package standard library
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Published: Jul 2, 2024 License: BSD-3-Clause Imports: 9 Imported by: 0



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.



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

Accept4Func is used to hook the accept4 call.

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

AcceptFunc is used to hook the accept call.

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var CloseFunc func(int) error = syscall.Close

CloseFunc is used to hook the close call.

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var ErrDeadlineExceeded error = &DeadlineExceededError{}

ErrDeadlineExceeded is returned for an expired deadline. This is exported by the os package as os.ErrDeadlineExceeded.

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

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

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var ErrNetClosing = errNetClosing{}

ErrNetClosing is returned when a network descriptor is used after it has been closed.

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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.

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var ErrNotPollable = errors.New("not pollable")

ErrNotPollable is returned when the file or socket is not suitable for event notification.

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var TestHookDidWritev = func(wrote int) {}

TestHookDidWritev is a hook for testing writev.


func CopyFileRange added in go1.15

func CopyFileRange(dst, src *FD, remain int64) (written int64, handled bool, err error)

CopyFileRange copies at most remain bytes of data from src to dst, using the copy_file_range system call. dst and src must refer to regular files.

func DupCloseOnExec added in go1.11

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

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

func IsPollDescriptor added in go1.12

func IsPollDescriptor(fd uintptr) bool

IsPollDescriptor reports whether fd is the descriptor being used by the poller. This is only used for testing.

func SendFile

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

SendFile wraps the sendfile system call.

func Splice added in go1.11

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 gets a pipe buffer from the pool or creates a new one if needed, 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.


type DeadlineExceededError added in go1.15

type DeadlineExceededError struct{}

DeadlineExceededError is returned for an expired deadline.

func (*DeadlineExceededError) Error added in go1.15

func (e *DeadlineExceededError) Error() string

Implement the net.Error interface. The string is "i/o timeout" because that is what was returned by earlier Go versions. Changing it may break programs that match on error strings.

func (*DeadlineExceededError) Temporary added in go1.15

func (e *DeadlineExceededError) Temporary() bool

func (*DeadlineExceededError) Timeout added in go1.15

func (e *DeadlineExceededError) Timeout() bool

type FD

type FD struct {

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

	// Platform dependent state of the file descriptor.

	// 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 added in go1.11

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) GetsockoptInt added in go1.21.0

func (fd *FD) GetsockoptInt(level, name int) (int, error)

GetsockoptInt wraps the getsockopt network call with an int argument.

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) ReadFromInet4 added in go1.18

func (fd *FD) ReadFromInet4(p []byte, from *syscall.SockaddrInet4) (int, error)

ReadFromInet4 wraps the recvfrom network call for IPv4.

func (*FD) ReadFromInet6 added in go1.18

func (fd *FD) ReadFromInet6(p []byte, from *syscall.SockaddrInet6) (int, error)

ReadFromInet6 wraps the recvfrom network call for IPv6.

func (*FD) ReadMsg

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

ReadMsg wraps the recvmsg network call.

func (*FD) ReadMsgInet4 added in go1.18

func (fd *FD) ReadMsgInet4(p []byte, oob []byte, flags int, sa4 *syscall.SockaddrInet4) (int, int, int, error)

ReadMsgInet4 is ReadMsg, but specialized for syscall.SockaddrInet4.

func (*FD) ReadMsgInet6 added in go1.18

func (fd *FD) ReadMsgInet6(p []byte, oob []byte, flags int, sa6 *syscall.SockaddrInet6) (int, int, int, error)

ReadMsgInet6 is ReadMsg, but specialized for syscall.SockaddrInet6.

func (*FD) Seek

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

Seek wraps syscall.Seek.

func (*FD) SetBlocking added in go1.10

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 syscall.Shutdown.

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) WriteMsgInet4 added in go1.18

func (fd *FD) WriteMsgInet4(p []byte, oob []byte, sa *syscall.SockaddrInet4) (int, int, error)

WriteMsgInet4 is WriteMsg specialized for syscall.SockaddrInet4.

func (*FD) WriteMsgInet6 added in go1.18

func (fd *FD) WriteMsgInet6(p []byte, oob []byte, sa *syscall.SockaddrInet6) (int, int, error)

WriteMsgInet6 is WriteMsg specialized for syscall.SockaddrInet6.

func (*FD) WriteOnce added in go1.10

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) WriteToInet4 added in go1.18

func (fd *FD) WriteToInet4(p []byte, sa *syscall.SockaddrInet4) (int, error)

WriteToInet4 wraps the sendto network call for IPv4 addresses.

func (*FD) WriteToInet6 added in go1.18

func (fd *FD) WriteToInet6(p []byte, sa *syscall.SockaddrInet6) (int, error)

WriteToInet6 wraps the sendto network call for IPv6 addresses.

func (*FD) Writev

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

Writev wraps the writev system call.

type String added in go1.22.0

type String string

String is an internal string definition for methods/functions that is not intended for use outside the standard libraries.

Other packages in std that import internal/poll and have some exported APIs (now we've got some in net.rawConn) which are only used internally and are not intended to be used outside the standard libraries, Therefore, we make those APIs use internal types like poll.FD or poll.String in their function signatures to disable the usability of these APIs from external codebase.

type SysFile added in go1.21.0

type SysFile struct {
	// contains filtered or unexported fields

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