Project structure refactor:

- Change package name general_server to gateway
- Changing the structure of directories and packages
- Adding vendor to the project

vendor/golang.org/x/net/netutil/listen.go

@@ -0,0 +1,87 @@
+// 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
+// acquired, 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) {
+	if !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.
+		// If it instead returns a spurious connection (due to a bug in the
+		// Listener, such as https://golang.org/issue/50216), we immediately close
+		// it and try again. Some buggy Listener implementations (like the one in
+		// the aforementioned issue) seem to assume that Accept will be called to
+		// completion, and may otherwise fail to clean up the client end of pending
+		// connections.
+		for {
+			c, err := l.Listener.Accept()
+			if err != nil {
+				return nil, err
+			}
+			c.Close()
+		}
+	}
+
+	c, err := l.Listener.Accept()
+	if err != nil {
+		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
+}