go.net: add netutil package with LimitListener
Update golang/go#6012
R=golang-dev, dsymonds, rsc
CC=golang-dev
https://golang.org/cl/12727043
diff --git a/netutil/listen.go b/netutil/listen.go
new file mode 100644
index 0000000..754703f
--- /dev/null
+++ b/netutil/listen.go
@@ -0,0 +1,44 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package netutil provides network utility functions, complementing the more
+// common ones in the net package.
+package netutil
+
+import "net"
+
+// LimitListener returns a Listener that accepts at most n simultaneous
+// connections from the provided Listener.
+func LimitListener(l net.Listener, n int) net.Listener {
+ ch := make(chan struct{}, n)
+ for i := 0; i < n; i++ {
+ ch <- struct{}{}
+ }
+ return &limitListener{l, ch}
+}
+
+type limitListener struct {
+ net.Listener
+ ch chan struct{}
+}
+
+func (l *limitListener) Accept() (net.Conn, error) {
+ <-l.ch
+ c, err := l.Listener.Accept()
+ if err != nil {
+ return nil, err
+ }
+ return &limitListenerConn{c, l.ch}, nil
+}
+
+type limitListenerConn struct {
+ net.Conn
+ ch chan<- struct{}
+}
+
+func (l *limitListenerConn) Close() error {
+ err := l.Conn.Close()
+ l.ch <- struct{}{}
+ return err
+}
