Put object on successful write returns full metadata, to avoid subsequent GetObjectMetadata() calls in driver

pkg/storage/donut/bucket.go

@@ -217,19 +217,19 @@ func (b bucket) ReadObject(objectName string) (reader io.ReadCloser, size int64,
 }
 
 // WriteObject - write a new object into bucket
-func (b bucket) WriteObject(objectName string, objectData io.Reader, expectedMD5Sum string, metadata map[string]string) (string, error) {
+func (b bucket) WriteObject(objectName string, objectData io.Reader, expectedMD5Sum string, metadata map[string]string) (ObjectMetadata, error) {
 	b.lock.Lock()
 	defer b.lock.Unlock()
 	if objectName == "" || objectData == nil {
-		return "", iodine.New(InvalidArgument{}, nil)
+		return ObjectMetadata{}, iodine.New(InvalidArgument{}, nil)
 	}
 	writers, err := b.getDiskWriters(normalizeObjectName(objectName), "data")
 	if err != nil {
-		return "", iodine.New(err, nil)
+		return ObjectMetadata{}, iodine.New(err, nil)
 	}
 	sumMD5 := md5.New()
 	sum512 := sha512.New()
-	objMetadata := new(ObjectMetadata)
+	objMetadata := ObjectMetadata{}
 	objMetadata.Version = objectMetadataVersion
 	objMetadata.Created = time.Now().UTC()
 	// if total writers are only '1' do not compute erasure
@@ -238,19 +238,19 @@ func (b bucket) WriteObject(objectName string, objectData io.Reader, expectedMD5
 		mw := io.MultiWriter(writers[0], sumMD5, sum512)
 		totalLength, err := io.Copy(mw, objectData)
 		if err != nil {
-			return "", iodine.New(err, nil)
+			return ObjectMetadata{}, iodine.New(err, nil)
 		}
 		objMetadata.Size = totalLength
 	case false:
 		// calculate data and parity dictated by total number of writers
 		k, m, err := b.getDataAndParity(len(writers))
 		if err != nil {
-			return "", iodine.New(err, nil)
+			return ObjectMetadata{}, iodine.New(err, nil)
 		}
 		// encoded data with k, m and write
 		chunkCount, totalLength, err := b.writeEncodedData(k, m, writers, objectData, sumMD5, sum512)
 		if err != nil {
-			return "", iodine.New(err, nil)
+			return ObjectMetadata{}, iodine.New(err, nil)
 		}
 		/// donutMetadata section
 		objMetadata.BlockSize = blockSize
@@ -271,20 +271,19 @@ func (b bucket) WriteObject(objectName string, objectData io.Reader, expectedMD5
 	// Verify if the written object is equal to what is expected, only if it is requested as such
 	if strings.TrimSpace(expectedMD5Sum) != "" {
 		if err := b.isMD5SumEqual(strings.TrimSpace(expectedMD5Sum), objMetadata.MD5Sum); err != nil {
-			return "", iodine.New(err, nil)
+			return ObjectMetadata{}, iodine.New(err, nil)
 		}
 	}
-
 	objMetadata.Metadata = metadata
 	// write object specific metadata
 	if err := b.writeObjectMetadata(normalizeObjectName(objectName), objMetadata); err != nil {
-		return "", iodine.New(err, nil)
+		return ObjectMetadata{}, iodine.New(err, nil)
 	}
 	// close all writers, when control flow reaches here
 	for _, writer := range writers {
 		writer.Close()
 	}
-	return objMetadata.MD5Sum, nil
+	return objMetadata, nil
 }
 
 // isMD5SumEqual - returns error if md5sum mismatches, other its `nil`
@@ -307,8 +306,8 @@ func (b bucket) isMD5SumEqual(expectedMD5Sum, actualMD5Sum string) error {
 }
 
 // writeObjectMetadata - write additional object metadata
-func (b bucket) writeObjectMetadata(objectName string, objMetadata *ObjectMetadata) error {
-	if objMetadata == nil {
+func (b bucket) writeObjectMetadata(objectName string, objMetadata ObjectMetadata) error {
+	if objMetadata.Object == "" {
 		return iodine.New(InvalidArgument{}, nil)
 	}
 	objMetadataWriters, err := b.getDiskWriters(objectName, objectMetadataConfig)
@@ -320,7 +319,7 @@ func (b bucket) writeObjectMetadata(objectName string, objMetadata *ObjectMetada
 	}
 	for _, objMetadataWriter := range objMetadataWriters {
 		jenc := json.NewEncoder(objMetadataWriter)
-		if err := jenc.Encode(objMetadata); err != nil {
+		if err := jenc.Encode(&objMetadata); err != nil {
 			return iodine.New(err, nil)
 		}
 	}