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 COMPONENTS_METRICS_METRICS_STATE_MANAGER_H_ 6 #define COMPONENTS_METRICS_METRICS_STATE_MANAGER_H_ 7 8 #include <string> 9 10 #include "base/basictypes.h" 11 #include "base/callback.h" 12 #include "base/gtest_prod_util.h" 13 #include "base/memory/scoped_ptr.h" 14 #include "base/metrics/field_trial.h" 15 16 class PrefService; 17 class PrefRegistrySimple; 18 19 namespace metrics { 20 21 class ClonedInstallDetector; 22 23 // Responsible for managing MetricsService state prefs, specifically the UMA 24 // client id and low entropy source. Code outside the metrics directory should 25 // not be instantiating or using this class directly. 26 class MetricsStateManager { 27 public: 28 virtual ~MetricsStateManager(); 29 30 // Returns true if the user opted in to sending metric reports. 31 bool IsMetricsReportingEnabled(); 32 33 // Returns the client ID for this client, or the empty string if the user is 34 // not opted in to metrics reporting. client_id()35 const std::string& client_id() const { return client_id_; } 36 37 // Forces the client ID to be generated. This is useful in case it's needed 38 // before recording. 39 void ForceClientIdCreation(); 40 41 // Checks if this install was cloned or imaged from another machine. If a 42 // clone is detected, resets the client id and low entropy source. This 43 // should not be called more than once. 44 void CheckForClonedInstall( 45 scoped_refptr<base::SingleThreadTaskRunner> task_runner); 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( 59 PrefService* local_state, 60 const base::Callback<bool(void)>& is_reporting_enabled_callback); 61 62 // Registers local state prefs used by this class. 63 static void RegisterPrefs(PrefRegistrySimple* registry); 64 65 private: 66 FRIEND_TEST_ALL_PREFIXES(MetricsStateManagerTest, EntropySourceUsed_Low); 67 FRIEND_TEST_ALL_PREFIXES(MetricsStateManagerTest, EntropySourceUsed_High); 68 FRIEND_TEST_ALL_PREFIXES(MetricsStateManagerTest, LowEntropySource0NotReset); 69 FRIEND_TEST_ALL_PREFIXES(MetricsStateManagerTest, 70 PermutedEntropyCacheClearedWhenLowEntropyReset); 71 FRIEND_TEST_ALL_PREFIXES(MetricsStateManagerTest, ResetMetricsIDs); 72 73 // Designates which entropy source was returned from this class. 74 // This is used for testing to validate that we return the correct source 75 // depending on the state of the service. 76 enum EntropySourceType { 77 ENTROPY_SOURCE_NONE, 78 ENTROPY_SOURCE_LOW, 79 ENTROPY_SOURCE_HIGH, 80 }; 81 82 // Creates the MetricsStateManager with the given |local_state|. Calls 83 // |is_reporting_enabled_callback| to query whether metrics reporting is 84 // enabled. Clients should instead use Create(), which enforces a single 85 // instance of this class is alive at any given time. 86 MetricsStateManager( 87 PrefService* local_state, 88 const base::Callback<bool(void)>& is_reporting_enabled_callback); 89 90 // Returns the low entropy source for this client. This is a random value 91 // that is non-identifying amongst browser clients. This method will 92 // generate the entropy source value if it has not been called before. 93 int GetLowEntropySource(); 94 95 // Returns the first entropy source that was returned by this service since 96 // start up, or NONE if neither was returned yet. This is exposed for testing 97 // only. entropy_source_returned()98 EntropySourceType entropy_source_returned() const { 99 return entropy_source_returned_; 100 } 101 102 // Reset the client id and low entropy source if the kMetricsResetMetricIDs 103 // pref is true. 104 void ResetMetricsIDsIfNecessary(); 105 106 // Whether an instance of this class exists. Used to enforce that there aren't 107 // multiple instances of this class at a given time. 108 static bool instance_exists_; 109 110 // Weak pointer to the local state prefs store. 111 PrefService* const local_state_; 112 113 const base::Callback<bool(void)> is_reporting_enabled_callback_; 114 115 // The identifier that's sent to the server with the log reports. 116 std::string client_id_; 117 118 // The non-identifying low entropy source value. 119 int low_entropy_source_; 120 121 // The last entropy source returned by this service, used for testing. 122 EntropySourceType entropy_source_returned_; 123 124 scoped_ptr<ClonedInstallDetector> cloned_install_detector_; 125 126 DISALLOW_COPY_AND_ASSIGN(MetricsStateManager); 127 }; 128 129 } // namespace metrics 130 131 #endif // COMPONENTS_METRICS_METRICS_STATE_MANAGER_H_ 132