Struct BackpressureConfig 

pub struct BackpressureConfig {
    pub max_concurrent: usize,
    pub max_queue: usize,
    pub acquire_timeout: Duration,
}

Backpressure configuration: bound how many backend data operations may be in flight at once, so a slow or failing backend cannot exhaust the caller’s connection pool or memory.

Defaults mirror the Python SDK’s BackpressureConfig (max_concurrent_requests: 100, queue_size: 1000, timeout: 0.1s).

Over-limit calls first join a bounded waiting queue; a caller that finds the queue full, or that waits longer than Self::acquire_timeout without a permit freeing up, is shed with a crate::error::BackendErrorKind::Backpressure error — never queued unboundedly. Shed calls do not reach the backend and do not count toward opening the circuit breaker.

On the #[cachekit] macro’s plain path a shed is outage-class — exactly like CircuitOpen, the wrapped function runs uncached (fail-open); secure paths fail closed on a shed like on every other backend error.

Fields

max_concurrent: usize

Maximum backend data operations in flight at once (default: 100). 0 behaves as 1; values above tokio’s Semaphore::MAX_PERMITS (usize::MAX >> 3) are clamped to it, so usize::MAX reads as “effectively unbounded” rather than panicking the builder.

max_queue: usize

Maximum callers waiting for a permit before further calls are shed immediately (default: 1000). 0 disables waiting entirely: a call that cannot take a permit on the spot is shed.

acquire_timeout: Duration

How long a queued caller waits for a permit before it is shed (default: 100 ms).

Trait Implementations

impl Clone for BackpressureConfig

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 BackpressureConfig

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

Formats the value using the given formatter.

impl Default for BackpressureConfig

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for BackpressureConfig

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for BackpressureConfig