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tsdb: use dennwc/varint to speed up WAL decoding (#9106)

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* tsdb: use dennwc/varint to speed up decoding

This is a tiny library, MIT-licensed, which unrolls the loop to go
about twice as fast.

Needed to copy the sign-inverting logic inline, previously provided by
the `binary` package.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>

* More comments to explain varint decoding

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
This commit is contained in:
Bryan Boreham 2021-07-27 05:32:57 +01:00 committed by GitHub
parent dcba645366
commit dea37853d9
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GPG key ID: 4AEE18F83AFDEB23
3 changed files with 13 additions and 3 deletions
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1
go.mod
View file

@ -13,6 +13,7 @@ require (
github.com/aws/aws-sdk-go v1.38.60
github.com/cespare/xxhash/v2 v2.1.1
github.com/containerd/containerd v1.5.3 // indirect
github.com/dennwc/varint v1.0.0
github.com/dgryski/go-sip13 v0.0.0-20200911182023-62edffca9245
github.com/digitalocean/godo v1.62.0
github.com/docker/docker v20.10.7+incompatible

2
go.sum
View file

@ -344,6 +344,8 @@ github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/denisenkom/go-mssqldb v0.0.0-20200428022330-06a60b6afbbc/go.mod h1:xbL0rPBG9cCiLr28tMa8zpbdarY27NDyej4t/EjAShU=
github.com/dennwc/varint v1.0.0 h1:kGNFFSSw8ToIy3obO/kKr8U9GZYUAxQEVuix4zfDWzE=
github.com/dennwc/varint v1.0.0/go.mod h1:hnItb35rvZvJrbTALZtY/iQfDs48JKRG1RPpgziApxA=
github.com/denverdino/aliyungo v0.0.0-20190125010748-a747050bb1ba/go.mod h1:dV8lFg6daOBZbT6/BDGIz6Y3WFGn8juu6G+CQ6LHtl0=
github.com/dgrijalva/jwt-go v0.0.0-20170104182250-a601269ab70c/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=
github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=

13
tsdb/encoding/encoding.go
View file

@ -19,6 +19,7 @@ import (
"hash/crc32"
"unsafe"
"github.com/dennwc/varint"
"github.com/pkg/errors"
)
@ -139,7 +140,7 @@ func NewDecbufUvarintAt(bs ByteSlice, off int, castagnoliTable *crc32.Table) Dec
}
b := bs.Range(off, off+binary.MaxVarintLen32)
l, n := binary.Uvarint(b)
l, n := varint.Uvarint(b)
if n <= 0 || n > binary.MaxVarintLen32 {
return Decbuf{E: errors.Errorf("invalid uvarint %d", n)}
}
@ -207,11 +208,17 @@ func (d *Decbuf) Varint64() int64 {
if d.E != nil {
return 0
}
x, n := binary.Varint(d.B)
// Decode as unsigned first, since that's what the varint library implements.
ux, n := varint.Uvarint(d.B)
if n < 1 {
d.E = ErrInvalidSize
return 0
}
// Now decode "ZigZag encoding" https://developers.google.com/protocol-buffers/docs/encoding#signed_integers.
x := int64(ux >> 1)
if ux&1 != 0 {
x = ^x
}
d.B = d.B[n:]
return x
}
@ -220,7 +227,7 @@ func (d *Decbuf) Uvarint64() uint64 {
if d.E != nil {
return 0
}
x, n := binary.Uvarint(d.B)
x, n := varint.Uvarint(d.B)
if n < 1 {
d.E = ErrInvalidSize
return 0