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

components/history/core/browser/thumbnail_database.cc

Index: components/history/core/browser/thumbnail_database.cc
diff --git a/components/history/core/browser/thumbnail_database.cc b/components/history/core/browser/thumbnail_database.cc
index c8b430f4f71d8dd70f0111995c5ce74297cec7d9..06d7176e5d31be142791c11f866b998e1c1e1db5 100644
--- a/components/history/core/browser/thumbnail_database.cc
+++ b/components/history/core/browser/thumbnail_database.cc
@@ -271,6 +271,22 @@ void DatabaseErrorCallback(sql::Connection* db,
     DLOG(FATAL) << db->GetErrorMessage();
 }
 
+void DeleteOrphanagedFaviconBitmaps(sql::Connection* db) {
+  sql::Statement favicons(db->GetCachedStatement(
+      SQL_FROM_HERE,
+      "DELETE FROM favicon_bitmaps WHERE NOT EXISTS (SELECT id FROM favicons "
+      "WHERE favicon_bitmaps.icon_id = favicons.id)"));
+  favicons.Run();
+}
+
+void DeleteOrphanagedMappings(sql::Connection* db) {
+  sql::Statement mappings(db->GetCachedStatement(
+      SQL_FROM_HERE,
+      "DELETE FROM icon_mapping WHERE NOT EXISTS (SELECT id FROM favicons "
+      "WHERE favicons.id = icon_mapping.icon_id)"));
+  mappings.Run();
+}
+
 }  // namespace
 
 ThumbnailDatabase::IconMappingEnumerator::IconMappingEnumerator() {
@@ -412,6 +428,151 @@ void ThumbnailDatabase::TrimMemory(bool aggressively) {
   db_.TrimMemory(aggressively);
 }
 
+void ThumbnailDatabase::ClearOldOnDemandFavicons(
+    base::Time deletion_threshold) {
+  // Select all bitmaps (and their page URLs) that have not been accessed for a
+  // while. Restrict to on-demand bitmaps (i.e. with last_requested != 0).
+  sql::Statement delete_candidates(db_.GetCachedStatement(
+      SQL_FROM_HERE,
+      "SELECT favicon_bitmaps.icon_id, icon_mapping.page_url FROM "
+      "favicon_bitmaps, icon_mapping WHERE favicon_bitmaps.icon_id = "
+      "icon_mapping.icon_id AND favicon_bitmaps.last_requested>0 AND "
+      "favicon_bitmaps.last_requested<?;"));
+  delete_candidates.BindInt64(0, deletion_threshold.ToInternalValue());
+
+  // 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;
+  while (delete_candidates.Step()) {
+    favicon_base::FaviconID icon_id = delete_candidates.ColumnInt64(0);
+    if (ids_of_icons_with_some_bookmarked_page.count(icon_id))
+      continue;
+
+    GURL page_url = GURL(delete_candidates.ColumnString(1));
+    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) {
+    sql::Statement statement(db_.GetCachedStatement(
+        SQL_FROM_HERE, "DELETE FROM favicons WHERE id=?"));
+    statement.BindInt64(0, icon_id);
+    statement.Run();
+  }
+
+  // The bitmaps and mappings for all deleted favicons are deleted at once.
+  DeleteOrphanagedFaviconBitmaps(&db_);
+  DeleteOrphanagedMappings(&db_);
+}
+
+void ThumbnailDatabase::ClearOldOnDemandFaviconsOneByOne(
+    base::Time deletion_threshold) {
+  // Select all bitmaps (and their page URLs) that have not been accessed for a
+  // while. Restrict to on-demand bitmaps (i.e. with last_requested != 0).
+  sql::Statement delete_candidates(db_.GetCachedStatement(
+      SQL_FROM_HERE,
+      "SELECT favicon_bitmaps.icon_id, icon_mapping.page_url FROM "
+      "favicon_bitmaps, icon_mapping WHERE favicon_bitmaps.icon_id = "
+      "icon_mapping.icon_id AND favicon_bitmaps.last_requested>0 AND "
+      "favicon_bitmaps.last_requested<?;"));
+  delete_candidates.BindInt64(0, deletion_threshold.ToInternalValue());
+
+  // 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;
+  while (delete_candidates.Step()) {
+    favicon_base::FaviconID icon_id = delete_candidates.ColumnInt64(0);
+    if (ids_of_icons_with_some_bookmarked_page.count(icon_id))
+      continue;
+
+    GURL page_url = GURL(delete_candidates.ColumnString(1));
+    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) {
+    sql::Statement statement(db_.GetCachedStatement(
+        SQL_FROM_HERE, "DELETE FROM favicons WHERE id=?"));
+    statement.BindInt64(0, icon_id);
+    statement.Run();
+
+    sql::Statement statement2(db_.GetCachedStatement(
+        SQL_FROM_HERE, "DELETE FROM favicon_bitmaps WHERE icon_id=?"));
+    statement2.BindInt64(0, icon_id);
+    statement2.Run();
+
+    sql::Statement statement3(db_.GetCachedStatement(
+        SQL_FROM_HERE, "DELETE FROM icon_mapping WHERE icon_id=?"));
+    statement3.BindInt64(0, icon_id);
+    statement3.Run();
+  }
+}
+
+void ThumbnailDatabase::ClearOldOnDemandFaviconsNoJoin(
+    base::Time deletion_threshold) {
+  // Select all bitmaps (and their page URLs) that have not been accessed for a
+  // while. Restrict to on-demand bitmaps (i.e. with last_requested != 0).
+  sql::Statement delete_candidates(
+      db_.GetCachedStatement(SQL_FROM_HERE,
+                             "SELECT icon_id FROM favicon_bitmaps WHERE "
+                             "favicon_bitmaps.last_requested>0 AND "
+                             "favicon_bitmaps.last_requested<?;"));
+  delete_candidates.BindInt64(0, deletion_threshold.ToInternalValue());
+
+  // 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;
+  while (delete_candidates.Step()) {
+    favicon_base::FaviconID icon_id = delete_candidates.ColumnInt64(0);
+    if (ids_of_icons_with_some_bookmarked_page.count(icon_id))
+      continue;
+
+    ids_of_icons_with_no_bookmarked_page.insert(icon_id);
+
+    if (!backend_client_)
+      continue;
+
+    sql::Statement delete_candidate_urls(db_.GetCachedStatement(
+        SQL_FROM_HERE,
+        "SELECT page_url FROM icon_mapping WHERE icon_mapping.icon_id=?;"));
+    delete_candidate_urls.BindInt64(0, icon_id);
+
+    while (delete_candidate_urls.Step()) {
+      GURL page_url = GURL(delete_candidate_urls.ColumnString(0));
+      if (!backend_client_->IsBookmarked(page_url))
+        continue;
+
+      ids_of_icons_with_some_bookmarked_page.insert(icon_id);
+      ids_of_icons_with_no_bookmarked_page.erase(icon_id);
+      break;
+    }
+  }
+
+  for (favicon_base::FaviconID icon_id : ids_of_icons_with_no_bookmarked_page) {
+    sql::Statement statement(db_.GetCachedStatement(
+        SQL_FROM_HERE, "DELETE FROM favicons WHERE id=?"));
+    statement.BindInt64(0, icon_id);
+    statement.Run();
+  }
+
+  // The bitmaps and mappings for all deleted favicons are deleted at once.
+  DeleteOrphanagedFaviconBitmaps(&db_);
+  DeleteOrphanagedMappings(&db_);
+}
+
 bool ThumbnailDatabase::GetFaviconBitmapIDSizes(
     favicon_base::FaviconID icon_id,
     std::vector<FaviconBitmapIDSize>* bitmap_id_sizes) {