Added option to hot reload templates for development.

util/cache.go

@@ -6,23 +6,30 @@ import (
 	"sync"
 )
 
+type cachedTemplate struct {
+	tpl   *template.Template
+	files []string
+}
+
 // TemplateCache caches templates.
 type TemplateCache struct {
-	templates map[string]*template.Template
+	templates map[string]cachedTemplate
+	disabled  bool
 	mutex     sync.RWMutex
 }
 
 // NewTemplateCache creates a new template cache.
-func NewTemplateCache() *TemplateCache {
-	return &TemplateCache{templates: make(map[string]*template.Template)}
+// If disabled is set to true, the templates are reloaded on each call.
+func NewTemplateCache(disabled bool) *TemplateCache {
+	return &TemplateCache{templates: make(map[string]cachedTemplate), disabled: disabled}
 }
 
 // ParseFiles parses the given template files and stores them as one template called name.
 func (tplcache *TemplateCache) ParseFiles(name string, files ...string) (*template.Template, error) {
-	if tplcache.templates[name] != nil {
+	if _, ok := tplcache.templates[name]; ok && !tplcache.disabled {
 		tplcache.mutex.RLock()
 		defer tplcache.mutex.RUnlock()
-		return tplcache.templates[name], nil
+		return tplcache.templates[name].tpl, nil
 	}
 
 	tplcache.mutex.Lock()
@@ -34,16 +41,27 @@ func (tplcache *TemplateCache) ParseFiles(name string, files ...string) (*templa
 		return nil, err
 	}
 
-	tplcache.templates[name] = tpl
+	tplcache.templates[name] = cachedTemplate{tpl, files}
 	return tpl, nil
 }
 
 // GetTemplate returns a cached template by name or nil if not found.
 func (tplcache *TemplateCache) GetTemplate(name string) *template.Template {
-	if tplcache.templates[name] != nil {
+	tpl, ok := tplcache.templates[name]
+
+	if ok && tplcache.disabled {
+		newTpl, err := tplcache.ParseFiles(name, tpl.files...)
+
+		if err != nil {
+			logbuch.Error("Error parsing file on cache rebuild", logbuch.Fields{"err": err, "name": name})
+			return nil
+		}
+
+		return newTpl
+	} else if ok {
 		tplcache.mutex.RLock()
 		defer tplcache.mutex.RUnlock()
-		return tplcache.templates[name]
+		return tplcache.templates[name].tpl
 	}
 
 	return nil
@@ -51,5 +69,15 @@ func (tplcache *TemplateCache) GetTemplate(name string) *template.Template {
 
 // Clear clears the template cache.
 func (tplcache *TemplateCache) Clear() {
-	tplcache.templates = make(map[string]*template.Template)
+	tplcache.templates = make(map[string]cachedTemplate)
+}
+
+// Enable enables the cache, so that each template is loaded from cache.
+func (tplcache *TemplateCache) Enable() {
+	tplcache.disabled = false
+}
+
+// Disable disables the cache, so that each template is reloaded on each call.
+func (tplcache *TemplateCache) Disable() {
+	tplcache.disabled = true
 }