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// 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.
#ifndef COMPONENTS_VARIATIONS_VARIATIONS_SEED_SIMULATOR_H_
#define COMPONENTS_VARIATIONS_VARIATIONS_SEED_SIMULATOR_H_
#include <string>
#include <vector>
#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/metrics/field_trial.h"
#include "base/version.h"
#include "components/variations/proto/study.pb.h"
#include "components/variations/proto/variations_seed.pb.h"
namespace variations {
class ProcessedStudy;
class VariationsSeed;
// VariationsSeedSimulator simulates the result of creating a set of studies
// and detecting which studies would result in group changes.
class VariationsSeedSimulator {
public:
// The result of variations seed simulation, counting the number of experiment
// group changes of each type that are expected to occur on a restart with the
// seed.
struct Result {
// The number of expected group changes that do not fall into any special
// category. This is a lower bound due to session randomized studies.
int normal_group_change_count;
// The number of expected group changes that fall in the category of killed
// experiments that should trigger the "best effort" restart mechanism.
int kill_best_effort_group_change_count;
// The number of expected group changes that fall in the category of killed
// experiments that should trigger the "critical" restart mechanism.
int kill_critical_group_change_count;
Result();
~Result();
};
// Creates the simulator with the given default and low entropy providers. The
// |low_entropy_provider| will be used for studies that should only use a low
// entropy source. This is defined by
// VariationsSeedProcessor::ShouldStudyUseLowEntropy, in
// variations_seed_processor.h.
VariationsSeedSimulator(
const base::FieldTrial::EntropyProvider& default_entropy_provider,
const base::FieldTrial::EntropyProvider& low_entropy_provider);
virtual ~VariationsSeedSimulator();
// Computes differences between the current process' field trial state and
// the result of evaluating |seed| with the given parameters. Returns the
// results of the simulation as a set of expected group change counts of each
// type.
Result SimulateSeedStudies(const VariationsSeed& seed,
const std::string& locale,
const base::Time& reference_date,
const base::Version& version,
Study_Channel channel,
Study_FormFactor form_factor,
const std::string& hardware_class,
const std::string& session_consistency_country,
const std::string& permanent_consistency_country);
private:
friend class VariationsSeedSimulatorTest;
enum ChangeType {
NO_CHANGE,
CHANGED,
CHANGED_KILL_BEST_EFFORT,
CHANGED_KILL_CRITICAL,
};
// Computes differences between the current process' field trial state and
// the result of evaluating the |processed_studies| list. It is expected that
// |processed_studies| have already been filtered and only contain studies
// that apply to the configuration being simulated. Returns the results of the
// simulation as a set of expected group change counts of each type.
Result ComputeDifferences(
const std::vector<ProcessedStudy>& processed_studies);
// Maps proto enum |type| to a ChangeType.
ChangeType ConvertExperimentTypeToChangeType(Study_Experiment_Type type);
// For the given |processed_study| with PERMANENT consistency, simulates group
// assignment and returns a corresponding ChangeType if the result differs
// from that study's group in the current process.
ChangeType PermanentStudyGroupChanged(const ProcessedStudy& processed_study,
const std::string& selected_group);
// For the given |processed_study| with SESSION consistency, determines if
// there are enough changes in the study config that restarting will result
// in a guaranteed different group assignment (or different params) and
// returns the corresponding ChangeType.
ChangeType SessionStudyGroupChanged(const ProcessedStudy& filtered_study,
const std::string& selected_group);
const base::FieldTrial::EntropyProvider& default_entropy_provider_;
const base::FieldTrial::EntropyProvider& low_entropy_provider_;
DISALLOW_COPY_AND_ASSIGN(VariationsSeedSimulator);
};
} // namespace variations
#endif // COMPONENTS_VARIATIONS_VARIATIONS_SEED_SIMULATOR_H_
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