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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 <functional>
#include <memory>
#include <vector>
#include "mongo/bson/timestamp.h"
#include "mongo/db/repl/optime.h"
#include "mongo/db/repl/repl_set_config.h"
#include "mongo/db/repl/scatter_gather_algorithm.h"
#include "mongo/db/repl/scatter_gather_runner.h"
#include "mongo/stdx/unordered_set.h"
namespace mongo {
class Status;
namespace repl {
class VoteRequester {
VoteRequester(const VoteRequester&) = delete;
VoteRequester& operator=(const VoteRequester&) = delete;
public:
enum class Result {
kSuccessfullyElected,
kStaleTerm,
kInsufficientVotes,
kPrimaryRespondedNo,
kCancelled
};
class Algorithm : public ScatterGatherAlgorithm {
public:
Algorithm(const ReplSetConfig& rsConfig,
long long candidateIndex,
long long term,
bool dryRun,
OpTime lastAppliedOpTime,
int primaryIndex);
virtual ~Algorithm();
virtual std::vector<executor::RemoteCommandRequest> getRequests() const;
virtual void processResponse(const executor::RemoteCommandRequest& request,
const executor::RemoteCommandResponse& response);
virtual bool hasReceivedSufficientResponses() const;
/**
* Returns a VoteRequest::Result indicating the result of the election.
*
* It is invalid to call this before hasReceivedSufficientResponses returns true.
*/
Result getResult() const;
/**
* Returns the list of nodes that responded to the VoteRequest command.
*/
stdx::unordered_set<HostAndPort> getResponders() const;
private:
enum class PrimaryVote { Pending, Yes, No };
const ReplSetConfig _rsConfig;
const long long _candidateIndex;
const long long _term;
bool _dryRun = false; // this bool indicates this is a mock election when true
const OpTime _lastAppliedOpTime;
std::vector<HostAndPort> _targets;
stdx::unordered_set<HostAndPort> _responders;
bool _staleTerm = false;
long long _responsesProcessed = 0;
long long _votes = 1;
boost::optional<HostAndPort> _primaryHost;
PrimaryVote _primaryVote = PrimaryVote::Pending;
};
VoteRequester();
virtual ~VoteRequester();
/**
* Begins the process of sending replSetRequestVotes commands to all non-DOWN nodes
* in currentConfig, in attempt to receive sufficient votes to win the election.
* If primaryIndex is not -1, then it means that the primary's vote is required
* to win the elction.
*
* evh can be used to schedule a callback when the process is complete.
* If this function returns Status::OK(), evh is then guaranteed to be signaled.
**/
StatusWith<executor::TaskExecutor::EventHandle> start(executor::TaskExecutor* executor,
const ReplSetConfig& rsConfig,
long long candidateIndex,
long long term,
bool dryRun,
OpTime lastAppliedOpTime,
int primaryIndex);
/**
* Informs the VoteRequester to cancel further processing.
*/
void cancel();
Result getResult() const;
stdx::unordered_set<HostAndPort> getResponders() const;
private:
std::shared_ptr<Algorithm> _algorithm;
std::unique_ptr<ScatterGatherRunner> _runner;
};
} // namespace repl
} // namespace mongo
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