golang fd 代码
文件路径：/src/internal/poll/fd.go
/ Copyright 2017 The Go Authors. All rights reserved.
/ Use of this source code is governed by a BSD-style
/ license that can be found in the LICENSE file.
/ 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.
package poll
import (
"errors"
)
/ errNetClosing is the type of the variable ErrNetClosing.
/ This is used to implement the net.Error interface.
type errNetClosing struct{}
/ Error returns the error message for ErrNetClosing.
/ Keep this string consistent because of issue #4373:
/ since historically programs have not been able to detect
/ this error, they look for the string.
func (e errNetClosing) Error() string { return "use of closed network connection" }
func (e errNetClosing) Timeout() bool { return false }
func (e errNetClosing) Temporary() bool { return false }
/ ErrNetClosing is returned when a network descriptor is used after
/ it has been closed.
var ErrNetClosing = errNetClosing{}
/ ErrFileClosing is returned when a file descriptor is used after it
/ has been closed.
var ErrFileClosing = errors.New("use of closed file")
/ ErrNoDeadline is returned when a request is made to set a deadline
/ on a file type that does not use the poller.
var ErrNoDeadline = errors.New("file type does not support deadline")
/ Return the appropriate closing error based on isFile.
func errClosing(isFile bool) error {
if isFile {
return ErrFileClosing
}
return ErrNetClosing
}
/ ErrDeadlineExceeded is returned for an expired deadline.
/ This is exported by the os package as os.ErrDeadlineExceeded.
var ErrDeadlineExceeded error = &DeadlineExceededError{}
/ DeadlineExceededError is returned for an expired deadline.
type DeadlineExceededError struct{}
/ 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 (e *DeadlineExceededError) Error() string { return "i/o timeout" }
func (e *DeadlineExceededError) Timeout() bool { return true }
func (e *DeadlineExceededError) Temporary() bool { return true }
/ ErrNotPollable is returned when the file or socket is not suitable
/ for event notification.
var ErrNotPollable = errors.New("not pollable")
/ consume removes data from a slice of byte slices, for writev.
func consume(v *[][]byte, n int64) {
for len(*v) > 0 {
ln0 := int64(len((*v)[0]))
if ln0 > n {
(*v)[0] = (*v)[0][n:]
return
}
n -= ln0
(*v)[0] = nil
*v = (*v)[1:]
}
}
/ TestHookDidWritev is a hook for testing writev.
var TestHookDidWritev = func(wrote int) {}