refactor: reduce path.join while walking repo

walk/config.go

@@ -49,15 +49,12 @@ func getWalkConfig(c *config.Config) *walkConfig {
 	return c.Exts[walkName].(*walkConfig)
 }
 
-func (wc *walkConfig) isExcluded(rel, base string) bool {
-	if base == ".git" {
-		return true
-	}
-	return matchAnyGlob(wc.excludes, path.Join(rel, base))
+func (wc *walkConfig) isExcluded(p string) bool {
+	return matchAnyGlob(wc.excludes, p)
 }
 
-func (wc *walkConfig) shouldFollow(rel, base string) bool {
-	return matchAnyGlob(wc.follow, path.Join(rel, base))
+func (wc *walkConfig) shouldFollow(p string) bool {
+	return matchAnyGlob(wc.follow, p)
 }
 
 var _ config.Configurer = (*Configurer)(nil)

walk/walk.go

@@ -122,16 +122,19 @@ func Walk(c *config.Config, cexts []config.Configurer, dirs []string, mode Mode,
 		log.Printf("error loading .bazelignore: %v", err)
 	}
 
-	visit(c, cexts, isBazelIgnored, knownDirectives, updateRels, wf, c.RepoRoot, "", false)
+	visit(c, cexts, isBazelIgnored, knownDirectives, updateRels, wf, "", false)
 }
 
-func visit(c *config.Config, cexts []config.Configurer, isBazelIgnored isIgnoredFunc, knownDirectives map[string]bool, updateRels *UpdateFilter, wf WalkFunc, dir, rel string, updateParent bool) {
+func visit(c *config.Config, cexts []config.Configurer, isBazelIgnored isIgnoredFunc, knownDirectives map[string]bool, updateRels *UpdateFilter, wf WalkFunc, rel string, updateParent bool) {
 	if isBazelIgnored(rel) {
 		return
 	}
 
 	haveError := false
 
+	// Absolute path to the directory being visited
+	dir := path.Join(c.RepoRoot, rel)
+
 	// TODO: OPT: ReadDir stats all the files, which is slow. We just care about
 	// names and modes, so we should use something like
 	// golang.org/x/tools/internal/fastwalk to speed this up.
@@ -155,31 +158,36 @@ func visit(c *config.Config, cexts []config.Configurer, isBazelIgnored isIgnored
 	c = configure(cexts, knownDirectives, c, rel, f)
 	wc := getWalkConfig(c)
 
-	if wc.isExcluded(rel, ".") {
+	// Don't recurse into excluded directories
+	if wc.isExcluded(rel) {
 		return
 	}
 
 	var subdirs, regularFiles []string
 	for _, ent := range ents {
-		base := ent.Name()
-		if isBazelIgnored(path.Join(rel, base)) || wc.isExcluded(rel, base) {
+		name := ent.Name()
+		entRel := path.Join(rel, name)
+
+		// Skip blank entry names, .git directories, ignored and excluded.
+		if name == "" || name == ".git" || isBazelIgnored(entRel) || wc.isExcluded(entRel) {
 			continue
 		}
-		ent := resolveFileInfo(wc, dir, rel, ent)
+
+		ent := resolveFileInfo(wc, dir, entRel, ent)
 		switch {
 		case ent == nil:
 			continue
 		case ent.IsDir():
-			subdirs = append(subdirs, base)
+			subdirs = append(subdirs, name)
 		default:
-			regularFiles = append(regularFiles, base)
+			regularFiles = append(regularFiles, name)
 		}
 	}
 
 	shouldUpdate := updateRels.shouldUpdate(rel, updateParent)
 	for _, sub := range subdirs {
 		if subRel := path.Join(rel, sub); updateRels.shouldVisit(subRel, shouldUpdate) {
-			visit(c, cexts, isBazelIgnored, knownDirectives, updateRels, wf, filepath.Join(dir, sub), subRel, shouldUpdate)
+			visit(c, cexts, isBazelIgnored, knownDirectives, updateRels, wf, subRel, shouldUpdate)
 		}
 	}
 
@@ -329,27 +337,23 @@ func findGenFiles(wc *walkConfig, f *rule.File) []string {
 
 	var genFiles []string
 	for _, s := range strs {
-		if !wc.isExcluded(f.Pkg, s) {
+		if !wc.isExcluded(path.Join(f.Pkg, s)) {
 			genFiles = append(genFiles, s)
 		}
 	}
 	return genFiles
 }
 
 func resolveFileInfo(wc *walkConfig, dir, rel string, ent fs.DirEntry) fs.DirEntry {
-	base := ent.Name()
-	if base == "" {
-		return nil
-	}
 	if ent.Type()&os.ModeSymlink == 0 {
 		// Not a symlink, use the original FileInfo.
 		return ent
 	}
-	if !wc.shouldFollow(rel, base) {
+	if !wc.shouldFollow(rel) {
 		// A symlink, but not one we should follow.
 		return nil
 	}
-	fi, err := os.Stat(path.Join(dir, base))
+	fi, err := os.Stat(path.Join(dir, ent.Name()))
 	if err != nil {
 		// A symlink, but not one we could resolve.
 		return nil