Merge pull request #678 from harshavardhana/pr_out_handle_racy_map_updates_in_listobjects_on_a_bucket

Avoid racy maps, read from disk on success return quickly. Many more optimizations

pkg/storage/donut/bucket.go

@@ -23,7 +23,6 @@ import (
 	"io"
 	"path/filepath"
 	"sort"
-	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -44,7 +43,6 @@ type bucket struct {
 	time      time.Time
 	donutName string
 	nodes     map[string]node
-	objects   map[string]object
 	lock      *sync.RWMutex
 }
 
@@ -66,13 +64,15 @@ func newBucket(bucketName, aclType, donutName string, nodes map[string]node) (bu
 	b.time = t
 	b.donutName = donutName
 	b.nodes = nodes
-	b.objects = make(map[string]object)
 	b.lock = new(sync.RWMutex)
 
 	metadata := BucketMetadata{}
+	metadata.Version = bucketMetadataVersion
 	metadata.Name = bucketName
 	metadata.ACL = aclType
 	metadata.Created = t
+	metadata.Metadata = make(map[string]string)
+	metadata.BucketObjectsMetadata = make(map[string]map[string]string)
 
 	return b, metadata, nil
 }
@@ -81,95 +81,115 @@ func (b bucket) getBucketName() string {
 	return b.name
 }
 
-func (b bucket) getObjectName(fileName, diskPath, bucketPath string) (string, error) {
+func (b bucket) GetObjectMetadata(objectName string) (ObjectMetadata, error) {
-	newObject, err := newObject(fileName, filepath.Join(diskPath, bucketPath))
+	b.lock.RLock()
+	defer b.lock.RUnlock()
+	metadataReaders, err := b.getDiskReaders(normalizeObjectName(objectName), objectMetadataConfig)
 	if err != nil {
-		return "", iodine.New(err, nil)
+		return ObjectMetadata{}, iodine.New(err, nil)
 	}
-	newObjectMetadata, err := newObject.GetObjectMetadata()
+	for _, metadataReader := range metadataReaders {
-	if err != nil {
+		defer metadataReader.Close()
-		return "", iodine.New(err, nil)
 	}
-	if newObjectMetadata.Object == "" {
+	objMetadata := ObjectMetadata{}
-		return "", iodine.New(ObjectCorrupted{Object: newObject.name}, nil)
+	for _, metadataReader := range metadataReaders {
+		jdec := json.NewDecoder(metadataReader)
+		if err := jdec.Decode(&objMetadata); err != nil {
+			return ObjectMetadata{}, iodine.New(err, nil)
+		}
+		return objMetadata, nil
 	}
-	b.objects[newObjectMetadata.Object] = newObject
+	return ObjectMetadata{}, iodine.New(InvalidArgument{}, nil)
-	return newObjectMetadata.Object, nil
 }
 
-func (b bucket) GetObjectMetadata(objectName string) (ObjectMetadata, error) {
+func (b bucket) getBucketMetadataReaders() ([]io.ReadCloser, error) {
-	return b.objects[objectName].GetObjectMetadata()
+	var readers []io.ReadCloser
+	for _, node := range b.nodes {
+		disks, err := node.ListDisks()
+		if err != nil {
+			return nil, iodine.New(err, nil)
+		}
+		readers = make([]io.ReadCloser, len(disks))
+		for order, disk := range disks {
+			bucketMetaDataReader, err := disk.OpenFile(filepath.Join(b.donutName, bucketMetadataConfig))
+			if err != nil {
+				return nil, iodine.New(err, nil)
+			}
+			readers[order] = bucketMetaDataReader
+		}
+	}
+	return readers, nil
+}
+
+func (b bucket) getBucketMetadata() (*AllBuckets, error) {
+	metadata := new(AllBuckets)
+	readers, err := b.getBucketMetadataReaders()
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	for _, reader := range readers {
+		defer reader.Close()
+	}
+	for _, reader := range readers {
+		jenc := json.NewDecoder(reader)
+		if err := jenc.Decode(metadata); err != nil {
+			return nil, iodine.New(err, nil)
+		}
+		return metadata, nil
+	}
+	return nil, iodine.New(InvalidArgument{}, nil)
 }
 
 // ListObjects - list all objects
 func (b bucket) ListObjects(prefix, marker, delimiter string, maxkeys int) ([]string, []string, bool, error) {
 	b.lock.RLock()
 	defer b.lock.RUnlock()
-
 	if maxkeys <= 0 {
 		maxkeys = 1000
 	}
 	var isTruncated bool
-	nodeSlice := 0
 	var objects []string
-	for _, node := range b.nodes {
+	bucketMetadata, err := b.getBucketMetadata()
-		disks, err := node.ListDisks()
+	if err != nil {
-		if err != nil {
+		return nil, nil, false, iodine.New(err, nil)
-			return nil, nil, false, iodine.New(err, nil)
+	}
-		}
+	for objectName := range bucketMetadata.Buckets[b.getBucketName()].BucketObjectsMetadata {
-		for order, disk := range disks {
+		if strings.HasPrefix(objectName, strings.TrimSpace(prefix)) {
-			bucketSlice := fmt.Sprintf("%s$%d$%d", b.name, nodeSlice, order)
+			if objectName > marker {
-			bucketPath := filepath.Join(b.donutName, bucketSlice)
+				objects = appendUniq(objects, objectName)
-			files, err := disk.ListDir(bucketPath)
-			if err != nil {
-				return nil, nil, false, iodine.New(err, nil)
-			}
-			for _, file := range files {
-				objectName, err := b.getObjectName(file.Name(), disk.GetPath(), bucketPath)
-				if err != nil {
-					return nil, nil, false, iodine.New(err, nil)
-				}
-				if strings.HasPrefix(objectName, strings.TrimSpace(prefix)) {
-					if objectName > marker {
-						objects = appendUniq(objects, objectName)
-					}
-				}
 			}
 		}
-		nodeSlice = nodeSlice + 1
 	}
-	{
+	if strings.TrimSpace(prefix) != "" {
-		if strings.TrimSpace(prefix) != "" {
+		objects = removePrefix(objects, prefix)
-			objects = removePrefix(objects, prefix)
+	}
-		}
+	var prefixes []string
-		var prefixes []string
+	var filteredObjects []string
-		var filteredObjects []string
+	if strings.TrimSpace(delimiter) != "" {
-		if strings.TrimSpace(delimiter) != "" {
+		filteredObjects = filterDelimited(objects, delimiter)
-			filteredObjects = filterDelimited(objects, delimiter)
+		prefixes = filterNotDelimited(objects, delimiter)
-			prefixes = filterNotDelimited(objects, delimiter)
+		prefixes = extractDelimited(prefixes, delimiter)
-			prefixes = extractDelimited(prefixes, delimiter)
+		prefixes = uniqueObjects(prefixes)
-			prefixes = uniqueObjects(prefixes)
+	} else {
-		} else {
+		filteredObjects = objects
-			filteredObjects = objects
+	}
-		}
+	var results []string
-		var results []string
+	var commonPrefixes []string
-		var commonPrefixes []string
 
-		sort.Strings(filteredObjects)
+	sort.Strings(filteredObjects)
-		for _, objectName := range filteredObjects {
+	for _, objectName := range filteredObjects {
-			if len(results) >= maxkeys {
+		if len(results) >= maxkeys {
-				isTruncated = true
+			isTruncated = true
-				break
+			break
-			}
-			results = appendUniq(results, prefix+objectName)
-		}
-		for _, commonPrefix := range prefixes {
-			commonPrefixes = appendUniq(commonPrefixes, prefix+commonPrefix)
 		}
-		sort.Strings(results)
+		results = appendUniq(results, prefix+objectName)
-		sort.Strings(commonPrefixes)
-		return results, commonPrefixes, isTruncated, nil
 	}
+	for _, commonPrefix := range prefixes {
+		commonPrefixes = appendUniq(commonPrefixes, prefix+commonPrefix)
+	}
+	sort.Strings(results)
+	sort.Strings(commonPrefixes)
+	return results, commonPrefixes, isTruncated, nil
 }
 
 // ReadObject - open an object to read
@@ -178,58 +198,58 @@ func (b bucket) ReadObject(objectName string) (reader io.ReadCloser, size int64,
 	defer b.lock.RUnlock()
 	reader, writer := io.Pipe()
 	// get list of objects
-	_, _, _, err = b.ListObjects(objectName, "", "", 1)
+	bucketMetadata, err := b.getBucketMetadata()
 	if err != nil {
 		return nil, 0, iodine.New(err, nil)
 	}
 	// check if object exists
-	object, ok := b.objects[objectName]
+	if _, ok := bucketMetadata.Buckets[b.getBucketName()].BucketObjectsMetadata[objectName]; !ok {
-	if !ok {
 		return nil, 0, iodine.New(ObjectNotFound{Object: objectName}, nil)
 	}
-	// verify if sysObjectMetadata is readable, before we server the request
+	objMetadata := ObjectMetadata{}
-	sysObjMetadata, err := object.GetSystemObjectMetadata()
+	metadataReaders, err := b.getDiskReaders(normalizeObjectName(objectName), objectMetadataConfig)
 	if err != nil {
 		return nil, 0, iodine.New(err, nil)
 	}
+	for _, metadataReader := range metadataReaders {
+		defer metadataReader.Close()
+	}
+	for _, metadataReader := range metadataReaders {
+		jdec := json.NewDecoder(metadataReader)
+		if err := jdec.Decode(&objMetadata); err != nil {
+			return nil, 0, iodine.New(err, nil)
+		}
+		break
+	}
 	// read and reply back to GetObject() request in a go-routine
-	go b.readEncodedData(b.normalizeObjectName(objectName), writer, sysObjMetadata)
+	go b.readEncodedData(normalizeObjectName(objectName), writer, objMetadata)
-	return reader, sysObjMetadata.Size, nil
+	return reader, objMetadata.Size, nil
 }
 
 // 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) (string, error) {
 	b.lock.Lock()
 	defer b.lock.Unlock()
 	if objectName == "" || objectData == nil {
 		return "", iodine.New(InvalidArgument{}, nil)
 	}
-	writers, err := b.getDiskWriters(b.normalizeObjectName(objectName), "data")
+	writers, err := b.getDiskWriters(normalizeObjectName(objectName), "data")
 	if err != nil {
 		return "", iodine.New(err, nil)
 	}
 	sumMD5 := md5.New()
 	sum512 := sha512.New()
-
 	objMetadata := new(ObjectMetadata)
-	sysObjMetadata := new(SystemObjectMetadata)
 	objMetadata.Version = objectMetadataVersion
-	sysObjMetadata.Version = systemObjectMetadataVersion
+	objMetadata.Created = time.Now().UTC()
-	size := metadata["contentLength"]
-	sizeInt, err := strconv.ParseInt(size, 10, 64)
-	if err != nil {
-		return "", iodine.New(err, nil)
-	}
-
 	// if total writers are only '1' do not compute erasure
 	switch len(writers) == 1 {
 	case true:
 		mw := io.MultiWriter(writers[0], sumMD5, sum512)
-		totalLength, err := io.CopyN(mw, objectData, sizeInt)
+		totalLength, err := io.Copy(mw, objectData)
 		if err != nil {
 			return "", iodine.New(err, nil)
 		}
-		sysObjMetadata.Size = totalLength
 		objMetadata.Size = totalLength
 	case false:
 		// calculate data and parity dictated by total number of writers
@@ -243,30 +263,20 @@ func (b bucket) WriteObject(objectName string, objectData io.Reader, expectedMD5
 			return "", iodine.New(err, nil)
 		}
 		/// donutMetadata section
-		sysObjMetadata.BlockSize = 10 * 1024 * 1024
+		objMetadata.BlockSize = 10 * 1024 * 1024
-		sysObjMetadata.ChunkCount = chunkCount
+		objMetadata.ChunkCount = chunkCount
-		sysObjMetadata.DataDisks = k
+		objMetadata.DataDisks = k
-		sysObjMetadata.ParityDisks = m
+		objMetadata.ParityDisks = m
-		sysObjMetadata.ErasureTechnique = "Cauchy"
+		objMetadata.ErasureTechnique = "Cauchy"
-		sysObjMetadata.Size = int64(totalLength)
-		// keep size inside ObjectMetadata as well for Object API requests
 		objMetadata.Size = int64(totalLength)
 	}
 	objMetadata.Bucket = b.getBucketName()
 	objMetadata.Object = objectName
-	objMetadata.Metadata = metadata
 	dataMD5sum := sumMD5.Sum(nil)
 	dataSHA512sum := sum512.Sum(nil)
-	objMetadata.Created = time.Now().UTC()
 
-	// keeping md5sum for the object in two different places
+	objMetadata.MD5Sum = hex.EncodeToString(dataMD5sum)
-	// one for object storage and another is for internal use
+	objMetadata.SHA512Sum = hex.EncodeToString(dataSHA512sum)
-	hexMD5Sum := hex.EncodeToString(dataMD5sum)
-	hex512Sum := hex.EncodeToString(dataSHA512sum)
-	objMetadata.MD5Sum = hexMD5Sum
-	objMetadata.SHA512Sum = hex512Sum
-	sysObjMetadata.MD5Sum = hexMD5Sum
-	sysObjMetadata.SHA512Sum = hex512Sum
 
 	// Verify if the written object is equal to what is expected, only if it is requested as such
 	if strings.TrimSpace(expectedMD5Sum) != "" {
@@ -274,12 +284,8 @@ func (b bucket) WriteObject(objectName string, objectData io.Reader, expectedMD5
 			return "", iodine.New(err, nil)
 		}
 	}
-	// write donut specific metadata
-	if err := b.writeSystemObjectMetadata(b.normalizeObjectName(objectName), sysObjMetadata); err != nil {
-		return "", iodine.New(err, nil)
-	}
 	// write object specific metadata
-	if err := b.writeObjectMetadata(b.normalizeObjectName(objectName), objMetadata); err != nil {
+	if err := b.writeObjectMetadata(normalizeObjectName(objectName), objMetadata); err != nil {
 		return "", iodine.New(err, nil)
 	}
 	// close all writers, when control flow reaches here
@@ -329,27 +335,6 @@ func (b bucket) writeObjectMetadata(objectName string, objMetadata *ObjectMetada
 	return nil
 }
 
-// writeSystemObjectMetadata - write donut related object metadata
-func (b bucket) writeSystemObjectMetadata(objectName string, sysObjMetadata *SystemObjectMetadata) error {
-	if sysObjMetadata == nil {
-		return iodine.New(InvalidArgument{}, nil)
-	}
-	sysObjMetadataWriters, err := b.getDiskWriters(objectName, sysObjectMetadataConfig)
-	if err != nil {
-		return iodine.New(err, nil)
-	}
-	for _, sysObjMetadataWriter := range sysObjMetadataWriters {
-		defer sysObjMetadataWriter.Close()
-	}
-	for _, sysObjMetadataWriter := range sysObjMetadataWriters {
-		jenc := json.NewEncoder(sysObjMetadataWriter)
-		if err := jenc.Encode(sysObjMetadata); err != nil {
-			return iodine.New(err, nil)
-		}
-	}
-	return nil
-}
-
 // TODO - This a temporary normalization of objectNames, need to find a better way
 //
 // normalizedObjectName - all objectNames with "/" get normalized to a simple objectName
@@ -358,7 +343,7 @@ func (b bucket) writeSystemObjectMetadata(objectName string, sysObjMetadata *Sys
 // user provided value - "this/is/my/deep/directory/structure"
 // donut normalized value - "this-is-my-deep-directory-structure"
 //
-func (b bucket) normalizeObjectName(objectName string) string {
+func normalizeObjectName(objectName string) string {
 	// replace every '/' with '-'
 	return strings.Replace(objectName, "/", "-", -1)
 }
@@ -407,12 +392,7 @@ func (b bucket) writeEncodedData(k, m uint8, writers []io.WriteCloser, objectDat
 }
 
 // readEncodedData -
-func (b bucket) readEncodedData(objectName string, writer *io.PipeWriter, sysObjMetadata SystemObjectMetadata) {
+func (b bucket) readEncodedData(objectName string, writer *io.PipeWriter, objMetadata ObjectMetadata) {
-	expectedMd5sum, err := hex.DecodeString(sysObjMetadata.MD5Sum)
-	if err != nil {
-		writer.CloseWithError(iodine.New(err, nil))
-		return
-	}
 	readers, err := b.getDiskReaders(objectName, "data")
 	if err != nil {
 		writer.CloseWithError(iodine.New(err, nil))
@@ -421,22 +401,27 @@ func (b bucket) readEncodedData(objectName string, writer *io.PipeWriter, sysObj
 	for _, reader := range readers {
 		defer reader.Close()
 	}
+	expectedMd5sum, err := hex.DecodeString(objMetadata.MD5Sum)
+	if err != nil {
+		writer.CloseWithError(iodine.New(err, nil))
+		return
+	}
 	hasher := md5.New()
 	mwriter := io.MultiWriter(writer, hasher)
 	switch len(readers) == 1 {
 	case false:
-		if sysObjMetadata.ErasureTechnique == "" {
+		if objMetadata.ErasureTechnique == "" {
 			writer.CloseWithError(iodine.New(MissingErasureTechnique{}, nil))
 			return
 		}
-		encoder, err := newEncoder(sysObjMetadata.DataDisks, sysObjMetadata.ParityDisks, sysObjMetadata.ErasureTechnique)
+		encoder, err := newEncoder(objMetadata.DataDisks, objMetadata.ParityDisks, objMetadata.ErasureTechnique)
 		if err != nil {
 			writer.CloseWithError(iodine.New(err, nil))
 			return
 		}
-		totalLeft := sysObjMetadata.Size
+		totalLeft := objMetadata.Size
-		for i := 0; i < sysObjMetadata.ChunkCount; i++ {
+		for i := 0; i < objMetadata.ChunkCount; i++ {
-			decodedData, err := b.decodeEncodedData(totalLeft, int64(sysObjMetadata.BlockSize), readers, encoder, writer)
+			decodedData, err := b.decodeEncodedData(totalLeft, int64(objMetadata.BlockSize), readers, encoder, writer)
 			if err != nil {
 				writer.CloseWithError(iodine.New(err, nil))
 				return
@@ -446,7 +431,7 @@ func (b bucket) readEncodedData(objectName string, writer *io.PipeWriter, sysObj
 				writer.CloseWithError(iodine.New(err, nil))
 				return
 			}
-			totalLeft = totalLeft - int64(sysObjMetadata.BlockSize)
+			totalLeft = totalLeft - int64(objMetadata.BlockSize)
 		}
 	case true:
 		_, err := io.Copy(writer, readers[0])

pkg/storage/donut/definitions.go

@@ -18,39 +18,23 @@ package donut
 
 import "time"
 
-// ObjectMetadata object specific metadata per object
+// ObjectMetadata container for object on donut system
 type ObjectMetadata struct {
 	// version
 	Version string `json:"version"`
 
 	// object metadata
-	Size    int64     `json:"size"`
 	Created time.Time `json:"created"`
 	Bucket  string    `json:"bucket"`
 	Object  string    `json:"object"`
-
+	Size    int64     `json:"size"`
-	// checksums
-	MD5Sum    string `json:"md5sum"`
-	SHA512Sum string `json:"sha512sum"`
-
-	// additional metadata
-	Metadata map[string]string `json:"metadata"`
-}
-
-// SystemObjectMetadata container for donut system specific metadata per object
-type SystemObjectMetadata struct {
-	// version
-	Version string `json:"version"`
 
 	// erasure
 	DataDisks        uint8  `json:"sys.erasureK"`
 	ParityDisks      uint8  `json:"sys.erasureM"`
 	ErasureTechnique string `json:"sys.erasureTechnique"`
-
+	BlockSize        int    `json:"sys.blockSize"`
-	// object metadata
+	ChunkCount       int    `json:"sys.chunkCount"`
-	Size       int64 `json:"sys.size"`
-	BlockSize  int   `json:"sys.blockSize"`
-	ChunkCount int   `json:"sys.chunkCount"`
 
 	// checksums
 	MD5Sum    string `json:"sys.md5sum"`
@@ -64,14 +48,16 @@ type Metadata struct {
 
 // AllBuckets container for all buckets
 type AllBuckets struct {
-	Buckets map[string]BucketMetadata
+	Version string                    `json:"version"`
+	Buckets map[string]BucketMetadata `json:"buckets"`
 }
 
 // BucketMetadata container for bucket level metadata
 type BucketMetadata struct {
-	Version  string            `json:"version"`
+	Version               string                       `json:"version"`
-	Name     string            `json:"name"`
+	Name                  string                       `json:"name"`
-	ACL      string            `json:"acl"`
+	ACL                   string                       `json:"acl"`
-	Created  time.Time         `json:"created"`
+	Created               time.Time                    `json:"created"`
-	Metadata map[string]string `json:"metadata"`
+	Metadata              map[string]string            `json:"metadata"`
+	BucketObjectsMetadata map[string]map[string]string `json:"objectsMetadata"`
 }

pkg/storage/donut/donut.go

@@ -39,8 +39,6 @@ type donut struct {
 
 // config files used inside Donut
 const (
-	// donut system object metadata
-	sysObjectMetadataConfig = "sysObjectMetadata.json"
 	// donut system config
 	donutConfig = "donutConfig.json"
 
@@ -49,8 +47,8 @@ const (
 	objectMetadataConfig = "objectMetadata.json"
 
 	// versions
-	objectMetadataVersion       = "1.0.0"
+	objectMetadataVersion = "1.0.0"
-	systemObjectMetadataVersion = "1.0.0"
+	bucketMetadataVersion = "1.0.0"
 )
 
 // attachDonutNode - wrapper function to instantiate a new node for associatedt donut
@@ -196,19 +194,21 @@ func (dt donut) PutObject(bucket, object, expectedMD5Sum string, reader io.ReadC
 	if _, ok := dt.buckets[bucket]; !ok {
 		return "", iodine.New(BucketNotFound{Bucket: bucket}, nil)
 	}
-	objectList, _, _, err := dt.buckets[bucket].ListObjects("", "", "", 1000)
+	bucketMeta, err := dt.getDonutBucketMetadata()
 	if err != nil {
-		return "", iodine.New(err, nil)
+		return "", iodine.New(err, errParams)
 	}
-	for _, objectName := range objectList {
+	if _, ok := bucketMeta.Buckets[bucket].BucketObjectsMetadata[object]; ok {
-		if objectName == object {
+		return "", iodine.New(ObjectExists{Object: object}, errParams)
-			return "", iodine.New(ObjectExists{Object: object}, nil)
-		}
 	}
-	md5sum, err := dt.buckets[bucket].WriteObject(object, reader, expectedMD5Sum, metadata)
+	md5sum, err := dt.buckets[bucket].WriteObject(object, reader, expectedMD5Sum)
 	if err != nil {
 		return "", iodine.New(err, errParams)
 	}
+	bucketMeta.Buckets[bucket].BucketObjectsMetadata[object] = metadata
+	if err := dt.setDonutBucketMetadata(bucketMeta); err != nil {
+		return "", iodine.New(err, errParams)
+	}
 	return md5sum, nil
 }
 
@@ -236,7 +236,7 @@ func (dt donut) GetObject(bucket, object string) (reader io.ReadCloser, size int
 }
 
 // GetObjectMetadata - get object metadata
-func (dt donut) GetObjectMetadata(bucket, object string) (ObjectMetadata, error) {
+func (dt donut) GetObjectMetadata(bucket, object string) (ObjectMetadata, map[string]string, error) {
 	dt.lock.RLock()
 	defer dt.lock.RUnlock()
 	errParams := map[string]string{
@@ -244,26 +244,23 @@ func (dt donut) GetObjectMetadata(bucket, object string) (ObjectMetadata, error)
 		"object": object,
 	}
 	if err := dt.listDonutBuckets(); err != nil {
-		return ObjectMetadata{}, iodine.New(err, errParams)
+		return ObjectMetadata{}, nil, iodine.New(err, errParams)
 	}
 	if _, ok := dt.buckets[bucket]; !ok {
-		return ObjectMetadata{}, iodine.New(BucketNotFound{Bucket: bucket}, errParams)
+		return ObjectMetadata{}, nil, iodine.New(BucketNotFound{Bucket: bucket}, errParams)
-	}
+	}
-	//
+	bucketMeta, err := dt.getDonutBucketMetadata()
-	// there is a potential issue here, if the object comes after the truncated list
-	// below GetObjectMetadata would fail as ObjectNotFound{}
-	//
-	// will fix it when we bring in persistent json into Donut - TODO
-	objectList, _, _, err := dt.buckets[bucket].ListObjects("", "", "", 1000)
 	if err != nil {
-		return ObjectMetadata{}, iodine.New(err, errParams)
+		return ObjectMetadata{}, nil, iodine.New(err, errParams)
 	}
-	for _, objectName := range objectList {
+	if _, ok := bucketMeta.Buckets[bucket].BucketObjectsMetadata[object]; !ok {
-		if objectName == object {
+		return ObjectMetadata{}, nil, iodine.New(ObjectNotFound{Object: object}, errParams)
-			return dt.buckets[bucket].GetObjectMetadata(object)
+	}
-		}
+	objectMetadata, err := dt.buckets[bucket].GetObjectMetadata(object)
+	if err != nil {
+		return ObjectMetadata{}, nil, iodine.New(err, nil)
 	}
-	return ObjectMetadata{}, iodine.New(ObjectNotFound{Object: object}, errParams)
+	return objectMetadata, bucketMeta.Buckets[bucket].BucketObjectsMetadata[object], nil
 }
 
 // getDiskWriters -
@@ -337,8 +334,9 @@ func (dt donut) getDonutBucketMetadata() (*AllBuckets, error) {
 		if err := jenc.Decode(metadata); err != nil {
 			return nil, iodine.New(err, nil)
 		}
+		return metadata, nil
 	}
-	return metadata, nil
+	return nil, iodine.New(InvalidArgument{}, nil)
 }
 
 func (dt donut) makeDonutBucket(bucketName, acl string) error {

pkg/storage/donut/donut_test.go

@@ -198,12 +198,12 @@ func (s *MySuite) TestNewObjectMetadata(c *C) {
 	c.Assert(err, IsNil)
 	c.Assert(calculatedMd5Sum, Equals, expectedMd5Sum)
 
-	objectMetadata, err := donut.GetObjectMetadata("foo", "obj")
+	_, additionalMetadata, err := donut.GetObjectMetadata("foo", "obj")
 	c.Assert(err, IsNil)
 
-	c.Assert(objectMetadata.Metadata["contentType"], Equals, metadata["contentType"])
+	c.Assert(additionalMetadata["contentType"], Equals, metadata["contentType"])
-	c.Assert(objectMetadata.Metadata["foo"], Equals, metadata["foo"])
+	c.Assert(additionalMetadata["foo"], Equals, metadata["foo"])
-	c.Assert(objectMetadata.Metadata["hello"], Equals, metadata["hello"])
+	c.Assert(additionalMetadata["hello"], Equals, metadata["hello"])
 }
 
 // test create object fails without name
@@ -252,7 +252,7 @@ func (s *MySuite) TestNewObjectCanBeWritten(c *C) {
 	c.Assert(err, IsNil)
 	c.Assert(actualData.Bytes(), DeepEquals, []byte(data))
 
-	actualMetadata, err := donut.GetObjectMetadata("foo", "obj")
+	actualMetadata, _, err := donut.GetObjectMetadata("foo", "obj")
 	c.Assert(err, IsNil)
 	c.Assert(expectedMd5Sum, Equals, actualMetadata.MD5Sum)
 	c.Assert(int64(len(data)), Equals, actualMetadata.Size)

pkg/storage/donut/interfaces.go

@@ -39,7 +39,7 @@ type ObjectStorage interface {
 
 	// Object operations
 	GetObject(bucket, object string) (io.ReadCloser, int64, error)
-	GetObjectMetadata(bucket, object string) (ObjectMetadata, error)
+	GetObjectMetadata(bucket, object string) (ObjectMetadata, map[string]string, error)
 	PutObject(bucket, object, expectedMD5Sum string, reader io.ReadCloser, metadata map[string]string) (string, error)
 }
 

pkg/storage/donut/object.go

@@ -1,66 +0,0 @@
-/*
- * Minimalist Object Storage, (C) 2015 Minio, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package donut
-
-import (
-	"encoding/json"
-	"io/ioutil"
-	"path/filepath"
-
-	"github.com/minio/minio/pkg/iodine"
-)
-
-// object internal struct
-type object struct {
-	name       string
-	objectPath string
-}
-
-// newObject - instantiate a new object
-func newObject(objectName, p string) (object, error) {
-	if objectName == "" {
-		return object{}, iodine.New(InvalidArgument{}, nil)
-	}
-	o := object{}
-	o.name = objectName
-	o.objectPath = filepath.Join(p, objectName)
-	return o, nil
-}
-
-func (o object) GetObjectMetadata() (ObjectMetadata, error) {
-	objMetadata := ObjectMetadata{}
-	objMetadataBytes, err := ioutil.ReadFile(filepath.Join(o.objectPath, objectMetadataConfig))
-	if err != nil {
-		return ObjectMetadata{}, iodine.New(ObjectNotFound{Object: o.name}, nil)
-	}
-	if err := json.Unmarshal(objMetadataBytes, &objMetadata); err != nil {
-		return ObjectMetadata{}, iodine.New(err, nil)
-	}
-	return objMetadata, nil
-}
-
-func (o object) GetSystemObjectMetadata() (SystemObjectMetadata, error) {
-	sysObjMetadata := SystemObjectMetadata{}
-	sysObjMetadataBytes, err := ioutil.ReadFile(filepath.Join(o.objectPath, sysObjectMetadataConfig))
-	if err != nil {
-		return SystemObjectMetadata{}, iodine.New(ObjectNotFound{Object: o.name}, nil)
-	}
-	if err := json.Unmarshal(sysObjMetadataBytes, &sysObjMetadata); err != nil {
-		return SystemObjectMetadata{}, iodine.New(err, nil)
-	}
-	return sysObjMetadata, nil
-}

pkg/storage/drivers/donut/donut.go

@@ -312,7 +312,7 @@ func (d donutDriver) GetObjectMetadata(bucketName, objectName string) (drivers.O
 	if !drivers.IsValidObjectName(objectName) || strings.TrimSpace(objectName) == "" {
 		return drivers.ObjectMetadata{}, iodine.New(drivers.ObjectNameInvalid{Object: objectName}, errParams)
 	}
-	metadata, err := d.donut.GetObjectMetadata(bucketName, objectName)
+	metadata, additionalMetadata, err := d.donut.GetObjectMetadata(bucketName, objectName)
 	if err != nil {
 		return drivers.ObjectMetadata{}, iodine.New(drivers.ObjectNotFound{
 			Bucket: bucketName,
@@ -323,7 +323,7 @@ func (d donutDriver) GetObjectMetadata(bucketName, objectName string) (drivers.O
 		Bucket: bucketName,
 		Key:    objectName,
 
-		ContentType: metadata.Metadata["contentType"],
+		ContentType: additionalMetadata["contentType"],
 		Created:     metadata.Created,
 		Md5:         metadata.MD5Sum,
 		Size:        metadata.Size,
@@ -365,7 +365,7 @@ func (d donutDriver) ListObjects(bucketName string, resources drivers.BucketReso
 	}
 	var results []drivers.ObjectMetadata
 	for _, objectName := range actualObjects {
-		objectMetadata, err := d.donut.GetObjectMetadata(bucketName, objectName)
+		objectMetadata, _, err := d.donut.GetObjectMetadata(bucketName, objectName)
 		if err != nil {
 			return nil, drivers.BucketResourcesMetadata{}, iodine.New(err, errParams)
 		}