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/**
* Copyright (C) 2017 MongoDB 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 <http://www.gnu.org/licenses/>.
*
* 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.
*/
#pragma once
#include "mongo/base/string_data.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/catalog/database.h"
#include "mongo/db/concurrency/d_concurrency.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/views/view.h"
namespace mongo {
/**
* RAII-style class, which acquires a lock on the specified database in the requested mode and
* obtains a reference to the database. Used as a shortcut for calls to
* DatabaseHolder::getDatabaseHolder().get().
*
* Use this when you want to do a database-level operation, like read a list of all collections, or
* drop a collection.
*
* It is guaranteed that the lock will be released when this object goes out of scope, therefore
* the database reference returned by this class should not be retained.
*/
class AutoGetDb {
MONGO_DISALLOW_COPYING(AutoGetDb);
public:
AutoGetDb(OperationContext* opCtx,
StringData dbName,
LockMode mode,
Date_t deadline = Date_t::max());
/**
* Returns nullptr if the database didn't exist.
*/
Database* getDb() const {
return _db;
}
private:
const Lock::DBLock _dbLock;
Database* const _db;
};
/**
* RAII-style class, which acquires a locks on the specified database and collection in the
* requested modes and obtains references to both.
*
* NOTE: Throws NamespaceNotFound if the collection UUID cannot be resolved to a name.
*
* Any acquired locks may be released when this object goes out of scope, therefore the database
* and the collection references returned by this class should not be retained.
*/
class AutoGetCollection {
MONGO_DISALLOW_COPYING(AutoGetCollection);
public:
enum ViewMode { kViewsPermitted, kViewsForbidden };
AutoGetCollection(OperationContext* opCtx,
const NamespaceStringOrUUID& nsOrUUID,
LockMode modeAll,
ViewMode viewMode = kViewsForbidden,
Date_t deadline = Date_t::max())
: AutoGetCollection(opCtx, nsOrUUID, modeAll, modeAll, viewMode, deadline) {}
AutoGetCollection(OperationContext* opCtx,
const NamespaceStringOrUUID& nsOrUUID,
LockMode modeDB,
LockMode modeColl,
ViewMode viewMode = kViewsForbidden,
Date_t deadline = Date_t::max());
/**
* Without acquiring any locks resolves the given NamespaceStringOrUUID to an actual namespace.
* Throws NamespaceNotFound if the collection UUID cannot be resolved to a name, or if the UUID
* can be resolved, but the resulting collection is in the wrong database.
*/
static NamespaceString resolveNamespaceStringOrUUID(OperationContext* opCtx,
NamespaceStringOrUUID nsOrUUID);
/**
* Returns nullptr if the database didn't exist.
*/
Database* getDb() const {
return _autoDb.getDb();
}
/**
* Returns nullptr if the collection didn't exist.
*/
Collection* getCollection() const {
return _coll;
}
/**
* Returns nullptr if the view didn't exist.
*/
ViewDefinition* getView() const {
return _view.get();
}
/**
* Returns the resolved namespace of the collection or view.
*/
const NamespaceString& getNss() const {
return _resolvedNss;
}
private:
// If the object was instantiated with a UUID, contains the resolved namespace, otherwise it is
// the same as the input namespace string
NamespaceString _resolvedNss;
AutoGetDb _autoDb;
// This field is boost::optional, because in the case of lookup by UUID, the collection lock
// might need to be relocked for the correct namespace
boost::optional<Lock::CollectionLock> _collLock;
Collection* _coll = nullptr;
std::shared_ptr<ViewDefinition> _view;
};
/**
* RAII-style class, which acquires a lock on the specified database in the requested mode and
* obtains a reference to the database, creating it was non-existing. Used as a shortcut for
* calls to DatabaseHolder::getDatabaseHolder().openDb(), taking care of locking details. The
* requested mode must be MODE_IX or MODE_X. If the database needs to be created, the lock will
* automatically be reacquired as MODE_X.
*
* Use this when you are about to perform a write, and want to create the database if it doesn't
* already exist.
*
* It is guaranteed that locks will be released when this object goes out of scope, therefore
* the database reference returned by this class should not be retained.
*/
class AutoGetOrCreateDb {
MONGO_DISALLOW_COPYING(AutoGetOrCreateDb);
public:
AutoGetOrCreateDb(OperationContext* opCtx,
StringData dbName,
LockMode mode,
Date_t deadline = Date_t::max());
Database* getDb() const {
return _db;
}
bool justCreated() const {
return _justCreated;
}
private:
boost::optional<AutoGetDb> _autoDb;
Database* _db;
bool _justCreated{false};
};
} // namespace mongo
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