Move InMemoryURLIndex Caching Operations to FILE Thread

chrome/browser/history/history.cc

 // Copyright (c) 2011 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.
 
 // The history system runs on a background thread so that potentially slow
 // database operations don't delay the browser. This backend processing is
 // represented by HistoryBackend. The HistoryService's job is to dispatch to
 // that thread.
 //
 // Main thread                       History thread
@@ skipping 19 matching lines @@
 #include "base/path_service.h"
 #include "base/string_util.h"
 #include "base/threading/thread.h"
 #include "chrome/browser/autocomplete/history_url_provider.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/history/history_backend.h"
 #include "chrome/browser/history/history_notifications.h"
 #include "chrome/browser/history/history_types.h"
 #include "chrome/browser/history/in_memory_database.h"
 #include "chrome/browser/history/in_memory_history_backend.h"
+#include "chrome/browser/history/in_memory_url_index.h"
 #include "chrome/browser/history/top_sites.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/profile_error_dialog.h"
 #include "chrome/browser/visitedlink/visitedlink_master.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_notification_types.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/thumbnail_score.h"
 #include "chrome/common/url_constants.h"
@@ skipping 124 matching lines @@
   return backend_loaded_;
 }
 
 void HistoryService::UnloadBackend() {
   if (!history_backend_)
     return;  // Already unloaded.
 
   // Get rid of the in-memory backend.
   in_memory_backend_.reset();
 
+  // Give the InMemoryURLIndex a chance to shutdown.
+  InMemoryIndex()->ShutDown();

[Peter Kasting, 2012/01/14 00:12:49]

Nit: Should this instead access |history_backend_| directly, to avoid the
LoadBackendIfNecessary() call?

[mrossetti, 2012/03/03 05:05:56]

Done.

+
   // The backend's destructor must run on the history thread since it is not
   // threadsafe. So this thread must not be the last thread holding a reference
   // to the backend, or a crash could happen.
   //
   // We have a reference to the history backend. There is also an extra
   // reference held by our delegate installed in the backend, which
   // HistoryBackend::Closing will release. This means if we scheduled a call
   // to HistoryBackend::Closing and *then* released our backend reference, there
   // will be a race between us and the backend's Closing function to see who is
   // the last holder of a reference. If the backend thread's Closing manages to
@@ skipping 47 matching lines @@
   if (in_memory_backend_.get())
     return in_memory_backend_->db();
   return NULL;
 }
 
 history::InMemoryURLIndex* HistoryService::InMemoryIndex() {
   // NOTE: See comments in BackendLoaded() as to why we call
   // LoadBackendIfNecessary() here even though it won't affect the return value
   // for this call.
   LoadBackendIfNecessary();
-  if (in_memory_backend_.get())
-    return in_memory_backend_->InMemoryIndex();
+  if (history_backend_.get())
+    return history_backend_->InMemoryIndex();
   return NULL;
 }
 
 void HistoryService::SetSegmentPresentationIndex(int64 segment_id, int index) {
   ScheduleAndForget(PRIORITY_UI,
                     &HistoryBackend::SetSegmentPresentationIndex,
                     segment_id, index);
 }
 
 void HistoryService::SetKeywordSearchTermsForURL(const GURL& url,
@@ skipping 539 matching lines @@
 
   content::NotificationService::current()->Notify(type, source, det);
 }
 
 void HistoryService::LoadBackendIfNecessary() {
   if (!thread_ || history_backend_)
     return;  // Failed to init, or already started loading.
 
   ++current_backend_id_;
   scoped_refptr<HistoryBackend> backend(
-      new HistoryBackend(history_dir_,
+      new HistoryBackend(profile_,
+                         history_dir_,
                          current_backend_id_,
                          new BackendDelegate(this, profile_),
                          bookmark_service_));
   history_backend_.swap(backend);
 
   // There may not be a profile when unit testing.
   std::string languages;
   if (profile_) {
     PrefService* prefs = profile_->GetPrefs();
     languages = prefs->GetString(prefs::kAcceptLanguages);
@@ skipping 30 matching lines @@
     history::TopSites* ts = profile_->GetTopSitesWithoutCreating();
     if (ts)
       ts->MigrateFromHistory();
   }
 }
 
 void HistoryService::OnTopSitesReady() {
   ScheduleAndForget(PRIORITY_NORMAL,
                     &HistoryBackend::MigrateThumbnailsDatabase);
 }