/** * Copyright (C) 2013 10gen Inc. * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License, version 3, * as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see . * * As a special exception, the copyright holders give permission to link the * code of portions of this program with the OpenSSL library under certain * conditions as described in each individual source file and distribute * linked combinations including the program with the OpenSSL library. You * must comply with the GNU Affero General Public License in all respects for * all of the code used other than as permitted herein. If you modify file(s) * with this exception, you may extend this exception to your version of the * file(s), but you are not obligated to do so. If you do not wish to do so, * delete this exception statement from your version. If you delete this * exception statement from all source files in the program, then also delete * it in the license file. */ #include #include "mongo/db/catalog/collection.h" #include "mongo/db/clientcursor.h" namespace mongo { /** * A RangePreserver prevents the RangeDeleter from removing any new data ranges in a collection. * Previously queued ranges may still be deleted but the documents in those ranges will be * filtered by CollectionMetadata::belongsToMe. */ class RangePreserver { public: /** * Sharding uses the set of active cursor IDs as the current state. We pin a dummy * ClientCursor, which creates an additional cursor ID. The cursor ID lasts as long as this * object does. The ClientCursorPin guarantees that the underlying ClientCursor is not deleted * until this object goes out of scope. */ RangePreserver(const Collection* collection) { // Empty collections don't have any data we need to preserve if (collection) { // Pin keeps the CC from being deleted while it's in scope. We delete it ourselves. _pin.emplace(collection->getCursorManager()->registerRangePreserverCursor(collection)); } } void release() { if (_pin) { _pin->deleteUnderlying(); _pin.reset(); } } ~RangePreserver() { release(); } private: boost::optional _pin; }; } // namespace mongo