zlog/internal/json/bytes.go
Olivier Poitrey 4ea03de40d Optimize JSON string encoding using a lookup table
benchstat old new
name                             old time/op    new time/op    delta
AppendString/MultiBytesFirst-8     77.9ns ± 5%    70.2ns ± 1%   -9.88%  (p=0.008 n=5+5)
AppendString/MultiBytesMiddle-8    64.2ns ± 1%    56.3ns ± 5%  -12.19%  (p=0.008 n=5+5)
AppendString/MultiBytesLast-8      51.2ns ± 2%    45.2ns ± 4%  -11.65%  (p=0.008 n=5+5)
AppendString/NoEncoding-8          36.2ns ± 4%    34.0ns ± 6%     ~     (p=0.087 n=5+5)
AppendString/EncodingFirst-8       67.7ns ± 2%    59.4ns ± 2%  -12.26%  (p=0.008 n=5+5)
AppendString/EncodingMiddle-8      56.5ns ± 2%    50.6ns ± 5%  -10.54%  (p=0.008 n=5+5)
AppendString/EncodingLast-8        41.3ns ± 1%    39.6ns ± 5%   -4.11%  (p=0.024 n=5+5)
AppendBytes/MultiBytesLast-8       53.5ns ± 6%    45.6ns ± 4%  -14.79%  (p=0.008 n=5+5)
AppendBytes/NoEncoding-8           36.3ns ± 3%    28.6ns ± 3%  -21.10%  (p=0.008 n=5+5)
AppendBytes/EncodingFirst-8        67.3ns ± 4%    62.1ns ± 4%   -7.75%  (p=0.008 n=5+5)
AppendBytes/EncodingMiddle-8       59.2ns ± 7%    51.0ns ± 6%  -13.85%  (p=0.008 n=5+5)
AppendBytes/EncodingLast-8         43.7ns ± 6%    34.4ns ± 2%  -21.32%  (p=0.008 n=5+5)
AppendBytes/MultiBytesFirst-8      77.7ns ± 2%    71.2ns ± 3%   -8.37%  (p=0.008 n=5+5)
AppendBytes/MultiBytesMiddle-8     63.6ns ± 3%    57.8ns ± 5%   -9.12%  (p=0.008 n=5+5)
2018-03-23 04:24:50 -07:00

86 lines
1.9 KiB
Go

package json
import "unicode/utf8"
// AppendBytes is a mirror of appendString with []byte arg
func AppendBytes(dst, s []byte) []byte {
dst = append(dst, '"')
for i := 0; i < len(s); i++ {
if !noEscapeTable[s[i]] {
dst = appendBytesComplex(dst, s, i)
return append(dst, '"')
}
}
dst = append(dst, s...)
return append(dst, '"')
}
// AppendHex encodes the input bytes to a hex string and appends
// the encoded string to the input byte slice.
//
// The operation loops though each byte and encodes it as hex using
// the hex lookup table.
func AppendHex(dst, s []byte) []byte {
dst = append(dst, '"')
for _, v := range s {
dst = append(dst, hex[v>>4], hex[v&0x0f])
}
return append(dst, '"')
}
// appendBytesComplex is a mirror of the appendStringComplex
// with []byte arg
func appendBytesComplex(dst, s []byte, i int) []byte {
start := 0
for i < len(s) {
b := s[i]
if b >= utf8.RuneSelf {
r, size := utf8.DecodeRune(s[i:])
if r == utf8.RuneError && size == 1 {
if start < i {
dst = append(dst, s[start:i]...)
}
dst = append(dst, `\ufffd`...)
i += size
start = i
continue
}
i += size
continue
}
if noEscapeTable[b] {
i++
continue
}
// We encountered a character that needs to be encoded.
// Let's append the previous simple characters to the byte slice
// and switch our operation to read and encode the remainder
// characters byte-by-byte.
if start < i {
dst = append(dst, s[start:i]...)
}
switch b {
case '"', '\\':
dst = append(dst, '\\', b)
case '\b':
dst = append(dst, '\\', 'b')
case '\f':
dst = append(dst, '\\', 'f')
case '\n':
dst = append(dst, '\\', 'n')
case '\r':
dst = append(dst, '\\', 'r')
case '\t':
dst = append(dst, '\\', 't')
default:
dst = append(dst, '\\', 'u', '0', '0', hex[b>>4], hex[b&0xF])
}
i++
start = i
}
if start < len(s) {
dst = append(dst, s[start:]...)
}
return dst
}