RAPPOR implementation

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 <string>
+
+#include "base/basictypes.h"
+#include "base/lazy_instance.h"
+#include "base/memory/weak_ptr.h"
+#include "base/prefs/pref_service.h"
+#include "base/time/time.h"
+#include "base/timer/timer.h"
+#include "components/rappor/log_uploader.h"
+#include "components/rappor/proto/rappor_metric.pb.h"
+#include "components/rappor/rappor_metric.h"
+#include "components/rappor/rappor_registry.h"
+
+class PrefRegistrySimple;
+
+namespace rappor {
+
+// 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();
+  virtual ~RapporService();
+
+  // Starts the periodic generation of reports and upload attempts.
+  void Start(PrefService* pref_service, net::URLRequestContextGetter* context);
+
+  // 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);
+
+  // Records a sample of the rappor metric specified by |parameters|.
+  // Creates and initializes the metric, if it doesn't yet exist.
+  void RecordSample(RapporRegistryIndex index, const std::string& sample);
+
+ protected:
+  // Logs all of the collected metrics to the reports proto message.  Exposed
+  // for tests.  Returns true if any metrics were recorded.
+  bool LogMetrics(RapporReports* reports);
+
+  // Records a sample of the rappor metric specified by |parameters|.
+  // Creates and initializes the metric, if it doesn't yet exist.
+  void RecordSampleInternal(const RapporParameters& parameters,
+                            const std::string& sample);
+
+  // The cohort this client is assigned to. -1 is uninitialized.
+  int32_t cohort_;
+ private:
+  // 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);
+
+  // Logs a single metric's output to the report message.
+  void LogMetric(const RapporMetric& metric, RapporReports::Report* report);
+
+  // 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 RapporParameters& parameters);
+
+  // Client-side secret used to generate fake bits.
+  std::string secret_;
+
+  // Timer which schedules calls to OnLogInterval()
+  base::OneShotTimer<RapporService> log_rotation_timer_;
+
+  // A private LogUploader instance for sending reports to the server.
+  scoped_ptr<LogUploader> uploader_;
+
+  // We keep all registered histograms in a map, from name to histogram.
+  std::map<std::string, RapporMetric*> metrics_map_;
+
+  // Lock protects access to above map.
+  base::Lock lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(RapporService);
+};
+
+}  // namespace rappor
+
+#endif  // COMPONENTS_RAPPOR_RAPPOR_SERVICE_H_