RELAND [RN][CDP] [3/n] RuntimeTarget refactor - RuntimeAgent --> RuntimeAgentDelegate

Summary:
This is a resubmission of D53266707 with a fix in the OSS version of `HermesExecutorFactory` (it was incorrectly referencing `HermesRuntimeAgent.h` which doesn't exist anymore). The original diff summary follows.

 ---

Changelog: [Internal]

I'm refactoring the way the Runtime concept works in the modern CDP backend to bring it in line with the Page/Instance concepts.

Overall, this will let us:

* Integrate with engines that require us to instantiate a shared Target-like object (e.g. Hermes AsyncDebuggingAPI) in addition to an per-session Agent-like object.
* Access JSI in a CDP context (both at target setup/teardown time and during a CDP session) to implement our own engine-agnostic functionality (`console` interception, `Runtime.addBinding`, etc).
* Manage CDP execution contexts natively in RN, and (down the line) enable first-class debugging support for multiple Runtimes in an Instance.

The core diffs in this stack will:

* ~~Introduce a `RuntimeTarget` class similar to `{Page,Instance}Target`.~~ (D53233914)
* ~~Make runtime registration explicit (`InstanceTarget::registerRuntime` similar to `PageTarget::registerInstance`).~~ (D53233914)
* Rename the existing `RuntimeAgent` interface to `RuntimeAgentDelegate`.   *← This diff*
* Create a new concrete `RuntimeAgent` class similar to `{Page,Instance}Agent`.   *← Also in this diff*
* Provide `RuntimeTarget` and `RuntimeAgent` with primitives for safe JSI access, namely a `RuntimeExecutor` for scheduling work on the JS thread.
  * We'll likely develop a similar mechanism for scheduling work on the "main" thread from the JS thread, for when we need to do more than just send a CDP message (which we can already do with the thread-safe `FrontendChannel`) in response to a JS event.

## Architecture diagrams

Before this stack:
https://pxl.cl/4h7m0

After this stack:
https://pxl.cl/4h7m7

Reviewed By: EdmondChuiHW

Differential Revision: D53748590

fbshipit-source-id: bd0cf9f74b95abc52b4903f8a7afddcefa303d8a

Author: motiz88

packages/react-native/ReactCommon/cxxreact/JSExecutor.cpp

@@ -35,10 +35,11 @@ double JSExecutor::performanceNow() {
   return duration / NANOSECONDS_IN_MILLISECOND;
 }
 
-std::unique_ptr<jsinspector_modern::RuntimeAgent> JSExecutor::createAgent(
+std::unique_ptr<jsinspector_modern::RuntimeAgentDelegate>
+JSExecutor::createAgentDelegate(
     jsinspector_modern::FrontendChannel frontendChannel,
     jsinspector_modern::SessionState& sessionState) {
-  return std::make_unique<jsinspector_modern::FallbackRuntimeAgent>(
+  return std::make_unique<jsinspector_modern::FallbackRuntimeAgentDelegate>(
       std::move(frontendChannel), sessionState, getDescription());
 }
 

packages/react-native/ReactCommon/cxxreact/JSExecutor.h

@@ -114,7 +114,7 @@ class RN_EXPORT JSExecutor : public jsinspector_modern::RuntimeTargetDelegate {
   /**
    * Returns whether or not the underlying executor supports debugging via the
    * Chrome remote debugging protocol. If true, the executor should also
-   * override the \c createAgent method.
+   * override the \c createAgentDelegate method.
    */
   virtual bool isInspectable() {
     return false;
@@ -141,9 +141,10 @@ class RN_EXPORT JSExecutor : public jsinspector_modern::RuntimeTargetDelegate {
   static double performanceNow();
 
   /**
-   * Create a RuntimeAgent that can be used to debug the JS VM instance.
+   * Create a RuntimeAgentDelegate that can be used to debug the JS VM instance.
    */
-  virtual std::unique_ptr<jsinspector_modern::RuntimeAgent> createAgent(
+  virtual std::unique_ptr<jsinspector_modern::RuntimeAgentDelegate>
+  createAgentDelegate(
       jsinspector_modern::FrontendChannel frontendChannel,
       jsinspector_modern::SessionState& sessionState) override;
 };

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

@@ -15,7 +15,7 @@
 #include <jsi/decorator.h>
 #include <jsinspector-modern/InspectorFlags.h>
 
-#include <hermes/inspector-modern/chrome/HermesRuntimeAgent.h>
+#include <hermes/inspector-modern/chrome/HermesRuntimeAgentDelegate.h>
 #include <hermes/inspector-modern/chrome/Registration.h>
 #include <hermes/inspector/RuntimeAdapter.h>
 
@@ -257,12 +257,13 @@ HermesExecutor::HermesExecutor(
       runtime_(runtime),
       hermesRuntime_(hermesRuntime) {}
 
-std::unique_ptr<jsinspector_modern::RuntimeAgent> HermesExecutor::createAgent(
+std::unique_ptr<jsinspector_modern::RuntimeAgentDelegate>
+HermesExecutor::createAgentDelegate(
     jsinspector_modern::FrontendChannel frontendChannel,
     jsinspector_modern::SessionState& sessionState) {
   std::shared_ptr<HermesRuntime> hermesRuntimeShared(runtime_, &hermesRuntime_);
-  return std::unique_ptr<jsinspector_modern::RuntimeAgent>(
-      new jsinspector_modern::HermesRuntimeAgent(
+  return std::unique_ptr<jsinspector_modern::RuntimeAgentDelegate>(
+      new jsinspector_modern::HermesRuntimeAgentDelegate(
           frontendChannel,
           sessionState,
           hermesRuntimeShared,

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

@@ -54,7 +54,8 @@ class HermesExecutor : public JSIExecutor {
       RuntimeInstaller runtimeInstaller,
       hermes::HermesRuntime& hermesRuntime);
 
-  virtual std::unique_ptr<jsinspector_modern::RuntimeAgent> createAgent(
+  virtual std::unique_ptr<jsinspector_modern::RuntimeAgentDelegate>
+  createAgentDelegate(
       jsinspector_modern::FrontendChannel frontendChannel,
       jsinspector_modern::SessionState& sessionState) override;
 

packages/react-native/ReactCommon/hermes/inspector-modern/chrome/HermesRuntimeAgent.cpp renamed to packages/react-native/ReactCommon/hermes/inspector-modern/chrome/HermesRuntimeAgentDelegate.cpp

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-#include "HermesRuntimeAgent.h"
+#include "HermesRuntimeAgentDelegate.h"
 
 // If HERMES_ENABLE_DEBUGGER isn't defined, we can't access any Hermes
 // CDPHandler headers or types.
@@ -14,7 +14,7 @@
 #include <hermes/inspector/RuntimeAdapter.h>
 #include <hermes/inspector/chrome/CDPHandler.h>
 #else // HERMES_ENABLE_DEBUGGER
-#include <jsinspector-modern/FallbackRuntimeAgent.h>
+#include <jsinspector-modern/FallbackRuntimeAgentDelegate.h>
 #endif // HERMES_ENABLE_DEBUGGER
 
 #include <hermes/hermes.h>
@@ -30,12 +30,12 @@ namespace {
 
 /**
  * An implementation of the Hermes RuntimeAdapter interface (part of
- * Hermes's CDPHandler API) for use within a React Native RuntimeAgent.
+ * Hermes's CDPHandler API) for use within a React Native RuntimeAgentDelegate.
  */
-class HermesRuntimeAgentAdapter
+class HermesRuntimeAgentDelegateAdapter
     : public hermes::inspector_modern::RuntimeAdapter {
  public:
-  HermesRuntimeAgentAdapter(
+  HermesRuntimeAgentDelegateAdapter(
       std::shared_ptr<hermes::HermesRuntime> runtime,
       RuntimeExecutor runtimeExecutor)
       : runtime_(runtime), runtimeExecutor_(runtimeExecutor) {}
@@ -60,10 +60,10 @@ class HermesRuntimeAgentAdapter
 } // namespace
 
 /**
- * A RuntimeAgent that handles requests from the Chrome DevTools Protocol for
- * an instance of Hermes.
+ * A RuntimeAgentDelegate that handles requests from the Chrome DevTools
+ * Protocol for an instance of Hermes.
  */
-class HermesRuntimeAgent::Impl final : public RuntimeAgent {
+class HermesRuntimeAgentDelegate::Impl final : public RuntimeAgentDelegate {
   using HermesCDPHandler = hermes::inspector_modern::chrome::CDPHandler;
 
  public:
@@ -84,7 +84,7 @@ class HermesRuntimeAgent::Impl final : public RuntimeAgent {
       std::shared_ptr<hermes::HermesRuntime> runtime,
       RuntimeExecutor runtimeExecutor)
       : hermes_(HermesCDPHandler::create(
-            std::make_unique<HermesRuntimeAgentAdapter>(
+            std::make_unique<HermesRuntimeAgentDelegateAdapter>(
                 runtime,
                 runtimeExecutor),
             /* waitForDebugger */ false,
@@ -133,25 +133,26 @@ class HermesRuntimeAgent::Impl final : public RuntimeAgent {
 #else // !HERMES_ENABLE_DEBUGGER
 
 /**
- * A stub for HermesRuntimeAgent when Hermes is compiled without debugging
- * support.
+ * A stub for HermesRuntimeAgentDelegate when Hermes is compiled without
+ * debugging support.
  */
-class HermesRuntimeAgent::Impl final : public FallbackRuntimeAgent {
+class HermesRuntimeAgentDelegate::Impl final
+    : public FallbackRuntimeAgentDelegate {
  public:
   Impl(
       FrontendChannel frontendChannel,
       SessionState& sessionState,
       std::shared_ptr<hermes::HermesRuntime> runtime,
       RuntimeExecutor)
-      : FallbackRuntimeAgent(
+      : FallbackRuntimeAgentDelegate(
             std::move(frontendChannel),
             sessionState,
             runtime->description()) {}
 };
 
 #endif // HERMES_ENABLE_DEBUGGER
 
-HermesRuntimeAgent::HermesRuntimeAgent(
+HermesRuntimeAgentDelegate::HermesRuntimeAgentDelegate(
     FrontendChannel frontendChannel,
     SessionState& sessionState,
     std::shared_ptr<hermes::HermesRuntime> runtime,
@@ -162,7 +163,8 @@ HermesRuntimeAgent::HermesRuntimeAgent(
           std::move(runtime),
           std::move(runtimeExecutor))) {}
 
-bool HermesRuntimeAgent::handleRequest(const cdp::PreparsedRequest& req) {
+bool HermesRuntimeAgentDelegate::handleRequest(
+    const cdp::PreparsedRequest& req) {
   return impl_->handleRequest(req);
 }
 

packages/react-native/ReactCommon/hermes/inspector-modern/chrome/HermesRuntimeAgent.h renamed to packages/react-native/ReactCommon/hermes/inspector-modern/chrome/HermesRuntimeAgentDelegate.h

@@ -15,10 +15,10 @@
 namespace facebook::react::jsinspector_modern {
 
 /**
- * A RuntimeAgent that handles requests from the Chrome DevTools Protocol for
- * an instance of Hermes.
+ * A RuntimeAgentDelegate that handles requests from the Chrome DevTools
+ * Protocol for an instance of Hermes.
  */
-class HermesRuntimeAgent : public RuntimeAgent {
+class HermesRuntimeAgentDelegate : public RuntimeAgentDelegate {
  public:
   /**
    * \param frontendChannel A channel used to send responses and events to the
@@ -31,7 +31,7 @@ class HermesRuntimeAgent : public RuntimeAgent {
    * \c runtimeExecutor may drop scheduled work if the runtime is destroyed
    * first.
    */
-  HermesRuntimeAgent(
+  HermesRuntimeAgentDelegate(
       FrontendChannel frontendChannel,
       SessionState& sessionState,
       std::shared_ptr<hermes::HermesRuntime> runtime,

packages/react-native/ReactCommon/jsinspector-modern/CONCEPTS.md

@@ -21,3 +21,7 @@ A single connection between a debugger frontend and a target. There can be multi
 ### Agent
 
 A handler for a subset of CDP messages for a specific target as part of a specific session.
+
+### Agent Delegate
+
+An interface between an Agent class and some integration-specific, per-session logic/state it relies on (that does not fit in a Target Delegate). For example, a RuntimeAgentDelegate is used by RuntimeAgent to host Hermes's native CDP handler and delegate messages to it. The interface may look exactly like an Agent (purely CDP messages in/out) or there may be a more involved API to expose state/functionality needed by the Agent.

packages/react-native/ReactCommon/jsinspector-modern/FallbackRuntimeAgent.cpp renamed to packages/react-native/ReactCommon/jsinspector-modern/FallbackRuntimeAgentDelegate.cpp

@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-#include <jsinspector-modern/FallbackRuntimeAgent.h>
+#include "FallbackRuntimeAgentDelegate.h"
 
 #include <chrono>
 #include <string>
@@ -22,7 +22,7 @@ namespace facebook::react::jsinspector_modern {
 #define ANSI_STYLE_RESET "\x1B[23m"
 #define ANSI_COLOR_BG_YELLOW "\x1B[48;2;253;247;231m"
 
-FallbackRuntimeAgent::FallbackRuntimeAgent(
+FallbackRuntimeAgentDelegate::FallbackRuntimeAgentDelegate(
     FrontendChannel frontendChannel,
     const SessionState& sessionState,
     std::string engineDescription)
@@ -32,7 +32,8 @@ FallbackRuntimeAgent::FallbackRuntimeAgent(
   }
 }
 
-bool FallbackRuntimeAgent::handleRequest(const cdp::PreparsedRequest& req) {
+bool FallbackRuntimeAgentDelegate::handleRequest(
+    const cdp::PreparsedRequest& req) {
   if (req.method == "Log.enable") {
     sendFallbackRuntimeWarning();
 
@@ -44,15 +45,15 @@ bool FallbackRuntimeAgent::handleRequest(const cdp::PreparsedRequest& req) {
   return false;
 }
 
-void FallbackRuntimeAgent::sendFallbackRuntimeWarning() {
+void FallbackRuntimeAgentDelegate::sendFallbackRuntimeWarning() {
   sendWarningLogEntry(
       "The current JavaScript engine, " ANSI_STYLE_ITALIC + engineDescription_ +
       ANSI_STYLE_RESET
       ", does not support debugging over the Chrome DevTools Protocol. "
       "See https://reactnative.dev/docs/debugging for more information.");
 }
 
-void FallbackRuntimeAgent::sendWarningLogEntry(std::string_view text) {
+void FallbackRuntimeAgentDelegate::sendWarningLogEntry(std::string_view text) {
   frontendChannel_(
       folly::toJson(folly::dynamic::object("method", "Log.entryAdded")(
           "params",

packages/react-native/ReactCommon/jsinspector-modern/FallbackRuntimeAgent.h renamed to packages/react-native/ReactCommon/jsinspector-modern/FallbackRuntimeAgentDelegate.h

@@ -15,10 +15,10 @@
 namespace facebook::react::jsinspector_modern {
 
 /**
- * A RuntimeAgent that handles requests from the Chrome DevTools Protocol for
- * a JavaScript runtime that does not support debugging.
+ * A RuntimeAgentDelegate that handles requests from the Chrome DevTools
+ * Protocol for a JavaScript runtime that does not support debugging.
  */
-class FallbackRuntimeAgent : public RuntimeAgent {
+class FallbackRuntimeAgentDelegate : public RuntimeAgentDelegate {
  public:
   /**
    * \param frontendChannel A channel used to send responses and events to the
@@ -27,7 +27,7 @@ class FallbackRuntimeAgent : public RuntimeAgent {
    * \param engineDescription A description of the JavaScript engine being
    * debugged. This string will be used in messages sent to the frontend.
    */
-  FallbackRuntimeAgent(
+  FallbackRuntimeAgentDelegate(
       FrontendChannel frontendChannel,
       const SessionState& sessionState,
       std::string engineDescription);

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

@@ -24,7 +24,7 @@ class InstanceTarget;
  * An Agent that handles requests from the Chrome DevTools Protocol for the
  * given InstanceTarget.
  */
-class InstanceAgent {
+class InstanceAgent final {
  public:
   /**
    * \param frontendChannel A channel used to send responses and events to the