RuntimeTarget refactor - Add RuntimeExecutor to RuntimeTarget

Summary:
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`. ~~
* ~~Make runtime registration explicit (`InstanceTarget::registerRuntime` similar to `PageTarget::registerInstance`). ~~
* ~~Rename the existing `RuntimeAgent` interface to `RuntimeAgentDelegate`.~~
* ~~Create a new concrete `RuntimeAgent` class similar to `{Page,Instance}Agent`.~~
* Provide `RuntimeTarget` and `RuntimeAgent` with primitives for safe JSI access, namely a `RuntimeExecutor` for scheduling work on the JS thread. *← This diff*
  * 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: hoxyq

Differential Revision: D53266710

fbshipit-source-id: df3a181fcc8e033c37a7f4f430f23a29b326b56a

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

@@ -67,8 +67,10 @@ void Instance::initializeBridge(
 
         if (parentInspectorTarget) {
           inspectorTarget_ = &parentInspectorTarget->registerInstance(*this);
+          RuntimeExecutor runtimeExecutorIfJsi = getRuntimeExecutor();
           runtimeInspectorTarget_ = &inspectorTarget_->registerRuntime(
-              nativeToJsBridge_->getInspectorTargetDelegate());
+              nativeToJsBridge_->getInspectorTargetDelegate(),
+              runtimeExecutorIfJsi ? runtimeExecutorIfJsi : [](auto) {});
         }
 
         /**

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

@@ -22,4 +22,5 @@ target_link_libraries(jsinspector
         folly_runtime
         glog
         react_featureflags
+        runtimeexecutor
 )

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

@@ -46,9 +46,10 @@ InstanceTarget::~InstanceTarget() {
 }
 
 RuntimeTarget& InstanceTarget::registerRuntime(
-    RuntimeTargetDelegate& delegate) {
+    RuntimeTargetDelegate& delegate,
+    RuntimeExecutor executor) {
   assert(!currentRuntime_ && "Only one Runtime allowed");
-  currentRuntime_.emplace(delegate);
+  currentRuntime_.emplace(delegate, executor);
   forEachAgent([currentRuntime = &*currentRuntime_](InstanceAgent& agent) {
     agent.setCurrentRuntime(currentRuntime);
   });

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

@@ -59,7 +59,9 @@ class InstanceTarget final {
       FrontendChannel channel,
       SessionState& sessionState);
 
-  RuntimeTarget& registerRuntime(RuntimeTargetDelegate& delegate);
+  RuntimeTarget& registerRuntime(
+      RuntimeTargetDelegate& delegate,
+      RuntimeExecutor executor);
   void unregisterRuntime(RuntimeTarget& runtime);
 
  private:

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

@@ -51,4 +51,5 @@ Pod::Spec.new do |s|
   s.dependency "RCT-Folly", folly_version
   s.dependency "React-featureflags"
   s.dependency "DoubleConversion"
+  s.dependency "React-runtimeexecutor", version
 end

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

@@ -8,8 +8,11 @@
 #include <jsinspector-modern/RuntimeTarget.h>
 
 namespace facebook::react::jsinspector_modern {
-RuntimeTarget::RuntimeTarget(RuntimeTargetDelegate& delegate)
-    : delegate_(delegate) {}
+
+RuntimeTarget::RuntimeTarget(
+    RuntimeTargetDelegate& delegate,
+    RuntimeExecutor executor)
+    : delegate_(delegate), executor_(executor) {}
 
 std::shared_ptr<RuntimeAgent> RuntimeTarget::createAgent(
     FrontendChannel channel,

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

@@ -7,6 +7,7 @@
 
 #pragma once
 
+#include <ReactCommon/RuntimeExecutor.h>
 #include "InspectorInterfaces.h"
 #include "RuntimeAgent.h"
 #include "SessionState.h"
@@ -53,8 +54,12 @@ class JSINSPECTOR_EXPORT RuntimeTarget final {
    * \param delegate The object that will receive events from this target.
    * The caller is responsible for ensuring that the delegate outlives this
    * object.
+   * \param executor A RuntimeExecutor that can be used to schedule work on
+   * the JS runtime's thread. The executor's queue should be empty when
+   * RuntimeTarget is constructed (i.e. anything scheduled during the
+   * constructor should be executed before any user code is run).
    */
-  explicit RuntimeTarget(RuntimeTargetDelegate& delegate);
+  RuntimeTarget(RuntimeTargetDelegate& delegate, RuntimeExecutor executor);
 
   RuntimeTarget(const RuntimeTarget&) = delete;
   RuntimeTarget(RuntimeTarget&&) = delete;
@@ -77,6 +82,7 @@ class JSINSPECTOR_EXPORT RuntimeTarget final {
 
  private:
   RuntimeTargetDelegate& delegate_;
+  RuntimeExecutor executor_;
   std::list<std::weak_ptr<RuntimeAgent>> agents_;
 
   /**

packages/react-native/ReactCommon/jsinspector-modern/tests/PageTargetTest.cpp

@@ -56,6 +56,9 @@ class PageTargetTest : public Test {
 
   MockInstanceTargetDelegate instanceTargetDelegate_;
   MockRuntimeTargetDelegate runtimeTargetDelegate_;
+  // We don't have access to a jsi::Runtime in these tests, so just use an
+  // executor that never runs the scheduled callbacks.
+  RuntimeExecutor runtimeExecutor_ = [](auto) {};
 
   UniquePtrFactory<StrictMock<MockRuntimeAgentDelegate>> runtimeAgentDelegates_;
 
@@ -252,7 +255,8 @@ TEST_F(PageTargetTest, ConnectToAlreadyRegisteredInstanceWithEvents) {
 
 TEST_F(PageTargetTest, ConnectToAlreadyRegisteredRuntimeWithEvents) {
   auto& instanceTarget = page_.registerInstance(instanceTargetDelegate_);
-  auto& runtimeTarget = instanceTarget.registerRuntime(runtimeTargetDelegate_);
+  auto& runtimeTarget =
+      instanceTarget.registerRuntime(runtimeTargetDelegate_, runtimeExecutor_);
 
   connect();
 
@@ -287,8 +291,8 @@ TEST_F(PageTargetTest, ConnectToAlreadyRegisteredRuntimeWithEvents) {
 TEST_F(PageTargetProtocolTest, RuntimeAgentDelegateLifecycle) {
   {
     auto& instanceTarget = page_.registerInstance(instanceTargetDelegate_);
-    auto& runtimeTarget =
-        instanceTarget.registerRuntime(runtimeTargetDelegate_);
+    auto& runtimeTarget = instanceTarget.registerRuntime(
+        runtimeTargetDelegate_, runtimeExecutor_);
 
     EXPECT_TRUE(runtimeAgentDelegates_[0]);
 
@@ -300,8 +304,8 @@ TEST_F(PageTargetProtocolTest, RuntimeAgentDelegateLifecycle) {
 
   {
     auto& instanceTarget = page_.registerInstance(instanceTargetDelegate_);
-    auto& runtimeTarget =
-        instanceTarget.registerRuntime(runtimeTargetDelegate_);
+    auto& runtimeTarget = instanceTarget.registerRuntime(
+        runtimeTargetDelegate_, runtimeExecutor_);
 
     EXPECT_TRUE(runtimeAgentDelegates_[1]);
 
@@ -316,7 +320,8 @@ TEST_F(PageTargetProtocolTest, MethodNotHandledByRuntimeAgentDelegate) {
   InSequence s;
 
   auto& instanceTarget = page_.registerInstance(instanceTargetDelegate_);
-  auto& runtimeTarget = instanceTarget.registerRuntime(runtimeTargetDelegate_);
+  auto& runtimeTarget =
+      instanceTarget.registerRuntime(runtimeTargetDelegate_, runtimeExecutor_);
 
   ASSERT_TRUE(runtimeAgentDelegates_[0]);
   EXPECT_CALL(*runtimeAgentDelegates_[0], handleRequest(_))
@@ -341,7 +346,8 @@ TEST_F(PageTargetProtocolTest, MethodHandledByRuntimeAgentDelegate) {
   InSequence s;
 
   auto& instanceTarget = page_.registerInstance(instanceTargetDelegate_);
-  auto& runtimeTarget = instanceTarget.registerRuntime(runtimeTargetDelegate_);
+  auto& runtimeTarget =
+      instanceTarget.registerRuntime(runtimeTargetDelegate_, runtimeExecutor_);
 
   ASSERT_TRUE(runtimeAgentDelegates_[0]);
   EXPECT_CALL(*runtimeAgentDelegates_[0], handleRequest(_))
@@ -384,7 +390,8 @@ TEST_F(PageTargetProtocolTest, MessageRoutingWhileNoRuntimeAgentDelegate) {
                          })");
 
   auto& instanceTarget = page_.registerInstance(instanceTargetDelegate_);
-  auto& runtimeTarget = instanceTarget.registerRuntime(runtimeTargetDelegate_);
+  auto& runtimeTarget =
+      instanceTarget.registerRuntime(runtimeTargetDelegate_, runtimeExecutor_);
 
   ASSERT_TRUE(runtimeAgentDelegates_[0]);
   EXPECT_CALL(*runtimeAgentDelegates_[0], handleRequest(_))
@@ -432,7 +439,8 @@ TEST_F(PageTargetProtocolTest, InstanceWithNullRuntimeAgentDelegate) {
       .WillRepeatedly(ReturnNull());
 
   auto& instanceTarget = page_.registerInstance(instanceTargetDelegate_);
-  auto& runtimeTarget = instanceTarget.registerRuntime(runtimeTargetDelegate_);
+  auto& runtimeTarget =
+      instanceTarget.registerRuntime(runtimeTargetDelegate_, runtimeExecutor_);
 
   EXPECT_FALSE(runtimeAgentDelegates_[0]);
 
@@ -466,7 +474,7 @@ TEST_F(PageTargetProtocolTest, RuntimeAgentDelegateHasAccessToSessionState) {
                          })");
 
   auto& instanceTarget = page_.registerInstance(instanceTargetDelegate_);
-  instanceTarget.registerRuntime(runtimeTargetDelegate_);
+  instanceTarget.registerRuntime(runtimeTargetDelegate_, runtimeExecutor_);
   ASSERT_TRUE(runtimeAgentDelegates_[0]);
 
   EXPECT_TRUE(runtimeAgentDelegates_[0]->sessionState.isRuntimeDomainEnabled);

packages/react-native/ReactCommon/react/runtime/ReactInstance.cpp

@@ -37,10 +37,6 @@ ReactInstance::ReactInstance(
       jsErrorHandler_(jsErrorHandlingFunc),
       hasFatalJsError_(std::make_shared<bool>(false)),
       parentInspectorTarget_(parentInspectorTarget) {
-  if (parentInspectorTarget_) {
-    inspectorTarget_ = &parentInspectorTarget_->registerInstance(*this);
-    runtimeInspectorTarget_ = &inspectorTarget_->registerRuntime(*runtime_);
-  }
   auto runtimeExecutor = [weakRuntime = std::weak_ptr<JSRuntime>(runtime_),
                           weakTimerManager =
                               std::weak_ptr<TimerManager>(timerManager_),
@@ -88,6 +84,12 @@ ReactInstance::ReactInstance(
     }
   };
 
+  if (parentInspectorTarget_) {
+    inspectorTarget_ = &parentInspectorTarget_->registerInstance(*this);
+    runtimeInspectorTarget_ =
+        &inspectorTarget_->registerRuntime(*runtime_, runtimeExecutor);
+  }
+
   runtimeScheduler_ =
       std::make_shared<RuntimeScheduler>(std::move(runtimeExecutor));