krabka_kraft_core/
action.rs

1//! Outputs from the consensus state machine. They are pure side-effect
2//! descriptions that the engine executes.
3
4use crate::types::{Epoch, LogOffsetMetadata, NodeId, SimInstant};
5
6#[derive(Debug, Clone, PartialEq, Eq, Hash)]
7pub enum TimerKind {
8    Election,
9    Fetch,
10    /// Leader-side check-quorum watchdog (KAFKA-15489). It expires when a
11    /// majority of the voters has not fetched, and the leader then resigns.
12    CheckQuorum,
13}
14
15#[derive(Debug, Clone, PartialEq, Eq, Hash)]
16pub enum Action {
17    /// Broadcast a Vote request to all other voters, as a pre-vote or a real vote.
18    SendVoteRequest { epoch: Epoch, pre_vote: bool },
19    /// Reply to a Vote request.
20    ///
21    /// Kafka's `VoteResponse` carries no pre-vote flag. The candidate matches
22    /// the reply to its round by its own role, so the responder does not echo
23    /// `pre_vote`.
24    ReplyVote {
25        to: NodeId,
26        epoch: Epoch,
27        granted: bool,
28    },
29    /// New leader announces its epoch to all voters.
30    SendBeginQuorumEpoch { epoch: Epoch },
31    /// Resigning leader tells voters to elect.
32    SendEndQuorumEpoch {
33        epoch: Epoch,
34        /// The other voters, most caught up first by the fetch progress the
35        /// leader validated: Kafka's
36        /// `LeaderState.nonLeaderVotersByDescendingFetchOffset`.
37        preferred_successors: Vec<NodeId>,
38    },
39    /// The follower or observer should fetch from this leader.
40    SendFetch { leader_id: NodeId },
41    /// We changed role. The variant carries the new role name for
42    /// observability and for tests.
43    TransitionedTo(&'static str),
44    /// Persist the durable quorum state: epoch, votedKey, or leaderId changed.
45    PersistQuorumState,
46    /// As new leader, append the `LeaderChange` control record for `epoch`.
47    AppendLeaderChange { epoch: Epoch },
48    /// Leader advanced the high watermark.
49    AdvanceHighWatermark(i64),
50    /// Truncate this node's own log to this point. A follower emits it when
51    /// the leader answered its Fetch with a diverging epoch.
52    TruncateTo(LogOffsetMetadata),
53    /// Leader answers the Fetch it is serving with this diverging epoch. It is
54    /// a reply for the follower, and it changes nothing in the leader's own
55    /// log: the leader holds the records the follower must truncate to.
56    ReplyDivergingEpoch(LogOffsetMetadata),
57    /// Arm or re-arm a timer to fire at `deadline`.
58    ResetTimer {
59        kind: TimerKind,
60        deadline: SimInstant,
61    },
62}
krabka_kraft_core/action.rs

krabka_kraft_core/
action.rs
