Alternative Multi-dimensional Rappor

components/rappor/sample.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_SAMPLE_H_
+#define COMPONENTS_RAPPOR_SAMPLE_H_
+
+#include <map>
+#include <string>
+
+#include "base/macros.h"
+#include "components/rappor/rappor_parameters.h"
+
+namespace rappor {
+
+class RapporReports;
+
+// Sample is a container for information about a single instance of some event
+// we are sending Rappor data about.  It may contain multiple different fields,
+// which describe different details of the event, and they will be sent in the
+// same Rappor report, enabling analysis of correlations between those fields.
+class Sample {
+ public:
+  // Constructs a sample.  Instead of calling this directly, call
+  // RapporService::MakeSampleObj to create a sample.

[Alexei Svitkine (slow), 2015/04/23 21:42:34]

How about making this ctor private and making RapporService a friend to enforce
this?

[Steven Holte, 2015/04/24 16:59:06]

Done.

+  Sample(int32_t cohort_seed, const RapporParameters& parameters);
+  ~Sample();
+
+  // Sets a string value field in this sample.
+  void SetStringField(const std::string& field_name, const std::string& value);
+
+  // Sets a group of boolean flags as a field in this sample.
+  // |flags| should be a set of boolean flags stored in the lowest |num_flags|
+  // bits of |flags|.
+  void SetFlagsField(const std::string& field_name,
+                     uint64_t flags,
+                     size_t num_flags);
+
+  // Generate randomized reports and store them in |reports|.
+  void ExportMetrics(const std::string& secret,
+                     const std::string& metric_name,
+                     RapporReports* reports) const;
+
+  const RapporParameters& parameters() { return parameters_; }
+
+ private:
+  const RapporParameters parameters_;
+
+  // Offset used for bloom filter hash functions.
+  uint32_t bloom_offset_;
+
+  // Size of each of the different fields, in bytes.
+  std::map<std::string, size_t> sizes_;
+
+  // The non-randomized report values for each field.
+  std::map<std::string, uint64_t> fields_;
+
+  DISALLOW_COPY_AND_ASSIGN(Sample);
+};
+
+}  // namespace rappor
+
+#endif  // COMPONENTS_RAPPOR_SAMPLE_H_