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send_stream.go
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send_stream.go
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package quic
import (
"context"
"fmt"
"sync"
"time"
"github.com/quic-go/quic-go/internal/ackhandler"
"github.com/quic-go/quic-go/internal/flowcontrol"
"github.com/quic-go/quic-go/internal/protocol"
"github.com/quic-go/quic-go/internal/qerr"
"github.com/quic-go/quic-go/internal/utils"
"github.com/quic-go/quic-go/internal/wire"
)
type sendStreamI interface {
SendStream
handleStopSendingFrame(*wire.StopSendingFrame)
hasData() bool
popStreamFrame(maxBytes protocol.ByteCount, v protocol.VersionNumber) (*ackhandler.Frame, bool)
closeForShutdown(error)
updateSendWindow(protocol.ByteCount)
}
type sendStream struct {
mutex sync.Mutex
numOutstandingFrames int64
retransmissionQueue []*wire.StreamFrame
ctx context.Context
ctxCancel context.CancelFunc
streamID protocol.StreamID
sender streamSender
writeOffset protocol.ByteCount
cancelWriteErr error
closeForShutdownErr error
closedForShutdown bool // set when CloseForShutdown() is called
finishedWriting bool // set once Close() is called
canceledWrite bool // set when CancelWrite() is called, or a STOP_SENDING frame is received
finSent bool // set when a STREAM_FRAME with FIN bit has been sent
completed bool // set when this stream has been reported to the streamSender as completed
dataForWriting []byte // during a Write() call, this slice is the part of p that still needs to be sent out
nextFrame *wire.StreamFrame
writeChan chan struct{}
writeOnce chan struct{}
deadline time.Time
flowController flowcontrol.StreamFlowController
}
var (
_ SendStream = &sendStream{}
_ sendStreamI = &sendStream{}
)
func newSendStream(
streamID protocol.StreamID,
sender streamSender,
flowController flowcontrol.StreamFlowController,
) *sendStream {
s := &sendStream{
streamID: streamID,
sender: sender,
flowController: flowController,
writeChan: make(chan struct{}, 1),
writeOnce: make(chan struct{}, 1), // cap: 1, to protect against concurrent use of Write
}
s.ctx, s.ctxCancel = context.WithCancel(context.Background())
return s
}
func (s *sendStream) StreamID() protocol.StreamID {
return s.streamID // same for receiveStream and sendStream
}
func (s *sendStream) Write(p []byte) (int, error) {
// Concurrent use of Write is not permitted (and doesn't make any sense),
// but sometimes people do it anyway.
// Make sure that we only execute one call at any given time to avoid hard to debug failures.
s.writeOnce <- struct{}{}
defer func() { <-s.writeOnce }()
s.mutex.Lock()
defer s.mutex.Unlock()
if s.finishedWriting {
return 0, fmt.Errorf("write on closed stream %d", s.streamID)
}
if s.canceledWrite {
return 0, s.cancelWriteErr
}
if s.closeForShutdownErr != nil {
return 0, s.closeForShutdownErr
}
if !s.deadline.IsZero() && !time.Now().Before(s.deadline) {
return 0, errDeadline
}
if len(p) == 0 {
return 0, nil
}
s.dataForWriting = p
var (
deadlineTimer *utils.Timer
bytesWritten int
notifiedSender bool
)
for {
var copied bool
var deadline time.Time
// As soon as dataForWriting becomes smaller than a certain size x, we copy all the data to a STREAM frame (s.nextFrame),
// which can then be popped the next time we assemble a packet.
// This allows us to return Write() when all data but x bytes have been sent out.
// When the user now calls Close(), this is much more likely to happen before we popped that last STREAM frame,
// allowing us to set the FIN bit on that frame (instead of sending an empty STREAM frame with FIN).
if s.canBufferStreamFrame() && len(s.dataForWriting) > 0 {
if s.nextFrame == nil {
f := wire.GetStreamFrame()
f.Offset = s.writeOffset
f.StreamID = s.streamID
f.DataLenPresent = true
f.Data = f.Data[:len(s.dataForWriting)]
copy(f.Data, s.dataForWriting)
s.nextFrame = f
} else {
l := len(s.nextFrame.Data)
s.nextFrame.Data = s.nextFrame.Data[:l+len(s.dataForWriting)]
copy(s.nextFrame.Data[l:], s.dataForWriting)
}
s.dataForWriting = nil
bytesWritten = len(p)
copied = true
} else {
bytesWritten = len(p) - len(s.dataForWriting)
deadline = s.deadline
if !deadline.IsZero() {
if !time.Now().Before(deadline) {
s.dataForWriting = nil
return bytesWritten, errDeadline
}
if deadlineTimer == nil {
deadlineTimer = utils.NewTimer()
defer deadlineTimer.Stop()
}
deadlineTimer.Reset(deadline)
}
if s.dataForWriting == nil || s.canceledWrite || s.closedForShutdown {
break
}
}
s.mutex.Unlock()
if !notifiedSender {
s.sender.onHasStreamData(s.streamID) // must be called without holding the mutex
notifiedSender = true
}
if copied {
s.mutex.Lock()
break
}
if deadline.IsZero() {
<-s.writeChan
} else {
select {
case <-s.writeChan:
case <-deadlineTimer.Chan():
deadlineTimer.SetRead()
}
}
s.mutex.Lock()
}
if bytesWritten == len(p) {
return bytesWritten, nil
}
if s.closeForShutdownErr != nil {
return bytesWritten, s.closeForShutdownErr
} else if s.cancelWriteErr != nil {
return bytesWritten, s.cancelWriteErr
}
return bytesWritten, nil
}
func (s *sendStream) canBufferStreamFrame() bool {
var l protocol.ByteCount
if s.nextFrame != nil {
l = s.nextFrame.DataLen()
}
return l+protocol.ByteCount(len(s.dataForWriting)) <= protocol.MaxPacketBufferSize
}
// popStreamFrame returns the next STREAM frame that is supposed to be sent on this stream
// maxBytes is the maximum length this frame (including frame header) will have.
func (s *sendStream) popStreamFrame(maxBytes protocol.ByteCount, v protocol.VersionNumber) (*ackhandler.Frame, bool /* has more data to send */) {
s.mutex.Lock()
f, hasMoreData := s.popNewOrRetransmittedStreamFrame(maxBytes, v)
if f != nil {
s.numOutstandingFrames++
}
s.mutex.Unlock()
if f == nil {
return nil, hasMoreData
}
af := ackhandler.GetFrame()
af.Frame = f
af.OnLost = s.queueRetransmission
af.OnAcked = s.frameAcked
return af, hasMoreData
}
func (s *sendStream) popNewOrRetransmittedStreamFrame(maxBytes protocol.ByteCount, v protocol.VersionNumber) (*wire.StreamFrame, bool /* has more data to send */) {
if s.canceledWrite || s.closeForShutdownErr != nil {
return nil, false
}
if len(s.retransmissionQueue) > 0 {
f, hasMoreRetransmissions := s.maybeGetRetransmission(maxBytes, v)
if f != nil || hasMoreRetransmissions {
if f == nil {
return nil, true
}
// We always claim that we have more data to send.
// This might be incorrect, in which case there'll be a spurious call to popStreamFrame in the future.
return f, true
}
}
if len(s.dataForWriting) == 0 && s.nextFrame == nil {
if s.finishedWriting && !s.finSent {
s.finSent = true
return &wire.StreamFrame{
StreamID: s.streamID,
Offset: s.writeOffset,
DataLenPresent: true,
Fin: true,
}, false
}
return nil, false
}
sendWindow := s.flowController.SendWindowSize()
if sendWindow == 0 {
if isBlocked, offset := s.flowController.IsNewlyBlocked(); isBlocked {
s.sender.queueControlFrame(&wire.StreamDataBlockedFrame{
StreamID: s.streamID,
MaximumStreamData: offset,
})
return nil, false
}
return nil, true
}
f, hasMoreData := s.popNewStreamFrame(maxBytes, sendWindow, v)
if dataLen := f.DataLen(); dataLen > 0 {
s.writeOffset += f.DataLen()
s.flowController.AddBytesSent(f.DataLen())
}
f.Fin = s.finishedWriting && s.dataForWriting == nil && s.nextFrame == nil && !s.finSent
if f.Fin {
s.finSent = true
}
return f, hasMoreData
}
func (s *sendStream) popNewStreamFrame(maxBytes, sendWindow protocol.ByteCount, v protocol.VersionNumber) (*wire.StreamFrame, bool) {
if s.nextFrame != nil {
nextFrame := s.nextFrame
s.nextFrame = nil
maxDataLen := utils.Min(sendWindow, nextFrame.MaxDataLen(maxBytes, v))
if nextFrame.DataLen() > maxDataLen {
s.nextFrame = wire.GetStreamFrame()
s.nextFrame.StreamID = s.streamID
s.nextFrame.Offset = s.writeOffset + maxDataLen
s.nextFrame.Data = s.nextFrame.Data[:nextFrame.DataLen()-maxDataLen]
s.nextFrame.DataLenPresent = true
copy(s.nextFrame.Data, nextFrame.Data[maxDataLen:])
nextFrame.Data = nextFrame.Data[:maxDataLen]
} else {
s.signalWrite()
}
return nextFrame, s.nextFrame != nil || s.dataForWriting != nil
}
f := wire.GetStreamFrame()
f.Fin = false
f.StreamID = s.streamID
f.Offset = s.writeOffset
f.DataLenPresent = true
f.Data = f.Data[:0]
hasMoreData := s.popNewStreamFrameWithoutBuffer(f, maxBytes, sendWindow, v)
if len(f.Data) == 0 && !f.Fin {
f.PutBack()
return nil, hasMoreData
}
return f, hasMoreData
}
func (s *sendStream) popNewStreamFrameWithoutBuffer(f *wire.StreamFrame, maxBytes, sendWindow protocol.ByteCount, v protocol.VersionNumber) bool {
maxDataLen := f.MaxDataLen(maxBytes, v)
if maxDataLen == 0 { // a STREAM frame must have at least one byte of data
return s.dataForWriting != nil || s.nextFrame != nil || s.finishedWriting
}
s.getDataForWriting(f, utils.Min(maxDataLen, sendWindow))
return s.dataForWriting != nil || s.nextFrame != nil || s.finishedWriting
}
func (s *sendStream) maybeGetRetransmission(maxBytes protocol.ByteCount, v protocol.VersionNumber) (*wire.StreamFrame, bool /* has more retransmissions */) {
f := s.retransmissionQueue[0]
newFrame, needsSplit := f.MaybeSplitOffFrame(maxBytes, v)
if needsSplit {
return newFrame, true
}
s.retransmissionQueue = s.retransmissionQueue[1:]
return f, len(s.retransmissionQueue) > 0
}
func (s *sendStream) hasData() bool {
s.mutex.Lock()
hasData := len(s.dataForWriting) > 0
s.mutex.Unlock()
return hasData
}
func (s *sendStream) getDataForWriting(f *wire.StreamFrame, maxBytes protocol.ByteCount) {
if protocol.ByteCount(len(s.dataForWriting)) <= maxBytes {
f.Data = f.Data[:len(s.dataForWriting)]
copy(f.Data, s.dataForWriting)
s.dataForWriting = nil
s.signalWrite()
return
}
f.Data = f.Data[:maxBytes]
copy(f.Data, s.dataForWriting)
s.dataForWriting = s.dataForWriting[maxBytes:]
if s.canBufferStreamFrame() {
s.signalWrite()
}
}
func (s *sendStream) frameAcked(f wire.Frame) {
f.(*wire.StreamFrame).PutBack()
s.mutex.Lock()
if s.canceledWrite {
s.mutex.Unlock()
return
}
s.numOutstandingFrames--
if s.numOutstandingFrames < 0 {
panic("numOutStandingFrames negative")
}
newlyCompleted := s.isNewlyCompleted()
s.mutex.Unlock()
if newlyCompleted {
s.sender.onStreamCompleted(s.streamID)
}
}
func (s *sendStream) isNewlyCompleted() bool {
completed := (s.finSent || s.canceledWrite) && s.numOutstandingFrames == 0 && len(s.retransmissionQueue) == 0
if completed && !s.completed {
s.completed = true
return true
}
return false
}
func (s *sendStream) queueRetransmission(f wire.Frame) {
sf := f.(*wire.StreamFrame)
sf.DataLenPresent = true
s.mutex.Lock()
if s.canceledWrite {
s.mutex.Unlock()
return
}
s.retransmissionQueue = append(s.retransmissionQueue, sf)
s.numOutstandingFrames--
if s.numOutstandingFrames < 0 {
panic("numOutStandingFrames negative")
}
s.mutex.Unlock()
s.sender.onHasStreamData(s.streamID)
}
func (s *sendStream) Close() error {
s.mutex.Lock()
if s.closedForShutdown {
s.mutex.Unlock()
return nil
}
if s.canceledWrite {
s.mutex.Unlock()
return fmt.Errorf("close called for canceled stream %d", s.streamID)
}
s.ctxCancel()
s.finishedWriting = true
s.mutex.Unlock()
s.sender.onHasStreamData(s.streamID) // need to send the FIN, must be called without holding the mutex
return nil
}
func (s *sendStream) CancelWrite(errorCode StreamErrorCode) {
s.cancelWriteImpl(errorCode, false)
}
// must be called after locking the mutex
func (s *sendStream) cancelWriteImpl(errorCode qerr.StreamErrorCode, remote bool) {
s.mutex.Lock()
if s.canceledWrite {
s.mutex.Unlock()
return
}
s.ctxCancel()
s.canceledWrite = true
s.cancelWriteErr = &StreamError{StreamID: s.streamID, ErrorCode: errorCode, Remote: remote}
s.numOutstandingFrames = 0
s.retransmissionQueue = nil
newlyCompleted := s.isNewlyCompleted()
s.mutex.Unlock()
s.signalWrite()
s.sender.queueControlFrame(&wire.ResetStreamFrame{
StreamID: s.streamID,
FinalSize: s.writeOffset,
ErrorCode: errorCode,
})
if newlyCompleted {
s.sender.onStreamCompleted(s.streamID)
}
}
func (s *sendStream) updateSendWindow(limit protocol.ByteCount) {
s.mutex.Lock()
hasStreamData := s.dataForWriting != nil || s.nextFrame != nil
s.mutex.Unlock()
s.flowController.UpdateSendWindow(limit)
if hasStreamData {
s.sender.onHasStreamData(s.streamID)
}
}
func (s *sendStream) handleStopSendingFrame(frame *wire.StopSendingFrame) {
s.cancelWriteImpl(frame.ErrorCode, true)
}
func (s *sendStream) Context() context.Context {
return s.ctx
}
func (s *sendStream) SetWriteDeadline(t time.Time) error {
s.mutex.Lock()
s.deadline = t
s.mutex.Unlock()
s.signalWrite()
return nil
}
// CloseForShutdown closes a stream abruptly.
// It makes Write unblock (and return the error) immediately.
// The peer will NOT be informed about this: the stream is closed without sending a FIN or RST.
func (s *sendStream) closeForShutdown(err error) {
s.mutex.Lock()
s.ctxCancel()
s.closedForShutdown = true
s.closeForShutdownErr = err
s.mutex.Unlock()
s.signalWrite()
}
// signalWrite performs a non-blocking send on the writeChan
func (s *sendStream) signalWrite() {
select {
case s.writeChan <- struct{}{}:
default:
}
}