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//! Defines the [`Event`] enum and related types.
use std::sync::Arc;
use crate::invocation::CoordNumOf;
use crate::invocation::EffectOf;
use crate::invocation::EjectionOf;
use crate::invocation::FrozenStateOf;
use crate::invocation::Invocation;
use crate::invocation::LogEntryOf;
use crate::invocation::NodeOf;
use crate::invocation::RoundNumOf;
use crate::invocation::SnapshotFor;
use crate::invocation::StateOf;
use crate::node::NodeStatus;
use crate::RoundNum;
/// Emitted by `Node`'s [`poll_events`][crate::Node::poll_events] method.
#[non_exhaustive]
pub enum Event<I: Invocation> {
/// First event that is fired immediately after construction.
Init {
/// Initial status of the node.
status: NodeStatus,
/// Round the node is in.
round: RoundNumOf<I>,
/// Initial state or `None` when no snapshot was given.
state: Option<Arc<FrozenStateOf<I>>>,
},
/// Node's status changed.
StatusChange {
/// Old status.
old_status: NodeStatus,
/// New status.
new_status: NodeStatus,
},
/// The node is transitioning to [partially active
/// participation][crate::node::Participation].
Activate(RoundNumOf<I>),
/// A snapshot was installed.
Install {
/// Round node is in after a snapshot was installed.
round: RoundNumOf<I>,
/// State the node is in after a snapshot was installed.
state: Option<Arc<FrozenStateOf<I>>>,
},
/// An entry has been committed to the log.
///
/// The event does not imply that the entry was applied to the shared state.
Commit {
/// The round for which `log_entry` was committed.
round: RoundNumOf<I>,
/// The log entry which was committed.
log_entry: Arc<LogEntryOf<I>>,
},
/// The next log entry was applied to the state.
Apply {
/// Round the log entry was applied in.
round: RoundNumOf<I>,
/// Log entry that was applied.
log_entry: Arc<LogEntryOf<I>>,
/// The event data that the application.
effect: EffectOf<I>,
/// Concurrency after this apply.
new_concurrency: std::num::NonZeroUsize,
},
/// A log entry was queued, preceeding entries are still missing.
///
/// Note: This event is emitted even when the queued entry is within the
/// concurrency bound or if this node created the gap itself. The second
/// case can arise when the leader tries to concurrently append multiple
/// entries and abandons some of the earlier appends.
Gaps(Vec<Gap<RoundNumOf<I>>>),
/// This node received a (potentially indirect) directive for the given
/// round and from the given node. The node used the mandate obtained with
/// the given coordination number to issue the directive.
///
/// This event is not emitted when this node is disoriented or lagging.
Directive {
/// Kind of directive, either `Prepare`, `Accept` or `Commit`.
kind: DirectiveKind,
/// Leader that issued the directive.
leader: NodeOf<I>,
/// Round for which the directive was issued.
round_num: RoundNumOf<I>,
/// Coordination number with which the directive was issued.
coord_num: CoordNumOf<I>,
/// Time the directive was (locally) registered.
timestamp: instant::Instant,
},
/// The node ejected its state.
Eject {
/// The reason for the ejection.
reason: EjectionOf<I>,
/// The ejected state.
state: StateOf<I>,
},
}
impl<I: Invocation> std::fmt::Debug for Event<I> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
Event::Init {
status,
round,
state,
} => f
.debug_struct("Event::Init")
.field("status", status)
.field("round", round)
.field("state", state)
.finish(),
Event::StatusChange {
old_status,
new_status,
} => f
.debug_struct("Event::StatusChange")
.field("old_status", old_status)
.field("new_status", new_status)
.finish(),
Event::Activate(round) => f.debug_tuple("Event::Activate").field(round).finish(),
Event::Install { round, state } => f
.debug_struct("Event::Install")
.field("round", round)
.field("state", state)
.finish(),
Event::Commit { round, log_entry } => f
.debug_struct("Event::Commit")
.field("round", round)
.field("log_entry", log_entry)
.finish(),
Event::Apply {
round,
log_entry,
effect: result,
new_concurrency,
} => f
.debug_struct("Event::Apply")
.field("round", round)
.field("log_entry", log_entry)
.field("result", result)
.field("new_concurrency", new_concurrency)
.finish(),
Event::Gaps(gaps) => f.debug_tuple("Event::Gaps").field(gaps).finish(),
Event::Directive {
kind,
leader,
round_num,
coord_num,
timestamp,
} => f
.debug_struct("Event::Directive")
.field("kind", kind)
.field("leader", leader)
.field("round_num", round_num)
.field("coord_num", coord_num)
.field("timestamp", timestamp)
.finish(),
Event::Eject { reason, state } => f
.debug_struct("Event::Eject")
.field("reason", reason)
.field("state", state)
.finish(),
}
}
}
/// Gap in the local log.
#[derive(Clone, Debug)]
pub struct Gap<R: RoundNum> {
/// The point in time when the gap appeared.
pub since: instant::Instant,
/// The locations of the gap within the log.
pub rounds: std::ops::Range<R>,
}
/// Kind of directive, see [`Event::Directive`].
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum DirectiveKind {
/// Prepare directive.
Prepare,
/// Accept directive.
Accept,
/// Commit directive.
Commit,
}
/// Emitted by `Shutdown`'s [`poll_shutdown`][crate::Shutdown::poll_shutdown]
/// method.
pub enum ShutdownEvent<I: Invocation> {
/// Regular event emitted during the shutdown process.
Regular(Event<I>),
/// Final event of the shutdown process.
///
/// When this event is received the shutdown procedure has completed.
#[non_exhaustive]
Final {
/// Snapshot that may be used to restart the node via
/// [`resuming_from`][crate::NodeBuilderWithNodeIdAndCommunicator::
/// resuming_from].
snapshot: SnapshotFor<I>,
},
}
impl<I: Invocation> From<Event<I>> for ShutdownEvent<I> {
fn from(e: Event<I>) -> Self {
ShutdownEvent::Regular(e)
}
}
impl<I: Invocation> std::fmt::Debug for ShutdownEvent<I> {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
ShutdownEvent::Regular(e) => f.debug_tuple("ShutdownEvent::Regular").field(e).finish(),
ShutdownEvent::Final { snapshot } => f
.debug_struct("ShutdownEvent::Last")
.field("snapshot", snapshot)
.finish(),
}
}
}