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refactor calculation of ACK ranges into a separate function

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This commit is contained in:
Marten Seemann
2018-04-19 22:46:53 +09:00
parent 83b670841a
commit 4891b65c4b
1 changed files with 19 additions and 28 deletions
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47
internal/wire/ack_frame.go
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@@ -99,31 +99,22 @@ func (f *AckFrame) Write(b *bytes.Buffer, version protocol.VersionNumber) error
return f.writeLegacy(b, version)
}
largestAcked := f.AckRanges[0].Largest
lowestInFirstRange := f.AckRanges[0].Smallest
b.WriteByte(0x0d)
utils.WriteVarInt(b, uint64(largestAcked))
utils.WriteVarInt(b, uint64(f.LargestAcked()))
utils.WriteVarInt(b, encodeAckDelay(f.DelayTime))
// TODO: limit the number of ACK ranges, such that the frame doesn't grow larger than an upper bound
utils.WriteVarInt(b, uint64(len(f.AckRanges)-1))
// write the first range
utils.WriteVarInt(b, uint64(largestAcked-lowestInFirstRange))
_, firstRange := f.encodeAckRange(0)
utils.WriteVarInt(b, firstRange)
// write all the other range
if f.HasMissingRanges() {
var lowest protocol.PacketNumber
for i, ackRange := range f.AckRanges {
if i == 0 {
lowest = lowestInFirstRange
continue
}
utils.WriteVarInt(b, uint64(lowest-ackRange.Largest-2))
utils.WriteVarInt(b, uint64(ackRange.Largest-ackRange.Smallest))
lowest = ackRange.Smallest
}
for i := 1; i < len(f.AckRanges); i++ {
gap, len := f.encodeAckRange(i)
utils.WriteVarInt(b, gap)
utils.WriteVarInt(b, len)
}
return nil
}
@@ -141,22 +132,22 @@ func (f *AckFrame) Length(version protocol.VersionNumber) protocol.ByteCount {
lowestInFirstRange := f.AckRanges[0].Smallest
length += utils.VarIntLen(uint64(largestAcked - lowestInFirstRange))
if !f.HasMissingRanges() {
return length
}
var lowest protocol.PacketNumber
for i, ackRange := range f.AckRanges {
if i == 0 {
lowest = ackRange.Smallest
continue
}
length += utils.VarIntLen(uint64(lowest - ackRange.Largest - 2))
length += utils.VarIntLen(uint64(ackRange.Largest - ackRange.Smallest))
lowest = ackRange.Smallest
for i := 1; i < len(f.AckRanges); i++ {
gap, len := f.encodeAckRange(i)
length += utils.VarIntLen(gap)
length += utils.VarIntLen(len)
}
return length
}
func (f *AckFrame) encodeAckRange(i int) (uint64 /* gap */, uint64 /* length */) {
if i == 0 {
return 0, uint64(f.AckRanges[0].Largest - f.AckRanges[0].Smallest)
}
return uint64(f.AckRanges[i-1].Smallest - f.AckRanges[i].Largest - 2),
uint64(f.AckRanges[i].Largest - f.AckRanges[i].Smallest)
}
// HasMissingRanges returns if this frame reports any missing packets
func (f *AckFrame) HasMissingRanges() bool {
return len(f.AckRanges) > 1