mux

Documentation

Overview

Package mux implements the ISO-8583 switch: it multiplexes request/response exchanges over a single full-duplex link.Link, correlating each response to its in-flight request by a caller-supplied key (typically STAN + terminal). A background reader dispatches frames to waiting callers; unmatched frames go to an optional unsolicited handler. (Named "mux" rather than "switch" because switch is a Go keyword and cannot be an import identifier.)

Index

• Variables
• type Keyer
  • func FieldKeyer(c *iso8583.Codec, des ...int) Keyer
• type Mux
  • func New(l *link.Link, key Keyer, opts ...Option) *Mux
  • func (m *Mux) Close() error
  • func (m *Mux) Done() <-chan struct{}
  • func (m *Mux) Err() error
  • func (m *Mux) Request(ctx context.Context, req []byte) ([]byte, error)
• type Option
  • func WithTimeout(d time.Duration) Option
  • func WithUnsolicitedHandler(h func([]byte)) Option

Variables

var (
	ErrTimeout      = errors.New("mux: request timed out")
	ErrClosed       = errors.New("mux: closed")
	ErrDuplicateKey = errors.New("mux: a request with this key is already in flight")
)

Mux errors.

Types

type Keyer

type Keyer func(msg []byte) (string, error)

Keyer extracts a correlation key from a message frame. The key for a request and its response must match.

func FieldKeyer

func FieldKeyer(c *iso8583.Codec, des ...int) Keyer

FieldKeyer builds a Keyer that decodes a frame with c and joins the string values of the given data elements (e.g. DE 11 STAN + DE 41 terminal) — the standard ISO-8583 request/response correlation key.

type Mux

type Mux struct {
	// contains filtered or unexported fields
}

Mux correlates requests and responses over a link.

func New

func New(l *link.Link, key Keyer, opts ...Option) *Mux

New starts a Mux over l, beginning the background read loop immediately.

func (*Mux) Close

func (m *Mux) Close() error

Close stops the read loop, closes the link, and unblocks pending requests.

func (*Mux) Done

func (m *Mux) Done() <-chan struct{}

Done returns a channel closed when the mux stops — because Close was called or the underlying link's read loop failed. A supervisor (e.g. a reconnecting connector) selects on it to learn the link died without issuing a request.

func (*Mux) Err

func (m *Mux) Err() error

Err returns the cause once Done is closed: the read-loop error that downed the link, or ErrClosed if it was closed cleanly. It returns nil while still live.

func (*Mux) Request

func (m *Mux) Request(ctx context.Context, req []byte) ([]byte, error)

Request sends req and waits for the response whose key matches req's key, honouring ctx and the configured timeout.

type Option

type Option func(*config)

Option configures a Mux.

func WithTimeout

func WithTimeout(d time.Duration) Option

WithTimeout sets the default per-request timeout (0 = none; rely on context).

func WithUnsolicitedHandler

func WithUnsolicitedHandler(h func([]byte)) Option

WithUnsolicitedHandler sets a handler for frames that match no in-flight request (server-initiated requests, late responses). It runs on the reader goroutine, so it must not block.