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use crate::core::{ElectionCore, State};
use crate::error::{to_storage_error, Result};
use crate::msg::Message;
use crate::{ElectionType, Event, HardState, InitialMode, Storage};
use crossbeam_channel::RecvTimeoutError;
use fxhash::FxHashSet;
pub struct Startup<'a, T: ElectionType> {
core: &'a mut ElectionCore<T>,
}
impl<'a, T: ElectionType> Startup<'a, T> {
#[inline]
pub fn new(core: &'a mut ElectionCore<T>) -> Self {
Self { core }
}
/// Note: No field will be changed If it returns error.
#[inline]
fn init_with_members(
&mut self,
members: Vec<T::NodeId>,
initial_mode: InitialMode,
set_prev_state: Option<&mut bool>,
) -> Result<()> {
let mut peers = FxHashSet::with_hasher(Default::default());
for m in members.into_iter().filter(|m| m != self.core.node_id()) {
peers.try_reserve(1)?;
peers.insert(m);
}
let member_num = peers.len() + 1;
if initial_mode == InitialMode::AsObserver {
self.core.set_state(State::Observer, set_prev_state);
info!(
"[{}][Term({})] this node is initialized with {} members, and transit to observer",
self.core.node_id(),
self.core.current_term(),
member_num
);
} else if initial_mode == InitialMode::AsCandidate {
self.core.set_state(State::PreCandidate, set_prev_state);
info!(
"[{}][Term({})] this node is initialized with {} members, and transit to pre-candidate",
self.core.node_id(),
self.core.current_term(),
member_num
);
} else if initial_mode == InitialMode::AsLeader || peers.is_empty() {
let hard_state = HardState {
current_term: self.core.current_term() + 1,
voted_for: Some(self.core.node_id().clone()),
};
self.core
.storage
.save_hard_state(&hard_state)
.map_err(to_storage_error::<T>)?;
self.core.hard_state = hard_state;
self.core.set_state(State::Leader, set_prev_state);
if initial_mode == InitialMode::AsLeader {
info!(
"[{}][Term({})] this node is forced to be leader",
self.core.node_id(),
self.core.current_term()
);
} else {
info!(
"[{}][Term({})] this node is initialized without other members, so directly transit to leader",
self.core.node_id(),
self.core.current_term()
);
}
} else {
// Do not to change to PreCandidate/Candidate,
// because we need to ensure that restarted nodes don't disrupt a stable cluster.
self.core.set_state(State::Follower, set_prev_state);
info!(
"[{}][Term({})] this node is initialized with {} members, and transit to follower",
self.core.node_id(),
self.core.current_term(),
member_num
);
}
self.core.members.init_peers(peers);
// The metrics will be updated in next state.
Ok(())
}
pub fn run(mut self) {
self.core.increase_state_id();
// Use set_prev_state to ensure prev_state can be set at most once.
let mut set_prev_state = Some(true);
assert!(self.core.is_state(State::Startup));
let _result = self.core.spawn_event_handling_task(Event::Startup);
let state = match self.core.storage.load_hard_state() {
Ok(s) => s,
Err(e) => {
error!(
"[{}][Term({})] this node is shutting down caused by fatal storage error: {}",
self.core.node_id(),
self.core.current_term(),
e
);
self.core.set_state(State::Shutdown, set_prev_state.as_mut());
return;
}
};
self.core.set_hard_state(state);
self.core.report_metrics();
info!(
"[{}][Term({})] start the startup loop",
self.core.node_id(),
self.core.current_term()
);
loop {
if !self.core.is_state(State::Startup) {
return;
}
let election_timeout = self.core.next_election_timeout();
match self.core.msg_rx.recv_deadline(election_timeout) {
Ok(msg) => {
match msg {
Message::Initialize {
members,
initial_mode,
tx,
} => {
let _ = tx.send(self.init_with_members(members, initial_mode, set_prev_state.as_mut()));
}
Message::UpdateOptions { options, tx } => {
info!(
"[{}][Term({})] election update options: {:?}",
self.core.node_id(),
self.core.current_term(),
options
);
self.core.update_options(options);
let _ = tx.send(Ok(()));
}
Message::Shutdown => {
info!(
"[{}][Term({})] election received shutdown message",
self.core.node_id(),
self.core.current_term()
);
self.core.set_state(State::Shutdown, set_prev_state.as_mut());
}
Message::EventHandlingResult { event, error, term, .. } => {
if let Some(e) = error {
error!(
"[{}][Term({})] failed to handle event ({:?}) in term {}: {} ",
self.core.node_id(),
self.core.current_term(),
event,
term,
e
);
}
}
Message::MoveLeader { tx, .. } => {
self.core.reject_move_leader(tx);
}
Message::MoveLeaderRequest { tx, .. } => {
self.core.reject_move_leader(tx);
}
Message::StepUpToLeader { tx, .. } => {
self.core.reject_step_up_to_leader(tx);
}
Message::StepDownToFollower { tx } => {
self.core.reject_step_down_to_follower(tx);
}
Message::HeartbeatRequest { .. } => {
// ignore heart message in startup state
// tx is dropped here, so user will receive a error
}
Message::HeartbeatResponse(_) => {
// ignore heartbeat response in startup state
}
Message::VoteRequest { .. } => {
// ignore vote request message in startup state
// tx is dropped here, so user will receive a error
}
Message::VoteResponse(_) => {
// ignore vote response in startup state
}
}
}
Err(e) => match e {
RecvTimeoutError::Timeout => {
self.core.next_election_timeout = None;
continue;
}
RecvTimeoutError::Disconnected => {
info!(
"[{}][Term({})] the election message channel is disconnected",
self.core.node_id(),
self.core.current_term()
);
self.core.set_state(State::Shutdown, set_prev_state.as_mut());
}
},
}
}
}
}