tplimpl: Refactor imageConfig into a struct

Updates #2701

tpl/tplimpl/template_funcs.go

@@ -40,6 +40,8 @@ import (
 	"time"
 	"unicode/utf8"
 
+	"github.com/spf13/hugo/hugofs"
+
 	"github.com/bep/inflect"
 	"github.com/spf13/afero"
 	"github.com/spf13/cast"
@@ -57,6 +59,7 @@ import (
 type templateFuncster struct {
 	funcMap        template.FuncMap
 	cachedPartials partialCache
+	image          *imageHandler
 	*deps.Deps
 }
 
@@ -64,6 +67,7 @@ func newTemplateFuncster(deps *deps.Deps) *templateFuncster {
 	return &templateFuncster{
 		Deps:           deps,
 		cachedPartials: partialCache{p: make(map[string]template.HTML)},
+		image:          &imageHandler{fs: deps.Fs, imageConfigCache: map[string]image.Config{}},
 	}
 }
 
@@ -395,64 +399,43 @@ func intersect(l1, l2 interface{}) (interface{}, error) {
 	}
 }
 
-// ResetCaches resets all caches that might be used during build.
-// TODO(bep) globals move image config cache to funcster
-func ResetCaches() {
-	resetImageConfigCache()
-}
-
-// imageConfigCache is a lockable cache for image.Config objects. It must be
-// locked before reading or writing to config.
-type imageConfigCache struct {
-	config map[string]image.Config
+type imageHandler struct {
+	imageConfigCache map[string]image.Config
 	sync.RWMutex
-}
-
-var defaultImageConfigCache = imageConfigCache{
-	config: map[string]image.Config{},
-}
-
-// resetImageConfigCache initializes and resets the imageConfig cache for the
-// imageConfig template function. This should be run once before every batch of
-// template renderers so the cache is cleared for new data.
-func resetImageConfigCache() {
-	defaultImageConfigCache.Lock()
-	defer defaultImageConfigCache.Unlock()
-
-	defaultImageConfigCache.config = map[string]image.Config{}
+	fs *hugofs.Fs
 }
 
 // imageConfig returns the image.Config for the specified path relative to the
-// working directory. resetImageConfigCache must be run beforehand.
-func (t *templateFuncster) imageConfig(path interface{}) (image.Config, error) {
+// working directory.
+func (ic *imageHandler) config(path interface{}) (image.Config, error) {
 	filename, err := cast.ToStringE(path)
 	if err != nil {
 		return image.Config{}, err
 	}
 
 	if filename == "" {
-		return image.Config{}, errors.New("imageConfig needs a filename")
+		return image.Config{}, errors.New("config needs a filename")
 	}
 
 	// Check cache for image config.
-	defaultImageConfigCache.RLock()
-	config, ok := defaultImageConfigCache.config[filename]
-	defaultImageConfigCache.RUnlock()
+	ic.RLock()
+	config, ok := ic.imageConfigCache[filename]
+	ic.RUnlock()
 
 	if ok {
 		return config, nil
 	}
 
-	f, err := t.Fs.WorkingDir.Open(filename)
+	f, err := ic.fs.WorkingDir.Open(filename)
 	if err != nil {
 		return image.Config{}, err
 	}
 
 	config, _, err = image.DecodeConfig(f)
 
-	defaultImageConfigCache.Lock()
-	defaultImageConfigCache.config[filename] = config
-	defaultImageConfigCache.Unlock()
+	ic.Lock()
+	ic.imageConfigCache[filename] = config
+	ic.Unlock()
 
 	return config, err
 }
@@ -2144,7 +2127,7 @@ func (t *templateFuncster) initFuncMap() {
 		"htmlEscape":    htmlEscape,
 		"htmlUnescape":  htmlUnescape,
 		"humanize":      humanize,
-		"imageConfig":   t.imageConfig,
+		"imageConfig":   t.image.config,
 		"in":            in,
 		"index":         index,
 		"int":           func(v interface{}) (int, error) { return cast.ToIntE(v) },