Conn Interface
// Conn is a generic stream-oriented network connection.
//
// Multiple goroutines may invoke methods on a Conn simultaneously.
type Conn interface {
// Read reads data from the connection.
// Read can be made to time out and return an Error with Timeout() == true
// after a fixed time limit; see SetDeadline and SetReadDeadline.
Read(b []byte) (n int, err error)
// Write writes data to the connection.
// Write can be made to time out and return an Error with Timeout() == true
// after a fixed time limit; see SetDeadline and SetWriteDeadline.
Write(b []byte) (n int, err error)
// Close closes the connection.
// Any blocked Read or Write operations will be unblocked and return errors.
Close() error
// LocalAddr returns the local network address.
LocalAddr() Addr
// RemoteAddr returns the remote network address.
RemoteAddr() Addr
// SetDeadline sets the read and write deadlines associated
// with the connection. It is equivalent to calling both
// SetReadDeadline and SetWriteDeadline.
//
// A deadline is an absolute time after which I/O operations
// fail with a timeout (see type Error) instead of
// blocking. The deadline applies to all future and pending
// I/O, not just the immediately following call to Read or
// Write. After a deadline has been exceeded, the connection
// can be refreshed by setting a deadline in the future.
//
// An idle timeout can be implemented by repeatedly extending
// the deadline after successful Read or Write calls.
//
// A zero value for t means I/O operations will not time out.
//
// Note that if a TCP connection has keep-alive turned on,
// which is the default unless overridden by Dialer.KeepAlive
// or ListenConfig.KeepAlive, then a keep-alive failure may
// also return a timeout error. On Unix systems a keep-alive
// failure on I/O can be detected using
// errors.Is(err, syscall.ETIMEDOUT).
SetDeadline(t time.Time) error
// SetReadDeadline sets the deadline for future Read calls
// and any currently-blocked Read call.
// A zero value for t means Read will not time out.
SetReadDeadline(t time.Time) error
// SetWriteDeadline sets the deadline for future Write calls
// and any currently-blocked Write call.
// Even if write times out, it may return n > 0, indicating that
// some of the data was successfully written.
// A zero value for t means Write will not time out.
SetWriteDeadline(t time.Time) error
}
TCPConn struct
// TCPConn is an implementation of the Conn interface for TCP network
// connections.
type TCPConn struct {
conn
}
// SyscallConn returns a raw network connection.
// This implements the syscall.Conn interface.
func (c *TCPConn) SyscallConn() (syscall.RawConn, error) {
if !c.ok() {
return nil, syscall.EINVAL
}
return newRawConn(c.fd)
}
// ReadFrom implements the io.ReaderFrom ReadFrom method.
func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) {
if !c.ok() {
return 0, syscall.EINVAL
}
n, err := c.readFrom(r)
if err != nil && err != io.EOF {
err = &OpError{Op: "readfrom", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
}
return n, err
}
// CloseRead shuts down the reading side of the TCP connection.
// Most callers should just use Close.
func (c *TCPConn) CloseRead() error {
if !c.ok() {
return syscall.EINVAL
}
if err := c.fd.closeRead(); err != nil {
return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
}
return nil
}
// CloseWrite shuts down the writing side of the TCP connection.
// Most callers should just use Close.
func (c *TCPConn) CloseWrite() error {
if !c.ok() {
return syscall.EINVAL
}
if err := c.fd.closeWrite(); err != nil {
return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
}
return nil
}
// SetLinger sets the behavior of Close on a connection which still
// has data waiting to be sent or to be acknowledged.
//
// If sec < 0 (the default), the operating system finishes sending the
// data in the background.
//
// If sec == 0, the operating system discards any unsent or
// unacknowledged data.
//
// If sec > 0, the data is sent in the background as with sec < 0. On
// some operating systems after sec seconds have elapsed any remaining
// unsent data may be discarded.
func (c *TCPConn) SetLinger(sec int) error {
if !c.ok() {
return syscall.EINVAL
}
if err := setLinger(c.fd, sec); err != nil {
return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
}
return nil
}
// SetKeepAlive sets whether the operating system should send
// keep-alive messages on the connection.
func (c *TCPConn) SetKeepAlive(keepalive bool) error {
if !c.ok() {
return syscall.EINVAL
}
if err := setKeepAlive(c.fd, keepalive); err != nil {
return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
}
return nil
}
// SetKeepAlivePeriod sets period between keep-alives.
func (c *TCPConn) SetKeepAlivePeriod(d time.Duration) error {
if !c.ok() {
return syscall.EINVAL
}
if err := setKeepAlivePeriod(c.fd, d); err != nil {
return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
}
return nil
}
// SetNoDelay controls whether the operating system should delay
// packet transmission in hopes of sending fewer packets (Nagle's
// algorithm). The default is true (no delay), meaning that data is
// sent as soon as possible after a Write.
func (c *TCPConn) SetNoDelay(noDelay bool) error {
if !c.ok() {
return syscall.EINVAL
}
if err := setNoDelay(c.fd, noDelay); err != nil {
return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
}
return nil
}
func newTCPConn(fd *netFD) *TCPConn {
c := &TCPConn{conn{fd}}
setNoDelay(c.fd, true)
return c
}
Reference