Add GC stats to GC timeline events

runtime/vm/heap.cc

Index: runtime/vm/heap.cc
diff --git a/runtime/vm/heap.cc b/runtime/vm/heap.cc
index ef4e14cbe5d21520d732074f25da7c7a9fa3b4de..5535d930748dfdc6f81bd6c86f5fdab54dea0a2a 100644
--- a/runtime/vm/heap.cc
+++ b/runtime/vm/heap.cc
@@ -381,6 +381,7 @@ void Heap::CollectNewSpaceGarbage(Thread* thread,
     UpdatePretenurePolicy();
     RecordAfterGC(kNew);
     PrintStats();
+    NOT_IN_PRODUCT(PrintStatsToTimeline(&tds));
     EndNewSpaceGC();
     if ((reason == kNewSpace) && old_space_.NeedsGarbageCollection()) {
       // Old collections should call the API callbacks.
@@ -403,6 +404,7 @@ void Heap::CollectOldSpaceGarbage(Thread* thread,
     old_space_.MarkSweep(invoke_api_callbacks);
     RecordAfterGC(kOld);
     PrintStats();
+    NOT_IN_PRODUCT(PrintStatsToTimeline(&tds));
     EndOldSpaceGC();
   }
 }
@@ -834,6 +836,64 @@ void Heap::PrintStats() {
 }
 
 
+void Heap::PrintStatsToTimeline(TimelineEventScope* event) {
+  if ((event == NULL) || !event->enabled()) {
+    return;
+  }
+  event->SetNumArguments(12);
+  event->FormatArgument(0,
+                        "Before.New.Used",
+                        "%" Pd "",

[rmacnak, 2016/05/09 19:32:17]

It's hard to figure out the units just from looking at the event. Either don't
round to kB or put a kB suffix on the string.

[Ivan Posva, 2016/05/09 19:39:58]

I guess another option is to put the unit on the name such as "Before.New.Used
(kB)" which will give the units without polluting the value in case somebody
wants to parse it out.

[Cutch, 2016/05/09 20:45:01]

Done.

+                        RoundWordsToKB(stats_.before_.new_.used_in_words));
+  event->FormatArgument(1,
+                        "After.New.Used",
+                        "%" Pd "",
+                        RoundWordsToKB(stats_.after_.new_.used_in_words));
+  event->FormatArgument(2,
+                        "Before.Old.Used",
+                        "%" Pd "",
+                        RoundWordsToKB(stats_.before_.old_.used_in_words));
+  event->FormatArgument(3,
+                        "After.Old.Used",
+                        "%" Pd "",
+                        RoundWordsToKB(stats_.after_.old_.used_in_words));
+
+  event->FormatArgument(4,
+                        "Before.New.Capacity",
+                        "%" Pd "",
+                        RoundWordsToKB(stats_.before_.new_.capacity_in_words));
+  event->FormatArgument(5,
+                        "After.New.Capacity",
+                        "%" Pd "",
+                        RoundWordsToKB(stats_.after_.new_.capacity_in_words));
+  event->FormatArgument(6,
+                        "Before.Old.Capacity",
+                        "%" Pd "",
+                        RoundWordsToKB(stats_.before_.old_.capacity_in_words));
+  event->FormatArgument(7,
+                        "After.Old.Capacity",
+                        "%" Pd "",
+                        RoundWordsToKB(stats_.after_.old_.capacity_in_words));
+
+  event->FormatArgument(8,
+                        "Before.New.External",
+                        "%" Pd "",
+                        RoundWordsToKB(stats_.before_.new_.external_in_words));
+  event->FormatArgument(9,
+                        "After.New.External",
+                        "%" Pd "",
+                        RoundWordsToKB(stats_.after_.new_.external_in_words));
+  event->FormatArgument(10,
+                        "Before.Old.External",
+                        "%" Pd "",
+                        RoundWordsToKB(stats_.before_.old_.external_in_words));
+  event->FormatArgument(11,
+                        "After.Old.External",
+                        "%" Pd "",
+                        RoundWordsToKB(stats_.after_.old_.external_in_words));

[Ivan Posva, 2016/05/09 19:39:58]

I would also like to add the times_ values, but they change from new to old gen.
So a possibility would be to pass their description as a parameter or somehow
record the description in the stats object.

[Cutch, 2016/05/09 20:45:01]

Acknowledged.

+}
+
+
 NoHeapGrowthControlScope::NoHeapGrowthControlScope()
     : StackResource(Thread::Current()) {
     Heap* heap = reinterpret_cast<Isolate*>(isolate())->heap();