poll

Documentation

Overview

Package poll supports non-blocking I/O on file descriptors with polling. This supports I/O operations that block only a goroutine, not a thread. This is used by the net and os packages. It uses a poller built into the runtime, with support from the runtime scheduler.

Index

• Variables
• func DupCloseOnExec(fd int) (int, string, error)
• func PollDescriptor() uintptr
• func SendFile(dstFD *FD, src int, remain int64) (int64, error)
• func Splice(dst, src *FD, remain int64) (written int64, handled bool, sc string, err error)
• type FD
  • func (fd *FD) Accept() (int, syscall.Sockaddr, string, error)
  • func (fd *FD) Close() error
  • func (fd *FD) Dup() (int, string, error)
  • func (fd *FD) Fchdir() error
  • func (fd *FD) Fchmod(mode uint32) error
  • func (fd *FD) Fchown(uid, gid int) error
  • func (fd *FD) Fstat(s *syscall.Stat_t) error
  • func (fd *FD) Fsync() error
  • func (fd *FD) Ftruncate(size int64) error
  • func (fd *FD) Init(net string, pollable bool) error
  • func (fd *FD) Pread(p []byte, off int64) (int, error)
  • func (fd *FD) Pwrite(p []byte, off int64) (int, error)
  • func (fd *FD) RawControl(f func(uintptr)) error
  • func (fd *FD) RawRead(f func(uintptr) bool) error
  • func (fd *FD) RawWrite(f func(uintptr) bool) error
  • func (fd *FD) Read(p []byte) (int, error)
  • func (fd *FD) ReadDirent(buf []byte) (int, error)
  • func (fd *FD) ReadFrom(p []byte) (int, syscall.Sockaddr, error)
  • func (fd *FD) ReadMsg(p []byte, oob []byte) (int, int, int, syscall.Sockaddr, error)
  • func (fd *FD) Seek(offset int64, whence int) (int64, error)
  • func (fd *FD) SetBlocking() error
  • func (fd *FD) SetDeadline(t time.Time) error
  • func (fd *FD) SetReadDeadline(t time.Time) error
  • func (fd *FD) SetWriteDeadline(t time.Time) error
  • func (fd *FD) SetsockoptByte(level, name int, arg byte) error
  • func (fd *FD) SetsockoptIPMreq(level, name int, mreq *syscall.IPMreq) error
  • func (fd *FD) SetsockoptIPMreqn(level, name int, mreq *syscall.IPMreqn) error
  • func (fd *FD) SetsockoptIPv6Mreq(level, name int, mreq *syscall.IPv6Mreq) error
  • func (fd *FD) SetsockoptInet4Addr(level, name int, arg [4]byte) error
  • func (fd *FD) SetsockoptInt(level, name, arg int) error
  • func (fd *FD) SetsockoptLinger(level, name int, l *syscall.Linger) error
  • func (fd *FD) Shutdown(how int) error
  • func (fd *FD) WaitWrite() error
  • func (fd *FD) Write(p []byte) (int, error)
  • func (fd *FD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (int, int, error)
  • func (fd *FD) WriteOnce(p []byte) (int, error)
  • func (fd *FD) WriteTo(p []byte, sa syscall.Sockaddr) (int, error)
  • func (fd *FD) Writev(v *[][]byte) (int64, error)
• type TimeoutError
  • func (e *TimeoutError) Error() string
  • func (e *TimeoutError) Temporary() bool
  • func (e *TimeoutError) Timeout() bool

Variables

var Accept4Func func(int, int) (int, syscall.Sockaddr, error) = syscall.Accept4

Accept4Func is used to hook the accept4 call.

var AcceptFunc func(int) (int, syscall.Sockaddr, error) = syscall.Accept

AcceptFunc is used to hook the accept call.

var CloseFunc func(int) error = syscall.Close

CloseFunc is used to hook the close call.

var ErrFileClosing = errors.New("use of closed file")

ErrFileClosing is returned when a file descriptor is used after it has been closed.

var ErrNetClosing = errors.New("use of closed network connection")

ErrNetClosing is returned when a network descriptor is used after it has been closed. Keep this string consistent because of issue #4373: since historically programs have not been able to detect this error, they look for the string.

var ErrNoDeadline = errors.New("file type does not support deadline")

ErrNoDeadline is returned when a request is made to set a deadline on a file type that does not use the poller.

var ErrTimeout error = &TimeoutError{}

ErrTimeout is returned for an expired deadline.

var TestHookDidWritev = func(wrote int) {}

TestHookDidWritev is a hook for testing writev.

Functions

func DupCloseOnExec

func DupCloseOnExec(fd int) (int, string, error)

DupCloseOnExec dups fd and marks it close-on-exec.

func PollDescriptor

func PollDescriptor() uintptr

PollDescriptor returns the descriptor being used by the poller, or ^uintptr(0) if there isn't one. This is only used for testing.

func SendFile

func SendFile(dstFD *FD, src int, remain int64) (int64, error)

SendFile wraps the sendfile system call.

func Splice

func Splice(dst, src *FD, remain int64) (written int64, handled bool, sc string, err error)

Splice transfers at most remain bytes of data from src to dst, using the splice system call to minimize copies of data from and to userspace.

Splice creates a temporary pipe, to serve as a buffer for the data transfer. src and dst must both be stream-oriented sockets.

If err != nil, sc is the system call which caused the error.

Types

type FD

type FD struct {

	// System file descriptor. Immutable until Close.
	Sysfd int

	// Whether this is a streaming descriptor, as opposed to a
	// packet-based descriptor like a UDP socket. Immutable.
	IsStream bool

	// Whether a zero byte read indicates EOF. This is false for a
	// message based socket connection.
	ZeroReadIsEOF bool
	// contains filtered or unexported fields
}

FD is a file descriptor. The net and os packages use this type as a field of a larger type representing a network connection or OS file.

func (*FD) Accept

func (fd *FD) Accept() (int, syscall.Sockaddr, string, error)

Accept wraps the accept network call.

func (*FD) Close

func (fd *FD) Close() error

Close closes the FD. The underlying file descriptor is closed by the destroy method when there are no remaining references.

func (*FD) Dup

func (fd *FD) Dup() (int, string, error)

Dup duplicates the file descriptor.

func (*FD) Fchdir

func (fd *FD) Fchdir() error

Fchdir wraps syscall.Fchdir.

func (*FD) Fchmod

func (fd *FD) Fchmod(mode uint32) error

Fchmod wraps syscall.Fchmod.

func (*FD) Fchown

func (fd *FD) Fchown(uid, gid int) error

Fchown wraps syscall.Fchown.

func (*FD) Fstat

func (fd *FD) Fstat(s *syscall.Stat_t) error

Fstat wraps syscall.Fstat

func (*FD) Fsync

func (fd *FD) Fsync() error

Fsync wraps syscall.Fsync.

func (*FD) Ftruncate

func (fd *FD) Ftruncate(size int64) error

Ftruncate wraps syscall.Ftruncate.

func (*FD) Init

func (fd *FD) Init(net string, pollable bool) error

Init initializes the FD. The Sysfd field should already be set. This can be called multiple times on a single FD. The net argument is a network name from the net package (e.g., "tcp"), or "file". Set pollable to true if fd should be managed by runtime netpoll.

func (*FD) Pread

func (fd *FD) Pread(p []byte, off int64) (int, error)

Pread wraps the pread system call.

func (*FD) Pwrite

func (fd *FD) Pwrite(p []byte, off int64) (int, error)

Pwrite wraps the pwrite system call.

func (*FD) RawControl

func (fd *FD) RawControl(f func(uintptr)) error

RawControl invokes the user-defined function f for a non-IO operation.

func (*FD) RawRead

func (fd *FD) RawRead(f func(uintptr) bool) error

RawRead invokes the user-defined function f for a read operation.

func (*FD) RawWrite

func (fd *FD) RawWrite(f func(uintptr) bool) error

RawWrite invokes the user-defined function f for a write operation.

func (*FD) Read

func (fd *FD) Read(p []byte) (int, error)

Read implements io.Reader.

func (*FD) ReadDirent

func (fd *FD) ReadDirent(buf []byte) (int, error)

ReadDirent wraps syscall.ReadDirent. We treat this like an ordinary system call rather than a call that tries to fill the buffer.

func (*FD) ReadFrom

func (fd *FD) ReadFrom(p []byte) (int, syscall.Sockaddr, error)

ReadFrom wraps the recvfrom network call.

func (*FD) ReadMsg

func (fd *FD) ReadMsg(p []byte, oob []byte) (int, int, int, syscall.Sockaddr, error)

ReadMsg wraps the recvmsg network call.

func (*FD) Seek

func (fd *FD) Seek(offset int64, whence int) (int64, error)

Seek wraps syscall.Seek.

func (*FD) SetBlocking

func (fd *FD) SetBlocking() error

SetBlocking puts the file into blocking mode.

func (*FD) SetDeadline

func (fd *FD) SetDeadline(t time.Time) error

SetDeadline sets the read and write deadlines associated with fd.

func (*FD) SetReadDeadline

func (fd *FD) SetReadDeadline(t time.Time) error

SetReadDeadline sets the read deadline associated with fd.

func (*FD) SetWriteDeadline

func (fd *FD) SetWriteDeadline(t time.Time) error

SetWriteDeadline sets the write deadline associated with fd.

func (*FD) SetsockoptByte

func (fd *FD) SetsockoptByte(level, name int, arg byte) error

SetsockoptByte wraps the setsockopt network call with a byte argument.

func (*FD) SetsockoptIPMreq

func (fd *FD) SetsockoptIPMreq(level, name int, mreq *syscall.IPMreq) error

SetsockoptIPMreq wraps the setsockopt network call with an IPMreq argument.

func (*FD) SetsockoptIPMreqn

func (fd *FD) SetsockoptIPMreqn(level, name int, mreq *syscall.IPMreqn) error

SetsockoptIPMreqn wraps the setsockopt network call with an IPMreqn argument.

func (*FD) SetsockoptIPv6Mreq

func (fd *FD) SetsockoptIPv6Mreq(level, name int, mreq *syscall.IPv6Mreq) error

SetsockoptIPv6Mreq wraps the setsockopt network call with an IPv6Mreq argument.

func (*FD) SetsockoptInet4Addr

func (fd *FD) SetsockoptInet4Addr(level, name int, arg [4]byte) error

SetsockoptInet4Addr wraps the setsockopt network call with an IPv4 address.

func (*FD) SetsockoptInt

func (fd *FD) SetsockoptInt(level, name, arg int) error

SetsockoptInt wraps the setsockopt network call with an int argument.

func (*FD) SetsockoptLinger

func (fd *FD) SetsockoptLinger(level, name int, l *syscall.Linger) error

SetsockoptLinger wraps the setsockopt network call with a Linger argument.

func (*FD) Shutdown

func (fd *FD) Shutdown(how int) error

Shutdown wraps the shutdown network call.

func (*FD) WaitWrite

func (fd *FD) WaitWrite() error

WaitWrite waits until data can be read from fd.

func (*FD) Write

func (fd *FD) Write(p []byte) (int, error)

Write implements io.Writer.

func (*FD) WriteMsg

func (fd *FD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (int, int, error)

WriteMsg wraps the sendmsg network call.

func (*FD) WriteOnce

func (fd *FD) WriteOnce(p []byte) (int, error)

WriteOnce is for testing only. It makes a single write call.

func (*FD) WriteTo

func (fd *FD) WriteTo(p []byte, sa syscall.Sockaddr) (int, error)

WriteTo wraps the sendto network call.

func (*FD) Writev

func (fd *FD) Writev(v *[][]byte) (int64, error)

Writev wraps the writev system call.

type TimeoutError

type TimeoutError struct{}

TimeoutError is returned for an expired deadline.

func (*TimeoutError) Error

func (e *TimeoutError) Error() string

Implement the net.Error interface.

func (*TimeoutError) Temporary

func (e *TimeoutError) Temporary() bool

func (*TimeoutError) Timeout

func (e *TimeoutError) Timeout() bool