1// Copyright 2017 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5// Package poll supports non-blocking I/O on file descriptors with polling. 6// This supports I/O operations that block only a goroutine, not a thread. 7// This is used by the net and os packages. 8// It uses a poller built into the runtime, with support from the 9// runtime scheduler. 10package poll 11 12import ( 13 "errors" 14) 15 16// ErrNetClosing is returned when a network descriptor is used after 17// it has been closed. Keep this string consistent because of issue 18// #4373: since historically programs have not been able to detect 19// this error, they look for the string. 20var ErrNetClosing = errors.New("use of closed network connection") 21 22// ErrFileClosing is returned when a file descriptor is used after it 23// has been closed. 24var ErrFileClosing = errors.New("use of closed file") 25 26// ErrNoDeadline is returned when a request is made to set a deadline 27// on a file type that does not use the poller. 28var ErrNoDeadline = errors.New("file type does not support deadline") 29 30// Return the appropriate closing error based on isFile. 31func errClosing(isFile bool) error { 32 if isFile { 33 return ErrFileClosing 34 } 35 return ErrNetClosing 36} 37 38// ErrTimeout is returned for an expired deadline. 39var ErrTimeout error = &TimeoutError{} 40 41// TimeoutError is returned for an expired deadline. 42type TimeoutError struct{} 43 44// Implement the net.Error interface. 45func (e *TimeoutError) Error() string { return "i/o timeout" } 46func (e *TimeoutError) Timeout() bool { return true } 47func (e *TimeoutError) Temporary() bool { return true } 48 49// ErrNotPollable is returned when the file or socket is not suitable 50// for event notification. 51var ErrNotPollable = errors.New("not pollable") 52 53// consume removes data from a slice of byte slices, for writev. 54func consume(v *[][]byte, n int64) { 55 for len(*v) > 0 { 56 ln0 := int64(len((*v)[0])) 57 if ln0 > n { 58 (*v)[0] = (*v)[0][n:] 59 return 60 } 61 n -= ln0 62 *v = (*v)[1:] 63 } 64} 65 66// TestHookDidWritev is a hook for testing writev. 67var TestHookDidWritev = func(wrote int) {} 68