Bug 759532 - Expose Enter/ExitProfileLabel to JS. r=ehsan

--HG--
extra : rebase_source : e1dbc7995ce2dfd52ece4c3fd3d76cc6cd95896f

tools/profiler/nsIProfiler.idl

@@ -18,6 +18,8 @@ interface nsIProfiler : nsISupports
   boolean IsActive();
   void GetResponsivenessTimes(out PRUint32 aCount, [retval, array, size_is(aCount)] out double aResult);
   void GetFeatures(out PRUint32 aCount, [retval, array, size_is(aCount)] out string aFeatures);
+  void EnterProfileLabel(in string aLabel);
+  void ExitProfileLabel();
 
   /**
    * Returns a JSON string of an array of shared library objects.

tools/profiler/nsProfiler.cpp

@@ -169,3 +169,21 @@ nsProfiler::GetFeatures(PRUint32 *aCount, char ***aFeatures)
   *aCount = len;
   return NS_OK;
 }
+
+NS_IMETHODIMP
+nsProfiler::EnterProfileLabel(const char *aLabel)
+{
+  if (!aLebel)
+    return NS_ERROR_FAILURE;
+
+  mozilla_sampler_call_enter(aLabel);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::ExitProfileLabel()
+{
+  mozilla_sampler_call_exit_no_handle();
+  return NS_OK;
+}
+

tools/profiler/sps_sampler.h

@@ -277,6 +277,25 @@ inline void mozilla_sampler_call_exit(void *aHandle)
   stack->pop();
 }
 
+inline void mozilla_sampler_call_exit_no_handle()
+{
+  // check if we've been initialized to avoid calling pthread_getspecific
+  // with a null tlsStack which will return undefined results.
+  if (!stack_key_initialized)
+    return;
+
+  ProfileStack *stack = tlsStack.get();
+  // we can't infer whether 'stack' has been initialized
+  // based on the value of stack_key_intiailized because
+  // 'stack' is only intialized when a thread is being
+  // profiled.
+  if (!stack) {
+    return;
+  }
+
+  stack->pop();
+}
+
 inline void mozilla_sampler_add_marker(const char *aMarker)
 {
   ProfileStack *stack = tlsStack.get();