Display average time between collections

runtime/vm/pages.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/pages.h"
 
 #include "platform/assert.h"
 #include "vm/compiler_stats.h"
 #include "vm/gc_marker.h"
 #include "vm/gc_sweeper.h"
@@ skipping 355 matching lines @@
 void PageSpace::WriteProtect(bool read_only) {
   HeapPage* page = pages_;
   while (page != NULL) {
     page->WriteProtect(read_only);
     page = NextPageAnySize(page);
   }
 }
 
 
 void PageSpace::PrintToJSONObject(JSONObject* object) {
+  Isolate* isolate = Isolate::Current();
+  ASSERT(isolate != NULL);
   JSONObject space(object, "old");
   space.AddProperty("type", "PageSpace");
   space.AddProperty("id", "heaps/old");
   space.AddProperty("name", "PageSpace");
   space.AddProperty("user_name", "old");
   space.AddProperty("collections", collections());
   space.AddProperty("used", UsedInWords() * kWordSize);
   space.AddProperty("capacity", CapacityInWords() * kWordSize);
   space.AddProperty("external", ExternalInWords() * kWordSize);
   space.AddProperty("time", MicrosecondsToSeconds(gc_time_micros()));
+  {
+    int64_t run_time = OS::GetCurrentTimeMicros() - isolate->start_time();

[koda, 2014/06/26 19:42:38]

Note to self: yet another reason to consider a Space base class.

+    run_time = Utils::Maximum(run_time, static_cast<int64_t>(0));
+    double run_time_millis = MicrosecondsToMilliseconds(run_time);
+    double avg_time_between_collections =
+        run_time_millis / static_cast<double>(collections());
+    space.AddProperty("avgCollectionPeriodMillis",
+                      avg_time_between_collections);
+  }
 }
 
 
 class HeapMapAsJSONVisitor : public ObjectVisitor {
  public:
   explicit HeapMapAsJSONVisitor(JSONArray* array)
       : ObjectVisitor(NULL), array_(array) {}
   virtual void VisitObject(RawObject* obj) {
     array_->AddValue(obj->Size() / kObjectAlignment);
     array_->AddValue(obj->GetClassId());
@@ skipping 286 matching lines @@
     return 0;
   } else {
     ASSERT(total_time >= gc_time);
     int result= static_cast<int>((static_cast<double>(gc_time) /
                              static_cast<double>(total_time)) * 100);
     return result;
   }
 }
 
 }  // namespace dart