components/rappor/sampler.cc

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "components/rappor/sampler.h"
   6
   7 #include <map>
   8 #include <string>
   9
  10 #include "base/rand_util.h"
  11
  12 namespace rappor {
  13
  14 namespace internal {
  15
  16 Sampler::Sampler() {}
  17
  18 Sampler::~Sampler() {}
  19
  20 void Sampler::AddSample(const std::string& metric_name,
  21                         scoped_ptr<Sample> sample) {
  22   ++sample_counts_[metric_name];
  23   // Replace the previous sample with a 1 in sample_count_ chance so that each
  24   // sample has equal probability of being reported.
  25   if (base::RandGenerator(sample_counts_[metric_name]) == 0)
  26     samples_.set(metric_name, sample.Pass());
  27 }
  28
  29 void Sampler::ExportMetrics(const std::string& secret, RapporReports* reports) {
  30   for (const auto& kv : samples_) {
  31     kv.second->ExportMetrics(secret, kv.first, reports);
  32   }
  33   samples_.clear();
  34   sample_counts_.clear();
  35 }
  36
  37 }  // namespace internal
  38
  39 }  // namespace rappor