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-rw-r--r--vendor/golang.org/x/net/netutil/listen.go74
1 files changed, 74 insertions, 0 deletions
diff --git a/vendor/golang.org/x/net/netutil/listen.go b/vendor/golang.org/x/net/netutil/listen.go
new file mode 100644
index 0000000..cee46e3
--- /dev/null
+++ b/vendor/golang.org/x/net/netutil/listen.go
@@ -0,0 +1,74 @@
+// 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 "golang.org/x/net/netutil"
+
+import (
+ "net"
+ "sync"
+)
+
+// 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{
+ Listener: l,
+ sem: make(chan struct{}, n),
+ done: make(chan struct{}),
+ }
+}
+
+type limitListener struct {
+ net.Listener
+ sem chan struct{}
+ closeOnce sync.Once // ensures the done chan is only closed once
+ done chan struct{} // no values sent; closed when Close is called
+}
+
+// acquire acquires the limiting semaphore. Returns true if successfully
+// accquired, false if the listener is closed and the semaphore is not
+// acquired.
+func (l *limitListener) acquire() bool {
+ select {
+ case <-l.done:
+ return false
+ case l.sem <- struct{}{}:
+ return true
+ }
+}
+func (l *limitListener) release() { <-l.sem }
+
+func (l *limitListener) Accept() (net.Conn, error) {
+ acquired := l.acquire()
+ // If the semaphore isn't acquired because the listener was closed, expect
+ // that this call to accept won't block, but immediately return an error.
+ c, err := l.Listener.Accept()
+ if err != nil {
+ if acquired {
+ l.release()
+ }
+ return nil, err
+ }
+ return &limitListenerConn{Conn: c, release: l.release}, nil
+}
+
+func (l *limitListener) Close() error {
+ err := l.Listener.Close()
+ l.closeOnce.Do(func() { close(l.done) })
+ return err
+}
+
+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
+}