XL: bring in new storage API. (#1780)

Fixes #1771

fs-v1-metadata.go

@@ -1,9 +1,7 @@
 package main
 
 import (
-	"bytes"
 	"encoding/json"
-	"io"
 	"path"
 	"sort"
 )
@@ -22,28 +20,6 @@ type fsMetaV1 struct {
 	Parts []objectPartInfo `json:"parts,omitempty"`
 }
 
-// ReadFrom - read from implements io.ReaderFrom interface for
-// unmarshalling fsMetaV1.
-func (m *fsMetaV1) ReadFrom(reader io.Reader) (n int64, err error) {
-	var buffer bytes.Buffer
-	n, err = buffer.ReadFrom(reader)
-	if err != nil {
-		return 0, err
-	}
-	err = json.Unmarshal(buffer.Bytes(), m)
-	return n, err
-}
-
-// WriteTo - write to implements io.WriterTo interface for marshalling fsMetaV1.
-func (m fsMetaV1) WriteTo(writer io.Writer) (n int64, err error) {
-	metadataBytes, err := json.Marshal(m)
-	if err != nil {
-		return 0, err
-	}
-	p, err := writer.Write(metadataBytes)
-	return int64(p), err
-}
-
 // ObjectPartIndex - returns the index of matching object part number.
 func (m fsMetaV1) ObjectPartIndex(partNumber int) (partIndex int) {
 	for i, part := range m.Parts {
@@ -81,12 +57,12 @@ func (m *fsMetaV1) AddObjectPart(partNumber int, partName string, partETag strin
 
 // readFSMetadata - returns the object metadata `fs.json` content.
 func (fs fsObjects) readFSMetadata(bucket, object string) (fsMeta fsMetaV1, err error) {
-	r, err := fs.storage.ReadFile(bucket, path.Join(object, fsMetaJSONFile), int64(0))
+	buffer := make([]byte, blockSize)
+	n, err := fs.storage.ReadFile(bucket, path.Join(object, fsMetaJSONFile), int64(0), buffer)
 	if err != nil {
 		return fsMetaV1{}, err
 	}
-	defer r.Close()
-	_, err = fsMeta.ReadFrom(r)
+	err = json.Unmarshal(buffer[:n], &fsMeta)
 	if err != nil {
 		return fsMetaV1{}, err
 	}
@@ -104,22 +80,16 @@ func newFSMetaV1() (fsMeta fsMetaV1) {
 
 // writeFSMetadata - writes `fs.json` metadata.
 func (fs fsObjects) writeFSMetadata(bucket, prefix string, fsMeta fsMetaV1) error {
-	w, err := fs.storage.CreateFile(bucket, path.Join(prefix, fsMetaJSONFile))
+	metadataBytes, err := json.Marshal(fsMeta)
 	if err != nil {
 		return err
 	}
-	_, err = fsMeta.WriteTo(w)
+	n, err := fs.storage.AppendFile(bucket, path.Join(prefix, fsMetaJSONFile), metadataBytes)
 	if err != nil {
-		if mErr := safeCloseAndRemove(w); mErr != nil {
-			return mErr
-		}
 		return err
 	}
-	if err = w.Close(); err != nil {
-		if mErr := safeCloseAndRemove(w); mErr != nil {
-			return mErr
-		}
-		return err
+	if n != int64(len(metadataBytes)) {
+		return errUnexpected
 	}
 	return nil
 }