mirror of
https://github.com/go-gitea/gitea.git
synced 2024-12-05 00:49:45 +01:00
e28cc79c92
This addresses https://github.com/go-gitea/gitea/issues/18352 It aims to improve performance (and resource use) of the `SyncReleasesWithTags` operation for pull-mirrors. For large repositories with many tags, `SyncReleasesWithTags` can be a costly operation (taking several minutes to complete). The reason is two-fold: 1. on sync, every upstream repo tag is compared (for changes) against existing local entries in the release table to ensure that they are up-to-date. 2. the procedure for getting _each tag_ involves a series of git operations ```bash git show-ref --tags -- v8.2.4477 git cat-file -t 29ab6ce9f36660cffaad3c8789e71162e5db5d2f git cat-file -p 29ab6ce9f36660cffaad3c8789e71162e5db5d2f git rev-list --count 29ab6ce9f36660cffaad3c8789e71162e5db5d2f ``` of which the `git rev-list --count` can be particularly heavy. This PR optimizes performance for pull-mirrors. We utilize the fact that a pull-mirror is always identical to its upstream and rebuild the entire release table on every sync and use a batch `git for-each-ref .. refs/tags` call to retrieve all tags in one go. For large mirror repos, with hundreds of annotated tags, this brings down the duration of the sync operation from several minutes to a few seconds. A few unscientific examples run on my local machine: - https://github.com/spring-projects/spring-boot (223 tags) - before: `0m28,673s` - after: `0m2,244s` - https://github.com/kubernetes/kubernetes (890 tags) - before: `8m00s` - after: `0m8,520s` - https://github.com/vim/vim (13954 tags) - before: `14m20,383s` - after: `0m35,467s` I added a `foreachref` package which contains a flexible way of specifying which reference fields are of interest (`git-for-each-ref(1)`) and to produce a parser for the expected output. These could be reused in other places where `for-each-ref` is used. I'll add unit tests for those if the overall PR looks promising.
85 lines
2.6 KiB
Go
85 lines
2.6 KiB
Go
// Copyright 2022 The Gitea Authors. All rights reserved.
|
|
// Use of this source code is governed by a MIT-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package foreachref
|
|
|
|
import (
|
|
"encoding/hex"
|
|
"fmt"
|
|
"io"
|
|
"strings"
|
|
)
|
|
|
|
var (
|
|
nullChar = []byte("\x00")
|
|
dualNullChar = []byte("\x00\x00")
|
|
)
|
|
|
|
// Format supports specifying and parsing an output format for 'git
|
|
// for-each-ref'. See See git-for-each-ref(1) for available fields.
|
|
type Format struct {
|
|
// fieldNames hold %(fieldname)s to be passed to the '--format' flag of
|
|
// for-each-ref. See git-for-each-ref(1) for available fields.
|
|
fieldNames []string
|
|
|
|
// fieldDelim is the character sequence that is used to separate fields
|
|
// for each reference. fieldDelim and refDelim should be selected to not
|
|
// interfere with each other and to not be present in field values.
|
|
fieldDelim []byte
|
|
// fieldDelimStr is a string representation of fieldDelim. Used to save
|
|
// us from repetitive reallocation whenever we need the delimiter as a
|
|
// string.
|
|
fieldDelimStr string
|
|
// refDelim is the character sequence used to separate reference from
|
|
// each other in the output. fieldDelim and refDelim should be selected
|
|
// to not interfere with each other and to not be present in field
|
|
// values.
|
|
refDelim []byte
|
|
}
|
|
|
|
// NewFormat creates a forEachRefFormat using the specified fieldNames. See
|
|
// git-for-each-ref(1) for available fields.
|
|
func NewFormat(fieldNames ...string) Format {
|
|
return Format{
|
|
fieldNames: fieldNames,
|
|
fieldDelim: nullChar,
|
|
fieldDelimStr: string(nullChar),
|
|
refDelim: dualNullChar,
|
|
}
|
|
}
|
|
|
|
// Flag returns a for-each-ref --format flag value that captures the fieldNames.
|
|
func (f Format) Flag() string {
|
|
var formatFlag strings.Builder
|
|
for i, field := range f.fieldNames {
|
|
// field key and field value
|
|
formatFlag.WriteString(fmt.Sprintf("%s %%(%s)", field, field))
|
|
|
|
if i < len(f.fieldNames)-1 {
|
|
// note: escape delimiters to allow control characters as
|
|
// delimiters. For example, '%00' for null character or '%0a'
|
|
// for newline.
|
|
formatFlag.WriteString(f.hexEscaped(f.fieldDelim))
|
|
}
|
|
}
|
|
formatFlag.WriteString(f.hexEscaped(f.refDelim))
|
|
return formatFlag.String()
|
|
}
|
|
|
|
// Parser returns a Parser capable of parsing 'git for-each-ref' output produced
|
|
// with this Format.
|
|
func (f Format) Parser(r io.Reader) *Parser {
|
|
return NewParser(r, f)
|
|
}
|
|
|
|
// hexEscaped produces hex-escpaed characters from a string. For example, "\n\0"
|
|
// would turn into "%0a%00".
|
|
func (f Format) hexEscaped(delim []byte) string {
|
|
escaped := ""
|
|
for i := 0; i < len(delim); i++ {
|
|
escaped += "%" + hex.EncodeToString([]byte{delim[i]})
|
|
}
|
|
return escaped
|
|
}
|