github.com/pmorton/docker@v1.5.0/pkg/listenbuffer/buffer.go (about)

     1  /*
     2     Package to allow go applications to immediately start
     3     listening on a socket, unix, tcp, udp but hold connections
     4     until the application has booted and is ready to accept them
     5  */
     6  package listenbuffer
     7  
     8  import "net"
     9  
    10  // NewListenBuffer returns a listener listening on addr with the protocol.
    11  func NewListenBuffer(proto, addr string, activate chan struct{}) (net.Listener, error) {
    12  	wrapped, err := net.Listen(proto, addr)
    13  	if err != nil {
    14  		return nil, err
    15  	}
    16  
    17  	return &defaultListener{
    18  		wrapped:  wrapped,
    19  		activate: activate,
    20  	}, nil
    21  }
    22  
    23  type defaultListener struct {
    24  	wrapped  net.Listener // the real listener to wrap
    25  	ready    bool         // is the listner ready to start accpeting connections
    26  	activate chan struct{}
    27  }
    28  
    29  func (l *defaultListener) Close() error {
    30  	return l.wrapped.Close()
    31  }
    32  
    33  func (l *defaultListener) Addr() net.Addr {
    34  	return l.wrapped.Addr()
    35  }
    36  
    37  func (l *defaultListener) Accept() (net.Conn, error) {
    38  	// if the listen has been told it is ready then we can go ahead and
    39  	// start returning connections
    40  	if l.ready {
    41  		return l.wrapped.Accept()
    42  	}
    43  	<-l.activate
    44  	l.ready = true
    45  	return l.Accept()
    46  }