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DemandBackpressure

laminar_core::subscription

Struct DemandBackpressure 

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pub struct DemandBackpressure { /* private fields */ }
Expand description

Demand-based backpressure (Reactive Streams request(n) model).

The subscriber calls DemandHandle::request to indicate it can accept N more events. The dispatcher calls try_consume before each delivery — if pending demand is 0, the event is not sent.

§Thread Safety

The pending demand counter is an AtomicU64 shared between the dispatcher (which decrements via try_consume) and the subscriber (which increments via request). The CAS loop in try_consume ensures correctness under concurrent access.

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impl DemandBackpressure

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pub fn new() -> (Self, DemandHandle)

Creates a new demand-based backpressure pair with initial demand of 0.

Returns (controller, handle) where the controller is held by the dispatcher and the handle is given to the subscriber.

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pub fn try_consume(&self) -> bool

Attempts to consume one unit of demand.

Returns true if demand was available (and decremented), false if pending demand was 0. Uses a CAS loop for lock-free correctness.

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pub fn pending(&self) -> u64

Returns the current pending demand.

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