[Thumbnails DB] Add functionality to clear unused on-demand favicons.

components/history/core/browser/expire_history_backend.cc

 // 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.
 
 #include "components/history/core/browser/expire_history_backend.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <functional>
 #include <limits>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
+#include "base/feature_list.h"
 #include "base/files/file_enumerator.h"
 #include "base/files/file_util.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/sequenced_task_runner.h"
 #include "components/history/core/browser/history_backend_client.h"
 #include "components/history/core/browser/history_backend_notifier.h"
 #include "components/history/core/browser/history_database.h"
 #include "components/history/core/browser/thumbnail_database.h"
 
@@ skipping 84 matching lines @@
 const int kExpirationDelaySec = 30;
 
 // The number of minutes between checking, as with kExpirationDelaySec, but
 // when we didn't find enough things to expire last time. If there was no
 // history to expire last iteration, it's likely there is nothing next
 // iteration, so we want to wait longer before checking to avoid wasting CPU.
 const int kExpirationEmptyDelayMin = 5;
 
 }  // namespace
 
+namespace internal {
+
+const base::Feature kClearOldOnDemandFavicons{
+    "ClearOldOnDemandFavicons", base::FEATURE_DISABLED_BY_DEFAULT};
+
+}  // namespace internal
 
 // ExpireHistoryBackend::DeleteEffects ----------------------------------------
 
 ExpireHistoryBackend::DeleteEffects::DeleteEffects() {
 }
 
 ExpireHistoryBackend::DeleteEffects::~DeleteEffects() {
 }
 
 
@@ skipping 341 matching lines @@
 
   const ExpiringVisitsReader* reader = work_queue_.front();
   bool more_to_expire = ExpireSomeOldHistory(
       GetCurrentExpirationTime(), reader, kNumExpirePerIteration);
 
   work_queue_.pop();
   // If there are more items to expire, add the reader back to the queue, thus
   // creating a new task for future iterations.
   if (more_to_expire)
     work_queue_.push(reader);
+  // Otherwise do a final clean-up - remove old favicons not bound to visits.
+  else
+    ClearOldOnDemandFavicons(GetCurrentExpirationTime());
 
   ScheduleExpire();
 }
 
+void ExpireHistoryBackend::ClearOldOnDemandFavicons(
+    base::Time expiration_threshold) {
+  if (!base::FeatureList::IsEnabled(internal::kClearOldOnDemandFavicons))
+    return;
+
+  std::vector<std::pair<favicon_base::FaviconID, GURL>> favicons =
+      thumb_db_->GetOldOnDemandFavicons(expiration_threshold);
+
+  // Multiple page URLs may map to the same favicon. We omit the favicon from
+  // cleaning if at least one of its associated page URLs is bookmarked.
+  std::set<favicon_base::FaviconID> ids_of_icons_with_some_bookmarked_page;
+  std::set<favicon_base::FaviconID> ids_of_icons_with_no_bookmarked_page;
+  for (auto id_and_url_pair : favicons) {
+    favicon_base::FaviconID icon_id = id_and_url_pair.first;
+    if (ids_of_icons_with_some_bookmarked_page.count(icon_id))
+      continue;
+
+    const GURL& page_url = id_and_url_pair.second;
+    if (backend_client_ && backend_client_->IsBookmarked(page_url)) {
+      ids_of_icons_with_some_bookmarked_page.insert(icon_id);
+      ids_of_icons_with_no_bookmarked_page.erase(icon_id);
+      continue;
+    }
+
+    ids_of_icons_with_no_bookmarked_page.insert(icon_id);
+  }
+
+  for (favicon_base::FaviconID icon_id : ids_of_icons_with_no_bookmarked_page) {
+    if (!thumb_db_->DeleteFavicon(icon_id) ||
+        !thumb_db_->DeleteIconMappingsForFaviconId(icon_id))

[pkotwicz, 2017/07/07 00:42:38]

Don't you need to update DeleteEffects::deleted_favicons ?

[jkrcal, 2017/07/07 08:45:16]

Done. 

This meant pulling also the icon_url. This was strong enough reason to create a
struct for the result and move some of the logic back to thumbnail_database.cc.
I like it much better now.

+      return;

[pkotwicz, 2017/07/07 00:42:38]

For the sake of consistency with DeleteFaviconsIfPossible() don't return if a
given deletion fails

[jkrcal, 2017/07/07 08:45:16]

Done.

+  }
+}
+
 bool ExpireHistoryBackend::ExpireSomeOldHistory(
     base::Time end_time,
     const ExpiringVisitsReader* reader,
     int max_visits) {
   if (!main_db_)
     return false;
 
   // Add an extra time unit to given end time, because
   // GetAllVisitsInRange, et al. queries' end value is non-inclusive.
   base::Time effective_end_time =
@@ skipping 11 matching lines @@
   BroadcastNotifications(&deleted_effects, DELETION_EXPIRED);
 
   return more_to_expire;
 }
 
 void ExpireHistoryBackend::ParanoidExpireHistory() {
   // TODO(brettw): Bug 1067331: write this to clean up any errors.
 }
 
 }  // namespace history