1 // Copyright (c) 2012 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.
5 #ifndef CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SERVICE_H_
6 #define CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SERVICE_H_
10 #include "base/compiler_specific.h"
11 #include "base/gtest_prod_util.h"
12 #include "base/memory/scoped_ptr.h"
13 #include "base/memory/weak_ptr.h"
14 #include "base/metrics/field_trial.h"
15 #include "base/observer_list.h"
16 #include "base/time/time.h"
17 #include "chrome/browser/metrics/variations/variations_request_scheduler.h"
18 #include "chrome/browser/metrics/variations/variations_seed_store.h"
19 #include "chrome/browser/web_resource/resource_request_allowed_notifier.h"
20 #include "chrome/common/chrome_version_info.h"
21 #include "components/variations/variations_seed_simulator.h"
22 #include "net/url_request/url_fetcher_delegate.h"
26 #include "chrome/browser/metrics/variations/variations_registry_syncer_win.h"
30 class PrefRegistrySimple;
37 class MetricsStateManager;
40 namespace user_prefs {
41 class PrefRegistrySyncable;
44 namespace variations {
48 namespace chrome_variations {
50 // Used to setup field trials based on stored variations seed data, and fetch
51 // new seed data from the variations server.
52 class VariationsService
53 : public net::URLFetcherDelegate,
54 public ResourceRequestAllowedNotifier::Observer {
58 // How critical a detected experiment change is. Whether it should be
59 // handled on a "best-effort" basis or, for a more critical change, if it
60 // should be given higher priority.
66 // Called when the VariationsService detects that there will be significant
67 // experiment changes on a restart. This notification can then be used to
68 // update UI (i.e. badging an icon).
69 virtual void OnExperimentChangesDetected(Severity severity) = 0;
72 virtual ~Observer() {}
75 ~VariationsService() override;
77 // Creates field trials based on Variations Seed loaded from local prefs. If
78 // there is a problem loading the seed data, all trials specified by the seed
79 // may not be created.
80 bool CreateTrialsFromSeed();
82 // Calls FetchVariationsSeed once and repeats this periodically. See
83 // implementation for details on the period. Must be called after
84 // |CreateTrialsFromSeed|.
85 void StartRepeatedVariationsSeedFetch();
87 // Adds an observer to listen for detected experiment changes.
88 void AddObserver(Observer* observer);
90 // Removes a previously-added observer.
91 void RemoveObserver(Observer* observer);
93 // Called when the application enters foreground. This may trigger a
94 // FetchVariationsSeed call.
95 // TODO(rkaplow): Handle this and the similar event in metrics_service by
96 // observing an 'OnAppEnterForeground' event instead of requiring the frontend
97 // code to notify each service individually.
98 void OnAppEnterForeground();
101 // Starts syncing Google Update Variation IDs with the registry.
102 void StartGoogleUpdateRegistrySync();
105 // Exposed for testing.
106 void SetCreateTrialsFromSeedCalledForTesting(bool called);
108 // Returns the variations server URL, which can vary if a command-line flag is
109 // set and/or the variations restrict pref is set in |local_prefs|. Declared
110 // static for test purposes.
111 static GURL GetVariationsServerURL(PrefService* local_prefs);
113 // Exposed for testing.
114 static std::string GetDefaultVariationsServerURLForTesting();
116 // Register Variations related prefs in Local State.
117 static void RegisterPrefs(PrefRegistrySimple* registry);
119 // Register Variations related prefs in the Profile prefs.
120 static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
122 // Factory method for creating a VariationsService. Does not take ownership of
123 // |state_manager|. Caller should ensure that |state_manager| is valid for the
124 // lifetime of this class.
125 static scoped_ptr<VariationsService> Create(
126 PrefService* local_state,
127 metrics::MetricsStateManager* state_manager);
129 // Set the PrefService responsible for getting policy-related preferences,
130 // such as the restrict parameter.
131 void set_policy_pref_service(PrefService* service) {
133 policy_pref_service_ = service;
137 // Starts the fetching process once, where |OnURLFetchComplete| is called with
139 virtual void DoActualFetch();
141 // Stores the seed to prefs. Set as virtual and protected so that it can be
142 // overridden by tests.
143 virtual void StoreSeed(const std::string& seed_data,
144 const std::string& seed_signature,
145 const base::Time& date_fetched);
147 // Creates the VariationsService with the given |local_state| prefs service
148 // and |state_manager|. This instance will take ownership of |notifier|.
149 // Does not take ownership of |state_manager|. Caller should ensure that
150 // |state_manager| is valid for the lifetime of this class. Use the |Create|
151 // factory method to create a VariationsService.
152 VariationsService(ResourceRequestAllowedNotifier* notifier,
153 PrefService* local_state,
154 metrics::MetricsStateManager* state_manager);
157 FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, Observer);
158 FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, SeedStoredWhenOKStatus);
159 FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, SeedNotStoredWhenNonOKStatus);
160 FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, SeedDateUpdatedOn304Status);
162 // Checks if prerequisites for fetching the Variations seed are met, and if
163 // so, performs the actual fetch using |DoActualFetch|.
164 void FetchVariationsSeed();
166 // Notify any observers of this service based on the simulation |result|.
167 void NotifyObservers(
168 const variations::VariationsSeedSimulator::Result& result);
170 // net::URLFetcherDelegate implementation:
171 void OnURLFetchComplete(const net::URLFetcher* source) override;
173 // ResourceRequestAllowedNotifier::Observer implementation:
174 void OnResourceRequestsAllowed() override;
176 // Performs a variations seed simulation with the given |seed| and |version|
177 // and logs the simulation results as histograms.
178 void PerformSimulationWithVersion(scoped_ptr<variations::VariationsSeed> seed,
179 const base::Version& version);
181 // Record the time of the most recent successful fetch.
182 void RecordLastFetchTime();
184 // The pref service used to store persist the variations seed.
185 PrefService* local_state_;
187 // Used for instantiating entropy providers for variations seed simulation.
189 metrics::MetricsStateManager* state_manager_;
191 // Used to obtain policy-related preferences. Depending on the platform, will
192 // either be Local State or Profile prefs.
193 PrefService* policy_pref_service_;
195 VariationsSeedStore seed_store_;
197 // Contains the scheduler instance that handles timing for requests to the
198 // server. Initially NULL and instantiated when the initial fetch is
200 scoped_ptr<VariationsRequestScheduler> request_scheduler_;
202 // Contains the current seed request. Will only have a value while a request
203 // is pending, and will be reset by |OnURLFetchComplete|.
204 scoped_ptr<net::URLFetcher> pending_seed_request_;
206 // The URL to use for querying the Variations server.
207 GURL variations_server_url_;
209 // Tracks whether |CreateTrialsFromSeed| has been called, to ensure that
210 // it gets called prior to |StartRepeatedVariationsSeedFetch|.
211 bool create_trials_from_seed_called_;
213 // Tracks whether the initial request to the variations server had completed.
214 bool initial_request_completed_;
216 // Helper class used to tell this service if it's allowed to make network
217 // resource requests.
218 scoped_ptr<ResourceRequestAllowedNotifier> resource_request_allowed_notifier_;
220 // The start time of the last seed request. This is used to measure the
221 // latency of seed requests. Initially zero.
222 base::TimeTicks last_request_started_time_;
224 // List of observers of the VariationsService.
225 ObserverList<Observer> observer_list_;
228 // Helper that handles synchronizing Variations with the Registry.
229 VariationsRegistrySyncer registry_syncer_;
232 base::WeakPtrFactory<VariationsService> weak_ptr_factory_;
234 DISALLOW_COPY_AND_ASSIGN(VariationsService);
237 } // namespace chrome_variations
239 #endif // CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SERVICE_H_