RAPPOR implementation

components/rappor/rappor_recorder.h

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// RapporRecorder holds all Rappors collected in the system, and methods for
+// retrieving the recorded data.
+
+#ifndef COMPONENTS_RAPPOR_RAPPOR_RECORDER_H_
+#define COMPONENTS_RAPPOR_RAPPOR_RECORDER_H_
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/gtest_prod_util.h"
+#include "base/lazy_instance.h"
+#include "base/synchronization/lock.h"
+#include "components/rappor/rappor.h"
+
+#define RAPPOR_SAMPLES(name, samples) \
+  rappor::g_rappor_recorder.Get().GetRappor(name)->AddSamples(samples);
+
+namespace rappor {
+
+class RapporRecorder {
+ public:
+  typedef std::vector<Rappor*> Rappors;
+
+  // Method for extracting rappors for use by UMA.
+  void GetRappors(Rappors* output);
+
+  // Clears all recorded rappors.
+  void ClearRappors();
+
+  // Find a rappor by name, and create it if it doesn't already exist. It
+  // matches the exact name. This method is thread safe.
+  Rappor* GetRappor(const std::string& name);

[jwd, 2013/12/17 23:00:25]

Can this return a weak_ptr? Similarly, can |Rappors| be a vector of weak_ptrs?

[Steven Holte, 2013/12/18 23:38:49]

Hid this pointer inside a RecordSamples() method.

For |Rappors|, I changed GetRappors into CollectRappors, which clears the
Recorder, so the pointers returned are unique references to the objects and can
be deleted by the caller.  I'm not sure if using scoped_ptr for the vector
objects might be more appropriate?

+
+  // The constructor just initializes static members. Usually client code should
+  // use Initialize to do this. But in test code, you can friend this class and
+  // call destructor/constructor to get a clean RapporRecorder.
+  RapporRecorder();
+  ~RapporRecorder();
+
+ private:
+  // We keep all registered histograms in a map, from name to histogram.
+  typedef std::map<std::string, Rappor*> RapporMap;
+
+  RapporMap rappors_;
+
+  // Lock protects access to above map.
+  base::Lock lock_;
+};
+
+extern base::LazyInstance<RapporRecorder>::Leaky g_rappor_recorder;
+
+}  // namespace rappor
+
+#endif  // COMPONENTS_RAPPOR_RAPPOR_RECORDER_H_