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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 <boost/optional.hpp>
#include <vector>
#include "mongo/base/disallow_copying.h"
#include "mongo/base/status_with.h"
#include "mongo/bson/bsonobj.h"
#include "mongo/db/cursor_id.h"
#include "mongo/executor/task_executor.h"
#include "mongo/s/query/async_results_merger_params_gen.h"
#include "mongo/stdx/mutex.h"
#include "mongo/util/net/hostandport.h"
#include "mongo/util/time_support.h"
namespace mongo {
class CursorResponse;
/**
* Establishes cursors on the remote shards by issuing requests in parallel, using the readPref to
* select a host within each shard.
*
* If any of the cursors fail to be established, this function performs cleanup by sending
* killCursors to any cursors that were established, then throws the error. If the namespace
* represents a view, an exception containing a ResolvedView is thrown. Calling code can then
* attempt to establish cursors against the base collection using this view.
*
* On success, the ownership of the cursors is transferred to the caller. This means the caller is
* now responsible for either exhausting the cursors or sending killCursors to them.
*
* @param allowPartialResults: If true, unreachable hosts are ignored, and only cursors established
* on reachable hosts are returned.
*
*/
std::vector<RemoteCursor> establishCursors(OperationContext* opCtx,
executor::TaskExecutor* executor,
const NamespaceString& nss,
const ReadPreferenceSetting readPref,
const std::vector<std::pair<ShardId, BSONObj>>& remotes,
bool allowPartialResults);
} // namespace mongo
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