Support stacktrace and objecthistogram service commands

runtime/vm/heap_histogram.h

 // Copyright (c) 2013, 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.
 
 #ifndef VM_HEAP_HISTOGRAM_H_
 #define VM_HEAP_HISTOGRAM_H_
 
 #include "platform/assert.h"
 #include "vm/flags.h"
 #include "vm/globals.h"
 #include "vm/raw_object.h"
 
 namespace dart {
 
+class JSONStream;
+
 DECLARE_FLAG(bool, print_object_histogram);
 
 // ObjectHistogram is used to compute an average object histogram over
 // the lifetime of an isolate and then print the histogram when the isolate
 // is shut down. Information is gathered at the back-edge of each major GC
 // event. When an object histogram is collected for an isolate, an extra major
 // GC is performed just prior to shutdown.
 class ObjectHistogram {
  public:
   explicit ObjectHistogram(Isolate* isolate);
   ~ObjectHistogram();
 
   // Called when a new class is registered in the isolate.
   void RegisterClass(const Class& cls);
 
   // Collect sample for the histogram. Called at back-edge of major GC.
   void Collect();
 
   // Print the histogram on stdout.
   void Print();
 
+  void PrintToJSONStream(JSONStream* stream);
+
  private:
   // Add obj to histogram
   void Add(RawObject* obj);
 
   // For each class an Element keeps track of the accounting.
   class Element : public ValueObject {
    public:
     void Add(int size) {
       count_++;
       size_ += size;
     }
     intptr_t class_id_;
     intptr_t count_;
     intptr_t size_;
   };
 
   // Compare function for sorting result.
   static int compare(const Element** a, const Element** b);
 
+  // This function returns a malloced array. Caller is responsible for calling
+  // free().
+  Element** GetSortedArray(intptr_t* array_length);
+
   intptr_t major_gc_count_;
   intptr_t table_length_;
   Element* table_;
   Isolate* isolate_;
 
   friend class ObjectHistogramVisitor;
 
   DISALLOW_COPY_AND_ASSIGN(ObjectHistogram);
 };
 
 }  // namespace dart
 
 #endif  // VM_HEAP_HISTOGRAM_H_