hugo/hugofs/rootmapping_fs.go
Bjørn Erik Pedersen 7285e74090
all: Rework page store, add a dynacache, improve partial rebuilds, and some general spring cleaning
There are some breaking changes in this commit, see #11455.

Closes #11455
Closes #11549

This fixes a set of bugs (see issue list) and it is also paying some technical debt accumulated over the years. We now build with Staticcheck enabled in the CI build.

The performance should be about the same as before for regular sized Hugo sites, but it should perform and scale much better to larger data sets, as objects that uses lots of memory (e.g. rendered Markdown, big JSON files read into maps with transform.Unmarshal etc.) will now get automatically garbage collected if needed. Performance on partial rebuilds when running the server in fast render mode should be the same, but the change detection should be much more accurate.

A list of the notable new features:

* A new dependency tracker that covers (almost) all of Hugo's API and is used to do fine grained partial rebuilds when running the server.
* A new and simpler tree document store which allows fast lookups and prefix-walking in all dimensions (e.g. language) concurrently.
* You can now configure an upper memory limit allowing for much larger data sets and/or running on lower specced PCs.
We have lifted the "no resources in sub folders" restriction for branch bundles (e.g. sections).
Memory Limit
* Hugos will, by default, set aside a quarter of the total system memory, but you can set this via the OS environment variable HUGO_MEMORYLIMIT (in gigabytes). This is backed by a partitioned LRU cache used throughout Hugo. A cache that gets dynamically resized in low memory situations, allowing Go's Garbage Collector to free the memory.

New Dependency Tracker: Hugo has had a rule based coarse grained approach to server rebuilds that has worked mostly pretty well, but there have been some surprises (e.g. stale content). This is now revamped with a new dependency tracker that can quickly calculate the delta given a changed resource (e.g. a content file, template, JS file etc.). This handles transitive relations, e.g. $page -> js.Build -> JS import, or $page1.Content -> render hook -> site.GetPage -> $page2.Title, or $page1.Content -> shortcode -> partial -> site.RegularPages -> $page2.Content -> shortcode ..., and should also handle changes to aggregated values (e.g. site.Lastmod) effectively.

This covers all of Hugo's API with 2 known exceptions (a list that may not be fully exhaustive):

Changes to files loaded with template func os.ReadFile may not be handled correctly. We recommend loading resources with resources.Get
Changes to Hugo objects (e.g. Page) passed in the template context to lang.Translate may not be detected correctly. We recommend having simple i18n templates without too much data context passed in other than simple types such as strings and numbers.
Note that the cachebuster configuration (when A changes then rebuild B) works well with the above, but we recommend that you revise that configuration, as it in most situations should not be needed. One example where it is still needed is with TailwindCSS and using changes to hugo_stats.json to trigger new CSS rebuilds.

Document Store: Previously, a little simplified, we split the document store (where we store pages and resources) in a tree per language. This worked pretty well, but the structure made some operations harder than they needed to be. We have now restructured it into one Radix tree for all languages. Internally the language is considered to be a dimension of that tree, and the tree can be viewed in all dimensions concurrently. This makes some operations re. language simpler (e.g. finding translations is just a slice range), but the idea is that it should also be relatively inexpensive to add more dimensions if needed (e.g. role).

Fixes #10169
Fixes #10364
Fixes #10482
Fixes #10630
Fixes #10656
Fixes #10694
Fixes #10918
Fixes #11262
Fixes #11439
Fixes #11453
Fixes #11457
Fixes #11466
Fixes #11540
Fixes #11551
Fixes #11556
Fixes #11654
Fixes #11661
Fixes #11663
Fixes #11664
Fixes #11669
Fixes #11671
Fixes #11807
Fixes #11808
Fixes #11809
Fixes #11815
Fixes #11840
Fixes #11853
Fixes #11860
Fixes #11883
Fixes #11904
Fixes #7388
Fixes #7425
Fixes #7436
Fixes #7544
Fixes #7882
Fixes #7960
Fixes #8255
Fixes #8307
Fixes #8863
Fixes #8927
Fixes #9192
Fixes #9324
2024-01-27 16:28:14 +01:00

831 lines
19 KiB
Go

// Copyright 2019 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package hugofs
import (
"errors"
"fmt"
iofs "io/fs"
"os"
"path"
"path/filepath"
"strings"
"github.com/gohugoio/hugo/common/herrors"
"github.com/gohugoio/hugo/common/paths"
"github.com/bep/overlayfs"
"github.com/gohugoio/hugo/hugofs/files"
"github.com/gohugoio/hugo/hugofs/glob"
radix "github.com/armon/go-radix"
"github.com/spf13/afero"
)
var filepathSeparator = string(filepath.Separator)
var _ ReverseLookupProvder = (*RootMappingFs)(nil)
// NewRootMappingFs creates a new RootMappingFs on top of the provided with
// root mappings with some optional metadata about the root.
// Note that From represents a virtual root that maps to the actual filename in To.
func NewRootMappingFs(fs afero.Fs, rms ...RootMapping) (*RootMappingFs, error) {
rootMapToReal := radix.New()
realMapToRoot := radix.New()
var virtualRoots []RootMapping
addMapping := func(key string, rm RootMapping, to *radix.Tree) {
var mappings []RootMapping
v, found := to.Get(key)
if found {
// There may be more than one language pointing to the same root.
mappings = v.([]RootMapping)
}
mappings = append(mappings, rm)
to.Insert(key, mappings)
}
for _, rm := range rms {
(&rm).clean()
rm.FromBase = files.ResolveComponentFolder(rm.From)
if len(rm.To) < 2 {
panic(fmt.Sprintf("invalid root mapping; from/to: %s/%s", rm.From, rm.To))
}
fi, err := fs.Stat(rm.To)
if err != nil {
if os.IsNotExist(err) {
continue
}
return nil, err
}
if rm.Meta == nil {
rm.Meta = NewFileMeta()
}
if !fi.IsDir() {
// We do allow single file mounts.
// However, the file system logic will be much simpler with just directories.
// So, convert this mount into a directory mount with a nameTo filter and renamer.
dirFrom, nameFrom := filepath.Split(rm.From)
dirTo, nameTo := filepath.Split(rm.To)
dirFrom, dirTo = strings.TrimSuffix(dirFrom, filepathSeparator), strings.TrimSuffix(dirTo, filepathSeparator)
rm.From = dirFrom
fi, err = fs.Stat(rm.To)
if err != nil {
if herrors.IsNotExist(err) {
continue
}
return nil, err
}
rm.fiSingleFile = NewFileMetaInfo(fi, rm.Meta.Copy())
rm.To = dirTo
rm.Meta.Rename = func(name string, toFrom bool) string {
if toFrom {
if name == nameTo {
return nameFrom
}
return name
}
if name == nameFrom {
return nameTo
}
return name
}
nameToFilename := filepathSeparator + nameTo
rm.Meta.InclusionFilter = rm.Meta.InclusionFilter.Append(glob.NewFilenameFilterForInclusionFunc(
func(filename string) bool {
return strings.HasPrefix(nameToFilename, filename)
},
))
// Refresh the FileInfo object.
fi, err = fs.Stat(rm.To)
if err != nil {
if herrors.IsNotExist(err) {
continue
}
return nil, err
}
}
if rm.FromBase == "" {
panic(" rm.FromBase is empty")
}
// Extract "blog" from "content/blog"
rm.path = strings.TrimPrefix(strings.TrimPrefix(rm.From, rm.FromBase), filepathSeparator)
rm.Meta.SourceRoot = fi.(MetaProvider).Meta().Filename
rm.Meta.BaseDir = rm.ToBase
rm.Meta.Module = rm.Module
rm.Meta.ModuleOrdinal = rm.ModuleOrdinal
rm.Meta.Component = rm.FromBase
rm.Meta.IsProject = rm.IsProject
meta := rm.Meta.Copy()
if !fi.IsDir() {
_, name := filepath.Split(rm.From)
meta.Name = name
}
rm.fi = NewFileMetaInfo(fi, meta)
addMapping(filepathSeparator+rm.From, rm, rootMapToReal)
rev := rm.To
if !strings.HasPrefix(rev, filepathSeparator) {
rev = filepathSeparator + rev
}
addMapping(rev, rm, realMapToRoot)
virtualRoots = append(virtualRoots, rm)
}
rootMapToReal.Insert(filepathSeparator, virtualRoots)
rfs := &RootMappingFs{
Fs: fs,
rootMapToReal: rootMapToReal,
realMapToRoot: realMapToRoot,
}
return rfs, nil
}
func newRootMappingFsFromFromTo(
baseDir string,
fs afero.Fs,
fromTo ...string,
) (*RootMappingFs, error) {
rms := make([]RootMapping, len(fromTo)/2)
for i, j := 0, 0; j < len(fromTo); i, j = i+1, j+2 {
rms[i] = RootMapping{
From: fromTo[j],
To: fromTo[j+1],
ToBase: baseDir,
}
}
return NewRootMappingFs(fs, rms...)
}
// RootMapping describes a virtual file or directory mount.
type RootMapping struct {
From string // The virtual mount.
FromBase string // The base directory of the virtual mount.
To string // The source directory or file.
ToBase string // The base of To. May be empty if an absolute path was provided.
Module string // The module path/ID.
ModuleOrdinal int // The module ordinal starting with 0 which is the project.
IsProject bool // Whether this is a mount in the main project.
Meta *FileMeta // File metadata (lang etc.)
fi FileMetaInfo
fiSingleFile FileMetaInfo // Also set when this mounts represents a single file with a rename func.
path string // The virtual mount point, e.g. "blog".
}
type keyRootMappings struct {
key string
roots []RootMapping
}
func (rm *RootMapping) clean() {
rm.From = strings.Trim(filepath.Clean(rm.From), filepathSeparator)
rm.To = filepath.Clean(rm.To)
}
func (r RootMapping) filename(name string) string {
if name == "" {
return r.To
}
return filepath.Join(r.To, strings.TrimPrefix(name, r.From))
}
func (r RootMapping) trimFrom(name string) string {
if name == "" {
return ""
}
return strings.TrimPrefix(name, r.From)
}
var _ FilesystemUnwrapper = (*RootMappingFs)(nil)
// A RootMappingFs maps several roots into one. Note that the root of this filesystem
// is directories only, and they will be returned in Readdir and Readdirnames
// in the order given.
type RootMappingFs struct {
afero.Fs
rootMapToReal *radix.Tree
realMapToRoot *radix.Tree
}
func (fs *RootMappingFs) Mounts(base string) ([]FileMetaInfo, error) {
base = filepathSeparator + fs.cleanName(base)
roots := fs.getRootsWithPrefix(base)
if roots == nil {
return nil, nil
}
fss := make([]FileMetaInfo, len(roots))
for i, r := range roots {
if r.fiSingleFile != nil {
// A single file mount.
fss[i] = r.fiSingleFile
continue
}
bfs := NewBasePathFs(fs.Fs, r.To)
fs := bfs
if r.Meta.InclusionFilter != nil {
fs = newFilenameFilterFs(fs, r.To, r.Meta.InclusionFilter)
}
fs = decorateDirs(fs, r.Meta)
fi, err := fs.Stat("")
if err != nil {
return nil, fmt.Errorf("RootMappingFs.Dirs: %w", err)
}
if !fi.IsDir() {
fi.(FileMetaInfo).Meta().Merge(r.Meta)
}
fss[i] = fi.(FileMetaInfo)
}
return fss, nil
}
func (fs *RootMappingFs) UnwrapFilesystem() afero.Fs {
return fs.Fs
}
// Filter creates a copy of this filesystem with only mappings matching a filter.
func (fs RootMappingFs) Filter(f func(m RootMapping) bool) *RootMappingFs {
rootMapToReal := radix.New()
fs.rootMapToReal.Walk(func(b string, v any) bool {
rms := v.([]RootMapping)
var nrms []RootMapping
for _, rm := range rms {
if f(rm) {
nrms = append(nrms, rm)
}
}
if len(nrms) != 0 {
rootMapToReal.Insert(b, nrms)
}
return false
})
fs.rootMapToReal = rootMapToReal
return &fs
}
// Open opens the named file for reading.
func (fs *RootMappingFs) Open(name string) (afero.File, error) {
fis, err := fs.doStat(name)
if err != nil {
return nil, err
}
return fs.newUnionFile(fis...)
}
// Stat returns the os.FileInfo structure describing a given file. If there is
// an error, it will be of type *os.PathError.
func (fs *RootMappingFs) Stat(name string) (os.FileInfo, error) {
fis, err := fs.doStat(name)
if err != nil {
return nil, err
}
return fis[0], nil
}
type ComponentPath struct {
Component string
Path string
Lang string
}
func (c ComponentPath) ComponentPathJoined() string {
return path.Join(c.Component, c.Path)
}
type ReverseLookupProvder interface {
ReverseLookup(filename string, checkExists bool) ([]ComponentPath, error)
}
// func (fs *RootMappingFs) ReverseStat(filename string) ([]FileMetaInfo, error)
func (fs *RootMappingFs) ReverseLookup(in string, checkExists bool) ([]ComponentPath, error) {
in = fs.cleanName(in)
key := filepathSeparator + in
s, roots := fs.getRootsReverse(key)
if len(roots) == 0 {
return nil, nil
}
var cps []ComponentPath
base := strings.TrimPrefix(key, s)
dir, name := filepath.Split(base)
for _, first := range roots {
if first.Meta.Rename != nil {
name = first.Meta.Rename(name, true)
}
// Now we know that this file _could_ be in this fs.
filename := filepathSeparator + filepath.Join(first.path, dir, name)
if checkExists {
// Confirm that it exists.
_, err := fs.Stat(first.FromBase + filename)
if err != nil {
continue
}
}
cps = append(cps, ComponentPath{
Component: first.FromBase,
Path: paths.ToSlashTrimLeading(filename),
Lang: first.Meta.Lang,
})
}
return cps, nil
}
func (fs *RootMappingFs) hasPrefix(prefix string) bool {
hasPrefix := false
fs.rootMapToReal.WalkPrefix(prefix, func(b string, v any) bool {
hasPrefix = true
return true
})
return hasPrefix
}
func (fs *RootMappingFs) getRoot(key string) []RootMapping {
v, found := fs.rootMapToReal.Get(key)
if !found {
return nil
}
return v.([]RootMapping)
}
func (fs *RootMappingFs) getRoots(key string) (string, []RootMapping) {
return fs.getRootsIn(key, fs.rootMapToReal)
}
func (fs *RootMappingFs) getRootsReverse(key string) (string, []RootMapping) {
return fs.getRootsIn(key, fs.realMapToRoot)
}
func (fs *RootMappingFs) getRootsIn(key string, tree *radix.Tree) (string, []RootMapping) {
s, v, found := tree.LongestPrefix(key)
if !found {
return "", nil
}
return s, v.([]RootMapping)
}
func (fs *RootMappingFs) getRootsWithPrefix(prefix string) []RootMapping {
var roots []RootMapping
fs.rootMapToReal.WalkPrefix(prefix, func(b string, v any) bool {
roots = append(roots, v.([]RootMapping)...)
return false
})
return roots
}
func (fs *RootMappingFs) getAncestors(prefix string) []keyRootMappings {
var roots []keyRootMappings
fs.rootMapToReal.WalkPath(prefix, func(s string, v any) bool {
if strings.HasPrefix(prefix, s+filepathSeparator) {
roots = append(roots, keyRootMappings{
key: s,
roots: v.([]RootMapping),
})
}
return false
})
return roots
}
func (fs *RootMappingFs) newUnionFile(fis ...FileMetaInfo) (afero.File, error) {
if len(fis) == 1 {
return fis[0].Meta().Open()
}
openers := make([]func() (afero.File, error), len(fis))
for i := len(fis) - 1; i >= 0; i-- {
fi := fis[i]
openers[i] = func() (afero.File, error) {
meta := fi.Meta()
f, err := meta.Open()
if err != nil {
return nil, err
}
return &rootMappingDir{DirOnlyOps: f, fs: fs, name: meta.Name, meta: meta}, nil
}
}
merge := func(lofi, bofi []iofs.DirEntry) []iofs.DirEntry {
// Ignore duplicate directory entries
for _, fi1 := range bofi {
var found bool
for _, fi2 := range lofi {
if !fi2.IsDir() {
continue
}
if fi1.Name() == fi2.Name() {
found = true
break
}
}
if !found {
lofi = append(lofi, fi1)
}
}
return lofi
}
info := func() (os.FileInfo, error) {
return fis[0], nil
}
return overlayfs.OpenDir(merge, info, openers...)
}
func (fs *RootMappingFs) cleanName(name string) string {
name = strings.Trim(filepath.Clean(name), filepathSeparator)
if name == "." {
name = ""
}
return name
}
func (rfs *RootMappingFs) collectDirEntries(prefix string) ([]iofs.DirEntry, error) {
prefix = filepathSeparator + rfs.cleanName(prefix)
var fis []iofs.DirEntry
seen := make(map[string]bool) // Prevent duplicate directories
level := strings.Count(prefix, filepathSeparator)
collectDir := func(rm RootMapping, fi FileMetaInfo) error {
f, err := fi.Meta().Open()
if err != nil {
return err
}
direntries, err := f.(iofs.ReadDirFile).ReadDir(-1)
if err != nil {
f.Close()
return err
}
for _, fi := range direntries {
meta := fi.(FileMetaInfo).Meta()
meta.Merge(rm.Meta)
if !rm.Meta.InclusionFilter.Match(strings.TrimPrefix(meta.Filename, meta.SourceRoot), fi.IsDir()) {
continue
}
if fi.IsDir() {
name := fi.Name()
if seen[name] {
continue
}
seen[name] = true
opener := func() (afero.File, error) {
return rfs.Open(filepath.Join(rm.From, name))
}
fi = newDirNameOnlyFileInfo(name, meta, opener)
} else if rm.Meta.Rename != nil {
if n := rm.Meta.Rename(fi.Name(), true); n != fi.Name() {
fi.(MetaProvider).Meta().Name = n
}
}
fis = append(fis, fi)
}
f.Close()
return nil
}
// First add any real files/directories.
rms := rfs.getRoot(prefix)
for _, rm := range rms {
if err := collectDir(rm, rm.fi); err != nil {
return nil, err
}
}
// Next add any file mounts inside the given directory.
prefixInside := prefix + filepathSeparator
rfs.rootMapToReal.WalkPrefix(prefixInside, func(s string, v any) bool {
if (strings.Count(s, filepathSeparator) - level) != 1 {
// This directory is not part of the current, but we
// need to include the first name part to make it
// navigable.
path := strings.TrimPrefix(s, prefixInside)
parts := strings.Split(path, filepathSeparator)
name := parts[0]
if seen[name] {
return false
}
seen[name] = true
opener := func() (afero.File, error) {
return rfs.Open(path)
}
fi := newDirNameOnlyFileInfo(name, nil, opener)
fis = append(fis, fi)
return false
}
rms := v.([]RootMapping)
for _, rm := range rms {
if !rm.fi.IsDir() {
// A single file mount
fis = append(fis, rm.fi)
continue
}
name := filepath.Base(rm.From)
if seen[name] {
continue
}
seen[name] = true
opener := func() (afero.File, error) {
return rfs.Open(rm.From)
}
fi := newDirNameOnlyFileInfo(name, rm.Meta, opener)
fis = append(fis, fi)
}
return false
})
// Finally add any ancestor dirs with files in this directory.
ancestors := rfs.getAncestors(prefix)
for _, root := range ancestors {
subdir := strings.TrimPrefix(prefix, root.key)
for _, rm := range root.roots {
if rm.fi.IsDir() {
fi, err := rm.fi.Meta().JoinStat(subdir)
if err == nil {
if err := collectDir(rm, fi); err != nil {
return nil, err
}
}
}
}
}
return fis, nil
}
func (fs *RootMappingFs) doStat(name string) ([]FileMetaInfo, error) {
name = fs.cleanName(name)
key := filepathSeparator + name
roots := fs.getRoot(key)
if roots == nil {
if fs.hasPrefix(key) {
// We have directories mounted below this.
// Make it look like a directory.
return []FileMetaInfo{newDirNameOnlyFileInfo(name, nil, fs.virtualDirOpener(name))}, nil
}
// Find any real directories with this key.
_, roots := fs.getRoots(key)
if roots == nil {
return nil, &os.PathError{Op: "LStat", Path: name, Err: os.ErrNotExist}
}
var err error
var fis []FileMetaInfo
for _, rm := range roots {
var fi FileMetaInfo
fi, err = fs.statRoot(rm, name)
if err == nil {
fis = append(fis, fi)
}
}
if fis != nil {
return fis, nil
}
if err == nil {
err = &os.PathError{Op: "LStat", Path: name, Err: err}
}
return nil, err
}
fileCount := 0
var wasFiltered bool
for _, root := range roots {
meta := root.fi.Meta()
if !meta.InclusionFilter.Match(strings.TrimPrefix(meta.Filename, meta.SourceRoot), root.fi.IsDir()) {
wasFiltered = true
continue
}
if !root.fi.IsDir() {
fileCount++
}
if fileCount > 1 {
break
}
}
if fileCount == 0 {
if wasFiltered {
return nil, os.ErrNotExist
}
// Dir only.
return []FileMetaInfo{newDirNameOnlyFileInfo(name, roots[0].Meta, fs.virtualDirOpener(name))}, nil
}
if fileCount > 1 {
// Not supported by this filesystem.
return nil, fmt.Errorf("found multiple files with name %q, use .Readdir or the source filesystem directly", name)
}
return []FileMetaInfo{roots[0].fi}, nil
}
func (fs *RootMappingFs) statRoot(root RootMapping, filename string) (FileMetaInfo, error) {
dir, name := filepath.Split(filename)
if root.Meta.Rename != nil {
if n := root.Meta.Rename(name, false); n != name {
filename = filepath.Join(dir, n)
}
}
if !root.Meta.InclusionFilter.Match(root.trimFrom(filename), root.fi.IsDir()) {
return nil, os.ErrNotExist
}
filename = root.filename(filename)
fi, err := fs.Fs.Stat(filename)
if err != nil {
return nil, err
}
var opener func() (afero.File, error)
if fi.IsDir() {
// Make sure metadata gets applied in ReadDir.
opener = fs.realDirOpener(filename, root.Meta)
} else {
if root.Meta.Rename != nil {
if n := root.Meta.Rename(fi.Name(), true); n != fi.Name() {
meta := fi.(MetaProvider).Meta()
meta.Name = n
}
}
// Opens the real file directly.
opener = func() (afero.File, error) {
return fs.Fs.Open(filename)
}
}
fim := decorateFileInfo(fi, opener, "", root.Meta)
return fim, nil
}
func (fs *RootMappingFs) virtualDirOpener(name string) func() (afero.File, error) {
return func() (afero.File, error) { return &rootMappingDir{name: name, fs: fs}, nil }
}
func (fs *RootMappingFs) realDirOpener(name string, meta *FileMeta) func() (afero.File, error) {
return func() (afero.File, error) {
f, err := fs.Fs.Open(name)
if err != nil {
return nil, err
}
return &rootMappingDir{name: name, meta: meta, fs: fs, DirOnlyOps: f}, nil
}
}
var _ iofs.ReadDirFile = (*rootMappingDir)(nil)
type rootMappingDir struct {
*noOpRegularFileOps
DirOnlyOps
fs *RootMappingFs
name string
meta *FileMeta
}
func (f *rootMappingDir) Close() error {
if f.DirOnlyOps == nil {
return nil
}
return f.DirOnlyOps.Close()
}
func (f *rootMappingDir) Name() string {
return f.name
}
func (f *rootMappingDir) ReadDir(count int) ([]iofs.DirEntry, error) {
if f.DirOnlyOps != nil {
fis, err := f.DirOnlyOps.(iofs.ReadDirFile).ReadDir(count)
if err != nil {
return nil, err
}
var result []iofs.DirEntry
for _, fi := range fis {
fim := decorateFileInfo(fi, nil, "", f.meta)
meta := fim.Meta()
if f.meta.InclusionFilter.Match(strings.TrimPrefix(meta.Filename, meta.SourceRoot), fim.IsDir()) {
result = append(result, fim)
}
}
return result, nil
}
return f.fs.collectDirEntries(f.name)
}
// Sentinal error to signal that a file is a directory.
var errIsDir = errors.New("isDir")
func (f *rootMappingDir) Stat() (iofs.FileInfo, error) {
return nil, errIsDir
}
func (f *rootMappingDir) Readdir(count int) ([]os.FileInfo, error) {
panic("not supported: use ReadDir")
}
// Note that Readdirnames preserves the order of the underlying filesystem(s),
// which is usually directory order.
func (f *rootMappingDir) Readdirnames(count int) ([]string, error) {
dirs, err := f.ReadDir(count)
if err != nil {
return nil, err
}
return dirEntriesToNames(dirs), nil
}
func dirEntriesToNames(fis []iofs.DirEntry) []string {
names := make([]string, len(fis))
for i, d := range fis {
names[i] = d.Name()
}
return names
}