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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.
*/
#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kReplicationElection
#include "mongo/platform/basic.h"
#include "mongo/db/repl/vote_requester.h"
#include <memory>
#include "mongo/base/status.h"
#include "mongo/db/repl/repl_set_request_votes_args.h"
#include "mongo/db/repl/scatter_gather_runner.h"
#include "mongo/logv2/log.h"
#include "mongo/rpc/get_status_from_command_result.h"
namespace mongo {
namespace repl {
namespace {
const Milliseconds maximumVoteRequestTimeoutMS(30 * 1000);
} // namespace
using executor::RemoteCommandRequest;
using executor::RemoteCommandResponse;
VoteRequester::Algorithm::Algorithm(const ReplSetConfig& rsConfig,
long long candidateIndex,
long long term,
bool dryRun,
OpTime lastAppliedOpTime,
int primaryIndex)
: _rsConfig(rsConfig),
_candidateIndex(candidateIndex),
_term(term),
_dryRun(dryRun),
_lastAppliedOpTime(lastAppliedOpTime) {
// populate targets with all voting members that aren't this node
long long index = 0;
for (auto member = _rsConfig.membersBegin(); member != _rsConfig.membersEnd(); member++) {
if (member->isVoter() && index != candidateIndex) {
_targets.push_back(member->getHostAndPort());
}
if (index == primaryIndex) {
_primaryHost = member->getHostAndPort();
}
index++;
}
}
VoteRequester::Algorithm::~Algorithm() {}
std::vector<RemoteCommandRequest> VoteRequester::Algorithm::getRequests() const {
BSONObjBuilder requestVotesCmdBuilder;
requestVotesCmdBuilder.append("replSetRequestVotes", 1);
requestVotesCmdBuilder.append("setName", _rsConfig.getReplSetName());
requestVotesCmdBuilder.append("dryRun", _dryRun);
requestVotesCmdBuilder.append("term", _term);
requestVotesCmdBuilder.append("candidateIndex", _candidateIndex);
requestVotesCmdBuilder.append("configVersion", _rsConfig.getConfigVersion());
if (_rsConfig.getConfigTerm() != -1) {
requestVotesCmdBuilder.append("configTerm", _rsConfig.getConfigTerm());
}
_lastAppliedOpTime.append(&requestVotesCmdBuilder, "lastAppliedOpTime");
const BSONObj requestVotesCmd = requestVotesCmdBuilder.obj();
std::vector<RemoteCommandRequest> requests;
for (const auto& target : _targets) {
requests.push_back(RemoteCommandRequest(
target,
"admin",
requestVotesCmd,
nullptr,
std::min(_rsConfig.getElectionTimeoutPeriod(), maximumVoteRequestTimeoutMS)));
}
return requests;
}
void VoteRequester::Algorithm::processResponse(const RemoteCommandRequest& request,
const RemoteCommandResponse& response) {
ReplSetRequestVotesResponse voteResponse;
Status status = Status::OK();
// All local variables captured in logAttrs needs to be above the guard that logs.
logv2::DynamicAttributes logAttrs;
auto logAtExit =
ScopeGuard([&logAttrs]() { LOGV2(51799, "VoteRequester processResponse", logAttrs); });
logAttrs.add("term", _term);
logAttrs.add("dryRun", _dryRun);
_responsesProcessed++;
if (!response.isOK()) { // failed response
logAttrs.add("failReason", "failed to receive response"_sd);
logAttrs.add("error", response.status);
logAttrs.add("from", request.target);
return;
}
_responders.insert(request.target);
// If the primary's vote is a yes, we will set _primaryVote to be Yes.
if (_primaryHost == request.target) {
_primaryVote = PrimaryVote::No;
}
status = getStatusFromCommandResult(response.data);
if (status.isOK()) {
status = voteResponse.initialize(response.data);
}
if (!status.isOK()) {
logAttrs.add("failReason", "received an invalid response"_sd);
logAttrs.add("error", status);
logAttrs.add("from", request.target);
logAttrs.add("message", response.data);
return;
}
if (voteResponse.getVoteGranted()) {
logAttrs.add("vote", "yes"_sd);
logAttrs.add("from", request.target);
if (_primaryHost == request.target) {
_primaryVote = PrimaryVote::Yes;
}
_votes++;
} else {
logAttrs.add("vote", "no"_sd);
logAttrs.add("from", request.target);
logAttrs.add("reason", voteResponse.getReason());
}
if (voteResponse.getTerm() > _term) {
_staleTerm = true;
}
logAttrs.add("message", response.data);
}
bool VoteRequester::Algorithm::hasReceivedSufficientResponses() const {
if (_primaryHost && _primaryVote == PrimaryVote::No) {
return true;
}
// We require the primary's response during catchup takeover. An error response from the primary
// is not a yes, no or pending, but is still a response. Therefore, we handle the case in which
// we have received some response (even if error) from all nodes first.
if (_responsesProcessed == static_cast<int>(_targets.size())) {
return true;
}
if (_primaryHost && _primaryVote == PrimaryVote::Pending) {
return false;
}
return _staleTerm || _votes >= _rsConfig.getMajorityVoteCount();
}
VoteRequester::Result VoteRequester::Algorithm::getResult() const {
if (_staleTerm) {
return Result::kStaleTerm;
} else if (_primaryHost && _primaryVote != PrimaryVote::Yes) {
return Result::kPrimaryRespondedNo;
} else if (_votes >= _rsConfig.getMajorityVoteCount()) {
return Result::kSuccessfullyElected;
} else {
return Result::kInsufficientVotes;
}
}
stdx::unordered_set<HostAndPort> VoteRequester::Algorithm::getResponders() const {
return _responders;
}
VoteRequester::VoteRequester() {}
VoteRequester::~VoteRequester() {}
StatusWith<executor::TaskExecutor::EventHandle> VoteRequester::start(
executor::TaskExecutor* executor,
const ReplSetConfig& rsConfig,
long long candidateIndex,
long long term,
bool dryRun,
OpTime lastAppliedOpTime,
int primaryIndex) {
_algorithm = std::make_shared<Algorithm>(
rsConfig, candidateIndex, term, dryRun, lastAppliedOpTime, primaryIndex);
_runner = std::make_unique<ScatterGatherRunner>(_algorithm, executor, "vote request");
return _runner->start();
}
void VoteRequester::cancel() {
_runner->cancel();
}
VoteRequester::Result VoteRequester::getResult() const {
return _algorithm->getResult();
}
stdx::unordered_set<HostAndPort> VoteRequester::getResponders() const {
return _algorithm->getResponders();
}
} // namespace repl
} // namespace mongo
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