Alternative Multi-dimensional Rappor

components/rappor/sampler.cc

+// 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.
+
+#include "components/rappor/sampler.h"
+
+#include <map>
+#include <string>
+
+#include "base/rand_util.h"
+
+namespace rappor {
+
+Sampler::Sampler() {}
+
+Sampler::~Sampler() {}
+
+void Sampler::AddSample(const std::string& metric_name,
+                        scoped_ptr<Sample> sample) {
+  ++sample_counts_[metric_name];
+  // Replace the previous sample with a 1 in sample_count_ chance so that each
+  // sample has equal probability of being reported.
+  if (base::RandGenerator(sample_counts_[metric_name]) == 0) {
+    samples_.set(metric_name, sample.Pass());
+  }
+}
+
+void Sampler::ExportMetrics(const std::string& secret, RapporReports* reports) {
+  for (auto it = samples_.begin(); it != samples_.end(); ++it) {

[Alexei Svitkine (slow), 2015/04/16 15:09:43]

Nit: Use C++11 for loop syntax, i.e.

for (const auto& entry : samples_) {
  entry.second->ExportMetrics(...);
}

[Steven Holte, 2015/04/22 19:24:28]

Done.

+    it->second->ExportMetrics(secret, it->first, reports);
+  }
+  samples_.clear();
+  sample_counts_.clear();
+}
+
+}  // namespace rappor