perf: improve try_files matcher

modules/caddyhttp/fileserver/matcher.go

@@ -416,15 +416,26 @@ func (m MatchFile) selectFile(r *http.Request) (bool, error) {
 
 	// setPlaceholders creates the placeholders for the matched file
 	setPlaceholders := func(candidate matchCandidate, info fs.FileInfo) {
-		repl.Set("http.matchers.file.relative", filepath.ToSlash(candidate.relative))
-		repl.Set("http.matchers.file.absolute", filepath.ToSlash(candidate.fullpath))
-		repl.Set("http.matchers.file.remainder", filepath.ToSlash(candidate.splitRemainder))
+		isDir := info.IsDir()
+		repl.Map(func(key string) (any, bool) {
+			switch key {
+			case "http.matchers.file.relative":
+				return filepath.ToSlash(candidate.relative), true
+			case "http.matchers.file.absolute":
+				return filepath.ToSlash(candidate.fullpath), true
+			case "http.matchers.file.remainder":
+				return filepath.ToSlash(candidate.splitRemainder), true
+			case "http.matchers.file.type":
+				if isDir {
+					return "directory", true
+				}
 
-		fileType := "file"
-		if info.IsDir() {
-			fileType = "directory"
-		}
-		repl.Set("http.matchers.file.type", fileType)
+				return "file", true
+
+			default:
+				return nil, false
+			}
+		})
 	}
 
 	// match file according to the configured policy

modules/caddyhttp/fileserver/matcher_test.go

@@ -416,3 +416,24 @@ func TestMatchExpressionMatch(t *testing.T) {
 		})
 	}
 }
+
+func BenchmarkFileMatcher(b *testing.B) {
+	m := &MatchFile{
+		fsmap:    &filesystems.FilesystemMap{},
+		Root:     "./testdata",
+		TryFiles: []string{"{http.request.uri.path}"},
+	}
+
+	u, _ := url.Parse("/foo.txt")
+	req := &http.Request{URL: u}
+	caddyhttp.NewTestReplacer(req)
+
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		ok, _ := m.MatchWithError(req)
+		if !ok {
+			panic("unexpected match result")
+		}
+	}
+}