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frame_sorter.go
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frame_sorter.go
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package quic
import (
"errors"
"sync"
"github.com/quic-go/quic-go/internal/protocol"
list "github.com/quic-go/quic-go/internal/utils/linkedlist"
)
// byteInterval is an interval from one ByteCount to the other
type byteInterval struct {
Start protocol.ByteCount
End protocol.ByteCount
}
var byteIntervalElementPool sync.Pool
func init() {
byteIntervalElementPool = *list.NewPool[byteInterval]()
}
type frameSorterEntry struct {
Data []byte
DoneCb func()
}
type frameSorter struct {
queue map[protocol.ByteCount]frameSorterEntry
readPos protocol.ByteCount
gaps *list.List[byteInterval]
}
var errDuplicateStreamData = errors.New("duplicate stream data")
func newFrameSorter() *frameSorter {
s := frameSorter{
gaps: list.NewWithPool[byteInterval](&byteIntervalElementPool),
queue: make(map[protocol.ByteCount]frameSorterEntry),
}
s.gaps.PushFront(byteInterval{Start: 0, End: protocol.MaxByteCount})
return &s
}
func (s *frameSorter) Push(data []byte, offset protocol.ByteCount, doneCb func()) error {
err := s.push(data, offset, doneCb)
if err == errDuplicateStreamData {
if doneCb != nil {
doneCb()
}
return nil
}
return err
}
func (s *frameSorter) push(data []byte, offset protocol.ByteCount, doneCb func()) error {
if len(data) == 0 {
return errDuplicateStreamData
}
start := offset
end := offset + protocol.ByteCount(len(data))
if end <= s.gaps.Front().Value.Start {
return errDuplicateStreamData
}
startGap, startsInGap := s.findStartGap(start)
endGap, endsInGap := s.findEndGap(startGap, end)
startGapEqualsEndGap := startGap == endGap
if (startGapEqualsEndGap && end <= startGap.Value.Start) ||
(!startGapEqualsEndGap && startGap.Value.End >= endGap.Value.Start && end <= startGap.Value.Start) {
return errDuplicateStreamData
}
startGapNext := startGap.Next()
startGapEnd := startGap.Value.End // save it, in case startGap is modified
endGapStart := endGap.Value.Start // save it, in case endGap is modified
endGapEnd := endGap.Value.End // save it, in case endGap is modified
var adjustedStartGapEnd bool
var wasCut bool
pos := start
var hasReplacedAtLeastOne bool
for {
oldEntry, ok := s.queue[pos]
if !ok {
break
}
oldEntryLen := protocol.ByteCount(len(oldEntry.Data))
if end-pos > oldEntryLen || (hasReplacedAtLeastOne && end-pos == oldEntryLen) {
// The existing frame is shorter than the new frame. Replace it.
delete(s.queue, pos)
pos += oldEntryLen
hasReplacedAtLeastOne = true
if oldEntry.DoneCb != nil {
oldEntry.DoneCb()
}
} else {
if !hasReplacedAtLeastOne {
return errDuplicateStreamData
}
// The existing frame is longer than the new frame.
// Cut the new frame such that the end aligns with the start of the existing frame.
data = data[:pos-start]
end = pos
wasCut = true
break
}
}
if !startsInGap && !hasReplacedAtLeastOne {
// cut the frame, such that it starts at the start of the gap
data = data[startGap.Value.Start-start:]
start = startGap.Value.Start
wasCut = true
}
if start <= startGap.Value.Start {
if end >= startGap.Value.End {
// The frame covers the whole startGap. Delete the gap.
s.gaps.Remove(startGap)
} else {
startGap.Value.Start = end
}
} else if !hasReplacedAtLeastOne {
startGap.Value.End = start
adjustedStartGapEnd = true
}
if !startGapEqualsEndGap {
s.deleteConsecutive(startGapEnd)
var nextGap *list.Element[byteInterval]
for gap := startGapNext; gap.Value.End < endGapStart; gap = nextGap {
nextGap = gap.Next()
s.deleteConsecutive(gap.Value.End)
s.gaps.Remove(gap)
}
}
if !endsInGap && start != endGapEnd && end > endGapEnd {
// cut the frame, such that it ends at the end of the gap
data = data[:endGapEnd-start]
end = endGapEnd
wasCut = true
}
if end == endGapEnd {
if !startGapEqualsEndGap {
// The frame covers the whole endGap. Delete the gap.
s.gaps.Remove(endGap)
}
} else {
if startGapEqualsEndGap && adjustedStartGapEnd {
// The frame split the existing gap into two.
s.gaps.InsertAfter(byteInterval{Start: end, End: startGapEnd}, startGap)
} else if !startGapEqualsEndGap {
endGap.Value.Start = end
}
}
if wasCut && len(data) < protocol.MinStreamFrameBufferSize {
newData := make([]byte, len(data))
copy(newData, data)
data = newData
if doneCb != nil {
doneCb()
doneCb = nil
}
}
if s.gaps.Len() > protocol.MaxStreamFrameSorterGaps {
return errors.New("too many gaps in received data")
}
s.queue[start] = frameSorterEntry{Data: data, DoneCb: doneCb}
return nil
}
func (s *frameSorter) findStartGap(offset protocol.ByteCount) (*list.Element[byteInterval], bool) {
for gap := s.gaps.Front(); gap != nil; gap = gap.Next() {
if offset >= gap.Value.Start && offset <= gap.Value.End {
return gap, true
}
if offset < gap.Value.Start {
return gap, false
}
}
panic("no gap found")
}
func (s *frameSorter) findEndGap(startGap *list.Element[byteInterval], offset protocol.ByteCount) (*list.Element[byteInterval], bool) {
for gap := startGap; gap != nil; gap = gap.Next() {
if offset >= gap.Value.Start && offset < gap.Value.End {
return gap, true
}
if offset < gap.Value.Start {
return gap.Prev(), false
}
}
panic("no gap found")
}
// deleteConsecutive deletes consecutive frames from the queue, starting at pos
func (s *frameSorter) deleteConsecutive(pos protocol.ByteCount) {
for {
oldEntry, ok := s.queue[pos]
if !ok {
break
}
oldEntryLen := protocol.ByteCount(len(oldEntry.Data))
delete(s.queue, pos)
if oldEntry.DoneCb != nil {
oldEntry.DoneCb()
}
pos += oldEntryLen
}
}
func (s *frameSorter) Pop() (protocol.ByteCount, []byte, func()) {
entry, ok := s.queue[s.readPos]
if !ok {
return s.readPos, nil, nil
}
delete(s.queue, s.readPos)
offset := s.readPos
s.readPos += protocol.ByteCount(len(entry.Data))
if s.gaps.Front().Value.End <= s.readPos {
panic("frame sorter BUG: read position higher than a gap")
}
return offset, entry.Data, entry.DoneCb
}
// HasMoreData says if there is any more data queued at *any* offset.
func (s *frameSorter) HasMoreData() bool {
return len(s.queue) > 0
}