Bug 1464506 - profiler_is_active_and_thread_is_registered - r=canaltinova

This can be used while the profiler is running, to know if the current thread is registered -- regardless of whether it is actively profiled.
This will help distinguish registered but non-profiled threads from threads that are not even registered (e.g., OS-generated threads).

Differential Revision: https://phabricator.services.mozilla.com/D76281

tools/profiler/core/platform.cpp

@@ -4796,6 +4796,16 @@ bool mozilla::profiler::detail::IsThreadBeingProfiled() {
   return racyRegisteredThread && racyRegisteredThread->IsBeingProfiled();
 }
 
+bool mozilla::profiler::detail::IsThreadRegistered() {
+  MOZ_RELEASE_ASSERT(CorePS::Exists());
+
+  const RacyRegisteredThread* racyRegisteredThread =
+      TLSRegisteredThread::RacyRegisteredThread();
+  // The simple presence of this TLS pointer is proof that the thread is
+  // registered.
+  return !!racyRegisteredThread;
+}
+
 bool profiler_thread_is_sleeping() {
   MOZ_RELEASE_ASSERT(NS_IsMainThread());
   MOZ_RELEASE_ASSERT(CorePS::Exists());

tools/profiler/public/GeckoProfiler.h

@@ -290,6 +290,7 @@ class RacyFeatures {
 };
 
 bool IsThreadBeingProfiled();
+bool IsThreadRegistered();
 
 }  // namespace detail
 }  // namespace profiler
@@ -536,6 +537,14 @@ inline bool profiler_thread_is_being_profiled() {
          mozilla::profiler::detail::IsThreadBeingProfiled();
 }
 
+// During profiling, if the current thread is registered, return true
+// (regardless of whether it is actively being profiled).
+// (Same caveats and recommented usage as profiler_is_active().)
+inline bool profiler_is_active_and_thread_is_registered() {
+  return profiler_is_active() &&
+         mozilla::profiler::detail::IsThreadRegistered();
+}
+
 // Is the profiler active and paused? Returns false if the profiler is inactive.
 bool profiler_is_paused();