Bug 785440 - Move profiler_is_active() implementation (and RacyFeatures) into GeckoProfiler.h. r=njn

MozReview-Commit-ID: D8y5RK2t6N4

--HG--
extra : rebase_source : 50513145561a1123c47741cb845e9b4adcf104a0
extra : intermediate-source : 85c8d7e4a5eb1616d36d4ec7916e3b077da3b236
extra : source : 5dda2adf525363b32844ea8162235fae3b54d17d

tools/profiler/core/platform.cpp

@@ -151,6 +151,7 @@
 #endif
 
 using namespace mozilla;
+using mozilla::profiler::detail::RacyFeatures;
 
 LazyLogModule gProfilerLog("prof");
 
@@ -600,50 +601,6 @@ uint32_t ActivePS::sNextGeneration = 0;
 // The mutex that guards accesses to CorePS and ActivePS.
 static PSMutex gPSMutex;
 
-// The preferred way to check profiler activeness and features is via
-// ActivePS(). However, that requires locking gPSMutex. There are some hot
-// operations where absolute precision isn't required, so we duplicate the
-// activeness/feature state in a lock-free manner in this class.
-class RacyFeatures
-{
-public:
-  static void SetActive(uint32_t aFeatures)
-  {
-    sActiveAndFeatures = Active | aFeatures;
-  }
-
-  static void SetInactive() { sActiveAndFeatures = 0; }
-
-  static bool IsActive() { return uint32_t(sActiveAndFeatures) & Active; }
-
-  static bool IsActiveWithFeature(uint32_t aFeature)
-  {
-    uint32_t af = sActiveAndFeatures;  // copy it first
-    return (af & Active) && (af & aFeature);
-  }
-
-  static bool IsActiveWithoutPrivacy()
-  {
-    uint32_t af = sActiveAndFeatures;  // copy it first
-    return (af & Active) && !(af & ProfilerFeature::Privacy);
-  }
-
-private:
-  static const uint32_t Active = 1u << 31;
-
-  // Ensure Active doesn't overlap with any of the feature bits.
-  #define NO_OVERLAP(n_, str_, Name_) \
-    static_assert(ProfilerFeature::Name_ != Active, "bad Active value");
-
-  PROFILER_FOR_EACH_FEATURE(NO_OVERLAP);
-
-  #undef NO_OVERLAP
-
-  // We combine the active bit with the feature bits so they can be read or
-  // written in a single atomic operation.
-  static Atomic<uint32_t> sActiveAndFeatures;
-};
-
 Atomic<uint32_t> RacyFeatures::sActiveAndFeatures(0);
 
 // Each live thread has a ThreadInfo, and we store a reference to it in TLS.
@@ -3071,17 +3028,6 @@ profiler_feature_active(uint32_t aFeature)
   return RacyFeatures::IsActiveWithFeature(aFeature);
 }
 
-bool
-profiler_is_active()
-{
-  // This function runs both on and off the main thread.
-
-  MOZ_RELEASE_ASSERT(CorePS::Exists());
-
-  // This function is hot enough that we use RacyFeatures, notActivePS.
-  return RacyFeatures::IsActive();
-}
-
 void
 profiler_register_thread(const char* aName, void* aGuessStackTop)
 {

tools/profiler/public/GeckoProfiler.h

@@ -142,6 +142,64 @@ struct ProfilerFeature
   #undef DECLARE
 };
 
+#ifdef MOZ_GECKO_PROFILER
+namespace mozilla {
+namespace profiler {
+namespace detail {
+
+// RacyFeatures is only defined in this header file so that its methods can
+// be inlined into profiler_is_active(). Please do not use anything from the
+// detail namespace outside the profiler.
+
+// Within the profiler's code, the preferred way to check profiler activeness
+// and features is via ActivePS(). However, that requires locking gPSMutex.
+// There are some hot operations where absolute precision isn't required, so we
+// duplicate the activeness/feature state in a lock-free manner in this class.
+class RacyFeatures
+{
+public:
+  static void SetActive(uint32_t aFeatures)
+  {
+    sActiveAndFeatures = Active | aFeatures;
+  }
+
+  static void SetInactive() { sActiveAndFeatures = 0; }
+
+  static bool IsActive() { return uint32_t(sActiveAndFeatures) & Active; }
+
+  static bool IsActiveWithFeature(uint32_t aFeature)
+  {
+    uint32_t af = sActiveAndFeatures;  // copy it first
+    return (af & Active) && (af & aFeature);
+  }
+
+  static bool IsActiveWithoutPrivacy()
+  {
+    uint32_t af = sActiveAndFeatures;  // copy it first
+    return (af & Active) && !(af & ProfilerFeature::Privacy);
+  }
+
+private:
+  static const uint32_t Active = 1u << 31;
+
+  // Ensure Active doesn't overlap with any of the feature bits.
+  #define NO_OVERLAP(n_, str_, Name_) \
+    static_assert(ProfilerFeature::Name_ != Active, "bad Active value");
+
+  PROFILER_FOR_EACH_FEATURE(NO_OVERLAP);
+
+  #undef NO_OVERLAP
+
+  // We combine the active bit with the feature bits so they can be read or
+  // written in a single atomic operation.
+  static mozilla::Atomic<uint32_t> sActiveAndFeatures;
+};
+
+} // namespace detail
+} // namespace profiler
+} // namespace mozilla
+#endif
+
 //---------------------------------------------------------------------------
 // Start and stop the profiler
 //---------------------------------------------------------------------------
@@ -263,7 +321,14 @@ void profiler_clear_js_context();
 // expensive data will end up being created but not used if another thread
 // stops the profiler between the CreateExpensiveData() and PROFILER_OPERATION
 // calls.
-bool profiler_is_active();
+inline bool profiler_is_active()
+{
+#ifdef MOZ_GECKO_PROFILER
+  return mozilla::profiler::detail::RacyFeatures::IsActive();
+#else
+  return false;
+#endif
+}
 
 // Is the profiler active and paused? Returns false if the profiler is inactive.
 bool profiler_is_paused();