minio/pkgs/storage/appendstorage/append_storage.go
2014-12-08 23:37:25 -08:00

100 lines
2.1 KiB
Go

package appendstorage
import (
"bytes"
"encoding/gob"
"io/ioutil"
"os"
"path"
"strconv"
"github.com/minio-io/minio/pkgs/storage"
)
type appendStorage struct {
RootDir string
file *os.File
objects map[string]Header
objectsFile string
}
type Header struct {
Path string
Offset int64
Length int
Crc []byte
}
func NewStorage(rootDir string, slice int) (storage.ObjectStorage, error) {
rootPath := path.Join(rootDir, strconv.Itoa(slice))
// TODO verify and fix partial writes
file, err := os.OpenFile(rootPath, os.O_APPEND|os.O_CREATE|os.O_RDWR, 0600)
if err != nil {
return &appendStorage{}, err
}
objectsFile := path.Join(rootDir, strconv.Itoa(slice)+".map")
objects := make(map[string]Header)
if _, err := os.Stat(objectsFile); err == nil {
mapFile, err := os.Open(objectsFile)
defer mapFile.Close()
if err != nil {
return &appendStorage{}, nil
}
dec := gob.NewDecoder(mapFile)
err = dec.Decode(&objects)
if err != nil {
return &appendStorage{}, nil
}
}
if err != nil {
return &appendStorage{}, err
}
return &appendStorage{
RootDir: rootDir,
file: file,
objects: objects,
objectsFile: objectsFile,
}, nil
}
func (storage *appendStorage) Get(objectPath string) ([]byte, error) {
header, ok := storage.objects[objectPath]
if ok == false {
return nil, nil
}
offset := header.Offset
length := header.Length
object := make([]byte, length)
_, err := storage.file.ReadAt(object, offset)
if err != nil {
return nil, err
}
return object, nil
}
func (storage *appendStorage) Put(objectPath string, object []byte) error {
header := Header{
Path: objectPath,
Offset: 0,
Length: 0,
Crc: nil,
}
offset, err := storage.file.Seek(0, os.SEEK_END)
if err != nil {
return err
}
if _, err := storage.file.Write(object); err != nil {
return err
}
header.Offset = offset
header.Length = len(object)
storage.objects[objectPath] = header
var mapBuffer bytes.Buffer
encoder := gob.NewEncoder(&mapBuffer)
encoder.Encode(storage.objects)
ioutil.WriteFile(storage.objectsFile, mapBuffer.Bytes(), 0600)
return nil
}