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// Copyright 2013 The etcd Authors
//
// Licensed 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 graceful
import (
"errors"
"net"
"sync"
"time"
)
// ErrNotTCP indicates that network connection is not a TCP connection.
var ErrNotTCP = errors.New("only tcp connections have keepalive")
// LimitListener returns a Listener that accepts at most n simultaneous
// connections from the provided Listener.
func LimitListener(l net.Listener, n int) net.Listener {
return &limitListener{l, make(chan struct{}, n)}
}
type limitListener struct {
net.Listener
sem chan struct{}
}
func (l *limitListener) acquire() { l.sem <- struct{}{} }
func (l *limitListener) release() { <-l.sem }
func (l *limitListener) Accept() (net.Conn, error) {
l.acquire()
c, err := l.Listener.Accept()
if err != nil {
l.release()
return nil, err
}
return &limitListenerConn{Conn: c, release: l.release}, nil
}
type limitListenerConn struct {
net.Conn
releaseOnce sync.Once
release func()
}
func (l *limitListenerConn) Close() error {
err := l.Conn.Close()
l.releaseOnce.Do(l.release)
return err
}
func (l *limitListenerConn) SetKeepAlive(doKeepAlive bool) error {
tcpc, ok := l.Conn.(*net.TCPConn)
if !ok {
return ErrNotTCP
}
return tcpc.SetKeepAlive(doKeepAlive)
}
func (l *limitListenerConn) SetKeepAlivePeriod(d time.Duration) error {
tcpc, ok := l.Conn.(*net.TCPConn)
if !ok {
return ErrNotTCP
}
return tcpc.SetKeepAlivePeriod(d)
}
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