github.com/TugasAkhir-QUIC/quic-go@v0.0.2-0.20240215011318-d20e25a9054c/frame_sorter.go (about) 1 package quic 2 3 import ( 4 "errors" 5 "sync" 6 7 "github.com/TugasAkhir-QUIC/quic-go/internal/protocol" 8 list "github.com/TugasAkhir-QUIC/quic-go/internal/utils/linkedlist" 9 ) 10 11 // byteInterval is an interval from one ByteCount to the other 12 type byteInterval struct { 13 Start protocol.ByteCount 14 End protocol.ByteCount 15 } 16 17 var byteIntervalElementPool sync.Pool 18 19 func init() { 20 byteIntervalElementPool = *list.NewPool[byteInterval]() 21 } 22 23 type frameSorterEntry struct { 24 Data []byte 25 DoneCb func() 26 } 27 28 type frameSorter struct { 29 queue map[protocol.ByteCount]frameSorterEntry 30 readPos protocol.ByteCount 31 gaps *list.List[byteInterval] 32 } 33 34 var errDuplicateStreamData = errors.New("duplicate stream data") 35 36 func newFrameSorter() *frameSorter { 37 s := frameSorter{ 38 gaps: list.NewWithPool[byteInterval](&byteIntervalElementPool), 39 queue: make(map[protocol.ByteCount]frameSorterEntry), 40 } 41 s.gaps.PushFront(byteInterval{Start: 0, End: protocol.MaxByteCount}) 42 return &s 43 } 44 45 func (s *frameSorter) Push(data []byte, offset protocol.ByteCount, doneCb func()) error { 46 err := s.push(data, offset, doneCb) 47 if err == errDuplicateStreamData { 48 if doneCb != nil { 49 doneCb() 50 } 51 return nil 52 } 53 return err 54 } 55 56 func (s *frameSorter) push(data []byte, offset protocol.ByteCount, doneCb func()) error { 57 if len(data) == 0 { 58 return errDuplicateStreamData 59 } 60 61 start := offset 62 end := offset + protocol.ByteCount(len(data)) 63 64 if end <= s.gaps.Front().Value.Start { 65 return errDuplicateStreamData 66 } 67 68 startGap, startsInGap := s.findStartGap(start) 69 endGap, endsInGap := s.findEndGap(startGap, end) 70 71 startGapEqualsEndGap := startGap == endGap 72 73 if (startGapEqualsEndGap && end <= startGap.Value.Start) || 74 (!startGapEqualsEndGap && startGap.Value.End >= endGap.Value.Start && end <= startGap.Value.Start) { 75 return errDuplicateStreamData 76 } 77 78 startGapNext := startGap.Next() 79 startGapEnd := startGap.Value.End // save it, in case startGap is modified 80 endGapStart := endGap.Value.Start // save it, in case endGap is modified 81 endGapEnd := endGap.Value.End // save it, in case endGap is modified 82 var adjustedStartGapEnd bool 83 var wasCut bool 84 85 pos := start 86 var hasReplacedAtLeastOne bool 87 for { 88 oldEntry, ok := s.queue[pos] 89 if !ok { 90 break 91 } 92 oldEntryLen := protocol.ByteCount(len(oldEntry.Data)) 93 if end-pos > oldEntryLen || (hasReplacedAtLeastOne && end-pos == oldEntryLen) { 94 // The existing frame is shorter than the new frame. Replace it. 95 delete(s.queue, pos) 96 pos += oldEntryLen 97 hasReplacedAtLeastOne = true 98 if oldEntry.DoneCb != nil { 99 oldEntry.DoneCb() 100 } 101 } else { 102 if !hasReplacedAtLeastOne { 103 return errDuplicateStreamData 104 } 105 // The existing frame is longer than the new frame. 106 // Cut the new frame such that the end aligns with the start of the existing frame. 107 data = data[:pos-start] 108 end = pos 109 wasCut = true 110 break 111 } 112 } 113 114 if !startsInGap && !hasReplacedAtLeastOne { 115 // cut the frame, such that it starts at the start of the gap 116 data = data[startGap.Value.Start-start:] 117 start = startGap.Value.Start 118 wasCut = true 119 } 120 if start <= startGap.Value.Start { 121 if end >= startGap.Value.End { 122 // The frame covers the whole startGap. Delete the gap. 123 s.gaps.Remove(startGap) 124 } else { 125 startGap.Value.Start = end 126 } 127 } else if !hasReplacedAtLeastOne { 128 startGap.Value.End = start 129 adjustedStartGapEnd = true 130 } 131 132 if !startGapEqualsEndGap { 133 s.deleteConsecutive(startGapEnd) 134 var nextGap *list.Element[byteInterval] 135 for gap := startGapNext; gap.Value.End < endGapStart; gap = nextGap { 136 nextGap = gap.Next() 137 s.deleteConsecutive(gap.Value.End) 138 s.gaps.Remove(gap) 139 } 140 } 141 142 if !endsInGap && start != endGapEnd && end > endGapEnd { 143 // cut the frame, such that it ends at the end of the gap 144 data = data[:endGapEnd-start] 145 end = endGapEnd 146 wasCut = true 147 } 148 if end == endGapEnd { 149 if !startGapEqualsEndGap { 150 // The frame covers the whole endGap. Delete the gap. 151 s.gaps.Remove(endGap) 152 } 153 } else { 154 if startGapEqualsEndGap && adjustedStartGapEnd { 155 // The frame split the existing gap into two. 156 s.gaps.InsertAfter(byteInterval{Start: end, End: startGapEnd}, startGap) 157 } else if !startGapEqualsEndGap { 158 endGap.Value.Start = end 159 } 160 } 161 162 if wasCut && len(data) < protocol.MinStreamFrameBufferSize { 163 newData := make([]byte, len(data)) 164 copy(newData, data) 165 data = newData 166 if doneCb != nil { 167 doneCb() 168 doneCb = nil 169 } 170 } 171 172 if s.gaps.Len() > protocol.MaxStreamFrameSorterGaps { 173 return errors.New("too many gaps in received data") 174 } 175 176 s.queue[start] = frameSorterEntry{Data: data, DoneCb: doneCb} 177 return nil 178 } 179 180 func (s *frameSorter) findStartGap(offset protocol.ByteCount) (*list.Element[byteInterval], bool) { 181 for gap := s.gaps.Front(); gap != nil; gap = gap.Next() { 182 if offset >= gap.Value.Start && offset <= gap.Value.End { 183 return gap, true 184 } 185 if offset < gap.Value.Start { 186 return gap, false 187 } 188 } 189 panic("no gap found") 190 } 191 192 func (s *frameSorter) findEndGap(startGap *list.Element[byteInterval], offset protocol.ByteCount) (*list.Element[byteInterval], bool) { 193 for gap := startGap; gap != nil; gap = gap.Next() { 194 if offset >= gap.Value.Start && offset < gap.Value.End { 195 return gap, true 196 } 197 if offset < gap.Value.Start { 198 return gap.Prev(), false 199 } 200 } 201 panic("no gap found") 202 } 203 204 // deleteConsecutive deletes consecutive frames from the queue, starting at pos 205 func (s *frameSorter) deleteConsecutive(pos protocol.ByteCount) { 206 for { 207 oldEntry, ok := s.queue[pos] 208 if !ok { 209 break 210 } 211 oldEntryLen := protocol.ByteCount(len(oldEntry.Data)) 212 delete(s.queue, pos) 213 if oldEntry.DoneCb != nil { 214 oldEntry.DoneCb() 215 } 216 pos += oldEntryLen 217 } 218 } 219 220 func (s *frameSorter) Pop() (protocol.ByteCount, []byte, func()) { 221 entry, ok := s.queue[s.readPos] 222 if !ok { 223 return s.readPos, nil, nil 224 } 225 delete(s.queue, s.readPos) 226 offset := s.readPos 227 s.readPos += protocol.ByteCount(len(entry.Data)) 228 if s.gaps.Front().Value.End <= s.readPos { 229 panic("frame sorter BUG: read position higher than a gap") 230 } 231 return offset, entry.Data, entry.DoneCb 232 } 233 234 // HasMoreData says if there is any more data queued at *any* offset. 235 func (s *frameSorter) HasMoreData() bool { 236 return len(s.queue) > 0 237 }