Light-weight stats counters for experiments.

runtime/vm/object_graph_test.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 "platform/assert.h"
 #include "vm/object_graph.h"
 #include "vm/unit_test.h"
 
 namespace dart {
 
-class Counter : public ObjectGraph::Visitor {
+class CounterVisitor : public ObjectGraph::Visitor {
  public:
   // Records the number of objects and total size visited, excluding 'skip'
   // and any objects only reachable through 'skip'.
-  Counter(RawObject* skip, RawObject* expected_parent)
+  CounterVisitor(RawObject* skip, RawObject* expected_parent)
       : count_(0), size_(0), skip_(skip), expected_parent_(expected_parent) { }
 
   virtual Direction VisitObject(ObjectGraph::StackIterator* it) {
     RawObject* obj = it->Get();
     if (obj == skip_) {
       EXPECT(it->MoveToParent());
       EXPECT_EQ(expected_parent_, it->Get());
       return kBacktrack;
     }
     ++count_;
@@ skipping 35 matching lines @@
     // No more allocation; raw pointers ahead.
     NoGCScope no_gc_scope;
     RawObject* b_raw = b.raw();
     // Clear handles to cut unintended retained paths.
     b = Array::null();
     c = Array::null();
     d = Array::null();
     ObjectGraph graph(isolate);
     {
       // Compare count and size when 'b' is/isn't skipped.
-      Counter with(Object::null(), Object::null());
+      CounterVisitor with(Object::null(), Object::null());
       graph.IterateObjectsFrom(a, &with);
-      Counter without(b_raw, a.raw());
+      CounterVisitor without(b_raw, a.raw());
       graph.IterateObjectsFrom(a, &without);
       // Only 'b' and 'c' were cut off.
       EXPECT_EQ(2, with.count() - without.count());
       EXPECT_EQ(b_size + c_size,
                 with.size() - without.size());
     }
     {
       // Like above, but iterate over the entire isolate. The counts and sizes
       // are thus larger, but the difference should still be just 'b' and 'c'.
-      Counter with(Object::null(), Object::null());
+      CounterVisitor with(Object::null(), Object::null());
       graph.IterateObjects(&with);
-      Counter without(b_raw, a.raw());
+      CounterVisitor without(b_raw, a.raw());
       graph.IterateObjects(&without);
       EXPECT_EQ(2, with.count() - without.count());
       EXPECT_EQ(b_size + c_size,
                 with.size() - without.size());
     }
     EXPECT_EQ(a_size + b_size + c_size + d_size,
               graph.SizeRetainedByInstance(a));
   }
   {
     // Get hold of c again.
@@ skipping 25 matching lines @@
       Array& expected_a = Array::Handle();
       expected_a ^= path.At(2);
       EXPECT(expected_c.raw() == c.raw());
       EXPECT(expected_b.raw() == a.At(0));
       EXPECT(expected_a.raw() == a.raw());
     }
   }
 }
 
 }  // namespace dart