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// Copyright (C) 2023 Andrew Ayer
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
// OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
//
// Except as contained in this notice, the name(s) of the above copyright
// holders shall not be used in advertising or otherwise to promote the
// sale, use or other dealings in this Software without prior written
// authorization.
package listener // import "src.agwa.name/go-listener"
import (
"errors"
"net"
"sync"
)
type multiAddr struct{}
func (multiAddr) Network() string { return "multi" }
func (multiAddr) String() string { return "multi" }
type multiListener struct {
listeners []net.Listener
closed chan struct{}
conns chan net.Conn
errors chan error
closeMu sync.Mutex
}
// Create a net.Listener that aggregates the provided listeners. Calling Accept() returns
// the next available connection among all the listeners. Calling Close() closes each of
// the listeners, and causes blocked Accept calls to return with net.ErrClosed. Addr()
// returns a placeholder address that is probably not useful.
func MultiListener(listeners ...net.Listener) net.Listener {
ml := &multiListener{
listeners: listeners,
closed: make(chan struct{}),
conns: make(chan net.Conn),
errors: make(chan error),
}
for _, l := range ml.listeners {
l := l
go ml.handleAccepts(l)
}
return ml
}
func (ml *multiListener) handleAccepts(l net.Listener) {
for {
conn, err := l.Accept()
if errors.Is(err, net.ErrClosed) {
break
} else if err != nil {
if !ml.sendError(err) {
break
}
} else {
if !ml.sendConn(conn) {
conn.Close()
break
}
}
}
}
func (ml *multiListener) sendError(err error) bool {
select {
case <-ml.closed:
return false
case ml.errors <- err:
return true
}
}
func (ml *multiListener) sendConn(conn net.Conn) bool {
select {
case <-ml.closed:
return false
case ml.conns <- conn:
return true
}
}
func (ml *multiListener) Accept() (net.Conn, error) {
select {
case <-ml.closed:
return nil, net.ErrClosed
case conn := <-ml.conns:
return conn, nil
case err := <-ml.errors:
return nil, err
}
}
func (ml *multiListener) Close() error {
ml.closeMu.Lock()
defer ml.closeMu.Unlock()
select {
case <-ml.closed:
return net.ErrClosed
default:
close(ml.closed)
for _, l := range ml.listeners {
l.Close()
}
return nil
}
}
func (ml *multiListener) Addr() net.Addr {
return multiAddr{}
}
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