Componentize expire_history_backend.{cc,h}

chrome/browser/history/expire_history_backend.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_EXPIRE_HISTORY_BACKEND_H_
-#define CHROME_BROWSER_HISTORY_EXPIRE_HISTORY_BACKEND_H_
-
-#include <queue>
-#include <set>
-#include <vector>
-
-#include "base/basictypes.h"
-#include "base/gtest_prod_util.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/weak_ptr.h"
-#include "base/time/time.h"
-#include "components/history/core/browser/history_types.h"
-
-class GURL;
-class TestingProfile;
-
-namespace history {
-
-class HistoryBackendNotifier;
-class HistoryClient;
-class HistoryDatabase;
-class ThumbnailDatabase;
-
-// Encapsulates visit expiration criteria and type of visits to expire.
-class ExpiringVisitsReader {
- public:
-  virtual ~ExpiringVisitsReader() {}
-  // Populates |visits| from |db|, using provided |end_time| and |max_visits|
-  // cap.
-  virtual bool Read(base::Time end_time, HistoryDatabase* db,
-                    VisitVector* visits, int max_visits) const = 0;
-};
-
-typedef std::vector<const ExpiringVisitsReader*> ExpiringVisitsReaders;
-
-// Helper component to HistoryBackend that manages expiration and deleting of
-// history.
-//
-// It will automatically start periodically expiring old history once you call
-// StartExpiringOldStuff().
-class ExpireHistoryBackend {
- public:
-  // The delegate pointer must be non-NULL. We will NOT take ownership of it.
-  // HistoryClient may be NULL. The HistoryClient is used when expiring URLS so
-  // that we don't remove any URLs or favicons that are bookmarked (visits are
-  // removed though).
-  ExpireHistoryBackend(HistoryBackendNotifier* notifier,
-                       HistoryClient* history_client);
-  ~ExpireHistoryBackend();
-
-  // Completes initialization by setting the databases that this class will use.
-  void SetDatabases(HistoryDatabase* main_db,
-                    ThumbnailDatabase* thumb_db);
-
-  // Begins periodic expiration of history older than the given threshold. This
-  // will continue until the object is deleted.
-  void StartExpiringOldStuff(base::TimeDelta expiration_threshold);
-
-  // Deletes everything associated with a URL.
-  void DeleteURL(const GURL& url);
-
-  // Deletes everything associated with each URL in the list.
-  void DeleteURLs(const std::vector<GURL>& url);
-
-  // Removes all visits to restrict_urls (or all URLs if empty) in the given
-  // time range, updating the URLs accordingly.
-  void ExpireHistoryBetween(const std::set<GURL>& restrict_urls,
-                            base::Time begin_time, base::Time end_time);
-
-  // Removes all visits to all URLs with the given times, updating the
-  // URLs accordingly.  |times| must be in reverse chronological order
-  // and not contain any duplicates.
-  void ExpireHistoryForTimes(const std::vector<base::Time>& times);
-
-  // Removes the given list of visits, updating the URLs accordingly (similar to
-  // ExpireHistoryBetween(), but affecting a specific set of visits).
-  void ExpireVisits(const VisitVector& visits);
-
-  // Expires all visits before and including the given time, updating the URLs
-  // accordingly. Currently only used for testing.
-  void ExpireHistoryBefore(base::Time end_time);
-
-  // Returns the current cut-off time before which we will start expiring stuff.
-  // Note that this as an absolute time rather than a delta, so the caller
-  // should not save it.
-  base::Time GetCurrentExpirationTime() const {
-    return base::Time::Now() - expiration_threshold_;
-  }
-
- private:
-  FRIEND_TEST_ALL_PREFIXES(ExpireHistoryTest, DeleteFaviconsIfPossible);
-  FRIEND_TEST_ALL_PREFIXES(ExpireHistoryTest, ExpireSomeOldHistory);
-  FRIEND_TEST_ALL_PREFIXES(ExpireHistoryTest, ExpiringVisitsReader);
-  FRIEND_TEST_ALL_PREFIXES(ExpireHistoryTest, ExpireSomeOldHistoryWithSource);
-  friend class ::TestingProfile;
-
-  struct DeleteEffects {
-    DeleteEffects();
-    ~DeleteEffects();
-
-    // The time range affected. These can be is_null() to be unbounded in one
-    // or both directions.
-    base::Time begin_time, end_time;
-
-    // The unique URL rows affected by this delete.
-    std::map<URLID, URLRow> affected_urls;
-
-    // The URLs modified, but not deleted, during this operation.
-    URLRows modified_urls;
-
-    // The URLs deleted during this operation.
-    URLRows deleted_urls;
-
-    // All favicon IDs that the deleted URLs had. Favicons will be shared
-    // between all URLs with the same favicon, so this is the set of IDs that we
-    // will need to check when the delete operations are complete.
-    std::set<favicon_base::FaviconID> affected_favicons;
-
-    // All favicon urls that were actually deleted from the thumbnail db.
-    std::set<GURL> deleted_favicons;
-  };
-
-  // Deletes the visit-related stuff for all the visits in the given list, and
-  // adds the rows for unique URLs affected to the affected_urls list in
-  // the dependencies structure.
-  void DeleteVisitRelatedInfo(const VisitVector& visits,
-                              DeleteEffects* effects);
-
-  // Finds or deletes dependency information for the given URL. Information that
-  // is specific to this URL (URL row, thumbnails, etc.) is deleted.
-  //
-  // This does not affect the visits! This is used for expiration as well as
-  // deleting from the UI, and they handle visits differently.
-  //
-  // Other information will be collected and returned in the output containers.
-  // This includes some of the things deleted that are needed elsewhere, plus
-  // some things like favicons that could be shared by many URLs, and need to
-  // be checked for deletion (this allows us to delete many URLs with only one
-  // check for shared information at the end).
-  //
-  // Assumes the main_db_ is non-NULL.
-  //
-  // NOTE: If the url is bookmarked only the segments and text db are updated,
-  // everything else is unchanged. This is done so that bookmarks retain their
-  // favicons and thumbnails.
-  void DeleteOneURL(const URLRow& url_row,
-                    bool is_bookmarked,
-                    DeleteEffects* effects);
-
-  // Deletes all the URLs in the given vector and handles their dependencies.
-  // This will delete starred URLs
-  void DeleteURLs(const URLRows& urls, DeleteEffects* effects);
-
-  // Expiration involves removing visits, then propagating the visits out from
-  // there and delete any orphaned URLs. These will be added to the deleted URLs
-  // field of the dependencies and DeleteOneURL will handle deleting out from
-  // there. This function does not handle favicons.
-  //
-  // When a URL is not deleted, the last visit time and the visit and typed
-  // counts will be updated.
-  //
-  // The visits in the given vector should have already been deleted from the
-  // database, and the list of affected URLs already be filled into
-  // |depenencies->affected_urls|.
-  //
-  // Starred URLs will not be deleted. The information in the dependencies that
-  // DeleteOneURL fills in will be updated, and this function will also delete
-  // any now-unused favicons.
-  void ExpireURLsForVisits(const VisitVector& visits, DeleteEffects* effects);
-
-  // Deletes the favicons listed in |effects->affected_favicons| if they are
-  // unsued. Fails silently (we don't care about favicons so much, so don't want
-  // to stop everything if it fails). Fills |expired_favicons| with the set of
-  // favicon urls that no longer have associated visits and were therefore
-  // expired.
-  void DeleteFaviconsIfPossible(DeleteEffects* effects);
-
-  // Enum representing what type of action resulted in the history DB deletion.
-  enum DeletionType {
-    // User initiated the deletion from the History UI.
-    DELETION_USER_INITIATED,
-    // History data was automatically expired due to being more than 90 days
-    // old.
-    DELETION_EXPIRED
-  };
-
-  // Broadcasts URL modified and deleted notifications.
-  void BroadcastNotifications(DeleteEffects* effects, DeletionType type);
-
-  // Schedules a call to DoExpireIteration.
-  void ScheduleExpire();
-
-  // Calls ExpireSomeOldHistory to expire some amount of old history, according
-  // to the items in work queue, and schedules another call to happen in the
-  // future.
-  void DoExpireIteration();
-
-  // Tries to expire the oldest |max_visits| visits from history that are older
-  // than |time_threshold|. The return value indicates if we think there might
-  // be more history to expire with the current time threshold (it does not
-  // indicate success or failure).
-  bool ExpireSomeOldHistory(base::Time end_time,
-                             const ExpiringVisitsReader* reader,
-                             int max_visits);
-
-  // Tries to detect possible bad history or inconsistencies in the database
-  // and deletes items. For example, URLs with no visits.
-  void ParanoidExpireHistory();
-
-  // Returns the HistoryClient, blocking until the bookmarks are loaded. This
-  // may return NULL during testing.
-  HistoryClient* GetHistoryClient();
-
-  // Initializes periodic expiration work queue by populating it with with tasks
-  // for all known readers.
-  void InitWorkQueue();
-
-  // Returns the reader for all visits. This method is only used by the unit
-  // tests.
-  const ExpiringVisitsReader* GetAllVisitsReader();
-
-  // Returns the reader for AUTO_SUBFRAME visits. This method is only used by
-  // the unit tests.
-  const ExpiringVisitsReader* GetAutoSubframeVisitsReader();
-
-  // Non-owning pointer to the notification delegate (guaranteed non-NULL).
-  HistoryBackendNotifier* notifier_;
-
-  // Non-owning pointers to the databases we deal with (MAY BE NULL).
-  HistoryDatabase* main_db_;       // Main history database.
-  ThumbnailDatabase* thumb_db_;    // Thumbnails and favicons.
-
-  // The threshold for "old" history where we will automatically delete it.
-  base::TimeDelta expiration_threshold_;
-
-  // List of all distinct types of readers. This list is used to populate the
-  // work queue.
-  ExpiringVisitsReaders readers_;
-
-  // Work queue for periodic expiration tasks, used by DoExpireIteration() to
-  // determine what to do at an iteration, as well as populate it for future
-  // iterations.
-  std::queue<const ExpiringVisitsReader*> work_queue_;
-
-  // Readers for various types of visits.
-  // TODO(dglazkov): If you are adding another one, please consider reorganizing
-  // into a map.
-  scoped_ptr<ExpiringVisitsReader> all_visits_reader_;
-  scoped_ptr<ExpiringVisitsReader> auto_subframe_visits_reader_;
-
-  // The HistoryClient; may be NULL.
-  //
-  // Use GetHistoryClient to access this, which makes sure the bookmarks are
-  // loaded before returning.
-  HistoryClient* history_client_;
-
-  // Used to generate runnable methods to do timers on this class. They will be
-  // automatically canceled when this class is deleted.
-  base::WeakPtrFactory<ExpireHistoryBackend> weak_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(ExpireHistoryBackend);
-};
-
-}  // namespace history
-
-#endif  // CHROME_BROWSER_HISTORY_EXPIRE_HISTORY_BACKEND_H_