github.com/FISCO-BCOS/crypto@v0.0.0-20200202032121-bd8ab0b5d4f1/internal/poll/fd.go (about)

     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) {}