Module backpressure 

Backpressure — limits concurrent active sessions.

When the coordinator reaches max_active_sessions, new session creation requests are rejected with BackpressureError::AtCapacity. This protects against memory exhaustion under load.

Existing sessions continue to be processed; only new ones are rejected until capacity frees up.

Structs

ActiveSlot

RAII guard for an acquired backpressure slot. When dropped, the slot is automatically released.

BackpressureConfig

Configuration for backpressure.

BackpressureGate

Backpressure gate — tracks active sessions and enforces the limit.

Enums

BackpressureError

Errors from backpressure enforcement.