Add a mechanism for collecting Rappor samples on a daily interval.

components/rappor/rappor_service.h

 // 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.
 
 #ifndef COMPONENTS_RAPPOR_RAPPOR_SERVICE_H_
 #define COMPONENTS_RAPPOR_RAPPOR_SERVICE_H_
 
 #include <map>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/timer/timer.h"
+#include "components/metrics/daily_interval.h"
 
 class PrefRegistrySimple;
 class PrefService;
 
 namespace net {
 class URLRequestContextGetter;
 }
 
 namespace rappor {
 
 class LogUploader;
 class RapporMetric;
 class RapporReports;
 struct RapporParameters;
 
 // The type of data stored in a metric.
 enum RapporType {
   // For sampling the eTLD+1 of a URL.
   ETLD_PLUS_ONE_RAPPOR_TYPE = 0,
   NUM_RAPPOR_TYPES
 };
 
 // This class provides an interface for recording samples for rappor metrics,
 // and periodically generates and uploads reports based on the collected data.
 class RapporService {
  public:
-  RapporService();
+  // Constructs a RapporService.
+  // Calling code is responsible for ensuring that the lifetime of
+  // |pref_service| is longer than the lifetime of RapporService.
+  explicit RapporService(PrefService* pref_service);
   virtual ~RapporService();
 
+  // Add an observer for collecting daily metrics. The RapporService will
+  // take ownership of all observers.

[Alexei Svitkine (slow), 2014/09/15 17:50:38]

If ownership is taken, pass the param by scoped_ptr (then in fact you don't need
this second sentence of the comment).

[Steven Holte, 2014/09/15 20:17:10]

Done.

+  void AddDailyObserver(metrics::DailyObserver* observer);
+
   // Starts the periodic generation of reports and upload attempts.
-  void Start(PrefService* pref_service,
-             net::URLRequestContextGetter* context,
+  void Start(net::URLRequestContextGetter* context,
              bool metrics_enabled);
 
   // Records a sample of the rappor metric specified by |metric_name|.
   // Creates and initializes the metric, if it doesn't yet exist.
   void RecordSample(const std::string& metric_name,
                     RapporType type,
                     const std::string& sample);
 
-  // Sets the cohort value.  For use by tests only.
+  // Sets the cohort value. For use by tests only.
   void SetCohortForTesting(uint32_t cohort) { cohort_ = cohort; }
 
-  // Sets the secret value.  For use by tests only.
+  // Sets the secret value. For use by tests only.
   void SetSecretForTesting(const std::string& secret) { secret_ = secret; }
 
   // Registers the names of all of the preferences used by RapporService in the
   // provided PrefRegistry. This should be called before calling Start().
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
  protected:
+  // Retrieves the cohort number this client was assigned to, generating it if
+  // doesn't already exist. The cohort should be persistent.
+  void LoadCohort();
+
+  // Retrieves the value for secret_ from preferences, generating it if doesn't
+  // already exist. The secret should be persistent, so that additional bits
+  // from the client do not get exposed over time.
+  void LoadSecret();
+
   // Logs all of the collected metrics to the reports proto message and clears
-  // the internal map.  Exposed for tests.  Returns true if any metrics were
+  // the internal map. Exposed for tests. Returns true if any metrics were
   // recorded.
   bool ExportMetrics(RapporReports* reports);
 
   // Records a sample of the rappor metric specified by |parameters|.
   // Creates and initializes the metric, if it doesn't yet exist.
   // Exposed for tests.
   void RecordSampleInternal(const std::string& metric_name,
                             const RapporParameters& parameters,
                             const std::string& sample);
 
  private:
   // Check if the service has been started successfully.
   bool IsInitialized() const;
 
-  // Retrieves the cohort number this client was assigned to, generating it if
-  // doesn't already exist.  The cohort should be persistent.
-  void LoadCohort(PrefService* pref_service);
-
-  // Retrieves the value for secret_ from preferences, generating it if doesn't
-  // already exist.  The secret should be persistent, so that additional bits
-  // from the client do not get exposed over time.
-  void LoadSecret(PrefService* pref_service);
-
   // Called whenever the logging interval elapses to generate a new log of
   // reports and pass it to the uploader.
   void OnLogInterval();
 
   // Finds a metric in the metrics_map_, creating it if it doesn't already
   // exist.
   RapporMetric* LookUpMetric(const std::string& metric_name,
                              const RapporParameters& parameters);
 
+  // A weak pointer to the PrefService used to read and write preferences.
+  PrefService* pref_service_;
+
   // Client-side secret used to generate fake bits.
   std::string secret_;
 
   // The cohort this client is assigned to. -1 is uninitialized.
   int32_t cohort_;
 
   // Timer which schedules calls to OnLogInterval().
   base::OneShotTimer<RapporService> log_rotation_timer_;
 
+  // A daily interval tracker for collecting metrics once a day.
+  metrics::DailyInterval daily_interval_;
+
   // A private LogUploader instance for sending reports to the server.
   scoped_ptr<LogUploader> uploader_;
 
   // We keep all registered metrics in a map, from name to metric.
   // The map owns the metrics it contains.
   std::map<std::string, RapporMetric*> metrics_map_;
 
   DISALLOW_COPY_AND_ASSIGN(RapporService);
 };
 
 }  // namespace rappor
 
 #endif  // COMPONENTS_RAPPOR_RAPPOR_SERVICE_H_