Save the thread ID in SamplingProfiler

Summary:
The sampling profiler currently records the thread ID during stack
walking. This works fine on POSIX platforms because the signal handler
actually runs on the runtime thread, but causes problems on Windows,
where it occurs on the timer thread.

To fix this, record the thread ID when the runtime is registered for a
particular thread, and just use that when walking the stack.

Reviewed By: rozele

Differential Revision: D69664487

fbshipit-source-id: d6d1d46729709505a563efbd498f9bc253ba2ef8

include/hermes/VM/Profiler/SamplingProfiler.h

@@ -192,6 +192,9 @@ class SamplingProfiler {
   /// Prellocated map that contains thread names mapping.
   ThreadNamesMap threadNames_;
 
+  /// Thread ID of the currently registered thread.
+  ThreadId threadID_;
+
   /// Unique GC event extra info strings container.
   std::unordered_set<std::string> gcEventExtraInfoSet_;
 

lib/VM/Profiler/SamplingProfiler.cpp

@@ -122,13 +122,14 @@ uint32_t SamplingProfiler::walkRuntimeStack(
       }
     }
   }
-  sampleStorage.tid = oscompat::global_thread_id();
+  sampleStorage.tid = threadID_;
   sampleStorage.timeStamp = std::chrono::steady_clock::now();
   return count;
 }
 
-SamplingProfiler::SamplingProfiler(Runtime &runtime) : runtime_{runtime} {
-  threadNames_[oscompat::global_thread_id()] = oscompat::thread_name();
+SamplingProfiler::SamplingProfiler(Runtime &runtime)
+    : threadID_{oscompat::global_thread_id()}, runtime_{runtime} {
+  threadNames_[threadID_] = oscompat::thread_name();
   sampling_profiler::Sampler::get()->registerRuntime(this);
 }
 

lib/VM/Profiler/SamplingProfilerPosix.cpp

@@ -481,6 +481,7 @@ void SamplingProfiler::setRuntimeThread() {
   auto profiler = static_cast<sampling_profiler::SamplingProfilerPosix *>(this);
   std::lock_guard<std::mutex> lock(profiler->runtimeDataLock_);
   profiler->currentThread_ = pthread_self();
+  threadID_ = oscompat::global_thread_id();
 }
 
 } // namespace vm

lib/VM/Profiler/SamplingProfilerWindows.cpp

@@ -222,6 +222,7 @@ void SamplingProfiler::setRuntimeThread() {
   std::lock_guard<std::mutex> lock(profiler->runtimeDataLock_);
   CloseHandle(profiler->currentThread_);
   profiler->currentThread_ = openCurrentThread();
+  threadID_ = oscompat::global_thread_id();
 }
 
 } // namespace vm