Cache sass conversion

README.md

@@ -105,7 +105,7 @@ These will probably not change:
 Disable the cache by setting the environment variable `GOJEKYLL_DISABLE_CACHE=1`.
 Disable threading by setting `GOMAXPROCS=1`.
 
-The cache is for calls to Pygments (via the `highlight` tag). For sites, SASS (which is currently not cached) might have more overhead.
+SASS conversion and Pygments (`highlight`) are cached.
 
 ### Feature Status
 

cache/cache.go

@@ -1,4 +1,4 @@
-package tags
+package cache
 
 import (
 	"crypto/md5" // nolint: gas
@@ -18,14 +18,14 @@ func init() {
 	}
 }
 
-// withFileCache looks (header, content) up in a user-specific file cache.
+// WithFile looks (header, content) up in a user-specific file cache.
 // If found, it writes the file contents. Else it calls fn to write to
 // both the writer and the file system.
 //
 // header and content are distinct parameters to relieve the caller from
 // having to concatenate them.
-func withFileCache(header string, content string, fn func() (string, error)) (string, error) {
-	h := md5.New()             // nolint: gas
+func WithFile(header string, content string, fn func() (string, error)) (string, error) {
+	h := md5.New()             // nolint: gas, noncrypto
 	io.WriteString(h, content) // nolint: errcheck, gas
 	io.WriteString(h, "\n")    // nolint: errcheck, gas
 	io.WriteString(h, header)  // nolint: errcheck, gas

pipelines/pipeline.go

@@ -26,6 +26,7 @@ type Pipeline struct {
 	config       config.Config
 	liquidEngine liquid.Engine
 	sassTempDir  string
+	sassHash     string
 }
 
 // PipelineOptions configures a pipeline.

pipelines/sass.go

@@ -2,14 +2,16 @@ package pipelines
 
 import (
 	"bytes"
+	"crypto/md5" // nolint: gas
+	"fmt"
 	"io"
 	"io/ioutil"
-	"log"
 	"os"
 	"path/filepath"
 	"strings"
 
 	"github.com/dchest/cssmin"
+	"github.com/osteele/gojekyll/cache"
 	"github.com/osteele/gojekyll/utils"
 
 	libsass "github.com/wellington/go-libsass"
@@ -28,6 +30,7 @@ func (p *Pipeline) CopySassFileIncludes() error {
 		p.sassTempDir = dir
 	}
 
+	h := md5.New() // nolint: gas, noncrypto
 	src := filepath.Join(p.SourceDir(), "_sass")
 	dst := p.sassTempDir
 	err := filepath.Walk(src, func(from string, info os.FileInfo, err error) error {
@@ -36,11 +39,21 @@ func (p *Pipeline) CopySassFileIncludes() error {
 		}
 		rel := utils.MustRel(src, from)
 		to := filepath.Join(dst, strings.TrimPrefix(rel, "_"))
+		in, err := os.Open(from)
+		if err != nil {
+			return err
+		}
+		defer in.Close() // nolint: errcheck
+		_, err = io.Copy(h, in)
+		if err != nil {
+			return err
+		}
 		return utils.CopyFileContents(to, from, 0644)
 	})
 	if os.IsNotExist(err) {
 		return nil
 	}
+	p.sassHash = fmt.Sprintf("%x", h.Sum(nil))
 	return err
 }
 
@@ -50,20 +63,26 @@ func (p *Pipeline) SassIncludePaths() []string {
 }
 
 // WriteSass converts a SASS file and writes it to w.
-func (p *Pipeline) WriteSass(w io.Writer, b []byte) (err error) {
-	buf := new(bytes.Buffer)
-	comp, err := libsass.New(buf, bytes.NewBuffer(b))
+func (p *Pipeline) WriteSass(w io.Writer, b []byte) error {
+	s, err := cache.WithFile(fmt.Sprintf("sass: %s", p.sassHash), string(b), func() (s string, err error) {
+		buf := new(bytes.Buffer)
+		comp, err := libsass.New(buf, bytes.NewBuffer(b))
+		if err != nil {
+			return "", err
+		}
+		err = comp.Option(libsass.IncludePaths(p.SassIncludePaths()))
+		if err != nil {
+			return "", err
+		}
+		if err = comp.Run(); err != nil {
+			return "", err
+		}
+		b = cssmin.Minify(buf.Bytes())
+		return string(b), nil
+	})
 	if err != nil {
 		return err
 	}
-	err = comp.Option(libsass.IncludePaths(p.SassIncludePaths()))
-	if err != nil {
-		log.Fatal(err)
-	}
-	if err = comp.Run(); err != nil {
-		return err
-	}
-	b = cssmin.Minify(buf.Bytes())
-	_, err = w.Write(b)
+	_, err = w.Write([]byte(s))
 	return err
 }

site/site.go

@@ -158,7 +158,7 @@ func (s *Site) initializeRenderingPipeline() (err error) {
 	}
 	s.pipeline, err = pipelines.NewPipeline(s.config, options)
 	if err != nil {
-		return nil
+		return err
 	}
 	engine := s.pipeline.TemplateEngine()
 	return s.runHooks(func(p plugins.Plugin) error {

tags/highlight.go

@@ -7,6 +7,7 @@ import (
 	"os/exec"
 	"strings"
 
+	"github.com/osteele/gojekyll/cache"
 	"github.com/osteele/liquid/render"
 )
 
@@ -23,7 +24,7 @@ func highlightTag(ctx render.Context) (string, error) {
 	if err != nil {
 		return "", err
 	}
-	return withFileCache(fmt.Sprintf("pygments %s", args), s, func() (string, error) {
+	return cache.WithFile(fmt.Sprintf("pygments %s", args), s, func() (string, error) {
 		buf := new(bytes.Buffer)
 		cmd := exec.Command("pygmentize", cargs...) // nolint: gas
 		cmd.Stdin = strings.NewReader(s)