Componentize URLDatabase

chrome/browser/history/url_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_URL_DATABASE_H_
-#define CHROME_BROWSER_HISTORY_URL_DATABASE_H_
-
-#include "base/basictypes.h"
-#include "chrome/browser/history/history_types.h"
-#include "components/history/core/browser/keyword_id.h"
-#include "components/query_parser/query_parser.h"
-#include "sql/statement.h"
-
-class GURL;
-
-namespace sql {
-class Connection;
-}
-
-namespace history {
-
-class VisitDatabase;  // For friend statement.
-
-// Encapsulates an SQL database that holds URL info.  This is a subset of the
-// full history data.  We split this class' functionality out from the larger
-// HistoryDatabase class to support maintaining separate databases of URLs with
-// different capabilities (for example, the in-memory database).
-//
-// This is refcounted to support calling InvokeLater() with some of its methods
-// (necessary to maintain ordering of DB operations).
-class URLDatabase {
- public:
-  // Must call CreateURLTable() and CreateURLIndexes() before using to make
-  // sure the database is initialized.
-  URLDatabase();
-
-  // This object must be destroyed on the thread where all accesses are
-  // happening to avoid thread-safety problems.
-  virtual ~URLDatabase();
-
-  // Converts a GURL to a string used in the history database. We plan to
-  // do more complex operations than just getting the spec out involving
-  // punycode, so this function should be used instead of url.spec() when
-  // interacting with the database.
-  //
-  // TODO(brettw) this should be moved out of the public section and the
-  // entire public HistoryDatabase interface should use GURL. This should
-  // also probably return a string instead since that is what the DB uses
-  // internally and we can avoid the extra conversion.
-  static std::string GURLToDatabaseURL(const GURL& url);
-
-  // URL table functions -------------------------------------------------------
-
-  // Looks up a url given an id. Fills info with the data. Returns true on
-  // success and false otherwise.
-  bool GetURLRow(URLID url_id, URLRow* info);
-
-  // Looks up all urls that were typed in manually. Fills info with the data.
-  // Returns true on success and false otherwise.
-  bool GetAllTypedUrls(URLRows* urls);
-
-  // Looks up the given URL and if it exists, fills the given pointers with the
-  // associated info and returns the ID of that URL. If the info pointer is
-  // NULL, no information about the URL will be filled in, only the ID will be
-  // returned. Returns 0 if the URL was not found.
-  URLID GetRowForURL(const GURL& url, URLRow* info);
-
-  // Given an already-existing row in the URL table, updates that URL's stats.
-  // This can not change the URL.  Returns true on success.
-  //
-  // This will NOT update the title used for full text indexing. If you are
-  // setting the title, call SetPageIndexedData with the new title.
-  bool UpdateURLRow(URLID url_id, const URLRow& info);
-
-  // Adds a line to the URL database with the given information and returns the
-  // newly generated ID for the row (the |id| in |info| is ignored). A row with
-  // the given URL must not exist. Returns 0 on error.
-  //
-  // This does NOT add a row to the full text search database. Use
-  // HistoryDatabase::SetPageIndexedData to do this.
-  URLID AddURL(const URLRow& info) {
-    return AddURLInternal(info, false);
-  }
-
-  // Either adds a new row to the URL table with the given information (with the
-  // the |id| as specified in |info|), or updates the pre-existing row with this
-  // |id| if there is one already. This is also known as an "upsert" or "merge"
-  // operation. Returns true on success.
-  bool InsertOrUpdateURLRowByID(const URLRow& info);
-
-  // Delete the row of the corresponding URL. Only the row in the URL table and
-  // corresponding keyword search terms will be deleted, not any other data that
-  // may refer to the URL row. Returns true if the row existed and was deleted.
-  bool DeleteURLRow(URLID id);
-
-  // URL mass-deleting ---------------------------------------------------------
-
-  // Begins the mass-deleting operation by creating a temporary URL table.
-  // The caller than adds the URLs it wants to preseve to the temporary table,
-  // and then deletes everything else by calling CommitTemporaryURLTable().
-  // Returns true on success.
-  bool CreateTemporaryURLTable();
-
-  // Adds a row to the temporary URL table. This must be called between
-  // CreateTemporaryURLTable() and CommitTemporaryURLTable() (see those for more
-  // info). The ID of the URL will change in the temporary table, so the new ID
-  // is returned. Returns 0 on failure.
-  URLID AddTemporaryURL(const URLRow& row) {
-    return AddURLInternal(row, true);
-  }
-
-  // Ends the mass-deleting by replacing the original URL table with the
-  // temporary one created in CreateTemporaryURLTable. Returns true on success.
-  bool CommitTemporaryURLTable();
-
-  // Enumeration ---------------------------------------------------------------
-
-  // A basic enumerator to enumerate urls database.
-  class URLEnumeratorBase {
-   public:
-    URLEnumeratorBase();
-    virtual ~URLEnumeratorBase();
-
-   private:
-    friend class URLDatabase;
-
-    bool initialized_;
-    sql::Statement statement_;
-
-    DISALLOW_COPY_AND_ASSIGN(URLEnumeratorBase);
-  };
-
-  // A basic enumerator to enumerate urls
-  class URLEnumerator : public URLEnumeratorBase {
-   public:
-    URLEnumerator();
-
-    // Retreives the next url. Returns false if no more urls are available
-    bool GetNextURL(history::URLRow* r);
-
-   private:
-    DISALLOW_COPY_AND_ASSIGN(URLEnumerator);
-  };
-
-  // Initializes the given enumerator to enumerator all URLs in the database.
-  bool InitURLEnumeratorForEverything(URLEnumerator* enumerator);
-
-  // Initializes the given enumerator to enumerator all URLs in the database
-  // that are historically significant: ones having been visited within 3 days,
-  // having their URL manually typed more than once, or having been visited
-  // more than 3 times.
-  bool InitURLEnumeratorForSignificant(URLEnumerator* enumerator);
-
-  // Favicons ------------------------------------------------------------------
-
-  // Autocomplete --------------------------------------------------------------
-
-  // Fills the given array with URLs matching the given prefix.  They will be
-  // sorted by typed count, then by visit count, then by visit date (most recent
-  // first) up to the given maximum number.  If |typed_only| is true, only urls
-  // that have been typed once are returned.  For caller convenience, returns
-  // whether any results were found.
-  bool AutocompleteForPrefix(const std::string& prefix,
-                             size_t max_results,
-                             bool typed_only,
-                             URLRows* results);
-
-  // Returns true if the database holds some past typed navigation to a URL on
-  // the provided hostname.
-  bool IsTypedHost(const std::string& host);
-
-  // Tries to find the shortest URL beginning with |base| that strictly
-  // prefixes |url|, and has minimum visit_ and typed_counts as specified.
-  // If found, fills in |info| and returns true; otherwise returns false,
-  // leaving |info| unchanged.
-  // We allow matches of exactly |base| iff |allow_base| is true.
-  bool FindShortestURLFromBase(const std::string& base,
-                               const std::string& url,
-                               int min_visits,
-                               int min_typed,
-                               bool allow_base,
-                               history::URLRow* info);
-
-  // History search ------------------------------------------------------------
-
-  // Performs a brute force search over the database to find any URLs or titles
-  // which match the |query| string.  Returns any matches in |results|.
-  bool GetTextMatches(const base::string16& query, URLRows* results);
-
-  // Keyword Search Terms ------------------------------------------------------
-
-  // Sets the search terms for the specified url/keyword pair.
-  bool SetKeywordSearchTermsForURL(URLID url_id,
-                                   KeywordID keyword_id,
-                                   const base::string16& term);
-
-  // Looks up a keyword search term given a url id. Returns all the search terms
-  // in |rows|. Returns true on success.
-  bool GetKeywordSearchTermRow(URLID url_id, KeywordSearchTermRow* row);
-
-  // Looks up all keyword search terms given a term, Fills the rows with data.
-  // Returns true on success and false otherwise.
-  bool GetKeywordSearchTermRows(const base::string16& term,
-                                std::vector<KeywordSearchTermRow>* rows);
-
-  // Deletes all search terms for the specified keyword that have been added by
-  // way of SetKeywordSearchTermsForURL.
-  void DeleteAllSearchTermsForKeyword(KeywordID keyword_id);
-
-  // Returns up to max_count of the most recent search terms for the specified
-  // keyword.
-  void GetMostRecentKeywordSearchTerms(
-      KeywordID keyword_id,
-      const base::string16& prefix,
-      int max_count,
-      std::vector<KeywordSearchTermVisit>* matches);
-
-  // Deletes all searches matching |term|.
-  bool DeleteKeywordSearchTerm(const base::string16& term);
-
-  // Deletes any search corresponding to |url_id|.
-  bool DeleteKeywordSearchTermForURL(URLID url_id);
-
-  // Migration -----------------------------------------------------------------
-
-  // Do to a bug we were setting the favicon of about:blank. This forces
-  // about:blank to have no icon or title. Returns true on success, false if
-  // the favicon couldn't be updated.
-  bool MigrateFromVersion11ToVersion12();
-
- protected:
-  friend class VisitDatabase;
-
-  // See HISTORY_URL_ROW_FIELDS below.
-  static const char kURLRowFields[];
-
-  // The number of fiends in kURLRowFields. If callers need additional
-  // fields, they can add their 0-based index to this value to get the index of
-  // fields following kURLRowFields.
-  static const int kNumURLRowFields;
-
-  // Drops the starred_id column from urls, returning true on success. This does
-  // nothing (and returns true) if the urls doesn't contain the starred_id
-  // column.
-  bool DropStarredIDFromURLs();
-
-  // Initialization functions. The indexing functions are separate from the
-  // table creation functions so the in-memory database and the temporary tables
-  // used when clearing history can populate the table and then create the
-  // index, which is faster than the reverse.
-  //
-  // is_temporary is false when generating the "regular" URLs table. The expirer
-  // sets this to true to generate the  temporary table, which will have a
-  // different name but the same schema.
-  bool CreateURLTable(bool is_temporary);
-
-  // Creates the index over URLs so we can quickly look up based on URL.
-  bool CreateMainURLIndex();
-
-  // Ensures the keyword search terms table exists.
-  bool InitKeywordSearchTermsTable();
-
-  // Creates the indices used for keyword search terms.
-  bool CreateKeywordSearchTermsIndices();
-
-  // Deletes the keyword search terms table.
-  bool DropKeywordSearchTermsTable();
-
-  // Inserts the given URL row into the URLs table, using the regular table
-  // if is_temporary is false, or the temporary URL table if is temporary is
-  // true. The current |id| of |info| will be ignored in both cases and a new ID
-  // will be generated, which will also constitute the return value, except in
-  // case of an error, when the return value is 0. The temporary table may only
-  // be used in between CreateTemporaryURLTable() and CommitTemporaryURLTable().
-  URLID AddURLInternal(const URLRow& info, bool is_temporary);
-
-  // Convenience to fill a history::URLRow. Must be in sync with the fields in
-  // kHistoryURLRowFields.
-  static void FillURLRow(sql::Statement& s, URLRow* i);
-
-  // Returns the database for the functions in this interface. The decendent of
-  // this class implements these functions to return its objects.
-  virtual sql::Connection& GetDB() = 0;
-
- private:
-  // True if InitKeywordSearchTermsTable() has been invoked. Not all subclasses
-  // have keyword search terms.
-  bool has_keyword_search_terms_;
-
-  query_parser::QueryParser query_parser_;
-
-  DISALLOW_COPY_AND_ASSIGN(URLDatabase);
-};
-
-// The fields and order expected by FillURLRow(). ID is guaranteed to be first
-// so that DISTINCT can be prepended to get distinct URLs.
-//
-// This is available BOTH as a macro and a static string (kURLRowFields). Use
-// the macro if you want to put this in the middle of an otherwise constant
-// string, it will save time doing string appends. If you have to build a SQL
-// string dynamically anyway, use the constant, it will save space.
-#define HISTORY_URL_ROW_FIELDS \
-    " urls.id, urls.url, urls.title, urls.visit_count, urls.typed_count, " \
-    "urls.last_visit_time, urls.hidden "
-
-}  // namespace history
-
-#endif  // CHROME_BROWSER_HISTORY_URL_DATABASE_H_