Bug 1330184 - Allow StreamMetaObject to be called on a background thread, but only include startTime and version for those calls. r=njn

MozReview-Commit-ID: 3AuX0a2Brrd

--HG--
extra : rebase_source : 8c5d2b4ccacbbec92711a9561d4166e1e7c376c7
extra : intermediate-source : e13b9e798e16185e54435a0b926970e8de134804
extra : source : edfdb14bd020233fa29771bb0f78bcfc55f6cbb3

tools/profiler/core/platform.cpp

@@ -1403,10 +1403,28 @@ StreamTaskTracer(PSLockRef aLock, SpliceableJSONWriter& aWriter)
 static void
 StreamMetaJSCustomObject(PSLockRef aLock, SpliceableJSONWriter& aWriter)
 {
-  MOZ_RELEASE_ASSERT(NS_IsMainThread());
   MOZ_RELEASE_ASSERT(CorePS::Exists() && ActivePS::Exists(aLock));
 
   aWriter.IntProperty("version", 6);
+
+  // The "startTime" field holds the number of milliseconds since midnight
+  // January 1, 1970 GMT. This grotty code computes (Now - (Now -
+  // ProcessStartTime)) to convert CorePS::ProcessStartTime() into that form.
+  mozilla::TimeDuration delta =
+    mozilla::TimeStamp::Now() - CorePS::ProcessStartTime(aLock);
+  aWriter.DoubleProperty(
+    "startTime", static_cast<double>(PR_Now()/1000.0 - delta.ToMilliseconds()));
+
+  if (!NS_IsMainThread()) {
+    // Leave the rest of the properties out if we're not on the main thread.
+    // At the moment, the only case in which this function is called on a
+    // background thread is if we're in a content process and are going to
+    // send this profile to the parent process. In that case, the parent
+    // process profile's "meta" object already has the rest of the properties,
+    // and the parent process profile is dumped on that process's main thread.
+    return;
+  }
+
   aWriter.DoubleProperty("interval", ActivePS::Interval(aLock));
   aWriter.IntProperty("stackwalk", ActivePS::FeatureStackWalk(aLock));
 
@@ -1421,14 +1439,6 @@ StreamMetaJSCustomObject(PSLockRef aLock, SpliceableJSONWriter& aWriter)
   bool asyncStacks = Preferences::GetBool("javascript.options.asyncstack");
   aWriter.IntProperty("asyncstack", asyncStacks);
 
-  // The "startTime" field holds the number of milliseconds since midnight
-  // January 1, 1970 GMT. This grotty code computes (Now - (Now -
-  // ProcessStartTime)) to convert CorePS::ProcessStartTime() into that form.
-  mozilla::TimeDuration delta =
-    mozilla::TimeStamp::Now() - CorePS::ProcessStartTime(aLock);
-  aWriter.DoubleProperty(
-    "startTime", static_cast<double>(PR_Now()/1000.0 - delta.ToMilliseconds()));
-
   aWriter.IntProperty("processType", XRE_GetProcessType());
 
   nsresult res;