Bug 1128768: Part 3 - Update BHR to allow for hang annotations; r=vladan

xpcom/threads/BackgroundHangMonitor.cpp

@@ -140,6 +140,10 @@ public:
   Telemetry::HangStack mHangStack;
   // Statistics for telemetry
   Telemetry::ThreadHangStats mStats;
+  // Annotations for the current hang
+  UniquePtr<HangMonitor::HangAnnotations> mAnnotations;
+  // Annotators registered for this thread
+  HangMonitor::Observer::Annotators mAnnotators;
 
   BackgroundHangThread(const char* aName,
                        uint32_t aTimeoutMs,
@@ -274,6 +278,8 @@ BackgroundHangManager::RunMonitorThread()
           currentThread->mStackHelper.GetStack(currentThread->mHangStack);
           currentThread->mHangStart = interval;
           currentThread->mHanging = true;
+          currentThread->mAnnotations =
+            currentThread->mAnnotators.GatherAnnotations();
         }
       } else {
         if (MOZ_LIKELY(interval != currentThread->mHangStart)) {
@@ -372,12 +378,12 @@ BackgroundHangThread::ReportHang(PRIntervalTime aHangTime)
        oldHistogram != mStats.mHangs.end(); oldHistogram++) {
     if (newHistogram == *oldHistogram) {
       // New histogram matches old one
-      oldHistogram->Add(aHangTime);
+      oldHistogram->Add(aHangTime, Move(mAnnotations));
       return *oldHistogram;
     }
   }
   // Add new histogram
-  newHistogram.Add(aHangTime);
+  newHistogram.Add(aHangTime, Move(mAnnotations));
   mStats.mHangs.append(Move(newHistogram));
   return mStats.mHangs.back();
 }
@@ -556,6 +562,33 @@ BackgroundHangMonitor::Allow()
 #endif
 }
 
+bool
+BackgroundHangMonitor::RegisterAnnotator(HangMonitor::Annotator& aAnnotator)
+{
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  BackgroundHangThread* thisThread = BackgroundHangThread::FindThread();
+  if (!thisThread) {
+    return false;
+  }
+  return thisThread->mAnnotators.Register(aAnnotator);
+#else
+  return false;
+#endif
+}
+
+bool
+BackgroundHangMonitor::UnregisterAnnotator(HangMonitor::Annotator& aAnnotator)
+{
+#ifdef MOZ_ENABLE_BACKGROUND_HANG_MONITOR
+  BackgroundHangThread* thisThread = BackgroundHangThread::FindThread();
+  if (!thisThread) {
+    return false;
+  }
+  return thisThread->mAnnotators.Unregister(aAnnotator);
+#else
+  return false;
+#endif
+}
 
 /* Because we are iterating through the BackgroundHangThread linked list,
    we need to take a lock. Using MonitorAutoLock as a base class makes

xpcom/threads/BackgroundHangMonitor.h

@@ -7,8 +7,9 @@
 #ifndef mozilla_BackgroundHangMonitor_h
 #define mozilla_BackgroundHangMonitor_h
 
-#include "mozilla/RefPtr.h"
+#include "mozilla/HangAnnotations.h"
 #include "mozilla/Monitor.h"
+#include "mozilla/RefPtr.h"
 
 #include <stdint.h>
 
@@ -227,6 +228,21 @@ public:
    * \see Prohibit()
    */
   static void Allow();
+
+  /**
+   * Register an annotator with BHR for the current thread.
+   * @param aAnnotator annotator to register
+   * @return true if the annotator was registered, otherwise false.
+   */
+  static bool RegisterAnnotator(HangMonitor::Annotator& aAnnotator);
+
+  /**
+   * Unregister an annotator that was previously registered via
+   * RegisterAnnotator.
+   * @param aAnnotator annotator to unregister
+   * @return true if there are still remaining annotators registered
+   */
+  static bool UnregisterAnnotator(HangMonitor::Annotator& aAnnotator);
 };
 
 } // namespace mozilla