Struct BestEffortBroadcast 

pub struct BestEffortBroadcast<P, L = PerfectLink<P>> { /* private fields */ }

Fan-out to every process over perfect links.

L is the link beneath, and it is a parameter rather than a fixed type. What this layer needs of it is stated in one bound and nowhere else: Link, the port. Anything satisfying it — a session link, a logged link, or an application’s own driver — can carry this broadcast without either side being edited. That is the seam docs/conditional-guarantees.md describes, made checkable.

Fan-out needs nothing of a scope boundary, so the bound is the port and nothing more. This layer composes over every link there is, and passes a boundary upward untouched because it has no redundancy with which to repair one.

It defaults to PerfectLink, so the ordinary stack is still written BestEffortBroadcast<P>.

Implementations

impl<P, L> BestEffortBroadcast<P, L>

pub fn with_link( me: NodeId, peers: impl IntoIterator<Item = NodeId>, link: L, ) -> Self

Broadcast among peers, which must include me, over a link the caller supplies.

pub fn peers(&self) -> impl Iterator<Item = NodeId> + '_

The processes this broadcasts to, in a stable order.

pub fn link(&self) -> &L

The link beneath, for a caller that has reason to inspect its own.

impl<P> BestEffortBroadcast<P, PerfectLink<P>>

pub fn new( me: NodeId, peers: impl IntoIterator<Item = NodeId>, interval: Duration, ) -> Self

Broadcast among peers, which must include me, over the book’s perfect link.

pub fn delivered_count(&self) -> usize

How many distinct messages the link below has delivered upward.

Specific to the perfect link, so it lives here rather than on every link.

Trait Implementations

impl<P: Debug, L: Debug> Debug for BestEffortBroadcast<P, L>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<P: Clone, L> Protocol for BestEffortBroadcast<P, L>

where L: VolatileLink<P>,

type Scope = <L as Protocol>::Scope

Whatever the link’s guarantees are conditional on, since this layer adds no condition of its own and cannot bridge the link’s.

type Meta = Infallible

Keeps nothing durably: a crash loses everything this protocol knows.

fn on_scope_event(&mut self, scope: L::Scope, cx: &mut ProtoCx<'_, Self>)

Hand the scope ending down to the link, which is the layer that knows what it means.

Scope is the link’s, so leaving this to the trait’s default would take a scope event the driver raised and drop it — the layer above would never learn its guarantees had lapsed, and neither would the link. That is the failure docs/conditional-guarantees.md calls cardinal, and the default is silent about committing it, which is why this handler exists even though its body only forwards.

type Cmd = Cmd<P>

Requests from the layer above.

type Ind = Ind<P>

Indications to the layer above — this protocol delivering on its guarantee.

type Msg = <L as Protocol>::Msg

What crosses the wire to a peer running the same protocol.

type Note = Note

The vocabulary in which this protocol narrates its decisions.

type Entry = Infallible

The durable entries this protocol appends: what accumulates.

fn on_cmd(&mut self, cmd: Cmd<P>, cx: &mut ProtoCx<'_, Self>)

Handle a request from the layer above.

fn on_msg(&mut self, from: NodeId, msg: L::Msg, cx: &mut ProtoCx<'_, Self>)

Handle a message received from from.

fn on_timer(&mut self, id: TimerId, cx: &mut ProtoCx<'_, Self>)

Handle a timer that fired somewhere in this protocol or in what it composes.

fn on_init( &mut self, _cx: &mut Cx<'_, Self::Msg, Self::Ind, Self::Note, Self::Meta, Self::Entry>, )

Begin, on a first start — when nothing has been written down.

fn on_recovery( &mut self, _cx: &mut Cx<'_, Self::Msg, Self::Ind, Self::Note, Self::Meta, Self::Entry>, )

Resume after a crash, reading what survived.