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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* 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 Server Side 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/executor/task_executor_pool.h"
#include "mongo/s/grid.h"
#include "mongo/s/query/async_results_merger_params_gen.h"
#include "mongo/s/query/establish_cursors.h"
namespace mongo {
/**
* A RAII wrapper class for RemoteCursor which schedules a killCursors request upon destruction if
* the cursor has not been released.
*/
class OwnedRemoteCursor {
public:
MONGO_DISALLOW_COPYING(OwnedRemoteCursor);
OwnedRemoteCursor(OperationContext* opCtx, RemoteCursor&& cursor, NamespaceString nss)
: _opCtx(opCtx), _remoteCursor(std::move(cursor)), _nss(std::move(nss)) {}
~OwnedRemoteCursor() {
if (_remoteCursor) {
killRemoteCursor(_opCtx,
Grid::get(_opCtx)->getExecutorPool()->getArbitraryExecutor(),
releaseCursor(),
_nss);
}
}
OwnedRemoteCursor(OwnedRemoteCursor&& other)
: _opCtx(other._opCtx), _remoteCursor(other.releaseCursor()), _nss(std::move(other._nss)) {}
OwnedRemoteCursor& operator=(OwnedRemoteCursor&& other) {
_remoteCursor = other.releaseCursor();
_opCtx = other._opCtx;
_nss = std::move(other._nss);
return *this;
}
RemoteCursor* operator->() {
invariant(_remoteCursor);
return &(*_remoteCursor);
}
RemoteCursor* operator*() {
invariant(_remoteCursor);
return &(*_remoteCursor);
}
/**
* Transfers ownership of the RemoteCursor to the caller, will not attempt to kill the cursor
* when this object is destroyed.
*/
RemoteCursor releaseCursor() {
auto cursor = std::move(*_remoteCursor);
_remoteCursor.reset();
return cursor;
}
private:
OperationContext* _opCtx;
boost::optional<RemoteCursor> _remoteCursor;
NamespaceString _nss;
};
} // namespace mongo
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