| // 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 "chrome/common/variations/uniformity_field_trials.h" |
| |
| #include <string> |
| |
| #include "base/metrics/field_trial.h" |
| #include "base/strings/stringprintf.h" |
| #include "base/time/time.h" |
| #include "chrome/common/variations/variation_ids.h" |
| #include "components/variations/variations_associated_data.h" |
| |
| namespace chrome_variations { |
| |
| namespace { |
| |
| // Set up a uniformity field trial. |one_time_randomized| indicates if the |
| // field trial is one-time randomized or session-randomized. |trial_name_string| |
| // must contain a "%d" since the percentage of the group will be inserted in |
| // the trial name. |num_trial_groups| must be a divisor of 100 (e.g. 5, 20) |
| void SetupSingleUniformityFieldTrial( |
| base::FieldTrial::RandomizationType randomization_type, |
| const std::string& trial_name_string, |
| const VariationID trial_base_id, |
| int num_trial_groups) { |
| // Probability per group remains constant for all uniformity trials, what |
| // changes is the probability divisor. |
| static const base::FieldTrial::Probability kProbabilityPerGroup = 1; |
| const std::string kDefaultGroupName = "default"; |
| const base::FieldTrial::Probability divisor = num_trial_groups; |
| |
| DCHECK_EQ(100 % num_trial_groups, 0); |
| const int group_percent = 100 / num_trial_groups; |
| const std::string trial_name = base::StringPrintf(trial_name_string.c_str(), |
| group_percent); |
| |
| DVLOG(1) << "Trial name = " << trial_name; |
| |
| scoped_refptr<base::FieldTrial> trial( |
| base::FieldTrialList::FactoryGetFieldTrial( |
| trial_name, divisor, kDefaultGroupName, 2015, 1, 1, |
| randomization_type, NULL)); |
| AssociateGoogleVariationID(GOOGLE_UPDATE_SERVICE, trial_name, |
| kDefaultGroupName, trial_base_id); |
| |
| // Loop starts with group 1 because the field trial automatically creates a |
| // default group, which would be group 0. |
| for (int group_number = 1; group_number < num_trial_groups; ++group_number) { |
| const std::string group_name = |
| base::StringPrintf("group_%02d", group_number); |
| DVLOG(1) << " Group name = " << group_name; |
| trial->AppendGroup(group_name, kProbabilityPerGroup); |
| AssociateGoogleVariationID( |
| GOOGLE_UPDATE_SERVICE, trial_name, group_name, |
| static_cast<VariationID>(trial_base_id + group_number)); |
| } |
| |
| // Now that all groups have been appended, call group() on the trial to |
| // ensure that our trial is registered. This resolves an off-by-one issue |
| // where the default group never gets chosen if we don't "use" the trial. |
| const int chosen_group = trial->group(); |
| DVLOG(1) << "Chosen Group: " << chosen_group; |
| } |
| |
| // Setup a 50% uniformity trial for new installs only. This is accomplished by |
| // disabling the trial on clients that were installed before a specified date. |
| void SetupNewInstallUniformityTrial(const base::Time install_date) { |
| const base::Time::Exploded kStartDate = { |
| 2012, 11, 0, 6, // Nov 6, 2012 |
| 0, 0, 0, 0 // 00:00:00.000 |
| }; |
| scoped_refptr<base::FieldTrial> trial( |
| base::FieldTrialList::FactoryGetFieldTrial( |
| "UMA-New-Install-Uniformity-Trial", 100, "Disabled", |
| 2015, 1, 1, base::FieldTrial::ONE_TIME_RANDOMIZED, NULL)); |
| trial->AppendGroup("Control", 50); |
| trial->AppendGroup("Experiment", 50); |
| const base::Time start_date = base::Time::FromLocalExploded(kStartDate); |
| if (install_date < start_date) |
| trial->Disable(); |
| else |
| trial->group(); |
| } |
| |
| } // namespace |
| |
| void SetupUniformityFieldTrials(const base::Time install_date) { |
| // The 100 percent field trial in which everyone is a member is a special |
| // case. It is useful to create as it permits viewing all UMA data in UIs |
| // and tools that require a field trial. |
| base::FieldTrial* trial = |
| base::FieldTrialList::CreateFieldTrial("UMA-Uniformity-Trial-100-Percent", |
| "group_01"); |
| // Call |group()| on the trial to ensure its reported in metrics. |
| trial->group(); |
| |
| // One field trial will be created for each entry in this array. The i'th |
| // field trial will have |trial_sizes[i]| groups in it, including the default |
| // group. Each group will have a probability of 1/|trial_sizes[i]|. |
| const int num_trial_groups[] = { 100, 20, 10, 5, 2 }; |
| |
| // Declare our variation ID bases along side this array so we can loop over it |
| // and assign the IDs appropriately. So for example, the 1 percent experiments |
| // should have a size of 100 (100/100 = 1). |
| const VariationID trial_base_ids[] = { |
| UNIFORMITY_1_PERCENT_BASE, |
| UNIFORMITY_5_PERCENT_BASE, |
| UNIFORMITY_10_PERCENT_BASE, |
| UNIFORMITY_20_PERCENT_BASE, |
| UNIFORMITY_50_PERCENT_BASE |
| }; |
| |
| const std::string kOneTimeRandomizedTrialName = |
| "UMA-Uniformity-Trial-%d-Percent"; |
| for (size_t i = 0; i < arraysize(num_trial_groups); ++i) { |
| SetupSingleUniformityFieldTrial(base::FieldTrial::ONE_TIME_RANDOMIZED, |
| kOneTimeRandomizedTrialName, |
| trial_base_ids[i], num_trial_groups[i]); |
| } |
| |
| // Setup a 5% session-randomized uniformity trial. |
| const std::string kSessionRandomizedTrialName = |
| "UMA-Session-Randomized-Uniformity-Trial-%d-Percent"; |
| SetupSingleUniformityFieldTrial( |
| base::FieldTrial::SESSION_RANDOMIZED, kSessionRandomizedTrialName, |
| UNIFORMITY_SESSION_RANDOMIZED_5_PERCENT_BASE, 20); |
| |
| SetupNewInstallUniformityTrial(install_date); |
| } |
| |
| } // namespace chrome_variations |