Add VMMetric and some sample metrics

runtime/vm/metrics.h

Index: runtime/vm/metrics.h
diff --git a/runtime/vm/metrics.h b/runtime/vm/metrics.h
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+++ b/runtime/vm/metrics.h
@@ -0,0 +1,137 @@
+// Copyright (c) 2014, 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_METRICS_H_
+#define VM_METRICS_H_
+
+#include "vm/allocation.h"
+
+namespace dart {
+
+class Isolate;
+class JSONStream;
+
+// Metrics for each isolate.
+#define ISOLATE_METRIC_LIST(V)                                                 \
+  V(VMMetricHeapOldUsed, HeapOldUsed, "heap.old.used", kByte)                  \
+  V(VMMetricHeapOldCapacity, HeapOldCapacity, "heap.old.capacity", kByte)      \
+  V(VMMetricHeapOldExternal, HeapOldExternal, "heap.old.external", kByte)      \
+  V(VMMetricHeapNewUsed, HeapNewUsed, "heap.new.used", kByte)                  \
+  V(VMMetricHeapNewCapacity, HeapNewCapacity, "heap.new.capacity", kByte)      \
+  V(VMMetricHeapNewExternal, HeapNewExternal, "heap.new.external", kByte)      \
+
+#define VM_METRIC_LIST(V)                                                      \
+  V(VMMetricIsolateCount, IsolateCount, "vm.isolate.count", kCounter)          \
+
+class VMMetric {
+ public:
+  enum Unit {
+    kCounter,
+    kByte,
+  };
+
+  VMMetric();
+
+  static void InitOnce();
+
+  // Initialize and register a counter for an isolate.
+  void Init(Isolate* isolate,
+            const char* name,
+            const char* description,
+            Unit unit);
+  // Initialize and register a counter for the VM.

[koda, 2014/08/13 22:43:00]

The terminology is a bit awkward here: the entire class is called VMMetric, but
then there are two cases, one of which is "for the VM".

Consider another term, like "cross-isolate" or "global". Or rename the class.

Also, "counter" -> "metric".

[Cutch, 2014/08/14 20:56:19]

Done. Renamed VMMetric -> Metric.

+  void Init(const char* name,
+            const char* description,
+            Unit unit);
+
+  virtual ~VMMetric();
+
+  void PrintJSON(JSONStream* stream);
+
+  int64_t value() const { return value_; }
+  void set_value(int64_t value) { value_ = value; }
+
+  void increment() { value_++; }
+
+  VMMetric* next() const { return next_; }
+  void set_next(VMMetric* next) {
+    next_ = next;
+  }
+
+  const char* name() const { return name_; }
+  const char* description() const { return description_; }
+  intptr_t unit() const { return unit_; }

[koda, 2014/08/13 22:42:59]

Use Unit type rather than intptr_t.

[Cutch, 2014/08/14 20:56:19]

Done.

+
+  Isolate* isolate() const { return isolate_; }

[koda, 2014/08/13 22:43:00]

Does this need to be public? If yes, at least say it's NULL for a VM-global
metric.

[Cutch, 2014/08/14 20:56:19]

Done.

+
+  static VMMetric* vm_head() { return vm_list_head_; }
+
+ protected:
+  // Override to get a callback when value is serialized to JSON.
+  // Use this for metrics that produce their value on demand.
+  virtual int64_t Value() const { return value(); }
+
+ private:
+  Isolate* isolate_;
+  const char* name_;
+  const char* description_;
+  intptr_t unit_;
+  int64_t value_;
+  VMMetric* next_;
+
+  void RegisterWithIsolate();
+  void DeregisterWithIsolate();
+  void RegisterWithVM();
+  void DeregisterWithVM();
+
+  static VMMetric* vm_list_head_;
+  DISALLOW_COPY_AND_ASSIGN(VMMetric);
+};
+
+
+class VMMetricHeapOldUsed : public VMMetric {
+ protected:
+  virtual int64_t Value() const;
+};
+
+
+class VMMetricHeapOldCapacity : public VMMetric {
+ protected:
+  virtual int64_t Value() const;
+};
+
+
+class VMMetricHeapOldExternal : public VMMetric {
+ protected:
+  virtual int64_t Value() const;
+};
+
+
+class VMMetricHeapNewUsed : public VMMetric {
+ protected:
+  virtual int64_t Value() const;
+};
+
+
+class VMMetricHeapNewCapacity : public VMMetric {
+ protected:
+  virtual int64_t Value() const;
+};
+
+
+class VMMetricHeapNewExternal : public VMMetric {
+ protected:
+  virtual int64_t Value() const;
+};
+
+
+class VMMetricIsolateCount : public VMMetric {
+ protected:
+  virtual int64_t Value() const;
+};
+
+
+}  // namespace dart
+
+#endif  // VM_METRICS_H_