components/variations/variations_seed_simulator.h

   1 // Copyright 2014 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_VARIATIONS_VARIATIONS_SEED_SIMULATOR_H_
   6 #define COMPONENTS_VARIATIONS_VARIATIONS_SEED_SIMULATOR_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/compiler_specific.h"
  12 #include "base/gtest_prod_util.h"
  13 #include "base/metrics/field_trial.h"
  14
  15 namespace chrome_variations {
  16
  17 class ProcessedStudy;
  18
  19 // VariationsSeedSimulator simulates the result of creating a set of studies
  20 // and detecting which studies would result in group changes.
  21 class VariationsSeedSimulator {
  22  public:
  23   // Creates the simulator with the given entropy |provider|.
  24   explicit VariationsSeedSimulator(
  25       const base::FieldTrial::EntropyProvider& provider);
  26   virtual ~VariationsSeedSimulator();
  27
  28   // Computes differences between the current process' field trial state and
  29   // the result of evaluating the |processed_studies| list. It is expected that
  30   // |processed_studies| have already been filtered and only contain studies
  31   // that apply to the configuration being simulated. Returns a lower bound on
  32   // the number of studies that are expected to change groups (lower bound due
  33   // to session randomized studies).
  34   int ComputeDifferences(
  35       const std::vector<ProcessedStudy>& processed_studies);
  36
  37  private:
  38   // For the given |processed_study| with PERMANENT consistency, simulates group
  39   // assignment and returns true if the result differs from that study's group
  40   // in the current process.
  41   bool PermanentStudyGroupChanged(const ProcessedStudy& processed_study,
  42                                   const std::string& selected_group);
  43
  44   // For the given |processed_study| with SESSION consistency, determines if
  45   // there are enough changes in the study config that restarting will result
  46   // in a guaranteed different group assignment (or different params).
  47   bool SessionStudyGroupChanged(const ProcessedStudy& filtered_study,
  48                                 const std::string& selected_group);
  49
  50   const base::FieldTrial::EntropyProvider& entropy_provider_;
  51
  52   DISALLOW_COPY_AND_ASSIGN(VariationsSeedSimulator);
  53 };
  54
  55 }  // namespace chrome_variations
  56
  57 #endif  // COMPONENTS_VARIATIONS_VARIATIONS_SEED_SIMULATOR_H_