Struct Expected 

pub struct Expected(/* private fields */);

The list the gate is enforcing right now.

A SIGHUP replaces it, so the handle is shared rather than copied: the socket wrapper is built once at bind time and has to see a reload without being rebuilt, since rebuilding it would mean rebinding the port.

Read once per receive batch rather than once per datagram, and written once per reload, so a plain RwLock around an Arc is all the sharing this needs.

The flag beside it answers “is there a list at all” without taking the lock, because an empty list is the shipped default and every release before v0.9.0 behaved that way. A gate that is off then costs a receive batch one atomic load rather than a read guard, an Arc clone and its drop.

Implementations

impl Expected

pub fn new(names: Names) -> Self

A handle starting on names.

pub fn set(&self, names: Names)

Replaces the list, for every datagram received from now on.

The list is written first and the flag second, with a Release store against the Acquire load in Expected::any, so a reader that sees the flag set also sees the list the flag is about.

The order matters in one direction only. A reader that has already loaded the flag while it still said “empty” judges its batch against the list that was in force a moment earlier, which is what a reload means for every datagram that arrived just before it and is why the gate can be reloaded at all. Storing the flag first would allow the opposite: a reader seeing “there is a list” and then reading a list that is not yet the new one, which is a judgement made against a list no configuration ever asked for.

pub fn any(&self) -> bool

Whether the list in force holds any name, without taking the lock.

pub fn current(&self) -> Arc<Names>

The list in force.

Poisoning would mean a panic while swapping an Arc; the value itself is immutable, so there is nothing to observe half-written.

Trait Implementations

impl Clone for Expected

fn clone(&self) -> Expected

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Expected

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

Formats the value using the given formatter.