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// Copyright 2009 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
import (
"errors"
"io"
"sync"
"sync/atomic"
"time"
)
type FD struct {
// Lock sysfd and serialize access to Read and Write methods.
fdmu fdMutex
Destroy func()
// deadlines
rmu sync.Mutex
wmu sync.Mutex
raio *asyncIO
waio *asyncIO
rtimer *time.Timer
wtimer *time.Timer
rtimedout atomic.Bool // set true when read deadline has been reached
wtimedout atomic.Bool // set true when write deadline has been reached
// Whether this is a normal file.
// On Plan 9 we do not use this package for ordinary files,
// so this is always false, but the field is present because
// shared code in fd_mutex.go checks it.
isFile bool
}
// We need this to close out a file descriptor when it is unlocked,
// but the real implementation has to live in the net package because
// it uses os.File's.
func (fd *FD) destroy() error {
if fd.Destroy != nil {
fd.Destroy()
}
return nil
}
// Close handles the locking for closing an FD. The real operation
// is in the net package.
func (fd *FD) Close() error {
if !fd.fdmu.increfAndClose() {
return errClosing(fd.isFile)
}
return nil
}
// Read implements io.Reader.
func (fd *FD) Read(fn func([]byte) (int, error), b []byte) (int, error) {
if err := fd.readLock(); err != nil {
return 0, err
}
defer fd.readUnlock()
if len(b) == 0 {
return 0, nil
}
fd.rmu.Lock()
if fd.rtimedout.Load() {
fd.rmu.Unlock()
return 0, ErrDeadlineExceeded
}
fd.raio = newAsyncIO(fn, b)
fd.rmu.Unlock()
n, err := fd.raio.Wait()
fd.raio = nil
if isHangup(err) {
err = io.EOF
}
if isInterrupted(err) {
err = ErrDeadlineExceeded
}
return n, err
}
// Write implements io.Writer.
func (fd *FD) Write(fn func([]byte) (int, error), b []byte) (int, error) {
if err := fd.writeLock(); err != nil {
return 0, err
}
defer fd.writeUnlock()
fd.wmu.Lock()
if fd.wtimedout.Load() {
fd.wmu.Unlock()
return 0, ErrDeadlineExceeded
}
fd.waio = newAsyncIO(fn, b)
fd.wmu.Unlock()
n, err := fd.waio.Wait()
fd.waio = nil
if isInterrupted(err) {
err = ErrDeadlineExceeded
}
return n, err
}
// SetDeadline sets the read and write deadlines associated with fd.
func (fd *FD) SetDeadline(t time.Time) error {
return setDeadlineImpl(fd, t, 'r'+'w')
}
// SetReadDeadline sets the read deadline associated with fd.
func (fd *FD) SetReadDeadline(t time.Time) error {
return setDeadlineImpl(fd, t, 'r')
}
// SetWriteDeadline sets the write deadline associated with fd.
func (fd *FD) SetWriteDeadline(t time.Time) error {
return setDeadlineImpl(fd, t, 'w')
}
func setDeadlineImpl(fd *FD, t time.Time, mode int) error {
d := t.Sub(time.Now())
if mode == 'r' || mode == 'r'+'w' {
fd.rmu.Lock()
defer fd.rmu.Unlock()
fd.rtimedout.Store(false)
}
if mode == 'w' || mode == 'r'+'w' {
fd.wmu.Lock()
defer fd.wmu.Unlock()
fd.wtimedout.Store(false)
}
if t.IsZero() || d < 0 {
// Stop timer
if mode == 'r' || mode == 'r'+'w' {
if fd.rtimer != nil {
fd.rtimer.Stop()
}
fd.rtimer = nil
}
if mode == 'w' || mode == 'r'+'w' {
if fd.wtimer != nil {
fd.wtimer.Stop()
}
fd.wtimer = nil
}
} else {
// Interrupt I/O operation once timer has expired
if mode == 'r' || mode == 'r'+'w' {
fd.rtimer = time.AfterFunc(d, func() {
fd.rmu.Lock()
fd.rtimedout.Store(true)
if fd.raio != nil {
fd.raio.Cancel()
}
fd.rmu.Unlock()
})
}
if mode == 'w' || mode == 'r'+'w' {
fd.wtimer = time.AfterFunc(d, func() {
fd.wmu.Lock()
fd.wtimedout.Store(true)
if fd.waio != nil {
fd.waio.Cancel()
}
fd.wmu.Unlock()
})
}
}
if !t.IsZero() && d < 0 {
// Interrupt current I/O operation
if mode == 'r' || mode == 'r'+'w' {
fd.rtimedout.Store(true)
if fd.raio != nil {
fd.raio.Cancel()
}
}
if mode == 'w' || mode == 'r'+'w' {
fd.wtimedout.Store(true)
if fd.waio != nil {
fd.waio.Cancel()
}
}
}
return nil
}
// On Plan 9 only, expose the locking for the net code.
// ReadLock wraps FD.readLock.
func (fd *FD) ReadLock() error {
return fd.readLock()
}
// ReadUnlock wraps FD.readUnlock.
func (fd *FD) ReadUnlock() {
fd.readUnlock()
}
func isHangup(err error) bool {
return err != nil && stringsHasSuffix(err.Error(), "Hangup")
}
func isInterrupted(err error) bool {
return err != nil && stringsHasSuffix(err.Error(), "interrupted")
}
// IsPollDescriptor reports whether fd is the descriptor being used by the poller.
// This is only used for testing.
func IsPollDescriptor(fd uintptr) bool {
return false
}
// RawControl invokes the user-defined function f for a non-IO
// operation.
func (fd *FD) RawControl(f func(uintptr)) error {
return errors.New("not implemented")
}
// RawRead invokes the user-defined function f for a read operation.
func (fd *FD) RawRead(f func(uintptr) bool) error {
return errors.New("not implemented")
}
// RawWrite invokes the user-defined function f for a write operation.
func (fd *FD) RawWrite(f func(uintptr) bool) error {
return errors.New("not implemented")
}
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