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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 <vector>
#include "mongo/executor/remote_command_request.h"
#include "mongo/executor/remote_command_response.h"
namespace mongo {
namespace repl {
/**
* Interface for a specialization of a scatter-gather algorithm that sends
* requests to a set of targets, and then processes responses until it has
* seen enough.
*
* To use, call getRequests() to get a vector of request objects describing network operations.
* Start performing the network operations in any order, and then, until
* hasReceivedSufficientResponses() returns true, call processResponse for each response as it
* arrives. Once hasReceivedSufficientResponses() you may cancel outstanding network
* operations, and must stop calling processResponse. Implementations of this interface may
* assume that processResponse() is never called after hasReceivedSufficientResponses() returns
* true.
*/
class ScatterGatherAlgorithm {
public:
/**
* Returns the list of requests that should be sent.
*/
virtual std::vector<executor::RemoteCommandRequest> getRequests() const = 0;
/**
* Method to call once for each received response.
*/
virtual void processResponse(const executor::RemoteCommandRequest& request,
const executor::RemoteCommandResponse& response) = 0;
/**
* Returns true if no more calls to processResponse are needed to consider the
* algorithm complete. Once this method returns true, one should no longer
* call processResponse.
*/
virtual bool hasReceivedSufficientResponses() const = 0;
protected:
virtual ~ScatterGatherAlgorithm(); // Shouldn't actually be virtual.
};
} // namespace repl
} // namespace mongo
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