khenaidoo | 59ce9dd | 2019-11-11 13:05:32 -0500 | [diff] [blame] | 1 | // Copyright 2013 The etcd Authors |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | // Package transport provides network utility functions, complementing the more |
| 16 | // common ones in the net package. |
| 17 | package transport |
| 18 | |
| 19 | import ( |
| 20 | "errors" |
| 21 | "net" |
| 22 | "sync" |
| 23 | "time" |
| 24 | ) |
| 25 | |
| 26 | var ( |
| 27 | ErrNotTCP = errors.New("only tcp connections have keepalive") |
| 28 | ) |
| 29 | |
| 30 | // LimitListener returns a Listener that accepts at most n simultaneous |
| 31 | // connections from the provided Listener. |
| 32 | func LimitListener(l net.Listener, n int) net.Listener { |
| 33 | return &limitListener{l, make(chan struct{}, n)} |
| 34 | } |
| 35 | |
| 36 | type limitListener struct { |
| 37 | net.Listener |
| 38 | sem chan struct{} |
| 39 | } |
| 40 | |
| 41 | func (l *limitListener) acquire() { l.sem <- struct{}{} } |
| 42 | func (l *limitListener) release() { <-l.sem } |
| 43 | |
| 44 | func (l *limitListener) Accept() (net.Conn, error) { |
| 45 | l.acquire() |
| 46 | c, err := l.Listener.Accept() |
| 47 | if err != nil { |
| 48 | l.release() |
| 49 | return nil, err |
| 50 | } |
| 51 | return &limitListenerConn{Conn: c, release: l.release}, nil |
| 52 | } |
| 53 | |
| 54 | type limitListenerConn struct { |
| 55 | net.Conn |
| 56 | releaseOnce sync.Once |
| 57 | release func() |
| 58 | } |
| 59 | |
| 60 | func (l *limitListenerConn) Close() error { |
| 61 | err := l.Conn.Close() |
| 62 | l.releaseOnce.Do(l.release) |
| 63 | return err |
| 64 | } |
| 65 | |
| 66 | func (l *limitListenerConn) SetKeepAlive(doKeepAlive bool) error { |
| 67 | tcpc, ok := l.Conn.(*net.TCPConn) |
| 68 | if !ok { |
| 69 | return ErrNotTCP |
| 70 | } |
| 71 | return tcpc.SetKeepAlive(doKeepAlive) |
| 72 | } |
| 73 | |
| 74 | func (l *limitListenerConn) SetKeepAlivePeriod(d time.Duration) error { |
| 75 | tcpc, ok := l.Conn.(*net.TCPConn) |
| 76 | if !ok { |
| 77 | return ErrNotTCP |
| 78 | } |
| 79 | return tcpc.SetKeepAlivePeriod(d) |
| 80 | } |