Precache tracking database

components/precache/core/precache_statistics_table.h

+// Copyright 2013 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_PRECACHE_CORE_PRECACHE_STATISTICS_TABLE_H_
+#define COMPONENTS_PRECACHE_CORE_PRECACHE_STATISTICS_TABLE_H_
+
+#include <map>
+
+#include "base/basictypes.h"
+#include "base/time/time.h"
+
+namespace sql {
+class Connection;
+}
+
+namespace precache {
+
+// Keeps track of daily precache statistics in a database table. Manages one
+// table { date (primary key), precached_bytes, downloaded_bytes,
+// downloaded_bytes_cellular, saved_bytes, saved_bytes_cellular }.
+class PrecacheStatisticsTable {
+ public:
+  // Struct of the statistics tracked by this class.
+  struct PrecacheStatistics {
+    // Initializes all statistics to zero.
+    PrecacheStatistics();
+    PrecacheStatistics(int64 precached_bytes, int64 downloaded_bytes,
+                       int64 downloaded_bytes_cellular, int64 saved_bytes,
+                       int64 saved_bytes_cellular);
+    bool operator==(const PrecacheStatistics& other) const;
+
+    int64 precached_bytes;

[mmenke, 2013/10/31 16:45:00]

I think these names are unclear.  I'm a fan of clear names, even if they are
painfully long, since they make code easier to follow.  I think we should also
add comments.

I suggest calling this downloaded_precache_motivated_bytes or
downloaded_precache_initiated_bytes, here and everywhere else it appears.

[sclittle, 2013/11/06 01:51:42]

Done.

+    int64 downloaded_bytes;

[mmenke, 2013/10/31 16:45:00]

I suggest calling this downloaded_non_precache_bytes.

[sclittle, 2013/11/06 01:51:42]

Done.

+    int64 downloaded_bytes_cellular;

[mmenke, 2013/10/31 16:45:00]

And this downloaded_non_precache_bytes_cellular.

[sclittle, 2013/11/06 01:51:42]

Done.

+    int64 saved_bytes;
+    int64 saved_bytes_cellular;
+  };
+
+  typedef std::map<base::Time, PrecacheStatistics> PrecacheStatisticsMap;
+
+  PrecacheStatisticsTable();
+  ~PrecacheStatisticsTable();
+
+  // Initialize the precache statistics table for use with the specified
+  // database connection. The caller keeps ownership of |db|, and |db| must not
+  // be NULL. Init must be called before any other methods.
+  void Init(sql::Connection* db);
+
+  // Increase the daily statistics for the day of |time_on_day|. If a row for
+  // the day of |time_on_day| does not already exist, a new row is created.
+  void IncreaseDailyStats(const base::Time& time_on_day,
+                          const PrecacheStatistics& stats_change);
+
+  // Returns stored daily statistics for days between the day of |start_time|
+  // and the day of |end_time|, inclusive.
+  void GetAllStatsBetween(const base::Time& start_time,
+                          const base::Time& end_time,
+                          PrecacheStatisticsMap* map);
+
+  // Deletes stored daily statistics for days between the day of |delete_begin|
+  // and the day of |delete_end|, inclusive.
+  void DeleteAllStatsBetween(const base::Time& delete_begin,
+                             const base::Time& delete_end);
+
+ private:
+  // Rounds |time_on_day| down to midnight of the start of the day of
+  // |time_on_day|, and returns the internal value.
+  static int64 GetKey(const base::Time& time_on_day);
+
+  void CreateTableIfNonExistent();
+
+  // Non-owning pointer.
+  sql::Connection* db_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrecacheStatisticsTable);
+};
+
+}  // namespace precache
+
+#endif  // COMPONENTS_PRECACHE_CORE_PRECACHE_STATISTICS_TABLE_H_