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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 // The InMemoryHistoryBackend is a wrapper around the in-memory URL database.
      6 // It maintains an in-memory cache of a subset of history that is required for
      7 // low-latency operations, such as in-line autocomplete.
      8 //
      9 // The in-memory cache provides the following guarantees:
     10 //  (1.) It will always contain URLRows that either have a |typed_count| > 0; or
     11 //       that have a corresponding search term, in which case information about
     12 //       the search term is also stored.
     13 //  (2.) It will be an actual subset, i.e., it will contain verbatim data, and
     14 //       will never contain more data that can be found in the main database.
     15 //
     16 // The InMemoryHistoryBackend is created on the history thread and passed to the
     17 // main thread where operations can be completed synchronously. It listens for
     18 // notifications from the "regular" history backend and keeps itself in sync.
     19 
     20 #ifndef CHROME_BROWSER_HISTORY_IN_MEMORY_HISTORY_BACKEND_H_
     21 #define CHROME_BROWSER_HISTORY_IN_MEMORY_HISTORY_BACKEND_H_
     22 
     23 #include <string>
     24 
     25 #include "base/basictypes.h"
     26 #include "base/gtest_prod_util.h"
     27 #include "base/memory/scoped_ptr.h"
     28 #include "components/history/core/browser/keyword_id.h"
     29 #include "content/public/browser/notification_observer.h"
     30 #include "content/public/browser/notification_registrar.h"
     31 
     32 class Profile;
     33 
     34 namespace base {
     35 class FilePath;
     36 }
     37 
     38 namespace history {
     39 
     40 class InMemoryDatabase;
     41 struct KeywordSearchUpdatedDetails;
     42 struct KeywordSearchDeletedDetails;
     43 class URLDatabase;
     44 class URLRow;
     45 struct URLsDeletedDetails;
     46 struct URLsModifiedDetails;
     47 
     48 class InMemoryHistoryBackend : public content::NotificationObserver {
     49  public:
     50   InMemoryHistoryBackend();
     51   virtual ~InMemoryHistoryBackend();
     52 
     53   // Initializes the backend from the history database pointed to by the
     54   // full path in |history_filename|.
     55   bool Init(const base::FilePath& history_filename);
     56 
     57   // Does initialization work when this object is attached to the history
     58   // system on the main thread. The argument is the profile with which the
     59   // attached history service is under.
     60   void AttachToHistoryService(Profile* profile);
     61 
     62   // Deletes all search terms for the specified keyword.
     63   void DeleteAllSearchTermsForKeyword(KeywordID keyword_id);
     64 
     65   // Returns the underlying database associated with this backend. The current
     66   // autocomplete code was written fro this, but it should probably be removed
     67   // so that it can deal directly with this object, rather than the DB.
     68   InMemoryDatabase* db() const {
     69     return db_.get();
     70   }
     71 
     72   // Notification callback.
     73   virtual void Observe(int type,
     74                        const content::NotificationSource& source,
     75                        const content::NotificationDetails& details) OVERRIDE;
     76 
     77  private:
     78   FRIEND_TEST_ALL_PREFIXES(HistoryBackendTest, DeleteAll);
     79 
     80   // Handler for HISTORY_URL_VISITED and HISTORY_URLS_MODIFIED.
     81   void OnURLVisitedOrModified(const URLRow& url_row);
     82 
     83   // Handler for HISTORY_URLS_DELETED.
     84   void OnURLsDeleted(const URLsDeletedDetails& details);
     85 
     86   // Handler for HISTORY_KEYWORD_SEARCH_TERM_UPDATED.
     87   void OnKeywordSearchTermUpdated(const KeywordSearchUpdatedDetails& details);
     88 
     89   // Handler for HISTORY_KEYWORD_SEARCH_TERM_DELETED.
     90   void OnKeywordSearchTermDeleted(const KeywordSearchDeletedDetails& details);
     91 
     92   content::NotificationRegistrar registrar_;
     93 
     94   scoped_ptr<InMemoryDatabase> db_;
     95 
     96   // The profile that this object is attached. May be NULL before
     97   // initialization.
     98   Profile* profile_;
     99 
    100   DISALLOW_COPY_AND_ASSIGN(InMemoryHistoryBackend);
    101 };
    102 
    103 }  // namespace history
    104 
    105 #endif  // CHROME_BROWSER_HISTORY_IN_MEMORY_HISTORY_BACKEND_H_
    106