Precache tracking database

components/precache/core/precache_database.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_DATABASE_H_
+#define COMPONENTS_PRECACHE_CORE_PRECACHE_DATABASE_H_
+
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/threading/thread_checker.h"
+
+class GURL;
+
+namespace base {
+class Time;
+}
+
+namespace sql {
+class Connection;
+}
+
+namespace precache {
+
+class PrecacheStatisticsTable;
+class PrecacheURLTable;
+
+// Class that tracks information related to precaching. This class can be
+// constructed or destroyed on any threads, but all other methods must be called
+// on the same thread (e.g. the DB thread).
+class PrecacheDatabase : public base::RefCountedThreadSafe<PrecacheDatabase> {
+ public:
+  // A PrecacheDatabase can be constructed on any thread.
+  PrecacheDatabase();
+
+  // Initializes the precache database with the specified connection. The
+  // PrecacheDatabase takes ownership of |db|. Init must be called before any
+  // other methods.
+  void Init(scoped_ptr<sql::Connection> db);
+
+  // Reports UMA of precache statistics for days up to but not including the day
+  // of |current_time|. The precache statistics for these days are deleted from
+  // the database after they have been reported, and expired precache history is
+  // deleted from the precache URL table.
+  void ReportAndDeleteOldStats(const base::Time& current_time);
+
+  // Update precache-related metrics in response to a URL being fetched, where
+  // the fetch was motivated by precaching.
+  void RecordURLPrecached(const GURL& url, const base::Time& fetch_time,
+                          int64 size, bool was_cached);
+
+  // Update precache-related metrics in response to a URL being fetched, where
+  // the fetch was not motivated by precaching. |is_connection_cellular|
+  // indicates whether the current network connection is a cellular network.
+  void RecordURLFetched(const GURL& url, const base::Time& fetch_time,
+                        int64 size, bool was_cached,
+                        bool is_connection_cellular);

[Scott Hess - ex-Googler, 2013/11/27 01:32:33]

While the |size| storage is 64-bit signed integer for each of these methods, is
that the appropriate API to expose?  size_t might be better.  I don't feel
strongly about this.

[sclittle, 2013/12/02 21:12:52]

The value for |size| would originally come from
URLRequest.received_response_content_length(), which is an int64.

+
+ private:
+  friend class base::RefCountedThreadSafe<PrecacheDatabase>;
+  friend class PrecacheDatabaseTest;
+
+  ~PrecacheDatabase();
+
+  bool IsDatabaseAccessible() const;
+
+  scoped_ptr<sql::Connection> db_;
+
+  // Table that keeps track of URLs that are in the cache because of precaching,
+  // and wouldn't be in the cache otherwise.
+  scoped_ptr<PrecacheURLTable> precache_url_table_;
+
+  // Table that keeps track of daily cumulative statistics that are relevant to
+  // precaching.
+  scoped_ptr<PrecacheStatisticsTable> precache_statistics_table_;
+
+  // ThreadChecker used to ensure that all methods other than the constructor
+  // or destructor are called on the same thread.
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrecacheDatabase);
+};
+
+}  // namespace precache
+
+#endif  // COMPONENTS_PRECACHE_CORE_PRECACHE_DATABASE_H_