Xray-core/transport/pipe/impl.go

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package pipe
import (
"errors"
"io"
"runtime"
"sync"
"time"
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"github.com/xtls/xray-core/common"
"github.com/xtls/xray-core/common/buf"
"github.com/xtls/xray-core/common/signal"
"github.com/xtls/xray-core/common/signal/done"
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)
type state byte
const (
open state = iota
closed
errord
)
type pipeOption struct {
limit int32 // maximum buffer size in bytes
discardOverflow bool
onTransmission func(buffer buf.MultiBuffer) buf.MultiBuffer
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}
func (o *pipeOption) isFull(curSize int32) bool {
return o.limit >= 0 && curSize > o.limit
}
type pipe struct {
sync.Mutex
data buf.MultiBuffer
readSignal *signal.Notifier
writeSignal *signal.Notifier
done *done.Instance
option pipeOption
state state
}
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var (
errBufferFull = errors.New("buffer full")
errSlowDown = errors.New("slow down")
)
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func (p *pipe) getState(forRead bool) error {
switch p.state {
case open:
if !forRead && p.option.isFull(p.data.Len()) {
return errBufferFull
}
return nil
case closed:
if !forRead {
return io.ErrClosedPipe
}
if !p.data.IsEmpty() {
return nil
}
return io.EOF
case errord:
return io.ErrClosedPipe
default:
panic("impossible case")
}
}
func (p *pipe) readMultiBufferInternal() (buf.MultiBuffer, error) {
p.Lock()
defer p.Unlock()
if err := p.getState(true); err != nil {
return nil, err
}
data := p.data
p.data = nil
return data, nil
}
func (p *pipe) ReadMultiBuffer() (buf.MultiBuffer, error) {
for {
data, err := p.readMultiBufferInternal()
if data != nil || err != nil {
p.writeSignal.Signal()
return data, err
}
select {
case <-p.readSignal.Wait():
case <-p.done.Wait():
}
}
}
func (p *pipe) ReadMultiBufferTimeout(d time.Duration) (buf.MultiBuffer, error) {
timer := time.NewTimer(d)
defer timer.Stop()
for {
data, err := p.readMultiBufferInternal()
if data != nil || err != nil {
p.writeSignal.Signal()
return data, err
}
select {
case <-p.readSignal.Wait():
case <-p.done.Wait():
case <-timer.C:
return nil, buf.ErrReadTimeout
}
}
}
func (p *pipe) writeMultiBufferInternal(mb buf.MultiBuffer) error {
p.Lock()
defer p.Unlock()
if err := p.getState(false); err != nil {
return err
}
if p.data == nil {
p.data = mb
return nil
}
p.data, _ = buf.MergeMulti(p.data, mb)
return errSlowDown
}
func (p *pipe) WriteMultiBuffer(mb buf.MultiBuffer) error {
if mb.IsEmpty() {
return nil
}
if p.option.onTransmission != nil {
mb = p.option.onTransmission(mb)
}
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for {
err := p.writeMultiBufferInternal(mb)
if err == nil {
p.readSignal.Signal()
return nil
}
if err == errSlowDown {
p.readSignal.Signal()
// Yield current goroutine. Hopefully the reading counterpart can pick up the payload.
runtime.Gosched()
return nil
}
if err == errBufferFull && p.option.discardOverflow {
buf.ReleaseMulti(mb)
return nil
}
if err != errBufferFull {
buf.ReleaseMulti(mb)
p.readSignal.Signal()
return err
}
select {
case <-p.writeSignal.Wait():
case <-p.done.Wait():
return io.ErrClosedPipe
}
}
}
func (p *pipe) Close() error {
p.Lock()
defer p.Unlock()
if p.state == closed || p.state == errord {
return nil
}
p.state = closed
common.Must(p.done.Close())
return nil
}
// Interrupt implements common.Interruptible.
func (p *pipe) Interrupt() {
p.Lock()
defer p.Unlock()
if p.state == closed || p.state == errord {
return
}
p.state = errord
if !p.data.IsEmpty() {
buf.ReleaseMulti(p.data)
p.data = nil
}
common.Must(p.done.Close())
}