chrome/browser/metrics/variations/variations_service.h

   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.
   4
   5 #ifndef CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SERVICE_H_
   6 #define CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SERVICE_H_
   7
   8 #include <string>
   9
  10 #include "base/compiler_specific.h"
  11 #include "base/gtest_prod_util.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "base/metrics/field_trial.h"
  14 #include "base/time/time.h"
  15 #include "chrome/browser/metrics/variations/variations_request_scheduler.h"
  16 #include "chrome/browser/web_resource/resource_request_allowed_notifier.h"
  17 #include "chrome/common/chrome_version_info.h"
  18 #include "net/url_request/url_fetcher_delegate.h"
  19 #include "url/gurl.h"
  20
  21 #if defined(OS_WIN)
  22 #include "chrome/browser/metrics/variations/variations_registry_syncer_win.h"
  23 #endif
  24
  25 class PrefService;
  26 class PrefRegistrySimple;
  27
  28 namespace chrome_variations {
  29
  30 class VariationsSeed;
  31
  32 // Used to setup field trials based on stored variations seed data, and fetch
  33 // new seed data from the variations server.
  34 class VariationsService
  35     : public net::URLFetcherDelegate,
  36       public ResourceRequestAllowedNotifier::Observer {
  37  public:
  38   virtual ~VariationsService();
  39
  40   // Creates field trials based on Variations Seed loaded from local prefs. If
  41   // there is a problem loading the seed data, all trials specified by the seed
  42   // may not be created.
  43   bool CreateTrialsFromSeed();
  44
  45   // Calls FetchVariationsSeed once and repeats this periodically. See
  46   // implementation for details on the period. Must be called after
  47   // |CreateTrialsFromSeed|.
  48   void StartRepeatedVariationsSeedFetch();
  49
  50   // Returns the variations server URL, which can vary if a command-line flag is
  51   // set and/or the variations restrict pref is set in |local_prefs|. Declared
  52   // static for test purposes.
  53   static GURL GetVariationsServerURL(PrefService* local_prefs);
  54
  55 #if defined(OS_WIN)
  56   // Starts syncing Google Update Variation IDs with the registry.
  57   void StartGoogleUpdateRegistrySync();
  58 #endif
  59
  60   // Exposed for testing.
  61   void SetCreateTrialsFromSeedCalledForTesting(bool called);
  62
  63   // Exposed for testing.
  64   static std::string GetDefaultVariationsServerURLForTesting();
  65
  66   // Register Variations related prefs in Local State.
  67   static void RegisterPrefs(PrefRegistrySimple* registry);
  68
  69   // Factory method for creating a VariationsService.
  70   static VariationsService* Create(PrefService* local_state);
  71
  72  protected:
  73   // Starts the fetching process once, where |OnURLFetchComplete| is called with
  74   // the response.
  75   virtual void DoActualFetch();
  76
  77   // This constructor exists for injecting a mock notifier. It is meant for
  78   // testing only. This instance will take ownership of |notifier|.
  79   VariationsService(ResourceRequestAllowedNotifier* notifier,
  80                     PrefService* local_state);
  81
  82  private:
  83   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, DoNotFetchIfOffline);
  84   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, DoNotFetchIfOnlineToOnline);
  85   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, FetchOnReconnect);
  86   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, LoadSeed);
  87   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, StoreSeed);
  88   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, SeedStoredWhenOKStatus);
  89   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, SeedNotStoredWhenNonOKStatus);
  90   FRIEND_TEST_ALL_PREFIXES(VariationsServiceTest, SeedDateUpdatedOn304Status);
  91
  92   // Creates the VariationsService with the given |local_state| prefs service.
  93   // Use the |Create| factory method to create a VariationsService.
  94   explicit VariationsService(PrefService* local_state);
  95
  96   // Checks if prerequisites for fetching the Variations seed are met, and if
  97   // so, performs the actual fetch using |DoActualFetch|.
  98   void FetchVariationsSeed();
  99
 100   // net::URLFetcherDelegate implementation:
 101   virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE;
 102
 103   // ResourceRequestAllowedNotifier::Observer implementation:
 104   virtual void OnResourceRequestsAllowed() OVERRIDE;
 105
 106   // Store the given seed data to the given local prefs. Note that |seed_data|
 107   // is assumed to be the raw serialized protobuf data stored in a string. It
 108   // will be Base64Encoded for storage. If the string is invalid or the encoding
 109   // fails, the existing prefs are left as is and the function returns false.
 110   bool StoreSeedData(const std::string& seed_data, const base::Time& seed_date);
 111
 112   // Loads the variations seed data from local state into |seed|. If there is a
 113   // problem with loading, the pref value is cleared and false is returned. If
 114   // successful, |seed| will contain the loaded data and true is returned.
 115   bool LoadVariationsSeedFromPref(VariationsSeed* seed);
 116
 117   // Record the time of the most recent successful fetch.
 118   void RecordLastFetchTime();
 119
 120   // The pref service used to store persist the variations seed.
 121   PrefService* local_state_;
 122
 123   // Contains the scheduler instance that handles timing for requests to the
 124   // server. Initially NULL and instantiated when the initial fetch is
 125   // requested.
 126   scoped_ptr<VariationsRequestScheduler> request_scheduler_;
 127
 128   // Contains the current seed request. Will only have a value while a request
 129   // is pending, and will be reset by |OnURLFetchComplete|.
 130   scoped_ptr<net::URLFetcher> pending_seed_request_;
 131
 132   // The URL to use for querying the Variations server.
 133   GURL variations_server_url_;
 134
 135   // Cached serial number from the most recently fetched Variations seed.
 136   std::string variations_serial_number_;
 137
 138   // Tracks whether |CreateTrialsFromSeed| has been called, to ensure that
 139   // it gets called prior to |StartRepeatedVariationsSeedFetch|.
 140   bool create_trials_from_seed_called_;
 141
 142   // Tracks whether the initial request to the variations server had completed.
 143   bool initial_request_completed_;
 144
 145   // Helper class used to tell this service if it's allowed to make network
 146   // resource requests.
 147   scoped_ptr<ResourceRequestAllowedNotifier> resource_request_allowed_notifier_;
 148
 149   // The start time of the last seed request. This is used to measure the
 150   // latency of seed requests. Initially zero.
 151   base::TimeTicks last_request_started_time_;
 152
 153 #if defined(OS_WIN)
 154   // Helper that handles synchronizing Variations with the Registry.
 155   VariationsRegistrySyncer registry_syncer_;
 156 #endif
 157
 158   DISALLOW_COPY_AND_ASSIGN(VariationsService);
 159 };
 160
 161 }  // namespace chrome_variations
 162
 163 #endif  // CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SERVICE_H_