/
pipelistener.go
105 lines (93 loc) · 2.79 KB
/
pipelistener.go
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// Licensed to Elasticsearch B.V. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you under
// the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
package transport
import (
"context"
"errors"
"net"
"sync"
)
// errListenerClosed is the error returned by the Accept
// and DialContext methods of a closed listener.
var errListenerClosed = errors.New("listener is closed")
// PipeListener is a net.PipeListener that uses net.Pipe
// It is only relevant for the APM Server instrumentation of itself
type PipeListener struct {
conns chan net.Conn
closeOnce sync.Once
closed chan struct{}
}
// NewPipeListener returns a new PipeListener.
func NewPipeListener() *PipeListener {
l := &PipeListener{
conns: make(chan net.Conn),
closed: make(chan struct{}),
}
return l
}
// Close closes the listener.
// This is part of the net.PipeListener interface.
func (l *PipeListener) Close() error {
l.closeOnce.Do(func() { close(l.closed) })
return nil
}
// Addr returns the listener's network address.
// This is part of the net.listener interface.
//
// The returned address's network and value are always both
// "pipe", the same as the addresses returned by net.Pipe
// connections.
func (l *PipeListener) Addr() net.Addr {
return pipeAddr{"pipe"}
}
// Accept waits for and returns the next connection to the listener.
// This is part of the net.listener address.
func (l *PipeListener) Accept() (net.Conn, error) {
select {
case <-l.closed:
return nil, errListenerClosed
case conn := <-l.conns:
return conn, nil
}
}
// DialContext dials a connection to the listener, blocking until
// a paired Accept call is made, the listener is closed, or the
// context is canceled/expired.
func (l *PipeListener) DialContext(ctx context.Context, network, addr string) (net.Conn, error) {
client, server := net.Pipe()
select {
case <-l.closed:
client.Close()
server.Close()
return nil, errListenerClosed
case <-ctx.Done():
client.Close()
server.Close()
return nil, ctx.Err()
case l.conns <- server:
return client, nil
}
}
type pipeAddr struct {
name string
}
func (a pipeAddr) Network() string {
return a.name
}
func (a pipeAddr) String() string {
return a.name
}