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 "errors" 13 14 // ErrNetClosing is returned when a network descriptor is used after 15 // it has been closed. Keep this string consistent because of issue 16 // #4373: since historically programs have not been able to detect 17 // this error, they look for the string. 18 var ErrNetClosing = errors.New("use of closed network connection") 19 20 // ErrFileClosing is returned when a file descriptor is used after it 21 // has been closed. 22 var ErrFileClosing = errors.New("use of closed file") 23 24 // ErrNoDeadline is returned when a request is made to set a deadline 25 // on a file type that does not use the poller. 26 var ErrNoDeadline = errors.New("file type does not support deadline") 27 28 // Return the appropriate closing error based on isFile. 29 func errClosing(isFile bool) error { 30 if isFile { 31 return ErrFileClosing 32 } 33 return ErrNetClosing 34 } 35 36 // ErrTimeout is returned for an expired deadline. 37 var ErrTimeout error = &TimeoutError{} 38 39 // TimeoutError is returned for an expired deadline. 40 type TimeoutError struct{} 41 42 // Implement the net.Error interface. 43 func (e *TimeoutError) Error() string { return "i/o timeout" } 44 func (e *TimeoutError) Timeout() bool { return true } 45 func (e *TimeoutError) Temporary() bool { return true } 46 47 // consume removes data from a slice of byte slices, for writev. 48 func consume(v *[][]byte, n int64) { 49 for len(*v) > 0 { 50 ln0 := int64(len((*v)[0])) 51 if ln0 > n { 52 (*v)[0] = (*v)[0][n:] 53 return 54 } 55 n -= ln0 56 *v = (*v)[1:] 57 } 58 } 59 60 // TestHookDidWritev is a hook for testing writev. 61 var TestHookDidWritev = func(wrote int) {} 62
