| // 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 transport provides network utility functions, complementing the more |
| // common ones in the net package. |
| package transport |
| |
| import ( |
| "errors" |
| "net" |
| "sync" |
| "time" |
| ) |
| |
| 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) |
| } |