1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182

use std::sync::Arc;
use std::time::Instant;

use crate::invocation::CoordNumOf;
use crate::invocation::EventOf;
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> {
    Init {
        status: NodeStatus,
        round: RoundNumOf<I>,
        state: Option<Arc<StateOf<I>>>,
    },

    StatusChange {
        old_status: NodeStatus,
        new_status: NodeStatus,
    },

    /// The node is transitioning to [partially active
    /// participation][crate::node::Participation].
    Activate(RoundNumOf<I>),

    /// A snapshot was installed.
    Install {
        round: RoundNumOf<I>,
        state: Arc<StateOf<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: RoundNumOf<I>,
        log_entry: Arc<LogEntryOf<I>>,
        result: EventOf<I>,
    },

    /// 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: DirectiveKind,
        leader: NodeOf<I>,
        round_num: RoundNumOf<I>,
        coord_num: CoordNumOf<I>,
        timestamp: Instant,
    },
}

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,
                result,
            } => f
                .debug_struct("Event::Apply")
                .field("round", round)
                .field("log_entry", log_entry)
                .field("result", result)
                .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(),
        }
    }
}

#[derive(Clone, Debug)]
pub struct Gap<R: RoundNum> {
    /// The point in time when the gap appeared.
    pub since: std::time::Instant,

    /// The locations of the gap within the log.
    pub rounds: std::ops::Range<R>,
}

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum DirectiveKind {
    Prepare,
    Accept,
    Commit,
}

/// Emitted by `Shutdown`'s [`poll_shutdown`][crate::Shutdown::poll_shutdown]
/// method.
pub enum ShutdownEvent<I: Invocation> {
    Regular(Event<I>),
    #[non_exhaustive]
    Last {
        snapshot: Option<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::Last { snapshot } => f
                .debug_struct("ShutdownEvent::Last")
                .field("snapshot", snapshot)
                .finish(),
        }
    }
}