public void Test()
{
// Arrange
Election.CurrentTerm = 1;
Election.VotedFor = Guid.NewGuid();
var message = new RequestVoteMessage();
RequestVote.Subscribe((m) =>
{
message = m;
});
// Act
Candidate.RequestElection();
// Assert
Assert.Equal(ServerIdentifier.Id, message.Candidate);
Assert.Equal(Election.CurrentTerm, message.Term);
}
public void VoteRequestReceived(RequestVoteMessage requestVote)
{
if (_serverIdentifier.Equals(requestVote.Candidate))
return;
if (_options.UseLogging)
_logger.LogInformation($"Processing {nameof(VoteRequestReceived)} \n\t\t Candidate {requestVote.Candidate} \n\t\t Term {requestVote.Term}");
if (!_nodes.Contains(requestVote.Candidate))
{
_nodes.Add(requestVote.Candidate);
}
// If your a term ahead you won't vote for that old candidate
if (requestVote.Term < _election.CurrentTerm)
{
_voteReply.OnNext(new RequestVoteResultMessage()
{
From = _serverIdentifier.Id,
Candidate = _election.VotedFor,
Term = _election.CurrentTerm,
VoteGranted = false
});
return;
}
// Your a term behind, you need to vote
if (requestVote.Term > _election.CurrentTerm)
{
_election.CurrentTerm = requestVote.Term;
// Do a check on the candidates log for completeness
var isComplete = LogCompletness(requestVote);
// Candidate looks good for being leader, vote for it
if (isComplete)
{
_election.VotedFor = requestVote.Candidate;
_voteReply.OnNext(new RequestVoteResultMessage()
{
From = _serverIdentifier,
Candidate = _election.VotedFor,
Term = _election.CurrentTerm,
VoteGranted = true,
});
_state?.OnNext(ServerStateType.Follower);
}
// We have detected a inconsistency in the candidate, so we must be a better candidate, votes for ourself
else
{
_election.VotedFor = _serverIdentifier;
_voteReply.OnNext(new RequestVoteResultMessage()
{
From = _serverIdentifier,
Candidate = _election.VotedFor,
Term = _election.CurrentTerm,
VoteGranted = false
});
_state?.OnNext(ServerStateType.Candidate);
}
return;
}
// You've already voted for this term
_voteReply.OnNext(new RequestVoteResultMessage()
{
From = _serverIdentifier.Id,
Candidate = _election.VotedFor, // send back who we voted for too make election more reliable to calculate the winner
Term = _election.CurrentTerm,
VoteGranted = _election.VotedFor == requestVote.Candidate
});
}
// Grants candidate vote if its log is more up-to-date or equal than ours
bool LogCompletness(RequestVoteMessage requestVote)
{
return requestVote.LastLogIndex >= _logReplication.LastApplied &&
requestVote.LastLogTerm >= _logReplication.LastTerm;
}