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Merge b835d3bdb4 into 677efa4678

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Bryan Boreham 2025-03-05 22:36:44 +08:00 committed by GitHub
parent 677efa4678 b835d3bdb4
commit f73f06cea6
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1 changed files with 22 additions and 52 deletions
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74
model/labels/labels_stringlabels.go
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@ -24,31 +24,24 @@ import (
)
// Labels is implemented by a single flat string holding name/value pairs.
// Each name and value is preceded by its length in varint encoding.
// Each name and value is preceded by its length, encoded as a single byte
// for size 0-254, or the following 3 bytes little-endian, if the first byte is 255.
// Maximum length allowed is 2^24 or 16MB.
// Names are in order.
type Labels struct {
data string
}
func decodeSize(data string, index int) (int, int) {
// Fast-path for common case of a single byte, value 0..127.
// Fast-path for common case of a single byte, value 0..254.
b := data[index]
index++
if b < 0x80 {
return int(b), index
if b < 255 {
return int(b), index + 1
}
size := int(b & 0x7F)
for shift := uint(7); ; shift += 7 {
// Just panic if we go of the end of data, since all Labels strings are constructed internally and
// malformed data indicates a bug, or memory corruption.
b := data[index]
index++
size |= int(b&0x7F) << shift
if b < 0x80 {
break
}
}
return size, index
// Otherwise it's encoded as 3 bytes little-endian.
// Just panic if we go of the end of data, since all Labels strings are constructed internally and
// malformed data indicates a bug, or memory corruption.
return int(data[index+1]) + (int(data[index+2]) << 8) + (int(data[index+3]) << 16), index + 4
}
func decodeString(data string, index int) (string, int) {
@ -527,48 +520,25 @@ func marshalLabelToSizedBuffer(m *Label, data []byte) int {
return len(data) - i
}
func sizeVarint(x uint64) (n int) {
// Most common case first
if x < 1<<7 {
func sizeWhenEncoded(x uint64) (n int) {
if x < 254 {
return 1
}
if x >= 1<<56 {
return 9
}
if x >= 1<<28 {
x >>= 28
n = 4
}
if x >= 1<<14 {
x >>= 14
n += 2
}
if x >= 1<<7 {
n++
}
return n + 1
return 4
}
func encodeVarint(data []byte, offset int, v uint64) int {
offset -= sizeVarint(v)
base := offset
for v >= 1<<7 {
data[offset] = uint8(v&0x7f | 0x80)
v >>= 7
offset++
}
data[offset] = uint8(v)
return base
}
// Special code for the common case that a size is less than 128
func encodeSize(data []byte, offset, v int) int {
if v < 1<<7 {
if v < 255 {
offset--
data[offset] = uint8(v)
return offset
}
return encodeVarint(data, offset, uint64(v))
offset -= 4
data[offset] = 255
data[offset+1] = byte(v)
data[offset+2] = byte((v >> 8))
data[offset+3] = byte((v >> 16))
return offset
}
func labelsSize(lbls []Label) (n int) {
@ -582,9 +552,9 @@ func labelsSize(lbls []Label) (n int) {
func labelSize(m *Label) (n int) {
// strings are encoded as length followed by contents.
l := len(m.Name)
n += l + sizeVarint(uint64(l))
n += l + sizeWhenEncoded(uint64(l))
l = len(m.Value)
n += l + sizeVarint(uint64(l))
n += l + sizeWhenEncoded(uint64(l))
return n
}