Track live instance and allocation counts for classes

runtime/vm/heap_class_stats.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_CLASS_STATS_H_
+#define VM_HEAP_CLASS_STATS_H_
+
+#include "platform/assert.h"
+#include "vm/globals.h"
+#include "vm/object.h"
+
+namespace dart {
+
+class JSONStream;
+
+// For each register class in an isolate we track the following:
+// 1) Number of live instances in old space.
+// 2) Number of live instances in new space.
+// 3) Number of instances allocated since last full GC.
+// Generated code will update (3) directly. See BumpAllocationCount.
+struct HeapClassData {
+  intptr_t live_old_space;
+  intptr_t live_new_space;
+  // This field is updated by generated code.
+  intptr_t allocated_since_gc;
+  static intptr_t allocated_since_gc_offset() {
+    return OFFSET_OF(HeapClassData, allocated_since_gc);
+  }
+};
+
+
+class HeapClassStatistics {
+ public:
+  explicit HeapClassStatistics(Isolate* isolate);
+  ~HeapClassStatistics();
+
+  // Called when a new class is registered in the isolate.
+  void RegisterClass(const Class& cls);
+
+  // Called whenever a class is allocated in the runtime.
+  void AllocateClass(intptr_t cid);
+
+  // Called whenever a major GC occurs.
+  void Collect();
+
+  // Used by generated code for class allocations.
+  uword ClassStatsTableAddress();
+
+ private:
+  friend class HeapClassStatsVisitor;
+  Isolate* isolate_;
+  HeapClassData* class_table_;
+  intptr_t class_table_size_;
+
+  void ResetCounters();
+  void ReportLiveOldSpace(intptr_t cid);
+  void ReportLiveNewSpace(intptr_t cid);
+
+  DISALLOW_COPY_AND_ASSIGN(HeapClassStatistics);
+};
+
+
+}  // namespace dart
+
+#endif  // VM_HEAP_CLASS_STATS_H_