RAPPOR implementation

components/rappor/rappor_metric.h

+// Copyright (c) 2012 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 <assert.h>
+#include <limits.h>
+#include <math.h>
+
+#include <string>
+#include <vector>
+
+#include "components/rappor/bloom_filter.h"
+#include "components/rappor/rappor_parameters.h"
+#include "components/rappor/byte_vector_utils.h"
+
+namespace rappor {
+
+// A RapporMetric is an object for 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:
+  RapporMetric(const RapporParameters* parameters);

[Alexei Svitkine (slow), 2013/12/24 16:59:30]

Nit: explicit.

What's the ownership model for |parameters|. Please document.

It seems your current code is keeping a weak ref to this. But the owner appears
to be whoever called the RapporService method. That doesn't seem like a good
ownership model. Maybe you could transfer ownership, by passing these as
scoped_ptr<RapporParameters> all the way down?

However, then the issue is logging new samples to an existing metric... Perhaps
you could create a helper RapporMetricRecorder class that handles this behind
the scenes (and observes RapporService destruction, so that when RapporService
goes away, the recorder acts sane).

Alternatively, just copy the params in this ctor and don't pass a weak pointer.

[Steven Holte, 2014/01/04 00:12:54]

Changed to copy in ctor.

On 2013/12/24 16:59:30, asvitkine (OOO until Jan 6th) wrote:

+
+  // Record additional samples in the bloom filter.
+  void AddSamples(const std::vector<std::string>& strings);
+  void AddSample(const std::string& str);
+
+  // Retrieves the current bloom filter bits.
+  const ByteVector& GetBytes() const;
+  const RapporParameters* parameters() const { return parameters_; }
+
+  ByteVector GetReport(const std::string& secret) const;
+
+ private:
+  const RapporParameters* parameters_;
+  BloomFilter bloom_;
+
+  DISALLOW_COPY_AND_ASSIGN(RapporMetric);
+};
+
+}  // namespace rappor
+
+#endif  // COMPONENTS_RAPPOR_RAPPOR_H_