chrome/browser/metrics/metrics_state_manager.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 CHROME_BROWSER_METRICS_METRICS_STATE_MANAGER_H_
   6 #define CHROME_BROWSER_METRICS_METRICS_STATE_MANAGER_H_
   7
   8 #include <string>
   9
  10 #include "base/basictypes.h"
  11 #include "base/gtest_prod_util.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "base/metrics/field_trial.h"
  14
  15 class PrefService;
  16 class PrefRegistrySimple;
  17
  18 namespace metrics {
  19
  20 class ClonedInstallDetector;
  21
  22 // Responsible for managing MetricsService state prefs, specifically the UMA
  23 // client id and low entropy source. Code outside the metrics directory should
  24 // not be instantiating or using this class directly.
  25 class MetricsStateManager {
  26  public:
  27   virtual ~MetricsStateManager();
  28
  29   // Returns true if the user opted in to sending metric reports.
  30   // TODO(asvitkine): This function does not report the correct value on
  31   // Android, see http://crbug.com/362192.
  32   bool IsMetricsReportingEnabled();
  33
  34   // Returns the client ID for this client, or the empty string if the user is
  35   // not opted in to metrics reporting.
  36   const std::string& client_id() const { return client_id_; }
  37
  38   // Forces the client ID to be generated. This is useful in case it's needed
  39   // before recording.
  40   void ForceClientIdCreation();
  41
  42   // Checks if this install was cloned or imaged from another machine. If a
  43   // clone is detected, resets the client id and low entropy source. This
  44   // should not be called more than once.
  45   void CheckForClonedInstall();
  46
  47   // Returns the preferred entropy provider used to seed persistent activities
  48   // based on whether or not metrics reporting is permitted on this client.
  49   //
  50   // If metrics reporting is enabled, this method returns an entropy provider
  51   // that has a high source of entropy, partially based on the client ID.
  52   // Otherwise, it returns an entropy provider that is based on a low entropy
  53   // source.
  54   scoped_ptr<const base::FieldTrial::EntropyProvider> CreateEntropyProvider();
  55
  56   // Creates the MetricsStateManager, enforcing that only a single instance
  57   // of the class exists at a time. Returns NULL if an instance exists already.
  58   static scoped_ptr<MetricsStateManager> Create(PrefService* local_state);
  59
  60   // Registers local state prefs used by this class.
  61   static void RegisterPrefs(PrefRegistrySimple* registry);
  62
  63  private:
  64   FRIEND_TEST_ALL_PREFIXES(MetricsStateManagerTest, EntropySourceUsed_Low);
  65   FRIEND_TEST_ALL_PREFIXES(MetricsStateManagerTest, EntropySourceUsed_High);
  66   FRIEND_TEST_ALL_PREFIXES(MetricsStateManagerTest, LowEntropySource0NotReset);
  67   FRIEND_TEST_ALL_PREFIXES(MetricsStateManagerTest,
  68                            PermutedEntropyCacheClearedWhenLowEntropyReset);
  69   FRIEND_TEST_ALL_PREFIXES(MetricsStateManagerTest, ResetMetricsIDs);
  70
  71   // Designates which entropy source was returned from this class.
  72   // This is used for testing to validate that we return the correct source
  73   // depending on the state of the service.
  74   enum EntropySourceType {
  75     ENTROPY_SOURCE_NONE,
  76     ENTROPY_SOURCE_LOW,
  77     ENTROPY_SOURCE_HIGH,
  78   };
  79
  80   // Creates the MetricsStateManager with the given |local_state|. Clients
  81   // should instead use Create(), which enforces a single instance of this class
  82   // is alive at any given time.
  83   explicit MetricsStateManager(PrefService* local_state);
  84
  85   // Returns the low entropy source for this client. This is a random value
  86   // that is non-identifying amongst browser clients. This method will
  87   // generate the entropy source value if it has not been called before.
  88   int GetLowEntropySource();
  89
  90   // Returns the first entropy source that was returned by this service since
  91   // start up, or NONE if neither was returned yet. This is exposed for testing
  92   // only.
  93   EntropySourceType entropy_source_returned() const {
  94     return entropy_source_returned_;
  95   }
  96
  97   // Reset the client id and low entropy source if the kMetricsResetMetricIDs
  98   // pref is true.
  99   void ResetMetricsIDsIfNecessary();
 100
 101   // Whether an instance of this class exists. Used to enforce that there aren't
 102   // multiple instances of this class at a given time.
 103   static bool instance_exists_;
 104
 105   // Weak pointer to the local state prefs store.
 106   PrefService* local_state_;
 107
 108   // The identifier that's sent to the server with the log reports.
 109   std::string client_id_;
 110
 111   // The non-identifying low entropy source value.
 112   int low_entropy_source_;
 113
 114   // The last entropy source returned by this service, used for testing.
 115   EntropySourceType entropy_source_returned_;
 116
 117   scoped_ptr<ClonedInstallDetector> cloned_install_detector_;
 118
 119   DISALLOW_COPY_AND_ASSIGN(MetricsStateManager);
 120 };
 121
 122 }  // namespace metrics
 123
 124 #endif  // CHROME_BROWSER_METRICS_METRICS_STATE_MANAGER_H_