Revert 152946 - Replace HistoryQuickProvider protobuf-based caching with an SQLite-based database.

chrome/browser/history/in_memory_url_cache_database.h

-// Copyright (c) 2012 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 CHROME_BROWSER_HISTORY_IN_MEMORY_URL_CACHE_DATABASE_H_
-#define CHROME_BROWSER_HISTORY_IN_MEMORY_URL_CACHE_DATABASE_H_
-
-#include <string>
-
-#include "base/basictypes.h"
-#include "base/callback_forward.h"
-#include "base/gtest_prod_util.h"
-#include "base/memory/ref_counted.h"
-#include "base/threading/sequenced_worker_pool.h"
-#include "chrome/browser/history/in_memory_url_index_types.h"
-#include "sql/connection.h"
-#include "sql/init_status.h"
-#include "sql/meta_table.h"
-
-class FilePath;
-
-namespace sql {
-class Statement;
-}
-
-namespace history {
-
-class InMemoryURLIndex;
-class URLIndexPrivateData;
-
-// Supports caching and restoring of the private data of the InMemoryURLIndex.
-// This class has intimate knowledge of InMemoryURLIndex's URLIndexPrivateData
-// class and directly pokes data therein during cache restoration. The only
-// client of this class is URLIndexPrivateData.
-//
-// Tables in this database:
-//    word         - Indexed words with IDs (from word_map_ and word_list_).
-//    char_words   - Indexed characters with IDs of words containing the
-//                   character (from char_word_map_).
-//    word_history - Word IDs with the IDs of history items containing the
-//                   word (from word_id_history_map_).
-//    url          - URLs and page titles along with visit and other metrics
-//                   (from the history_info_map_ and word_starts_map_).
-//    url_word_starts - History IDs with the starting position of each word
-//                   found in its URL.
-//    title_word_starts - History IDs with the starting position of each word
-//                   found in its page title.
-//
-// NOTE: The history IDs in this database for URLs are identical to those in the
-// main history database.
-class InMemoryURLCacheDatabase
-    : public base::RefCountedThreadSafe<InMemoryURLCacheDatabase> {
- public:
-  InMemoryURLCacheDatabase();
-
-  // Initializes the database connection. This must return true before any other
-  // functions on this class are called. |file_path| gives the path to where
-  // the cache database is located. |sequence_token| is used to coordinate all
-  // access to the cache database. This is normally called on the DB thread but
-  // may also be called in the sequenced worker pool for certain unit tests.
-  bool Init(const FilePath& file_path,
-            const base::SequencedWorkerPool::SequenceToken& sequence_token);
-
-  // Shuts down the database connection. Posts a sequenced task that performs
-  // the matching ShutDownTask function below.
-  void Shutdown();
-
-  // Restore the private InMemoryURLIndex |data| from the database. Returns true
-  // if there was data to restore and the restore was successful. It is
-  // considered an error and false is returned if _any_ of the restored data
-  // structures in the private data, except |available_words_|, are empty after
-  // restoration. Technically, the case where _all_ data structures are empty
-  // after a restore is an error only when the user's history has _not_ been
-  // cleared. In the case where history _has_ been cleared and the data
-  // structures are legitimately empty we still return a false as the cost of
-  // attempting to rebuild the private data from an empty history database is
-  // negligible.
-  bool RestorePrivateData(URLIndexPrivateData* data);
-
-  // Reset the database by dropping and recreating all database tables. Return
-  // true if successful. Note that a failure does not close the database.
-  virtual bool Reset();
-
-  // Adds information for a new |row| to the various database tables. These
-  // functions post a sequenced task that performs the matching '[name]Task'
-  // functions below. The client should wrap these functions in a transaction
-  // by the client by calling BeginTransaction(), whatever combination of these
-  // function as appropriate, and finally CommitTransaction(). The
-  // CommitTransaction() will notify the client if any failure occurs.
-  void AddHistoryToURLs(HistoryID history_id, const URLRow& row);
-  void AddHistoryToWordHistory(WordID word_id, HistoryID history_id);
-  void AddWordToWords(WordID word_id, const string16& uni_word);
-  void AddWordToCharWords(char16 uni_char, WordID word_id);
-  void AddRowWordStarts(HistoryID history_id,
-                        const RowWordStarts& row_word_starts);
-
-  // Deletes row information from the various database tables. These functions
-  // post a sequenced task that performs the matching '[name]Task' functions
-  // below.
-  void RemoveHistoryIDFromURLs(HistoryID history_id);
-  void RemoveHistoryIDFromWordHistory(HistoryID history_id);
-  void RemoveWordFromWords(WordID word_id);
-  void RemoveWordStarts(HistoryID history_id);
-
-  // Wraps transactions on the database. We support nested transactions and only
-  // commit when the outermost one is committed (sqlite doesn't support true
-  // nested transactions). These functions post a sequenced task that performs
-  // the matching '[name]Task' functions below.
-  void BeginTransaction();
-  void CommitTransaction();
-
-  // Completely replaces all data in the cache database with a fresh image.
-  // Returns true upon success. Must not be called on the main thread and and
-  // the caller should ensure that no other cache database update operations
-  // take place while this method is being performed. Returns true if the
-  // refresh was successful.
-  virtual bool Refresh(const URLIndexPrivateData& index_data);
-
- private:
-  friend class base::RefCountedThreadSafe<InMemoryURLCacheDatabase>;
-  friend class InMemoryURLIndexCacheTest;
-  friend class InMemoryURLIndexTest;
-  friend class InterposingCacheDatabase;
-  FRIEND_TEST_ALL_PREFIXES(InMemoryURLIndexTest, CacheAddRemove);
-
-  virtual ~InMemoryURLCacheDatabase();
-
-  // Initializes the database and returns true if successful.
-  bool InitDatabase();
-
-  // Posts the given |task| for sequential execution using a pool task
-  // coordinated by |sequence_token_|.
-  void PostSequencedDBTask(const tracked_objects::Location& from_here,
-                           const base::Closure& task);
-
-  // Closes the database.
-  void ShutdownTask();
-
-  // Makes sure the version is up-to-date, updating if necessary. Notify the
-  // user if the database is newer than expected.
-  sql::InitStatus EnsureCurrentVersion();
-
-  // Starts a database transaction.
-  void BeginTransactionTask();
-
-  // Commits the database transaction if no update operations failed after
-  // BeginTransactionTask() was called, otherwise rolls back the transaction.
-  // Sends a NOTIFICATION_IN_MEMORY_URL_CACHE_DATABASE_FAILURE notification
-  // if the transaction failed.
-  void CommitTransactionTask();
-
-  // Returns true if all tables exist.
-  bool VerifyTables();
-
-  // Creates the various tables and indexes returning true if successful.
-  bool CreateTables();
-
-  // Notifies observers that a failure occurred during a database update
-  // operation.
-  void NotifyDatabaseFailure();
-
-  // Executes |statement|, sets |update_error_| if the statement did not
-  // run successfully, and returns true if the statement was run successfully.
-  bool RunStatement(sql::Statement* statement);
-
-  // Adds information about a new row to the various database tables.
-  void AddHistoryToURLsTask(HistoryID history_id, const URLRow& row);
-  void AddHistoryToWordHistoryTask(WordID word_id, HistoryID history_id);
-  // Note: AddWordToWordsTask is virtual so that it can be overridden by
-  // unit tests to simulate database failures.
-  virtual void AddWordToWordsTask(WordID word_id, const string16& uni_word);
-  void AddWordToCharWordsTask(char16 uni_char, WordID word_id);
-  void AddRowWordStartsTask(HistoryID history_id,
-                            const RowWordStarts& row_word_starts);
-
-  // Deletes row information from the various database tables. Returns true if
-  // successful.
-  void RemoveHistoryIDFromURLsTask(HistoryID history_id);
-  void RemoveHistoryIDFromWordHistoryTask(HistoryID history_id);
-  void RemoveWordFromWordsTask(WordID word_id);
-  void RemoveWordStartsTask(HistoryID history_id);
-
-  // Completely replaces all data in the cache with a fresh image. Returns true
-  // if successful.
-  bool RefreshWords(const URLIndexPrivateData& index_data);
-  bool RefreshCharWords(const URLIndexPrivateData& index_data);
-  bool RefreshWordHistory(const URLIndexPrivateData& index_data);
-  bool RefreshURLs(const URLIndexPrivateData& index_data);
-  bool RefreshWordStarts(const URLIndexPrivateData& index_data);
-
-  // Restores individual sections of the private data for the InMemoryURLIndex.
-  // Returns true if there was data to restore and the restore was successful.
-  bool RestoreWords(URLIndexPrivateData* index_data);
-  bool RestoreCharWords(URLIndexPrivateData* index_data);
-  bool RestoreWordHistory(URLIndexPrivateData* index_data);
-  bool RestoreURLs(URLIndexPrivateData* index_data);
-  bool RestoreWordStarts(URLIndexPrivateData* index_data);
-
-  // Returns the database connection.
-  sql::Connection* get_db_for_testing() { return &db_; }
-
-  // Sequence token for coordinating database tasks.
-  base::SequencedWorkerPool::SequenceToken sequence_token_;
-
-  // The database.
-  sql::Connection db_;
-  sql::MetaTable meta_table_;
-  int update_error_;
-
-  // Set to true once the shutdown process has begun.
-  bool shutdown_;
-
-  DISALLOW_COPY_AND_ASSIGN(InMemoryURLCacheDatabase);
-};
-
-}  // namespace history
-
-#endif  // CHROME_BROWSER_HISTORY_IN_MEMORY_URL_CACHE_DATABASE_H_