components/rappor/sampler.h

   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 #ifndef COMPONENTS_RAPPOR_SAMPLER_H_
   6 #define COMPONENTS_RAPPOR_SAMPLER_H_
   7
   8 #include <map>
   9 #include <string>
  10
  11 #include "base/containers/scoped_ptr_hash_map.h"
  12 #include "base/macros.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "components/rappor/rappor_parameters.h"
  15 #include "components/rappor/sample.h"
  16
  17 namespace rappor {
  18
  19 class RapporReports;
  20
  21 namespace internal {
  22
  23 // Sampler manages the collection and storage of Sample objects.
  24 // For each metric name, it will randomly select one Sample to store and
  25 // use when generating RapporReports.
  26 class Sampler {
  27  public:
  28   Sampler();
  29   ~Sampler();
  30
  31   // Store this sample for metric name, randomly selecting a sample if
  32   // others have already been recorded.
  33   void AddSample(const std::string& metric_name, scoped_ptr<Sample> sample);
  34
  35   // Generate randomized reports for all stored samples and store them
  36   // in |reports|, then discard the samples.
  37   void ExportMetrics(const std::string& secret, RapporReports* reports);
  38
  39  private:
  40   // The number of samples recorded for each metric since the last export.
  41   std::map<std::string, int> sample_counts_;
  42
  43   // Stores a Sample for each metric, by metric name.
  44   base::ScopedPtrHashMap<std::string, scoped_ptr<Sample>> samples_;
  45
  46   DISALLOW_COPY_AND_ASSIGN(Sampler);
  47 };
  48
  49 }  // namespace internal
  50
  51 }  // namespace rappor
  52
  53 #endif  // COMPONENTS_RAPPOR_SAMPLER_H_