hugofs: Make FileMeta a struct

This commit started out investigating a `concurrent map read write` issue, ending by replacing the map with a struct.

This is easier to reason about, and it's more effective:

```
name                                  old time/op    new time/op    delta
SiteNew/Regular_Deep_content_tree-16    71.5ms ± 3%    69.4ms ± 5%    ~     (p=0.200 n=4+4)

name                                  old alloc/op   new alloc/op   delta
SiteNew/Regular_Deep_content_tree-16    29.7MB ± 0%    27.9MB ± 0%  -5.82%  (p=0.029 n=4+4)

name                                  old allocs/op  new allocs/op  delta
SiteNew/Regular_Deep_content_tree-16      313k ± 0%      303k ± 0%  -3.35%  (p=0.029 n=4+4)
```

See #8749

commands/hugo.go

@@ -697,7 +697,7 @@ func (c *commandeer) getDirList() ([]string, error) {
 				return filepath.SkipDir
 			}
 
-			filenames = append(filenames, fi.Meta().Filename())
+			filenames = append(filenames, fi.Meta().Filename)
 		}
 
 		return nil
@@ -706,7 +706,7 @@ func (c *commandeer) getDirList() ([]string, error) {
 	watchFiles := c.hugo().PathSpec.BaseFs.WatchDirs()
 	for _, fi := range watchFiles {
 		if !fi.IsDir() {
-			filenames = append(filenames, fi.Meta().Filename())
+			filenames = append(filenames, fi.Meta().Filename)
 			continue
 		}
 

commands/new.go

@@ -118,7 +118,7 @@ func newContentPathSection(h *hugolib.HugoSites, path string) (string, string) {
 
 	if h != nil {
 		for _, dir := range h.BaseFs.Content.Dirs {
-			createpath = strings.TrimPrefix(createpath, dir.Meta().Filename())
+			createpath = strings.TrimPrefix(createpath, dir.Meta().Filename)
 		}
 	}
 

common/hugo/hugo.go

@@ -102,7 +102,7 @@ func GetExecEnviron(workDir string, cfg config.Provider, fs afero.Fs) []string {
 	if err == nil {
 		for _, fi := range fis {
 			key := fmt.Sprintf("HUGO_FILE_%s", strings.ReplaceAll(strings.ToUpper(fi.Name()), ".", "_"))
-			value := fi.(hugofs.FileMetaInfo).Meta().Filename()
+			value := fi.(hugofs.FileMetaInfo).Meta().Filename
 			config.SetEnvVars(&env, key, value)
 		}
 	}

create/content.go

@@ -123,7 +123,7 @@ func NewContent(
 
 func targetSite(sites *hugolib.HugoSites, fi hugofs.FileMetaInfo) *hugolib.Site {
 	for _, s := range sites.Sites {
-		if fi.Meta().Lang() == s.Language().Lang {
+		if fi.Meta().Lang == s.Language().Lang {
 			return s
 		}
 	}
@@ -137,7 +137,7 @@ func newContentFromDir(
 	cm archetypeMap, name, targetPath string) error {
 	for _, f := range cm.otherFiles {
 		meta := f.Meta()
-		filename := meta.Path()
+		filename := meta.Path
 		// Just copy the file to destination.
 		in, err := meta.Open()
 		if err != nil {
@@ -166,7 +166,7 @@ func newContentFromDir(
 	}
 
 	for _, f := range cm.contentFiles {
-		filename := f.Meta().Path()
+		filename := f.Meta().Path
 		s := targetSite(sites, f)
 		targetFilename := filepath.Join(targetPath, strings.TrimPrefix(filename, archetypeDir))
 
@@ -274,15 +274,15 @@ func resolveContentPath(sites *hugolib.HugoSites, fs afero.Fs, targetPath string
 
 	for _, dir := range sites.BaseFs.Content.Dirs {
 		meta := dir.Meta()
-		contentDir := meta.Filename()
+		contentDir := meta.Filename
 
 		if !strings.HasSuffix(contentDir, helpers.FilePathSeparator) {
 			contentDir += helpers.FilePathSeparator
 		}
 
 		if strings.HasPrefix(targetPath, contentDir) {
 			siteContentDir = contentDir
-			dirLang = meta.Lang()
+			dirLang = meta.Lang
 			break
 		}
 	}
@@ -317,8 +317,8 @@ func resolveContentPath(sites *hugolib.HugoSites, fs afero.Fs, targetPath string
 	} else {
 		var contentDir string
 		for _, dir := range sites.BaseFs.Content.Dirs {
-			contentDir = dir.Meta().Filename()
-			if dir.Meta().Lang() == s.Lang() {
+			contentDir = dir.Meta().Filename
+			if dir.Meta().Lang == s.Lang() {
 				break
 			}
 		}

helpers/general.go

@@ -497,7 +497,7 @@ func PrintFs(fs afero.Fs, path string, w io.Writer) {
 		var filename string
 		var meta interface{}
 		if fim, ok := info.(hugofs.FileMetaInfo); ok {
-			filename = fim.Meta().Filename()
+			filename = fim.Meta().Filename
 			meta = fim.Meta()
 		}
 		fmt.Fprintf(w, "    %q %q\t\t%v\n", path, filename, meta)

hugofs/decorators.go

@@ -23,7 +23,7 @@ import (
 	"github.com/spf13/afero"
 )
 
-func decorateDirs(fs afero.Fs, meta FileMeta) afero.Fs {
+func decorateDirs(fs afero.Fs, meta *FileMeta) afero.Fs {
 	ffs := &baseFileDecoratorFs{Fs: fs}
 
 	decorator := func(fi os.FileInfo, name string) (os.FileInfo, error) {
@@ -82,9 +82,11 @@ func NewBaseFileDecorator(fs afero.Fs, callbacks ...func(fi FileMetaInfo)) afero
 
 	decorator := func(fi os.FileInfo, filename string) (os.FileInfo, error) {
 		// Store away the original in case it's a symlink.
-		meta := FileMeta{metaKeyName: fi.Name()}
+		meta := NewFileMeta()
+		meta.Name = fi.Name()
+
 		if fi.IsDir() {
-			meta[metaKeyJoinStat] = func(name string) (FileMetaInfo, error) {
+			meta.JoinStatFunc = func(name string) (FileMetaInfo, error) {
 				joinedFilename := filepath.Join(filename, name)
 				fi, _, err := lstatIfPossible(fs, joinedFilename)
 				if err != nil {
@@ -102,15 +104,15 @@ func NewBaseFileDecorator(fs afero.Fs, callbacks ...func(fi FileMetaInfo)) afero
 
 		isSymlink := isSymlink(fi)
 		if isSymlink {
-			meta[metaKeyOriginalFilename] = filename
+			meta.OriginalFilename = filename
 			var link string
 			var err error
 			link, fi, err = evalSymlinks(fs, filename)
 			if err != nil {
 				return nil, err
 			}
 			filename = link
-			meta[metaKeyIsSymlink] = true
+			meta.IsSymlink = true
 		}
 
 		opener := func() (afero.File, error) {