Alternative Multi-dimensional Rappor

components/rappor/sampler.h

+// Copyright 2015 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.
+
+#ifndef COMPONENTS_RAPPOR_SAMPLER_H_
+#define COMPONENTS_RAPPOR_SAMPLER_H_
+
+#include <map>
+#include <string>
+
+#include "base/containers/scoped_ptr_hash_map.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "components/rappor/rappor_parameters.h"
+#include "components/rappor/sample.h"
+
+namespace rappor {
+
+class RapporReports;
+
+namespace internal {
+
+// Sampler manages the collection and storage of Sample objects.
+// For each metric name, it will randomly select one Sample to store and
+// use when generating RapporReports.
+class Sampler {
+ public:
+  Sampler();
+  ~Sampler();
+
+  // Store this sample for metric name, randomly selecting a sample if
+  // others have already been recorded.
+  void AddSample(const std::string& metric_name, scoped_ptr<Sample> sample);
+
+  // Generate randomized reports for all stored samples and store them
+  // in |reports|, then discard the samples.
+  void ExportMetrics(const std::string& secret, RapporReports* reports);
+
+ private:
+  // The number of samples recorded for each metric since the last export.
+  std::map<std::string, int> sample_counts_;
+
+  // Stores a Sample for each metric, by metric name.
+  base::ScopedPtrHashMap<std::string, Sample> samples_;
+
+  DISALLOW_COPY_AND_ASSIGN(Sampler);
+};
+
+}  // namespace internal
+
+}  // namespace rappor
+
+#endif  // COMPONENTS_RAPPOR_SAMPLER_H_