Amortize data usage using TrafficStats on Android.

components/data_usage/core/data_use_aggregator.h

 // Copyright 2015 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_DATA_USAGE_CORE_DATA_USE_AGGREGATOR_H_
 #define COMPONENTS_DATA_USAGE_CORE_DATA_USE_AGGREGATOR_H_
 
 #include <stdint.h>
 
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/threading/thread_checker.h"
 #include "net/base/network_change_notifier.h"
 
 namespace net {
 class URLRequest;
 }
 
 namespace data_usage {
 
+class DataUseAmortizer;
 class DataUseAnnotator;
 struct DataUse;
 
 // Class that collects and aggregates network usage, reporting the usage to
 // observers. Should only be used on the IO thread.
 class DataUseAggregator
     : public net::NetworkChangeNotifier::ConnectionTypeObserver {
  public:
   class Observer {
    public:
     virtual ~Observer() {}
     // Each of the elements of |data_use_sequence| are guaranteed to be
     // non-NULL.
     virtual void OnDataUse(
         const std::vector<const DataUse*>& data_use_sequence) = 0;
   };
 
-  // Constructs a new DataUseAggregator with the given |annotator|. A NULL
-  // annotator will be treated as a no-op annotator.
-  explicit DataUseAggregator(scoped_ptr<DataUseAnnotator> annotator);
+  // Constructs a new DataUseAggregator with the given |annotator| and
+  // |amortizer|. A NULL |annotator| will be treated as a no-op annotator, and a
+  // NULL |amortizer| will be treated as a no-op amortizer.
+  DataUseAggregator(scoped_ptr<DataUseAnnotator> annotator,
+                    scoped_ptr<DataUseAmortizer> amortizer);
+
   ~DataUseAggregator() override;
 
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
   // Virtual for testing.
   virtual void ReportDataUse(net::URLRequest* request,
                              int64_t tx_bytes,
                              int64_t rx_bytes);
 
   // Account for off-the-record data use. This usage is only kept track of here
   // so that it can be taken out of any amortized data usage calculations, and a
   // per-request breakdown of off-the-record data usage will never leave the
   // DataUseAggregator.
   // Virtual for testing.
   virtual void ReportOffTheRecordDataUse(int64_t tx_bytes, int64_t rx_bytes);
 
   base::WeakPtr<DataUseAggregator> GetWeakPtr();
 
  protected:
   // net::NetworkChangeNotifier::ConnectionTypeObserver implementation.
   // Protected for testing.
   void OnConnectionTypeChanged(
       net::NetworkChangeNotifier::ConnectionType type) override;
 
   // Protected for testing.
   void SetMccMncForTests(const std::string& mcc_mnc);
 
  private:
-  // Appends |data_use| to the buffer of unreported data use and prepares to
-  // notify observers.
-  void AppendDataUse(scoped_ptr<DataUse> data_use);
+  // Passes |data_use| to |amortizer_| if it exists, or calls
+  // OnAmortizationComplete directly if |amortizer_| doesn't exist.
+  void PassDataUseToAmortizer(scoped_ptr<DataUse> data_use);
 
-  // Flush any buffered data use and notify observers.
-  void FlushBufferedDataUse();
+  // Notifies observers with the data use from |amortized_data_use|.
+  void OnAmortizationComplete(scoped_ptr<DataUse> amortized_data_use);
 
   base::ThreadChecker thread_checker_;
   scoped_ptr<DataUseAnnotator> annotator_;
+  scoped_ptr<DataUseAmortizer> amortizer_;
   base::ObserverList<Observer> observer_list_;
 
-  // Buffer of unreported data use.
-  ScopedVector<DataUse> buffered_data_use_;
-
   // Current connection type as notified by NetworkChangeNotifier.
   net::NetworkChangeNotifier::ConnectionType connection_type_;
 
   // MCC+MNC (mobile country code + mobile network code) of the current SIM
   // provider.  Set to empty string if SIM is not present. |mcc_mnc_| is set
   // even if the current active network is not a cellular network.
   std::string mcc_mnc_;
 
-  // The total amount of off-the-record data usage that has happened since the
-  // last time the buffer was flushed.
-  int64_t off_the_record_tx_bytes_since_last_flush_;
-  int64_t off_the_record_rx_bytes_since_last_flush_;
-
-  // Indicates if a FlushBufferedDataUse() callback has been posted to run later
-  // on the IO thread.
-  bool is_flush_pending_;
-
   base::WeakPtrFactory<DataUseAggregator> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DataUseAggregator);
 };
 
 }  // namespace data_usage
 
 #endif  // COMPONENTS_DATA_USAGE_CORE_DATA_USE_AGGREGATOR_H_