jsinspector: refactor domain notifications implementation (facebook#54244)

Summary:
Pull Request resolved: facebook#54244

# Changelog: [Internal]

Refactors the logic a bit.

We will use `Runtime` domain as a signal for installation of `console.createTask()` implementation.

Reviewed By: huntie

Differential Revision: D85274860

fbshipit-source-id: 80c91a8a83ba2b95b70aa38a72529bbd20275c0d

Author: hoxyq

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

@@ -179,40 +179,71 @@ void RuntimeTarget::notifyDomainStateChanged(
     Domain domain,
     bool enabled,
     const RuntimeAgent& notifyingAgent) {
-  bool runtimeAndLogStatusBefore = false, runtimeAndLogStatusAfter = false;
-  if (domain == Domain::Log || domain == Domain::Runtime) {
-    runtimeAndLogStatusBefore =
-        agentsByEnabledDomain_[Domain::Runtime].contains(&notifyingAgent) &&
-        agentsByEnabledDomain_[Domain::Log].contains(&notifyingAgent);
-  }
-
-  if (enabled) {
-    agentsByEnabledDomain_[domain].insert(&notifyingAgent);
-  } else {
-    agentsByEnabledDomain_[domain].erase(&notifyingAgent);
-  }
-  threadSafeDomainStatus_[domain] = !agentsByEnabledDomain_[domain].empty();
-
-  if (domain == Domain::Log || domain == Domain::Runtime) {
-    runtimeAndLogStatusAfter =
-        agentsByEnabledDomain_[Domain::Runtime].contains(&notifyingAgent) &&
-        agentsByEnabledDomain_[Domain::Log].contains(&notifyingAgent);
+  auto [domainStateChangedLocally, domainStateChangedGlobally] =
+      processDomainChange(domain, enabled, notifyingAgent);
+
+  switch (domain) {
+    case Domain::Log:
+    case Domain::Runtime: {
+      auto otherDomain = domain == Domain::Log ? Domain::Runtime : Domain::Log;
+      // There should be an agent that enables both Log and Runtime domains.
+      if (!agentsByEnabledDomain_[otherDomain].contains(&notifyingAgent)) {
+        break;
+      }
 
-    if (runtimeAndLogStatusBefore != runtimeAndLogStatusAfter) {
-      if (runtimeAndLogStatusAfter) {
+      if (domainStateChangedGlobally && enabled) {
+        assert(agentsWithRuntimeAndLogDomainsEnabled_ == 0);
+        emitDebuggerSessionCreated();
+        ++agentsWithRuntimeAndLogDomainsEnabled_;
+      } else if (domainStateChangedGlobally) {
+        assert(agentsWithRuntimeAndLogDomainsEnabled_ == 1);
+        emitDebuggerSessionDestroyed();
+        --agentsWithRuntimeAndLogDomainsEnabled_;
+      } else if (domainStateChangedLocally && enabled) {
+        // This is a case when given domain was already enabled by other Agent,
+        // so global state didn't change.
         if (++agentsWithRuntimeAndLogDomainsEnabled_ == 1) {
           emitDebuggerSessionCreated();
         }
-      } else {
-        assert(agentsWithRuntimeAndLogDomainsEnabled_ > 0);
+      } else if (domainStateChangedLocally) {
         if (--agentsWithRuntimeAndLogDomainsEnabled_ == 0) {
           emitDebuggerSessionDestroyed();
         }
       }
+
+      break;
+    }
+    case Domain::Network:
+      break;
+    case Domain::kMaxValue: {
+      throw std::logic_error("Unexpected kMaxValue domain value provided");
     }
   }
 }
 
+std::pair<bool, bool> RuntimeTarget::processDomainChange(
+    Domain domain,
+    bool enabled,
+    const RuntimeAgent& notifyingAgent) {
+  bool domainHadAgentsBefore = !agentsByEnabledDomain_[domain].empty();
+  bool domainHasBeenEnabledBefore =
+      agentsByEnabledDomain_[domain].contains(&notifyingAgent);
+
+  if (enabled) {
+    agentsByEnabledDomain_[domain].insert(&notifyingAgent);
+  } else {
+    agentsByEnabledDomain_[domain].erase(&notifyingAgent);
+  }
+  threadSafeDomainStatus_[domain] = !agentsByEnabledDomain_[domain].empty();
+
+  bool domainHasAgentsAfter = !agentsByEnabledDomain_[domain].empty();
+
+  return {
+      domainHasBeenEnabledBefore ^ enabled,
+      domainHadAgentsBefore ^ domainHasAgentsAfter,
+  };
+}
+
 bool RuntimeTarget::isDomainEnabled(Domain domain) const {
   return threadSafeDomainStatus_[domain];
 }

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

@@ -21,6 +21,7 @@
 #include <jsinspector-modern/tracing/TraceRecordingState.h>
 
 #include <memory>
+#include <utility>
 
 #ifndef JSINSPECTOR_EXPORT
 #ifdef _MSC_VER
@@ -116,7 +117,7 @@ class RuntimeTargetDelegate {
  */
 class RuntimeTargetController {
  public:
-  enum class Domain { Network, Runtime, Log, kMaxValue };
+  enum class Domain { Log, Network, Runtime, kMaxValue };
 
   explicit RuntimeTargetController(RuntimeTarget &target);
 
@@ -330,6 +331,22 @@ class JSINSPECTOR_EXPORT RuntimeTarget : public EnableExecutorFromThis<RuntimeTa
    */
   void notifyDomainStateChanged(Domain domain, bool enabled, const RuntimeAgent &notifyingAgent);
 
+  /**
+   * Processes the changes to the state of a given domain.
+   *
+   * Returns a pair of booleans:
+   *   1. Returns true, if an only if the given domain state changed locally,
+   *   for a given session.
+   *   2. Returns true, if and only if the given domain state changed globally:
+   *   when the given Agent is the only Agent that enabled given domain across
+   *   sessions, or when the only Agent that had this domain enabled has
+   *   disconnected.
+   */
+  std::pair<bool, bool> processDomainChange(
+      Domain domain,
+      bool enabled,
+      const RuntimeAgent& notifyingAgent);
+
   /**
    * Checks whether the given domain is enabled in at least one session
    * that is currently connected. This may be called from any thread, with