Add InspectorFlags, conditionally disable Hermes CDP registration (#4…

…1672)

Summary:
Pull Request resolved: #41672

Progress towards an opt-in setup for our new CDP backend.

- Adds `InspectorFlags.h`, a singleton intended to allow convienient access to static boolean feature flags for the new CDP backend/inspector features across platforms. This will be written to in upcoming diffs, with the accessor for `enable_modern_cdp_registry` soft-defaulting to `false` here.
- References this to conditionally disable legacy ~CDP registration in `HermesExecutorFactory` (Bridge) and `HermesInstance` (Bridgeless) code paths.
- Stubs a `false` value for `react_native_devx:enable_modern_cdp_registry` in `EmptyReactNativeConfig` (documentation/convenience point for open source partners and integrators).

Changelog: [Internal]

Reviewed By: motiz88

Differential Revision: D51563107

fbshipit-source-id: 446f319228ec627fdc0ecba9517a1a3faad9d262

packages/react-native/ReactCommon/hermes/executor/HermesExecutorFactory.cpp

@@ -13,6 +13,7 @@
 #include <cxxreact/SystraceSection.h>
 #include <hermes/hermes.h>
 #include <jsi/decorator.h>
+#include <jsinspector-modern/InspectorFlags.h>
 
 #include <hermes/inspector-modern/chrome/Registration.h>
 #include <hermes/inspector/RuntimeAdapter.h>
@@ -200,11 +201,14 @@ std::unique_ptr<JSExecutor> HermesExecutorFactory::createJSExecutor(
   }
 
   HermesRuntime& hermesRuntimeRef = *hermesRuntime;
+  auto& inspectorFlags = jsinspector_modern::InspectorFlags::getInstance();
+  bool enableDebugger =
+      !inspectorFlags.getEnableModernCDPRegistry() && enableDebugger_;
   auto decoratedRuntime = std::make_shared<DecoratedRuntime>(
       std::move(hermesRuntime),
       hermesRuntimeRef,
       jsQueue,
-      enableDebugger_,
+      enableDebugger,
       debuggerName_);
 
   // So what do we have now?

packages/react-native/ReactCommon/jsinspector-modern/CMakeLists.txt

@@ -14,3 +14,7 @@ file(GLOB jsinspector_SRC CONFIGURE_DEPENDS *.cpp)
 add_library(jsinspector STATIC ${jsinspector_SRC})
 
 target_include_directories(jsinspector PUBLIC ${REACT_COMMON_DIR})
+
+target_link_libraries(jsinspector
+        glog
+)

packages/react-native/ReactCommon/jsinspector-modern/InspectorFlags.cpp

@@ -0,0 +1,40 @@
+/*
+ * 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 <glog/logging.h>
+#include <cassert>
+
+#include "InspectorFlags.h"
+
+namespace facebook::react::jsinspector_modern {
+
+InspectorFlags& InspectorFlags::getInstance() {
+  static InspectorFlags instance;
+  return instance;
+}
+
+void InspectorFlags::initFromConfig(
+    const ReactNativeConfig& reactNativeConfig) {
+  bool enableModernCDPRegistry =
+      reactNativeConfig.getBool("react_native_devx:enable_modern_cdp_registry");
+  if (enableModernCDPRegistry_.has_value()) {
+    assert(
+        *enableModernCDPRegistry_ == enableModernCDPRegistry &&
+        "Flag value was changed after init");
+  }
+  enableModernCDPRegistry_ = enableModernCDPRegistry;
+}
+
+bool InspectorFlags::getEnableModernCDPRegistry() const {
+  if (!enableModernCDPRegistry_.has_value()) {
+    LOG(WARNING)
+        << "InspectorFlags::getEnableModernCDPRegistry was called before init";
+  }
+  return enableModernCDPRegistry_.value_or(false);
+}
+
+} // namespace facebook::react::jsinspector_modern

packages/react-native/ReactCommon/jsinspector-modern/InspectorFlags.h

@@ -0,0 +1,45 @@
+/*
+ * 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 <optional>
+
+#include <react/config/ReactNativeConfig.h>
+
+namespace facebook::react::jsinspector_modern {
+
+/**
+ * A container for all inspector related feature flags (Meyers singleton
+ * pattern). Flags must be set before they are accessed and are static for the
+ * lifetime of the app.
+ */
+class InspectorFlags {
+ public:
+  static InspectorFlags& getInstance();
+
+  /**
+   * Initialize flags from a `ReactNativeConfig` instance. Validates that flag
+   * values are not changed across multiple calls.
+   */
+  void initFromConfig(const ReactNativeConfig& reactNativeConfig);
+
+  /**
+   * Flag determining if the modern CDP backend should be enabled.
+   */
+  bool getEnableModernCDPRegistry() const;
+
+ private:
+  InspectorFlags() = default;
+  InspectorFlags(const InspectorFlags&) = delete;
+  InspectorFlags& operator=(const InspectorFlags&) = delete;
+  ~InspectorFlags() = default;
+
+  std::optional<bool> enableModernCDPRegistry_;
+};
+
+} // namespace facebook::react::jsinspector_modern

packages/react-native/ReactCommon/jsinspector-modern/React-jsinspector.podspec

@@ -28,4 +28,8 @@ Pod::Spec.new do |s|
   s.source_files           = "*.{cpp,h}"
   s.header_dir             = 'jsinspector'
   s.pod_target_xcconfig    = { "CLANG_CXX_LANGUAGE_STANDARD" => "c++20" }
+
+  s.dependency "glog"
+
+  add_dependency(s, "React-nativeconfig")
 end

packages/react-native/ReactCommon/react/config/ReactNativeConfig.cpp

@@ -9,20 +9,13 @@
 
 namespace facebook::react {
 
-/**
- * ReactNative configuration as provided by the hosting app.
- * Provide a sub-class implementation to allow app specific customization.
- */
-ReactNativeConfig::ReactNativeConfig() {}
-
-ReactNativeConfig::~ReactNativeConfig() {}
-
-EmptyReactNativeConfig::EmptyReactNativeConfig() {}
-
 bool EmptyReactNativeConfig::getBool(const std::string& param) const {
   if (param == "react_fabric:enabled_layout_animations_ios") {
     return true;
   }
+  if (param == "react_native_devx:enable_modern_cdp_registry") {
+    return false;
+  }
   return false;
 }
 

packages/react-native/ReactCommon/react/config/ReactNativeConfig.h

@@ -17,8 +17,8 @@ namespace facebook::react {
  */
 class ReactNativeConfig {
  public:
-  ReactNativeConfig();
-  virtual ~ReactNativeConfig();
+  ReactNativeConfig() = default;
+  virtual ~ReactNativeConfig() = default;
 
   virtual bool getBool(const std::string& param) const = 0;
   virtual std::string getString(const std::string& param) const = 0;
@@ -31,7 +31,7 @@ class ReactNativeConfig {
  */
 class EmptyReactNativeConfig : public ReactNativeConfig {
  public:
-  EmptyReactNativeConfig();
+  EmptyReactNativeConfig() = default;
 
   bool getBool(const std::string& param) const override;
   std::string getString(const std::string& param) const override;

packages/react-native/ReactCommon/react/runtime/hermes/HermesInstance.cpp

@@ -8,6 +8,7 @@
 #include "HermesInstance.h"
 
 #include <jsi/jsilib.h>
+#include <jsinspector-modern/InspectorFlags.h>
 
 #ifdef HERMES_ENABLE_DEBUGGER
 #include <hermes/inspector-modern/chrome/Registration.h>
@@ -141,10 +142,13 @@ std::unique_ptr<JSRuntime> HermesInstance::createJSRuntime(
       hermes::makeHermesRuntime(runtimeConfigBuilder.build());
 
 #ifdef HERMES_ENABLE_DEBUGGER
-  std::unique_ptr<DecoratedRuntime> decoratedRuntime =
-      std::make_unique<DecoratedRuntime>(
-          std::move(hermesRuntime), msgQueueThread);
-  return std::make_unique<JSIRuntimeHolder>(std::move(decoratedRuntime));
+  auto& inspectorFlags = jsinspector_modern::InspectorFlags::getInstance();
+  if (!inspectorFlags.getEnableModernCDPRegistry()) {
+    std::unique_ptr<DecoratedRuntime> decoratedRuntime =
+        std::make_unique<DecoratedRuntime>(
+            std::move(hermesRuntime), msgQueueThread);
+    return std::make_unique<JSIRuntimeHolder>(std::move(decoratedRuntime));
+  }
 #endif
 
   return std::make_unique<JSIRuntimeHolder>(std::move(hermesRuntime));