Add --print-metrics vm flag for printing metrics to console

runtime/vm/metrics.cc

 // 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.
 
 #include "vm/metrics.h"
 
 #include "vm/isolate.h"
 #include "vm/json_stream.h"
 #include "vm/native_entry.h"
 #include "vm/runtime_entry.h"
 #include "vm/object.h"
+#include "vm/log.h"
 
 namespace dart {
 
+DEFINE_FLAG(bool, print_metrics, false,
+            "Print metrics when isolates (and the VM) are shutdown.");
+
 Metric* Metric::vm_list_head_ = NULL;
 
 Metric::Metric()
     : isolate_(NULL),
       name_(NULL),
       description_(NULL),
       unit_(kCounter),
       value_(0),
       next_(NULL) {
 }
@@ skipping 60 matching lines @@
     obj.AddFixedServiceId("vm/metrics/%s", name_);
   } else {
     obj.AddFixedServiceId("metrics/native/%s", name_);
   }
   // TODO(johnmccutchan): Overflow?
   double value_as_double = static_cast<double>(Value());
   obj.AddProperty("value", value_as_double);
 }
 
 
+char* Metric::ValueToString(int64_t value, Unit unit) {
+  Thread* thread = Thread::Current();
+  ASSERT(thread != NULL);
+  Zone* zone = thread->zone();
+  ASSERT(zone != NULL);
+  switch (unit) {
+    case kCounter:
+      return zone->PrintToString("%" Pd64 "", value);
+    case kByte: {
+      const char* scaled_suffix = "b";
+      double scaled_value = static_cast<double>(value);
+      if (value > KB) {
+        scaled_suffix = "kb";
+        scaled_value /= KB;
+      } else if (value > MB) {
+        scaled_suffix = "mb";
+        scaled_value /= MB;
+      } else if (value > GB) {
+        scaled_suffix = "gb";
+        scaled_value /= GB;
+      }
+      return zone->PrintToString("%.3f %s (%" Pd64 ")",
+                                 scaled_value,
+                                 scaled_suffix,
+                                 value);
+    }
+    default:
+      UNREACHABLE();
+      return NULL;
+  }
+}
+
+
+char* Metric::ToString() {
+  Thread* thread = Thread::Current();
+  ASSERT(thread != NULL);
+  Zone* zone = thread->zone();
+  ASSERT(zone != NULL);
+  return zone->PrintToString("%s %s", name(), ValueToString(value(), unit()));
+}
+
+
 bool Metric::NameExists(Metric* head, const char* name) {
   ASSERT(name != NULL);
   while (head != NULL) {
     const char* metric_name = head->name();
     ASSERT(metric_name != NULL);
     if (strcmp(metric_name, name) == 0) {
       return true;
     }
     head = head->next();
   }
@@ skipping 135 matching lines @@
 #undef VM_METRIC_VARIABLE
 
 
 void Metric::InitOnce() {
 #define VM_METRIC_INIT(type, variable, name, unit)                             \
   vm_metric_##variable##_.Init(name, NULL, Metric::unit);
   VM_METRIC_LIST(VM_METRIC_INIT);
 #undef VM_METRIC_INIT
 }
 
+void Metric::Cleanup() {
+  if (FLAG_print_metrics) {
+    // Create a zone to allocate temporary strings in.
+    StackZone sz(Thread::Current());
+    OS::Print("Printing metrics for VM\n");
+    Metric* current = Metric::vm_head();
+    while (current != NULL) {
+      OS::Print("%s\n", current->ToString());
+      current = current->next();
+    }
+    OS::Print("\n");
+  }
+}
+
 }  // namespace dart