Module balancer 

Shared upstream load balancer.

A Balancer owns a pool of backend Targets and picks one per request/connection according to a Strategy (round-robin, least-connections, or client-IP hash). It is deliberately transport-neutral: the HTTP upstream node and the L4 (TCP/UDP) stream proxy both select targets through it, so the load-balancing logic lives in exactly one place.

least_connections is backed by per-target in-flight counters. Callers bump a counter for the life of a request/connection by holding a guard: ConnGuard (borrowed — held on the stack for a single request) or OwnedConnGuard (owns an Arc<Balancer> — for a long-lived connection stored outside the borrowing scope, e.g. a UDP session in a map). Both decrement on drop.

Structs

Balancer

A pool of backend targets plus the state driving target selection.

ConnGuard

Decrements a target’s in-flight counter when a request/connection completes.

OwnedConnGuard

Owned counterpart to ConnGuard for connections tracked outside the borrowing scope; decrements the target’s in-flight counter on drop.

Target

A single backend address (host:port) connections can be forwarded to.

Enums

Strategy

Strategy for picking a target from the pool.