openraft 0.9.24

Advanced Raft consensus
Documentation 
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use std::collections::BTreeSet;
use std::sync::Arc;

use maplit::btreeset;
use pretty_assertions::assert_eq;

use crate::core::ServerState;
use crate::engine::testing::UTConfig;
use crate::engine::Command;
use crate::engine::Engine;
use crate::engine::LogIdList;
use crate::raft::VoteRequest;
use crate::testing::log_id;
use crate::utime::UTime;
use crate::CommittedLeaderId;
use crate::EffectiveMembership;
use crate::LogId;
use crate::Membership;
use crate::TokioInstant;
use crate::Vote;

fn m1() -> Membership<u64, ()> {
    Membership::new(vec![btreeset! {1}], None)
}

fn m12() -> Membership<u64, ()> {
    Membership::new(vec![btreeset! {1,2}], None)
}

fn eng() -> Engine<UTConfig> {
    let mut eng = Engine::default();
    eng.state.log_ids = LogIdList::new([LogId::new(CommittedLeaderId::new(0, 0), 0)]);
    eng.state.enable_validation(false); // Disable validation for incomplete state
    eng
}

#[test]
fn test_elect_single_node() -> anyhow::Result<()> {
    tracing::info!("--- single node: still need to wait for Vote to persist");
    {
        let mut eng = eng();
        eng.config.id = 1;
        eng.state
            .membership_state
            .set_effective(Arc::new(EffectiveMembership::new(Some(log_id(0, 1, 1)), m1())));

        eng.elect();

        assert_eq!(Vote::new(1, 1), *eng.state.vote_ref());
        assert!(eng.leader.is_none());
        assert!(eng.candidate_ref().is_some(), "candidate state is pending");

        assert_eq!(ServerState::Candidate, eng.state.server_state);

        assert_eq!(
            vec![
                //
                Command::SaveVote { vote: Vote::new(1, 1) },
                Command::SendVote {
                    vote_req: VoteRequest {
                        vote: Vote::new(1, 1),
                        last_log_id: Some(log_id(0, 0, 0)),
                    },
                },
            ],
            eng.output.take_commands()
        );
    }

    Ok(())
}

#[test]
fn test_elect_single_node_elect_again() -> anyhow::Result<()> {
    tracing::info!("--- single node: electing again will override previous state");
    {
        let mut eng = eng();
        eng.config.id = 1;
        eng.state
            .membership_state
            .set_effective(Arc::new(EffectiveMembership::new(Some(log_id(0, 1, 1)), m1())));

        // Build in-progress election state
        eng.state.vote = UTime::new(TokioInstant::now(), Vote::new_committed(1, 2));
        eng.testing_new_leader();
        eng.candidate_mut().map(|candidate| candidate.grant_by(&1));

        eng.elect();

        assert_eq!(Vote::new(2, 1), *eng.state.vote_ref());
        assert_eq!(Vote::new(2, 1), *eng.candidate_ref().unwrap().vote_ref());

        assert!(eng.candidate_mut().is_some(), "candidate state is pending");

        assert_eq!(ServerState::Candidate, eng.state.server_state);

        assert_eq!(
            vec![
                //
                Command::SaveVote { vote: Vote::new(2, 1) },
                Command::SendVote {
                    vote_req: VoteRequest {
                        vote: Vote::new(2, 1),
                        last_log_id: Some(log_id(0, 0, 0)),
                    },
                },
            ],
            eng.output.take_commands()
        );
    }
    Ok(())
}

#[test]
fn test_elect_multi_node_enter_candidate() -> anyhow::Result<()> {
    tracing::info!("--- multi nodes: enter candidate state");
    {
        let mut eng = eng();
        eng.config.id = 1;
        eng.state
            .membership_state
            .set_effective(Arc::new(EffectiveMembership::new(Some(log_id(0, 1, 1)), m12())));
        eng.state.log_ids = LogIdList::new(vec![log_id(1, 1, 1)]);

        eng.elect();

        assert_eq!(Vote::new(1, 1), *eng.state.vote_ref());
        assert!(eng.leader.is_none());
        assert_eq!(Vote::new(1, 1), *eng.candidate_ref().unwrap().vote_ref());

        assert_eq!(
            Some(btreeset! {},),
            eng.candidate_ref().map(|x| x.granters().collect::<BTreeSet<_>>())
        );

        assert_eq!(ServerState::Candidate, eng.state.server_state);

        assert_eq!(
            vec![
                //
                Command::SaveVote { vote: Vote::new(1, 1) },
                Command::SendVote {
                    vote_req: VoteRequest::new(Vote::new(1, 1), Some(log_id(1, 1, 1)))
                },
            ],
            eng.output.take_commands()
        );
    }
    Ok(())
}