++++
 .../renderer/core/ReactRootViewTagGenerator.h | 16 ++++++++++++++
 4 files changed, 41 insertions(+), 2 deletions(-)
 create mode 100644 packages/react-native/ReactCommon/react/renderer/core/ReactRootViewTagGenerator.cpp
 create mode 100644 packages/react-native/ReactCommon/react/renderer/core/ReactRootViewTagGenerator.h

diff --git a/packages/react-native/React/Modules/RCTUIManagerUtils.m b/packages/react-native/React/Modules/RCTUIManagerUtils.m
index 887fa52f4405fe..66c8471ca51398 100644
--- a/packages/react-native/React/Modules/RCTUIManagerUtils.m
+++ b/packages/react-native/React/Modules/RCTUIManagerUtils.m
@@ -97,7 +97,8 @@ void RCTUnsafeExecuteOnUIManagerQueueSync(dispatch_block_t block)
 
 NSNumber *RCTAllocateRootViewTag(void)
 {
-  // Numbering of these tags goes from 1, 11, 21, 31, ..., 100501, ...
+  // Keep in sync with ReactRootViewTagGenerator.h - see that file for an explanation on why the
+  // increment here is 10.
   static _Atomic int64_t rootViewTagCounter = 0;
   return @(atomic_fetch_add_explicit(&rootViewTagCounter, 1, memory_order_relaxed) * 10 + 1);
 }
diff --git a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/ReactRootViewTagGenerator.kt b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/ReactRootViewTagGenerator.kt
index 20081d8b0ccedc..a42ae379b57aa9 100644
--- a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/ReactRootViewTagGenerator.kt
+++ b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/uimanager/ReactRootViewTagGenerator.kt
@@ -10,7 +10,7 @@ package com.facebook.react.uimanager
 /** Incremental counter for React Root View tag. */
 public object ReactRootViewTagGenerator {
 
-  // Keep in sync with ReactIOSTagHandles JS module - see that file for an explanation on why the
+  // Keep in sync with ReactRootViewTagGenerator.h - see that file for an explanation on why the
   // increment here is 10.
   private const val ROOT_VIEW_TAG_INCREMENT = 10
   private var nextRootViewTag = 1
diff --git a/packages/react-native/ReactCommon/react/renderer/core/ReactRootViewTagGenerator.cpp b/packages/react-native/ReactCommon/react/renderer/core/ReactRootViewTagGenerator.cpp
new file mode 100644
index 00000000000000..8ae8d1e3d7ad5d
--- /dev/null
+++ b/packages/react-native/ReactCommon/react/renderer/core/ReactRootViewTagGenerator.cpp
@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include "ReactRootViewTagGenerator.h"
+
+#include <atomic>
+
+namespace facebook::react {
+
+constexpr SurfaceId ROOT_VIEW_TAG_INCREMENT = 10;
+
+SurfaceId getNextRootViewTag() noexcept {
+  // Numbering of these tags goes from 11, 21, 31, ..., 100501, ...
+  static std::atomic<SurfaceId> nextRootViewTag = 1;
+  return nextRootViewTag += ROOT_VIEW_TAG_INCREMENT;
+}
+
+} // namespace facebook::react
diff --git a/packages/react-native/ReactCommon/react/renderer/core/ReactRootViewTagGenerator.h b/packages/react-native/ReactCommon/react/renderer/core/ReactRootViewTagGenerator.h
new file mode 100644
index 00000000000000..f52c91ddd3104a
--- /dev/null
+++ b/packages/react-native/ReactCommon/react/renderer/core/ReactRootViewTagGenerator.h
@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <react/renderer/core/ReactPrimitives.h>
+
+namespace facebook::react {
+
+SurfaceId getNextRootViewTag() noexcept;
+
+} // namespace facebook::react