RAPPOR implementation

components/rappor/rappor_metric.h

+// Copyright 2014 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_RAPPOR_H_
+#define COMPONENTS_RAPPOR_RAPPOR_H_
+
+#include <string>
+
+#include "components/rappor/bloom_filter.h"
+#include "components/rappor/byte_vector_utils.h"
+#include "components/rappor/rappor_parameters.h"
+
+namespace rappor {
+
+// A RapporMetric is an object that collects string samples into a Bloom filter,
+// and generates randomized reports about the collected data.
+//
+// For a full description of the rappor metrics, see
+// http://www.chromium.org/developers/design-documents/rappor
+class RapporMetric {
+ public:
+  // Takes the |metric_name| that this will be reported to the server with,
+  // a |parameters| describing size and probability weights to be used in
+  // recording this metric, and cohort value, which modifies the hash
+  // functions and used in the bloom filter.
+  explicit RapporMetric(const std::string& metric_name,
+                        const RapporParameters& parameters,
+                        int32_t cohort);
+  ~RapporMetric();
+
+  // Records an additional sample in the Bloom filter.
+  void AddSample(const std::string& str);
+
+  // Retrieves the current Bloom filter bits.
+  const ByteVector& bytes() const { return bloom_filter_.bytes(); }
+
+  // Gets the parameter values this metric was constructed with.
+  const RapporParameters& parameters() const { return parameters_; }
+
+  // Generates the bits to report for this metric.  Using the secret as a seed,
+  // randomly selects bits for redaction.  Then flips coins to generate the
+  // final report bits.
+  ByteVector GetReport(const std::string& secret) const;
+
+ private:
+  const std::string metric_name_;
+  const RapporParameters parameters_;
+  BloomFilter bloom_filter_;
+
+  DISALLOW_COPY_AND_ASSIGN(RapporMetric);
+};
+
+}  // namespace rappor
+
+#endif  // COMPONENTS_RAPPOR_RAPPOR_H_