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package electron
import (
// Closed is an alias for io.EOF. It is returned as an error when an endpoint
// was closed cleanly.
var Closed = io.EOF
// EOF is an alias for io.EOF. It is returned as an error when an endpoint
// was closed cleanly.
var EOF = io.EOF
// Endpoint is the local end of a communications channel to the remote peer
// process. The following interface implement Endpoint: Connection, Session,
// Sender and Receiver.
// You can create an endpoint with functions on Container, Connection and
// Session. You can accept incoming endpoints from the remote peer using
// Connection.Incoming()
type Endpoint interface {
// Close an endpoint and signal an error to the remote end if error != nil.
// String is a human readable identifier, useful for debugging and logging.
String() string
// Error returns nil if the endpoint is open, otherwise returns an error.
// Error() == Closed means the endpoint was closed without error.
Error() error
// Connection is the connection associated with this endpoint.
Connection() Connection
// Done returns a channel that will close when the endpoint closes.
// After Done() has closed, Error() will return the reason for closing.
Done() <-chan struct{}
// Sync() waits for the remote peer to confirm the endpoint is active or
// reject it with an error. You can call it immediately on new endpoints
// for more predictable error handling.
// AMQP is an asynchronous protocol. It is legal to create an endpoint and
// start using it without waiting for confirmation. This avoids a needless
// delay in the non-error case and throughput by "assuming the best".
// However if there *is* an error, these "optimistic" actions will fail. The
// endpoint and its children will be closed with an error. The error will only
// be detected when you try to use one of these endpoints or call Sync()
Sync() error
type endpointInternal interface {
// Called in handler goroutine when endpoint is remotely closed.
closed(err error) error
// Base implementation for Endpoint
type endpoint struct {
err proton.ErrorHolder
str string // String() return value.
done chan struct{}
active chan struct{}
func (e *endpoint) init(s string) {
e.str = s
e.done = make(chan struct{}) = make(chan struct{})
// Called in proton goroutine on remote open.
func (e *endpoint) wakeSync() {
select { // Close active channel if not already closed.
case <
// Called in proton goroutine (from handler) on a Closed or Disconnected event.
// Set err if there is not already an error on the endpoint.
// Return Error()
func (e *endpoint) closed(err error) error {
select {
case <-e.done:
// Already closed
e.wakeSync() // Make sure we wake up Sync()
return e.Error()
func (e *endpoint) String() string { return e.str }
func (e *endpoint) Error() error { return e.err.Get() }
func (e *endpoint) Done() <-chan struct{} { return e.done }
func (e *endpoint) Sync() error {
return e.Error()
// Call in proton goroutine to initiate closing an endpoint locally
// handler will complete the close when remote end closes.
func localClose(ep proton.Endpoint, err error) {
if ep.State().LocalActive() {
proton.CloseError(ep, err)
// Incoming is the interface for incoming endpoints, see Connection.Incoming()
// Call Incoming.Accept() to open the endpoint or Incoming.Reject() to close it
// with optional error
// Implementing types are *IncomingConnection, *IncomingSession, *IncomingSender
// and *IncomingReceiver. Each type provides methods to examine the incoming
// endpoint request and set configuration options for the local endpoint
// before calling Accept() or Reject()
type Incoming interface {
// Accept and open the endpoint.
Accept() Endpoint
// Reject the endpoint with an error
// wait for and call the accept function, call in proton goroutine.
wait() error
pEndpoint() proton.Endpoint
type incoming struct {
pep proton.Endpoint
acceptCh chan func() error
func makeIncoming(e proton.Endpoint) incoming {
return incoming{pep: e, acceptCh: make(chan func() error)}
func (in *incoming) String() string { return fmt.Sprintf("%s: %s", in.pep.Type(), in.pep) }
func (in *incoming) Reject(err error) { in.acceptCh <- func() error { return err } }
// Call in proton goroutine, wait for and call the accept function.
func (in *incoming) wait() error { return (<-in.acceptCh)() }
func (in *incoming) pEndpoint() proton.Endpoint { return in.pep }
// Called in app goroutine to send an accept function to proton and return the resulting endpoint.
func (in *incoming) accept(f func() Endpoint) Endpoint {
done := make(chan Endpoint)
in.acceptCh <- func() error {
ep := f()
done <- ep
return nil
return <-done