From e14f8c1463df8564afafa8d64c2bb818a8ff0b97 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ferdinand=20M=C3=BCtsch?= <ferdinand@muetsch.io>
Date: Mon, 20 Dec 2021 16:41:50 +0100
Subject: [PATCH] chore: minor performance improvements

---
 main.go              | 14 ++++++--------
 utils/fs/exists.go   | 42 +++++++++++++++++++++++++++++++++---------
 utils/fs/neutered.go |  6 +++---
 3 files changed, 42 insertions(+), 20 deletions(-)

diff --git a/main.go b/main.go
index b6cc66d..e0c0d74 100644
--- a/main.go
+++ b/main.go
@@ -247,14 +247,12 @@ func main() {
 	// https://github.com/golang/go/issues/43431
 	embeddedStatic, _ := fs.Sub(staticFiles, "static")
 	static := conf.ChooseFS("static", embeddedStatic)
-
-	fileServer := gzipped.FileServer(fsutils.NewExistsHttpFs(
-		fsutils.ExistsFS{
-			Fs: fsutils.NeuteredFileSystem{
-				Fs: static,
-			},
-		}),
-	)
+	fileServer := gzipped.FileServer(fsutils.NewExistsHttpFS(
+		fsutils.NewExistsFS(
+			fsutils.NeuteredFileSystem{
+				FS: static,
+			}).WithCache(!config.IsDev()),
+	))
 
 	router.PathPrefix("/contribute.json").Handler(fileServer)
 	router.PathPrefix("/assets").Handler(fileServer)
diff --git a/utils/fs/exists.go b/utils/fs/exists.go
index 355e845..08c256d 100644
--- a/utils/fs/exists.go
+++ b/utils/fs/exists.go
@@ -1,35 +1,59 @@
 package fs
 
 import (
+	"github.com/patrickmn/go-cache"
 	"io/fs"
 	"net/http"
 	"strings"
 )
 
+func NewExistsFS(fs fs.FS) ExistsFS {
+	return ExistsFS{
+		FS:    fs,
+		cache: cache.New(cache.NoExpiration, cache.NoExpiration),
+	}
+}
+
 type ExistsFS struct {
-	Fs fs.FS
+	fs.FS
+	UseCache bool
+	cache    *cache.Cache
+}
+
+func (efs ExistsFS) WithCache(withCache bool) ExistsFS {
+	efs.UseCache = withCache
+	return efs
 }
 
 func (efs ExistsFS) Exists(name string) bool {
-	_, err := fs.Stat(efs.Fs, name)
-	return err == nil
+	if efs.UseCache {
+		if result, ok := efs.cache.Get(name); ok {
+			return result.(bool)
+		}
+	}
+	_, err := fs.Stat(efs.FS, name)
+	result := err == nil
+	if efs.UseCache {
+		efs.cache.SetDefault(name, result)
+	}
+	return result
 }
 
 func (efs ExistsFS) Open(name string) (fs.File, error) {
-	return efs.Fs.Open(name)
+	return efs.FS.Open(name)
 }
 
 // ---
 
 type ExistsHttpFS struct {
-	Fs     ExistsFS
+	ExistsFS
 	httpFs http.FileSystem
 }
 
-func NewExistsHttpFs(fs ExistsFS) ExistsHttpFS {
+func NewExistsHttpFS(fs ExistsFS) ExistsHttpFS {
 	return ExistsHttpFS{
-		Fs:     fs,
-		httpFs: http.FS(fs),
+		ExistsFS: fs,
+		httpFs:   http.FS(fs),
 	}
 }
 
@@ -37,7 +61,7 @@ func (ehfs ExistsHttpFS) Exists(name string) bool {
 	if strings.HasPrefix(name, "/") {
 		name = name[1:]
 	}
-	return ehfs.Fs.Exists(name)
+	return ehfs.ExistsFS.Exists(name)
 }
 
 func (ehfs ExistsHttpFS) Open(name string) (http.File, error) {
diff --git a/utils/fs/neutered.go b/utils/fs/neutered.go
index ca103f0..a65abd1 100644
--- a/utils/fs/neutered.go
+++ b/utils/fs/neutered.go
@@ -8,11 +8,11 @@ import (
 // https://www.alexedwards.net/blog/disable-http-fileserver-directory-listings
 
 type NeuteredFileSystem struct {
-	Fs fs.FS
+	fs.FS
 }
 
 func (nfs NeuteredFileSystem) Open(path string) (fs.File, error) {
-	f, err := nfs.Fs.Open(path)
+	f, err := nfs.FS.Open(path)
 	if err != nil {
 		return nil, err
 	}
@@ -20,7 +20,7 @@ func (nfs NeuteredFileSystem) Open(path string) (fs.File, error) {
 	s, err := f.Stat()
 	if s.IsDir() {
 		index := filepath.Join(path, "index.html")
-		if _, err := nfs.Fs.Open(index); err != nil {
+		if _, err := nfs.FS.Open(index); err != nil {
 			closeErr := f.Close()
 			if closeErr != nil {
 				return nil, closeErr