Module middleware 

Stateful, composable interception of owned protocol messages.

Middleware receives ownership of a decoded message and a mutable reference to caller-defined state. Returning the input unchanged is a no-op; implementations may instead mutate it or return another message of the same type. Protocol session APIs remain responsible for checking that the result is legal in their current state before advancing.

Structs

AsynchronousBackendMessage

Validated backend traffic which does not advance the current protocol phase.

Identity

Middleware which returns every message unchanged.

Middleware

Owns user state and middleware as one reusable interception unit.

Then

Two middleware stages evaluated from first to second.

WireAdapter

Adapts one direction-wide wire middleware to every generated typed phase.

Enums

ChainError

Identifies which stage of a two-part middleware chain failed.

ClientRole

Marker for middleware handling messages sent by a PostgreSQL client.

InterceptError

Failure while applying or validating middleware output.

ReceiveError

I/O or interception failure while receiving a middleware-checked message.

ServerRole

Marker for middleware handling messages sent by a PostgreSQL server.

TypedBackendMessage

Any server message legal in a phase, including non-advancing asynchronous traffic.

TypedReceiveError

Failure while receiving through compile-time phase-checked middleware.

WireAdapterError

Failure from direction-wide middleware adapted to a typed phase.

Traits

AcceptsMessage

State-aware validation of one directional protocol message type.

MessageMiddleware

Intercepts an owned message with access to caller-defined state.

MessageMiddlewareExt

Adds composition to every sized middleware implementation.

ReconstructableMessage

A protocol message which can verify that it has a valid wire representation.

TypedMiddleware

Middleware whose role, protocol phase, and legal message set are type indexed.

TypedPhase

Associates a connection typestate with its generated legal message type.