Factor out a Histogram class from HistogramTimer, and use it to measure external fragmentation

src/counters.cc

Index: src/counters.cc
diff --git a/src/counters.cc b/src/counters.cc
index faad6d409ade1cdb7acac4d2c1f72488d0136d28..10213f3e481ecb86c11b58cc1d79069a5fe82c43 100644
--- a/src/counters.cc
+++ b/src/counters.cc
@@ -64,9 +64,19 @@ void StatsCounterTimer::Stop() {
   counter_.Increment(milliseconds);
 }
 
+void Histogram::AddSample(int sample) {
+  if (Enabled())

[Michael Starzinger, 2012/07/02 21:09:56]

Curly brackets if not on one line.

[jochen (gone - plz use gerrit), 2012/07/13 09:48:08]

Done.

+    Isolate::Current()->stats_table()->AddHistogramSample(histogram_, sample);
+}
+
+void* Histogram::CreateHistogram() const {
+  return Isolate::Current()->stats_table()->
+      CreateHistogram(name_, min_, max_, num_buckets_);
+}
+
 // Start the timer.
 void HistogramTimer::Start() {
-  if (GetHistogram() != NULL) {
+  if (histogram_.Enabled()) {
     stop_time_ = 0;
     start_time_ = OS::Ticks();
   }
@@ -74,20 +84,13 @@ void HistogramTimer::Start() {
 
 // Stop the timer and record the results.
 void HistogramTimer::Stop() {
-  if (histogram_ != NULL) {
+  if (histogram_.Enabled()) {
     stop_time_ = OS::Ticks();
 
     // Compute the delta between start and stop, in milliseconds.
     int milliseconds = static_cast<int>(stop_time_ - start_time_) / 1000;
-    Isolate::Current()->stats_table()->
-        AddHistogramSample(histogram_, milliseconds);
+    histogram_.AddSample(milliseconds);
   }
 }
 
-
-void* HistogramTimer::CreateHistogram() const {
-  return Isolate::Current()->stats_table()->
-      CreateHistogram(name_, 0, 10000, 50);
-}
-
 } }  // namespace v8::internal