Merge pull request #6 from rubyist/master

Unexpected client disconnections can cause a panic and crash the server

grace.go

@@ -59,11 +59,12 @@ type deadliner interface {
 // Allows for us to notice when the connection is closed.
 type conn struct {
 	net.Conn
-	wg *sync.WaitGroup
+	wg   *sync.WaitGroup
+	once sync.Once
 }
 
-func (c conn) Close() error {
-	defer c.wg.Done()
+func (c *conn) Close() error {
+	defer c.once.Do(c.wg.Done)
 	return c.Conn.Close()
 }
 
@@ -133,7 +134,7 @@ func (l *listener) Accept() (net.Conn, error) {
 		}
 		return nil, err
 	}
-	return conn{Conn: c, wg: &l.wg}, nil
+	return &conn{Conn: c, wg: &l.wg}, nil
 }
 
 type Process struct {