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. 10 package poll 11 12 import ( 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. 20 var 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. 24 var 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. 28 var ErrNoDeadline = errors.New("file type does not support deadline") 29 30 // Return the appropriate closing error based on isFile. 31 func errClosing(isFile bool) error { 32 if isFile { 33 return ErrFileClosing 34 } 35 return ErrNetClosing 36 } 37 38 // ErrTimeout is returned for an expired deadline. 39 var ErrTimeout error = &TimeoutError{} 40 41 // TimeoutError is returned for an expired deadline. 42 type TimeoutError struct{} 43 44 // Implement the net.Error interface. 45 func (e *TimeoutError) Error() string { return "i/o timeout" } 46 func (e *TimeoutError) Timeout() bool { return true } 47 func (e *TimeoutError) Temporary() bool { return true } 48 49 // ErrNotPollable is returned when the file or socket is not suitable 50 // for event notification. 51 var ErrNotPollable = errors.New("not pollable") 52 53 // consume removes data from a slice of byte slices, for writev. 54 func 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. 67 var TestHookDidWritev = func(wrote int) {} 68