/**
 *    Copyright (C) 2015 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/executor/task_executor.h"
#include "mongo/s/query/async_results_merger.h"
#include "mongo/s/query/cluster_client_cursor_params.h"
#include "mongo/s/query/router_exec_stage.h"
#include "mongo/util/net/hostandport.h"

namespace mongo {

/**
 * Draws results from the AsyncShardResultsMerger, which is the underlying source of the stream of
 * merged documents manipulated by the MergerPlanStage pipeline. Used to present a stream of
 * documents merged from the shards to the stages later in the pipeline.
 */
class RouterStageMerge final : public RouterExecStage {
public:
    RouterStageMerge(executor::TaskExecutor* executor, ClusterClientCursorParams* params);

    StatusWith<ClusterQueryResult> next(OperationContext* txn) final;

    void kill(OperationContext* txn) final;

    bool remotesExhausted() final;

    Status setAwaitDataTimeout(Milliseconds awaitDataTimeout) final;

private:
    // Not owned here.
    executor::TaskExecutor* _executor;

    // Schedules remote work and merges results from 'remotes'.
    AsyncResultsMerger _arm;
};

}  // namespace mongo