Improve sync performance for pull-mirrors (#19125)
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.release
Peter Gardfjäll
GitHub
parent
b877504b03
commit
e28cc79c92
@ -0,0 +1,84 @@
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// Copyright 2022 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package foreachref
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import (
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"encoding/hex"
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"fmt"
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"io"
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"strings"
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)
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var (
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nullChar = []byte("\x00")
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dualNullChar = []byte("\x00\x00")
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)
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// Format supports specifying and parsing an output format for 'git
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// for-each-ref'. See See git-for-each-ref(1) for available fields.
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type Format struct {
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// fieldNames hold %(fieldname)s to be passed to the '--format' flag of
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// for-each-ref. See git-for-each-ref(1) for available fields.
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fieldNames []string
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// fieldDelim is the character sequence that is used to separate fields
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// for each reference. fieldDelim and refDelim should be selected to not
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// interfere with each other and to not be present in field values.
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fieldDelim []byte
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// fieldDelimStr is a string representation of fieldDelim. Used to save
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// us from repetitive reallocation whenever we need the delimiter as a
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// string.
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fieldDelimStr string
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// refDelim is the character sequence used to separate reference from
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// each other in the output. fieldDelim and refDelim should be selected
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// to not interfere with each other and to not be present in field
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// values.
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refDelim []byte
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}
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// NewFormat creates a forEachRefFormat using the specified fieldNames. See
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// git-for-each-ref(1) for available fields.
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func NewFormat(fieldNames ...string) Format {
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return Format{
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fieldNames: fieldNames,
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fieldDelim: nullChar,
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fieldDelimStr: string(nullChar),
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refDelim: dualNullChar,
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}
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}
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// Flag returns a for-each-ref --format flag value that captures the fieldNames.
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func (f Format) Flag() string {
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var formatFlag strings.Builder
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for i, field := range f.fieldNames {
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// field key and field value
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formatFlag.WriteString(fmt.Sprintf("%s %%(%s)", field, field))
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if i < len(f.fieldNames)-1 {
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// note: escape delimiters to allow control characters as
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// delimiters. For example, '%00' for null character or '%0a'
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// for newline.
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formatFlag.WriteString(f.hexEscaped(f.fieldDelim))
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}
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}
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formatFlag.WriteString(f.hexEscaped(f.refDelim))
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return formatFlag.String()
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}
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// Parser returns a Parser capable of parsing 'git for-each-ref' output produced
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// with this Format.
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func (f Format) Parser(r io.Reader) *Parser {
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return NewParser(r, f)
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}
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// hexEscaped produces hex-escpaed characters from a string. For example, "\n\0"
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// would turn into "%0a%00".
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func (f Format) hexEscaped(delim []byte) string {
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escaped := ""
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for i := 0; i < len(delim); i++ {
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escaped += "%" + hex.EncodeToString([]byte{delim[i]})
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}
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return escaped
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}
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@ -0,0 +1,67 @@
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// Copyright 2022 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package foreachref_test
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import (
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"testing"
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"code.gitea.io/gitea/modules/git/foreachref"
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"github.com/stretchr/testify/require"
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)
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func TestFormat_Flag(t *testing.T) {
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tests := []struct {
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name string
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givenFormat foreachref.Format
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wantFlag string
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}{
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{
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name: "references are delimited by dual null chars",
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// no reference fields requested
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givenFormat: foreachref.NewFormat(),
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// only a reference delimiter field in --format
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wantFlag: "%00%00",
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},
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{
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name: "a field is a space-separated key-value pair",
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givenFormat: foreachref.NewFormat("refname:short"),
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// only a reference delimiter field
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wantFlag: "refname:short %(refname:short)%00%00",
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},
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{
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name: "fields are separated by a null char field-delimiter",
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givenFormat: foreachref.NewFormat("refname:short", "author"),
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wantFlag: "refname:short %(refname:short)%00author %(author)%00%00",
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},
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{
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name: "multiple fields",
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givenFormat: foreachref.NewFormat("refname:short", "objecttype", "objectname"),
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wantFlag: "refname:short %(refname:short)%00objecttype %(objecttype)%00objectname %(objectname)%00%00",
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},
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}
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for _, test := range tests {
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tc := test // don't close over loop variable
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t.Run(tc.name, func(t *testing.T) {
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gotFlag := tc.givenFormat.Flag()
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require.Equal(t, tc.wantFlag, gotFlag, "unexpected for-each-ref --format string. wanted: '%s', got: '%s'", tc.wantFlag, gotFlag)
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})
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}
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}
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@ -0,0 +1,131 @@
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// Copyright 2022 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package foreachref
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import (
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"bufio"
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"bytes"
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"fmt"
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"io"
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"strings"
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)
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// Parser parses 'git for-each-ref' output according to a given output Format.
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type Parser struct {
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// tokenizes 'git for-each-ref' output into "reference paragraphs".
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scanner *bufio.Scanner
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// format represents the '--format' string that describes the expected
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// 'git for-each-ref' output structure.
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format Format
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// err holds the last encountered error during parsing.
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err error
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}
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// NewParser creates a 'git for-each-ref' output parser that will parse all
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// references in the provided Reader. The references in the output are assumed
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// to follow the specified Format.
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func NewParser(r io.Reader, format Format) *Parser {
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scanner := bufio.NewScanner(r)
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// in addition to the reference delimiter we specified in the --format,
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// `git for-each-ref` will always add a newline after every reference.
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refDelim := make([]byte, 0, len(format.refDelim)+1)
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refDelim = append(refDelim, format.refDelim...)
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refDelim = append(refDelim, '\n')
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// Split input into delimiter-separated "reference blocks".
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scanner.Split(
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func(data []byte, atEOF bool) (advance int, token []byte, err error) {
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// Scan until delimiter, marking end of reference.
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delimIdx := bytes.Index(data, refDelim)
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if delimIdx >= 0 {
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token := data[:delimIdx]
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advance := delimIdx + len(refDelim)
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return advance, token, nil
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}
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// If we're at EOF, we have a final, non-terminated reference. Return it.
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if atEOF {
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return len(data), data, nil
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}
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// Not yet a full field. Request more data.
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return 0, nil, nil
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})
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return &Parser{
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scanner: scanner,
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format: format,
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err: nil,
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}
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}
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// Next returns the next reference as a collection of key-value pairs. nil
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// denotes EOF but is also returned on errors. The Err method should always be
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// consulted after Next returning nil.
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//
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// It could, for example return something like:
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//
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// { "objecttype": "tag", "refname:short": "v1.16.4", "object": "f460b7543ed500e49c133c2cd85c8c55ee9dbe27" }
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//
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func (p *Parser) Next() map[string]string {
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if !p.scanner.Scan() {
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return nil
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}
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fields, err := p.parseRef(p.scanner.Text())
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if err != nil {
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p.err = err
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return nil
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}
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return fields
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}
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// Err returns the latest encountered parsing error.
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func (p *Parser) Err() error {
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return p.err
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}
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// parseRef parses out all key-value pairs from a single reference block, such as
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//
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// "objecttype tag\0refname:short v1.16.4\0object f460b7543ed500e49c133c2cd85c8c55ee9dbe27"
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//
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func (p *Parser) parseRef(refBlock string) (map[string]string, error) {
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if refBlock == "" {
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// must be at EOF
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return nil, nil
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}
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fieldValues := make(map[string]string)
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fields := strings.Split(refBlock, p.format.fieldDelimStr)
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if len(fields) != len(p.format.fieldNames) {
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return nil, fmt.Errorf("unexpected number of reference fields: wanted %d, was %d",
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len(fields), len(p.format.fieldNames))
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}
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for i, field := range fields {
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field = strings.TrimSpace(field)
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var fieldKey string
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var fieldVal string
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firstSpace := strings.Index(field, " ")
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if firstSpace > 0 {
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fieldKey = field[:firstSpace]
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fieldVal = field[firstSpace+1:]
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} else {
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// could be the case if the requested field had no value
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fieldKey = field
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}
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// enforce the format order of fields
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if p.format.fieldNames[i] != fieldKey {
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return nil, fmt.Errorf("unexpected field name at position %d: wanted: '%s', was: '%s'",
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i, p.format.fieldNames[i], fieldKey)
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}
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fieldValues[fieldKey] = fieldVal
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}
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return fieldValues, nil
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}
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@ -0,0 +1,228 @@
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// Copyright 2022 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package foreachref_test
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import (
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"errors"
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"fmt"
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"io"
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"strings"
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"testing"
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"code.gitea.io/gitea/modules/git/foreachref"
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"code.gitea.io/gitea/modules/json"
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"github.com/stretchr/testify/require"
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)
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type refSlice = []map[string]string
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func TestParser(t *testing.T) {
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tests := []struct {
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name string
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givenFormat foreachref.Format
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givenInput io.Reader
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wantRefs refSlice
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wantErr bool
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expectedErr error
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}{
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// this would, for example, be the result when running `git
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// for-each-ref refs/tags` on a repo without tags.
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{
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name: "no references on empty input",
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givenFormat: foreachref.NewFormat("refname:short"),
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givenInput: strings.NewReader(``),
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wantRefs: []map[string]string{},
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},
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// note: `git for-each-ref` will add a newline between every
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// reference (in addition to the ref-delimiter we've chosen)
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{
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name: "single field requested, single reference in output",
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givenFormat: foreachref.NewFormat("refname:short"),
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givenInput: strings.NewReader("refname:short v0.0.1\x00\x00" + "\n"),
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wantRefs: []map[string]string{
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{"refname:short": "v0.0.1"},
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},
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},
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{
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name: "single field requested, multiple references in output",
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givenFormat: foreachref.NewFormat("refname:short"),
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givenInput: strings.NewReader(
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"refname:short v0.0.1\x00\x00" + "\n" +
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"refname:short v0.0.2\x00\x00" + "\n" +
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"refname:short v0.0.3\x00\x00" + "\n"),
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wantRefs: []map[string]string{
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{"refname:short": "v0.0.1"},
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{"refname:short": "v0.0.2"},
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{"refname:short": "v0.0.3"},
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},
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},
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{
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name: "multiple fields requested for each reference",
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givenFormat: foreachref.NewFormat("refname:short", "objecttype", "objectname"),
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givenInput: strings.NewReader(
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"refname:short v0.0.1\x00objecttype commit\x00objectname 7b2c5ac9fc04fc5efafb60700713d4fa609b777b\x00\x00" + "\n" +
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"refname:short v0.0.2\x00objecttype commit\x00objectname a1f051bc3eba734da4772d60e2d677f47cf93ef4\x00\x00" + "\n" +
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"refname:short v0.0.3\x00objecttype commit\x00objectname ef82de70bb3f60c65fb8eebacbb2d122ef517385\x00\x00" + "\n",
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),
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wantRefs: []map[string]string{
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{
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"refname:short": "v0.0.1",
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"objecttype": "commit",
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"objectname": "7b2c5ac9fc04fc5efafb60700713d4fa609b777b",
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},
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{
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"refname:short": "v0.0.2",
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"objecttype": "commit",
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"objectname": "a1f051bc3eba734da4772d60e2d677f47cf93ef4",
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},
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{
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"refname:short": "v0.0.3",
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"objecttype": "commit",
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"objectname": "ef82de70bb3f60c65fb8eebacbb2d122ef517385",
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},
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},
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},
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{
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name: "must handle multi-line fields such as 'content'",
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givenFormat: foreachref.NewFormat("refname:short", "contents", "author"),
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givenInput: strings.NewReader(
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"refname:short v0.0.1\x00contents Create new buffer if not present yet (#549)\n\nFixes a nil dereference when ProcessFoo is used\nwith multiple commands.\x00author Foo Bar <foo@bar.com> 1507832733 +0200\x00\x00" + "\n" +
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"refname:short v0.0.2\x00contents Update CI config (#651)\n\n\x00author John Doe <john.doe@foo.com> 1521643174 +0000\x00\x00" + "\n" +
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"refname:short v0.0.3\x00contents Fixed code sample for bash completion (#687)\n\n\x00author Foo Baz <foo@baz.com> 1524836750 +0200\x00\x00" + "\n",
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),
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wantRefs: []map[string]string{
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{
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"refname:short": "v0.0.1",
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"contents": "Create new buffer if not present yet (#549)\n\nFixes a nil dereference when ProcessFoo is used\nwith multiple commands.",
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"author": "Foo Bar <foo@bar.com> 1507832733 +0200",
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},
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{
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"refname:short": "v0.0.2",
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"contents": "Update CI config (#651)",
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"author": "John Doe <john.doe@foo.com> 1521643174 +0000",
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},
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{
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"refname:short": "v0.0.3",
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"contents": "Fixed code sample for bash completion (#687)",
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"author": "Foo Baz <foo@baz.com> 1524836750 +0200",
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},
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},
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},
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|
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{
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name: "must handle fields without values",
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|
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givenFormat: foreachref.NewFormat("refname:short", "object", "objecttype"),
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givenInput: strings.NewReader(
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"refname:short v0.0.1\x00object \x00objecttype commit\x00\x00" + "\n" +
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"refname:short v0.0.2\x00object \x00objecttype commit\x00\x00" + "\n" +
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"refname:short v0.0.3\x00object \x00objecttype commit\x00\x00" + "\n",
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),
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wantRefs: []map[string]string{
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{
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"refname:short": "v0.0.1",
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"object": "",
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"objecttype": "commit",
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},
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{
|
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"refname:short": "v0.0.2",
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"object": "",
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"objecttype": "commit",
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},
|
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{
|
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"refname:short": "v0.0.3",
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"object": "",
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"objecttype": "commit",
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},
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},
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},
|
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|
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{
|
||||
name: "must fail when the number of fields in the input doesn't match expected format",
|
||||
|
||||
givenFormat: foreachref.NewFormat("refname:short", "objecttype", "objectname"),
|
||||
givenInput: strings.NewReader(
|
||||
"refname:short v0.0.1\x00objecttype commit\x00\x00" + "\n" +
|
||||
"refname:short v0.0.2\x00objecttype commit\x00\x00" + "\n" +
|
||||
"refname:short v0.0.3\x00objecttype commit\x00\x00" + "\n",
|
||||
),
|
||||
|
||||
wantErr: true,
|
||||
expectedErr: errors.New("unexpected number of reference fields: wanted 2, was 3"),
|
||||
},
|
||||
|
||||
{
|
||||
name: "must fail input fields don't match expected format",
|
||||
|
||||
givenFormat: foreachref.NewFormat("refname:short", "objectname"),
|
||||
givenInput: strings.NewReader(
|
||||
"refname:short v0.0.1\x00objecttype commit\x00\x00" + "\n" +
|
||||
"refname:short v0.0.2\x00objecttype commit\x00\x00" + "\n" +
|
||||
"refname:short v0.0.3\x00objecttype commit\x00\x00" + "\n",
|
||||
),
|
||||
|
||||
wantErr: true,
|
||||
expectedErr: errors.New("unexpected field name at position 1: wanted: 'objectname', was: 'objecttype'"),
|
||||
},
|
||||
}
|
||||
|
||||
for _, test := range tests {
|
||||
tc := test // don't close over loop variable
|
||||
t.Run(tc.name, func(t *testing.T) {
|
||||
parser := tc.givenFormat.Parser(tc.givenInput)
|
||||
|
||||
//
|
||||
// parse references from input
|
||||
//
|
||||
gotRefs := make([]map[string]string, 0)
|
||||
for {
|
||||
ref := parser.Next()
|
||||
if ref == nil {
|
||||
break
|
||||
}
|
||||
gotRefs = append(gotRefs, ref)
|
||||
}
|
||||
err := parser.Err()
|
||||
|
||||
//
|
||||
// verify expectations
|
||||
//
|
||||
if tc.wantErr {
|
||||
require.Error(t, err)
|
||||
require.EqualError(t, err, tc.expectedErr.Error())
|
||||
} else {
|
||||
require.NoError(t, err, "for-each-ref parser unexpectedly failed with: %v", err)
|
||||
require.Equal(t, tc.wantRefs, gotRefs, "for-each-ref parser produced unexpected reference set. wanted: %v, got: %v", pretty(tc.wantRefs), pretty(gotRefs))
|
||||
}
|
||||
})
|
||||
}
|
||||
}
|
||||
|
||||
func pretty(v interface{}) string {
|
||||
data, err := json.MarshalIndent(v, "", " ")
|
||||
if err != nil {
|
||||
// shouldn't happen
|
||||
panic(fmt.Sprintf("json-marshalling failed: %v", err))
|
||||
}
|
||||
return string(data)
|
||||
}
|
||||
Loading…
Reference in New Issue