Enum CircuitState 

#[non_exhaustive]
pub enum CircuitState {
    Closed {
        error_count: u32,
        threshold: u32,
    },
    Open {
        opened_at: MonoTime,
        cooldown: Duration,
        threshold: u32,
    },
    HalfOpen {
        threshold: u32,
    },
}

Circuit breaker state for a remote node or service.

Implements the standard closed/open/half-open pattern to prevent cascading failures when a remote node becomes unreachable.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Closed

Normal operation – requests flow through.

Fields

error_count: u32

threshold: u32

Open

Too many failures – requests blocked for cooldown.

Fields

opened_at: MonoTime

cooldown: Duration

threshold: u32

HalfOpen

Testing if service has recovered (one probe allowed).

Fields

threshold: u32

Implementations

impl CircuitState

pub fn new(threshold: u32) -> Self

Create a new circuit breaker in the closed state.

pub fn record_success(&mut self)

Record a successful call. Resets to closed state.

pub fn record_failure(&mut self) -> bool

Record a failed call. Returns true if the circuit just opened.

Uses the production RealClock. Prefer Self::record_failure_at when a Clock is available.

pub fn record_failure_at(&mut self, clock: &dyn Clock) -> bool

Record a failure at clock.now().

pub fn is_allowed(&mut self) -> bool

Check if requests should be allowed through.

Uses the production RealClock. Prefer Self::is_allowed_at when a Clock is available.

pub fn is_allowed_at(&mut self, clock: &dyn Clock) -> bool

Check allowance using an injectable Clock.

• Closed: always allowed.
• Open: allowed only after cooldown expires (transitions to half-open).
• HalfOpen: allowed (probe request).

Trait Implementations

impl Clone for CircuitState

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CircuitState

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

Formats the value using the given formatter.