Bug 853896 - Turn off MOZ_EVENT_TRACE when profiling. r=ted

--HG--
extra : rebase_source : 2ae36f2f4be730528b0f18154377fa32ee25b49a

toolkit/xre/EventTracer.cpp

@@ -71,6 +71,10 @@ namespace {
 PRThread* sTracerThread = NULL;
 bool sExit = false;
 
+struct TracerStartClosure {
+  bool mLogTracing;
+};
+
 /*
  * The tracer thread fires events at the native event loop roughly
  * every kMeasureInterval. It will sleep to attempt not to send them
@@ -85,6 +89,8 @@ void TracerThread(void *arg)
 {
   PR_SetCurrentThreadName("Event Tracer");
 
+  TracerStartClosure* threadArgs = static_cast<TracerStartClosure*>(arg);
+
   // These are the defaults. They can be overridden by environment vars.
   // This should be set to the maximum latency we'd like to allow
   // for responsiveness.
@@ -117,7 +123,9 @@ void TracerThread(void *arg)
     }
   }
 
-  fprintf(log, "MOZ_EVENT_TRACE start %llu\n", PR_Now() / PR_USEC_PER_MSEC);
+  if (threadArgs->mLogTracing) {
+    fprintf(log, "MOZ_EVENT_TRACE start %llu\n", PR_Now() / PR_USEC_PER_MSEC);
+  }
 
   while (!sExit) {
     TimeStamp start(TimeStamp::Now());
@@ -130,7 +138,7 @@ void TracerThread(void *arg)
     if (FireAndWaitForTracerEvent()) {
       TimeDuration duration = TimeStamp::Now() - start;
       // Only report samples that exceed our measurement threshold.
-      if (duration.ToMilliseconds() > threshold) {
+      if (threadArgs->mLogTracing && duration.ToMilliseconds() > threshold) {
         fprintf(log, "MOZ_EVENT_TRACE sample %llu %d\n",
                 PR_Now() / PR_USEC_PER_MSEC,
                 int(duration.ToSecondsSigDigits() * 1000));
@@ -151,17 +159,21 @@ void TracerThread(void *arg)
     }
   }
 
-  fprintf(log, "MOZ_EVENT_TRACE stop %llu\n", PR_Now() / PR_USEC_PER_MSEC);
+  if (threadArgs->mLogTracing) {
+    fprintf(log, "MOZ_EVENT_TRACE stop %llu\n", PR_Now() / PR_USEC_PER_MSEC);
+  }
 
   if (log != stdout)
     fclose(log);
+
+  delete threadArgs;
 }
 
 } // namespace
 
 namespace mozilla {
 
-bool InitEventTracing()
+bool InitEventTracing(bool aLog)
 {
   if (sTracerThread)
     return true;
@@ -170,12 +182,16 @@ bool InitEventTracing()
   if (!InitWidgetTracing())
     return false;
 
+  // The tracer thread owns the object and will delete it.
+  TracerStartClosure* args = new TracerStartClosure();
+  args->mLogTracing = aLog;
+
   // Create a thread that will fire events back at the
   // main thread to measure responsiveness.
   NS_ABORT_IF_FALSE(!sTracerThread, "Event tracing already initialized!");
   sTracerThread = PR_CreateThread(PR_USER_THREAD,
                                   TracerThread,
-                                  NULL,
+                                  args,
                                   PR_PRIORITY_NORMAL,
                                   PR_GLOBAL_THREAD,
                                   PR_JOINABLE_THREAD,

toolkit/xre/EventTracer.h

@@ -10,7 +10,9 @@ namespace mozilla {
 // Create a thread that will fire events back at the
 // main thread to measure responsiveness. Return true
 // if the thread was created successfully.
-bool InitEventTracing();
+//   aLog If the tracing results should be printed to
+//        the console.
+bool InitEventTracing(bool aLog);
 
 // Signal the background thread to stop, and join it.
 // Must be called from the same thread that called InitEventTracing.

toolkit/xre/nsAppRunner.cpp

@@ -3872,7 +3872,8 @@ XREMain::XRE_mainRun()
 
 #ifdef MOZ_INSTRUMENT_EVENT_LOOP
   if (PR_GetEnv("MOZ_INSTRUMENT_EVENT_LOOP") || profiler_is_active()) {
-    mozilla::InitEventTracing();
+    bool logToConsole = !!PR_GetEnv("MOZ_INSTRUMENT_EVENT_LOOP");
+    mozilla::InitEventTracing(logToConsole);
   }
 #endif /* MOZ_INSTRUMENT_EVENT_LOOP */
 

tools/profiler/nsProfiler.cpp

@@ -79,7 +79,8 @@ nsProfiler::StartProfiler(uint32_t aEntries, uint32_t aInterval,
 
   profiler_start(aEntries, aInterval, aFeatures, aFeatureCount);
 #ifdef MOZ_INSTRUMENT_EVENT_LOOP
-  mozilla::InitEventTracing();
+  bool printToConsole = false;
+  mozilla::InitEventTracing(printToConsole);
 #endif
   return NS_OK;
 }