RAPPOR implementation

components/rappor/rappor_parameters.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_PARAMETERS_H_
+#define COMPONENTS_RAPPOR_RAPPOR_PARAMETERS_H_
+
+#include <ostream>
+#include <string>
+
+namespace rappor {
+
+enum Probability {
+  PROBABILITY_75,    // 75%
+  PROBABILITY_50,    // 50%
+};
+
+// An object describing a rappor metric and the parameters used to generate it.
+//
+// For a full description of the rappor metrics, see
+// http://www.chromium.org/developers/design-documents/rappor
+struct RapporParameters {
+  // The name of the metric.
+  std::string rappor_name;
+
+  // The number of bytes stored in the Bloom filter.
+  int bloom_filter_size_bytes;
+  // The number of hash functions used in the Bloom filter.
+  int bloom_filter_hash_function_count;
+
+  // The probability that a bit will be redacted with fake data.
+  Probability fake_prob;
+  // The probability that a fake bit will be a one.
+  Probability fake_one_prob;
+
+  // The probability that a one bit in the redacted data reports as one.
+  Probability one_coin_prob;
+  // The probability that a zero bit in the redacted data reports as one.
+  Probability zero_coin_prob;
+};
+
+std::ostream& operator<<(std::ostream& out, const RapporParameters& rhs);

[Alexei Svitkine (slow), 2014/01/21 18:14:04]

Generally, operator overloads are discouraged. I'd instead make a ToString() and
IsEqual() methods.

[Steven Holte, 2014/01/21 20:25:14]

These only exist to make DCHECK_EQ work and I've added a comment to that effect.
 Is there a better way to enable that?

[Alexei Svitkine (slow), 2014/01/21 20:30:39]

How about just doing DCHECK_EQ() on ToString() result? Sure its costly, but its
only for debug builds anyway.

[Steven Holte, 2014/01/21 21:05:32]

Done.

+
+bool operator==(const RapporParameters& lhs, const RapporParameters& rhs);
+
+}  // namespace rappor
+
+#endif  // COMPONENTS_RAPPOR_RAPPOR_PARAMETERS_H_