New Cache FileSystem implementation

core/cache/spread_fs.go

@@ -0,0 +1,83 @@
+package cache
+
+import (
+	"crypto/md5"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/djherbis/fscache"
+	"github.com/karrick/godirwalk"
+	"gopkg.in/djherbis/atime.v1"
+	"gopkg.in/djherbis/stream.v1"
+)
+
+type spreadFs struct {
+	root string
+	mode os.FileMode
+	init func() error
+}
+
+// NewSpreadFs returns a FileSystem rooted at directory dir. It
+// Dir is created with perms if it doesn't exist.
+func NewSpreadFs(dir string, mode os.FileMode) (fscache.FileSystem, error) {
+	fs := &spreadFs{root: dir, mode: mode, init: func() error {
+		return os.MkdirAll(dir, mode)
+	}}
+	return fs, fs.init()
+}
+
+func (fs *spreadFs) Reload(f func(key string, name string)) error {
+	return godirwalk.Walk(fs.root, &godirwalk.Options{
+		Callback: func(absoluteFilePath string, de *godirwalk.Dirent) error {
+			path, err := filepath.Rel(fs.root, absoluteFilePath)
+			if err != nil {
+				return nil
+			}
+
+			parts := strings.Split(path, string(os.PathSeparator))
+			if len(parts) != 3 || len(parts[0]) != 2 || len(parts[1]) != 2 {
+				return nil
+			}
+
+			key := filepath.Base(path)
+			f(key, absoluteFilePath)
+			return nil
+		},
+		Unsorted: true,
+	})
+}
+
+func (fs *spreadFs) Create(name string) (stream.File, error) {
+	key := fmt.Sprintf("%x", md5.Sum([]byte(name)))
+	path := fmt.Sprintf("%s%c%s", key[0:2], os.PathSeparator, key[2:4])
+	err := os.MkdirAll(filepath.Join(fs.root, path), fs.mode)
+	if err != nil {
+		return nil, err
+	}
+	return os.OpenFile(filepath.Join(fs.root, path, key), os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)
+}
+
+func (fs *spreadFs) Open(name string) (stream.File, error) {
+	return os.Open(name)
+}
+
+func (fs *spreadFs) Remove(name string) error {
+	return os.Remove(name)
+}
+
+func (fs *spreadFs) Stat(name string) (fscache.FileInfo, error) {
+	stat, err := os.Stat(name)
+	if err != nil {
+		return fscache.FileInfo{}, err
+	}
+	return fscache.FileInfo{FileInfo: stat, Atime: atime.Get(stat)}, nil
+}
+
+func (fs *spreadFs) RemoveAll() error {
+	if err := os.RemoveAll(fs.root); err != nil {
+		return err
+	}
+	return fs.init()
+}