markdown: only update template when file changed (#1909)

Signed-off-by: Tw <tw19881113@gmail.com>

caddyhttp/markdown/markdown.go

@@ -68,8 +68,13 @@ type Config struct {
 	// Template(s) to render with
 	Template *template.Template
 
-	// a pair of template's name and its underlying file path
-	TemplateFiles map[string]string
+	// a pair of template's name and its underlying file information
+	TemplateFiles map[string]*cachedFileInfo
+}
+
+type cachedFileInfo struct {
+	path string
+	fi   os.FileInfo
 }
 
 // ServeHTTP implements the http.Handler interface.

caddyhttp/markdown/setup.go

@@ -62,7 +62,7 @@ func markdownParse(c *caddy.Controller) ([]*Config, error) {
 			Extensions:    make(map[string]struct{}),
 			Template:      GetDefaultTemplate(),
 			IndexFiles:    []string{},
-			TemplateFiles: make(map[string]string),
+			TemplateFiles: make(map[string]*cachedFileInfo),
 		}
 
 		// Get the path scope
@@ -133,7 +133,9 @@ func loadParams(c *caddy.Controller, mdc *Config) error {
 				return c.Errf("default template parse error: %v", err)
 			}
 
-			mdc.TemplateFiles[""] = fpath
+			mdc.TemplateFiles[""] = &cachedFileInfo{
+				path: fpath,
+			}
 			return nil
 		case 2:
 			fpath := filepath.ToSlash(filepath.Clean(cfg.Root + string(filepath.Separator) + tArgs[1]))
@@ -142,7 +144,9 @@ func loadParams(c *caddy.Controller, mdc *Config) error {
 				return c.Errf("template parse error: %v", err)
 			}
 
-			mdc.TemplateFiles[tArgs[0]] = fpath
+			mdc.TemplateFiles[tArgs[0]] = &cachedFileInfo{
+				path: fpath,
+			}
 			return nil
 		}
 	case "templatedir":
@@ -164,7 +168,9 @@ func loadParams(c *caddy.Controller, mdc *Config) error {
 			return c.Errf("glob %q failed: %v", pattern, err)
 		}
 		for _, path := range paths {
-			mdc.TemplateFiles[filepath.Base(path)] = path
+			mdc.TemplateFiles[filepath.Base(path)] = &cachedFileInfo{
+				path: path,
+			}
 		}
 		return nil
 	default:

caddyhttp/markdown/setup_test.go

@@ -77,7 +77,7 @@ func TestMarkdownParse(t *testing.T) {
 			Styles:        []string{"/resources/css/blog.css"},
 			Scripts:       []string{"/resources/js/blog.js"},
 			Template:      GetDefaultTemplate(),
-			TemplateFiles: make(map[string]string),
+			TemplateFiles: make(map[string]*cachedFileInfo),
 		}}},
 		{`markdown /blog {
 	ext .md
@@ -88,8 +88,8 @@ func TestMarkdownParse(t *testing.T) {
 				".md": {},
 			},
 			Template: setDefaultTemplate("./testdata/tpl_with_include.html"),
-			TemplateFiles: map[string]string{
-				"": "testdata/tpl_with_include.html",
+			TemplateFiles: map[string]*cachedFileInfo{
+				"": {path: "testdata/tpl_with_include.html"},
 			},
 		}}},
 	}

caddyhttp/markdown/template.go

@@ -17,6 +17,8 @@ package markdown
 import (
 	"bytes"
 	"io/ioutil"
+	"os"
+	"sync"
 	"text/template"
 
 	"github.com/mholt/caddy/caddyhttp/httpserver"
@@ -41,6 +43,8 @@ func (d Data) Include(filename string, args ...interface{}) (string, error) {
 	return httpserver.ContextInclude(filename, d, d.Root)
 }
 
+var templateUpdateMu sync.RWMutex
+
 // execTemplate executes a template given a requestPath, template, and metadata
 func execTemplate(c *Config, mdata metadata.Metadata, meta map[string]string, files []FileInfo, ctx httpserver.Context) ([]byte, error) {
 	mdData := Data{
@@ -51,18 +55,43 @@ func execTemplate(c *Config, mdata metadata.Metadata, meta map[string]string, fi
 		Meta:    meta,
 		Files:   files,
 	}
-
 	templateName := mdata.Template
-	// reload template on every request for now
-	// TODO: cache templates by a general plugin
-	if templateFile, ok := c.TemplateFiles[templateName]; ok {
-		err := SetTemplate(c.Template, templateName, templateFile)
-		if err != nil {
-			return nil, err
+
+	updateTemplate := func() error {
+		templateUpdateMu.Lock()
+		defer templateUpdateMu.Unlock()
+
+		templateFile, ok := c.TemplateFiles[templateName]
+		if !ok {
+			return nil
 		}
+
+		currentFileInfo, err := os.Lstat(templateFile.path)
+		if err != nil {
+			return err
+		}
+
+		if !fileChanged(currentFileInfo, templateFile.fi) {
+			return nil
+		}
+
+		// update template due to file changes
+		err = SetTemplate(c.Template, templateName, templateFile.path)
+		if err != nil {
+			return err
+		}
+
+		templateFile.fi = currentFileInfo
+		return nil
+	}
+
+	if err := updateTemplate(); err != nil {
+		return nil, err
 	}
 
 	b := new(bytes.Buffer)
+	templateUpdateMu.RLock()
+	defer templateUpdateMu.RUnlock()
 	if err := c.Template.ExecuteTemplate(b, templateName, mdData); err != nil {
 		return nil, err
 	}
@@ -70,6 +99,21 @@ func execTemplate(c *Config, mdata metadata.Metadata, meta map[string]string, fi
 	return b.Bytes(), nil
 }
 
+func fileChanged(new, old os.FileInfo) bool {
+	// never checked before
+	if old == nil {
+		return true
+	}
+
+	if new.Size() != old.Size() ||
+		new.Mode() != old.Mode() ||
+		new.ModTime() != old.ModTime() {
+		return true
+	}
+
+	return false
+}
+
 // SetTemplate reads in the template with the filename provided. If the file does not exist or is not parsable, it will return an error.
 func SetTemplate(t *template.Template, name, filename string) error {