openraft 0.10.0-alpha.18

Advanced Raft consensus
Documentation 
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use std::sync::Arc;
use std::time::Duration;

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

use crate::Membership;
use crate::MembershipState;
use crate::Vote;
use crate::core::ServerState;
use crate::engine::Command;
use crate::engine::Engine;
use crate::engine::LogIdList;
use crate::engine::TargetProgress;
use crate::engine::testing::UTConfig;
use crate::engine::testing::log_id;
use crate::progress::Inflight;
use crate::progress::Progress;
use crate::progress::entry::ProgressEntry;
use crate::progress::inflight_id::InflightId;
use crate::progress::stream_id::StreamId;
use crate::replication::payload::Payload;
use crate::replication::replicate::Replicate;
use crate::type_config::TypeConfigExt;
use crate::type_config::alias::EffectiveMembershipOf;
use crate::utime::Leased;
use crate::vote::raft_vote::RaftVoteExt;

fn m01() -> Membership<u64, ()> {
    Membership::<u64, ()>::new_with_defaults(vec![btreeset! {0,1}], [])
}

fn m23() -> Membership<u64, ()> {
    Membership::<u64, ()>::new_with_defaults(vec![btreeset! {2,3}], [])
}

fn m23_45() -> Membership<u64, ()> {
    Membership::<u64, ()>::new_with_defaults(vec![btreeset! {2,3}], btreeset! {4,5})
}

fn m34() -> Membership<u64, ()> {
    Membership::<u64, ()>::new_with_defaults(vec![btreeset! {3,4}], [])
}

fn m4_356() -> Membership<u64, ()> {
    Membership::<u64, ()>::new_with_defaults(vec![btreeset! {4}], btreeset! {3,5,6})
}

fn eng() -> Engine<UTConfig> {
    let mut eng = Engine::testing_default(0);
    eng.config.id = 2;
    eng.state.membership_state = MembershipState::new(
        Arc::new(EffectiveMembershipOf::<UTConfig>::new(Some(log_id(1, 1, 1)), m01())),
        Arc::new(EffectiveMembershipOf::<UTConfig>::new(Some(log_id(2, 1, 3)), m23())),
    );
    eng.state.vote = Leased::new(
        UTConfig::<()>::now(),
        Duration::from_millis(500),
        Vote::new_committed(6, 2),
    );
    eng.state.server_state = eng.calc_server_state();
    eng
}

#[test]
fn test_leader_append_membership_for_leader() -> anyhow::Result<()> {
    let mut eng = eng();
    // Make it a real leader: voted for itself and vote is committed.
    eng.testing_new_leader();
    eng.output.take_commands();

    eng.replication_handler().append_membership(&log_id(3, 1, 4), &m34());

    assert_eq!(
        MembershipState::new(
            Arc::new(EffectiveMembershipOf::<UTConfig>::new(Some(log_id(2, 1, 3)), m23())),
            Arc::new(EffectiveMembershipOf::<UTConfig>::new(Some(log_id(3, 1, 4)), m34()))
        ),
        eng.state.membership_state
    );
    assert_eq!(
        ServerState::Leader,
        eng.state.server_state,
        "Leader wont be affected by membership change"
    );

    assert_eq!(
        vec![
            //
            Command::RebuildReplicationStreams {
                leader_vote: Vote::new(6, 2).into_committed(),
                targets: vec![
                    TargetProgress {
                        target: 3,
                        target_node: (),
                        progress: ProgressEntry::empty(StreamId::new(2), 0),
                    },
                    TargetProgress {
                        target: 4,
                        target_node: (),
                        progress: ProgressEntry::empty(StreamId::new(5), 0),
                    }
                ], /* node-2 is leader,
                    * won't be removed */
                close_old_streams: false,
            },
            // Pipeline mode kicks in for new followers
            Command::Replicate {
                target: 3,
                req: Replicate {
                    inflight_id: InflightId::new(1),
                    payload: Payload::LogsSince { prev: None },
                },
            },
            Command::Replicate {
                target: 4,
                req: Replicate {
                    inflight_id: InflightId::new(2),
                    payload: Payload::LogsSince { prev: None },
                },
            },
        ],
        eng.output.take_commands()
    );

    assert!(
        eng.leader.as_ref().unwrap().progress.get(&4).matching().is_none(),
        "exists, but it is a None"
    );

    Ok(())
}

#[test]
fn test_leader_append_membership_update_learner_process() -> anyhow::Result<()> {
    // When updating membership, voter progress should inherit from learner progress, and
    // learner process should inherit from voter process. If voter changes to
    // learner or vice versa.

    let mut eng = eng();
    // Last-per-leader format: leader (0,0) last at 0, leader (1,1) last at 9, leader (5,1) last at 10
    // This preserves the original ranges: (1,1) covers indices 1-9, (5,1) covers index 10
    eng.state.log_ids = LogIdList::new(None, [log_id(0, 0, 0), log_id(1, 1, 9), log_id(5, 1, 10)]);

    eng.state.membership_state.set_effective(Arc::new(EffectiveMembershipOf::<UTConfig>::new(
        Some(log_id(2, 1, 3)),
        m23_45(),
    )));

    // Make it a real leader: voted for itself and vote is committed.
    eng.testing_new_leader();

    if let Some(l) = &mut eng.leader.as_mut() {
        assert_eq!(&ProgressEntry::empty(StreamId::new(3), 11), l.progress.get(&4));
        assert_eq!(&ProgressEntry::empty(StreamId::new(4), 11), l.progress.get(&5));

        let p = ProgressEntry::testing_new(Some(log_id(1, 1, 4)));
        l.progress.update(&4, p.clone()).ok();
        assert_eq!(&p, l.progress.get(&4));

        let p = ProgressEntry::testing_new(Some(log_id(1, 1, 5)));
        l.progress.update(&5, p.clone()).ok();
        assert_eq!(&p, l.progress.get(&5));

        let p = ProgressEntry::testing_new(Some(log_id(1, 1, 3)));
        l.progress.update(&3, p.clone()).ok();
        assert_eq!(&p, l.progress.get(&3));
    } else {
        unreachable!("leader should not be None");
    }

    eng.replication_handler().append_membership(&log_id(3, 1, 4), &m4_356());

    assert_eq!(
        MembershipState::new(
            Arc::new(EffectiveMembershipOf::<UTConfig>::new(Some(log_id(2, 1, 3)), m23_45())),
            Arc::new(EffectiveMembershipOf::<UTConfig>::new(Some(log_id(3, 1, 4)), m4_356()))
        ),
        eng.state.membership_state
    );

    if let Some(l) = &mut eng.leader.as_mut() {
        // Progress entries with matching.next_index() == searching_end enter pipeline mode
        assert_eq!(
            &ProgressEntry::testing_new(Some(log_id(1, 1, 4)))
                .with_inflight(Inflight::logs_since(Some(log_id(1, 1, 4)), InflightId::new(1))),
            l.progress.get(&4),
            "learner-4 progress should be transferred to voter progress (pipeline mode)"
        );

        assert_eq!(
            &ProgressEntry::testing_new(Some(log_id(1, 1, 3)))
                .with_inflight(Inflight::logs_since(Some(log_id(1, 1, 3)), InflightId::new(2))),
            l.progress.get(&3),
            "voter-3 progress should be transferred to learner progress (pipeline mode)"
        );

        assert_eq!(
            &ProgressEntry::testing_new(Some(log_id(1, 1, 5)))
                .with_inflight(Inflight::logs_since(Some(log_id(1, 1, 5)), InflightId::new(3))),
            l.progress.get(&5),
            "learner-5 has previous value (pipeline mode)"
        );

        // Node 6 is new, with matching=None and searching_end=11
        // matching.next_index()=0 != searching_end=11, so NOT pipeline mode
        assert_eq!(
            &ProgressEntry::empty(StreamId::new(9), 11).with_inflight(Inflight::logs(
                None,
                Some(log_id(5, 1, 10)),
                InflightId::new(4)
            )),
            l.progress.get(&6),
            "node-6 is new, not pipeline mode"
        );
    } else {
        unreachable!("leader should not be None");
    }

    Ok(())
}