Update data reduction proxy statistics prefs less often on desktop

components/data_reduction_proxy/browser/data_reduction_proxy_delayed_pref_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_DATA_REDUCTION_PROXY_BROWSER_DATA_REDUCTION_PROXY_DELAYED_PREF_SERVICE_H_
+#define COMPONENTS_DATA_REDUCTION_PROXY_BROWSER_DATA_REDUCTION_PROXY_DELAYED_PREF_SERVICE_H_
+
+#include <map>
+
+#include "base/memory/weak_ptr.h"

[bengr, 2014/08/14 17:39:42]

#include "base/time/time.h" here and remove the forward declaration of TimeDelta
below. 

[megjablon, 2014/08/26 19:28:41]

Done.

+
+class PrefService;
+
+namespace base {
+  class ListValue;

[bengr, 2014/08/14 17:39:42]

remove indent.

[megjablon, 2014/08/26 19:28:41]

Done.

+  class SequencedTaskRunner;
+  class TimeDelta;
+}
+
+namespace data_reduction_proxy {
+
+// Data reduction proxy delayed pref service reduces the number calls to pref
+// service by storing prefs in memory and writing to the given PrefService after
+// |delay| amount of time. If |delay| is zero, the delayed pref service writes
+// directly to the PrefService and does not store the prefs in memory. All
+// variables are stored and should be read on the UI thread.

[bengr, 2014/08/14 17:39:42]

should be stored and read...

[megjablon, 2014/08/26 19:28:41]

Done.

+class DataReductionProxyDelayedPrefService
+    : public base::SupportsWeakPtr<DataReductionProxyDelayedPrefService>{
+public:
+  typedef std::map<const char*, int64> DataReductionProxyPrefMap;
+  typedef std::map<const char*, base::ListValue*>
+  DataReductionProxyListPrefMap;

[bengr, 2014/08/14 17:39:42]

indent 4

[megjablon, 2014/08/26 19:28:41]

Done.

+
+  // Constructs a data reduction proxy delayed pref service object using
+  // |pref_service|. Writes prefs to |pref_service| after |delay| amount of time
+  // and stores in |pref_map_| and |list_pref_map| between writes. If |delay| is
+  // zero, writes directly to the PrefService and does not store in the maps.
+  DataReductionProxyDelayedPrefService(
+      PrefService* pref_service,
+      scoped_refptr<base::SequencedTaskRunner> task_runner,
+      base::TimeDelta delay);
+  virtual ~DataReductionProxyDelayedPrefService();
+
+  // Gets the int64 pref at |pref_path| from the |DataReductionProxyPrefMap|.
+  // If |pref_path| is not in the map, gets the pref from |pref_service_| and
+  // stores it in the map.
+  int64 GetInt64(const char* pref_path);
+
+  // Updates the pref value in the |DataReductionProxyPrefMap| map. If
+  // |pref_path| is not in the map, gets the pref from |pref_service_| and
+  // stores it in the map. The pref is later written to |pref service_|.
+  void SetInt64(const char* pref_path, int64 pref_value);
+
+  // Gets the pref list at |pref_path| from the |DataReductionProxyPrefMap|.
+  // If |pref_path| is not in the map, gets the pref from |pref_service_| and
+  // stores it in the map.
+  base::ListValue* GetList(const char* pref_path);
+
+private:
+  // Writes the prefs stored in |DataReductionProxyPrefMap| and
+  // |DataReductionProxyListPrefMap| to |pref_service|.
+  void WritePrefs();
+
+  // Writes the stored prefs to |pref_service| and then posts another a delayed
+  // task to write prefs again in |kMinutesBetweenWrites|.
+  void WritePrefsAndPost();
+
+  // Copies the values at each index of |from_list| to the same index in
+  // |to_list|.
+  void TransferList(const base::ListValue& from_list,
+                    base::ListValue* to_list);
+
+  // Gets an int64, stored as a string, in a ListPref at the specified
+  // index.
+  int64 GetListPrefInt64Value(const base::ListValue& list_update, size_t index);
+
+  PrefService* pref_service_;
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
+  base::TimeDelta delay_;
+  bool delayed_task_posted_;
+  DataReductionProxyPrefMap* pref_map_;

[bengr, 2014/08/14 17:39:42]

Why do these need to be pointers?

[megjablon, 2014/08/26 19:28:41]

Done.

+  DataReductionProxyListPrefMap* list_pref_map_;
+};
+
+} // namespace data_reduction_proxy
+
+#endif  // COMPONENTS_DATA_REDUCTION_PROXY_BROWSER_DATA_REDUCTION_PROXY_DELAYED_PREF_SERVICE_H_