Add full API tests, move storage/donut to donut, add disk tests as well

pkg/donut/.gitignore

@@ -0,0 +1,2 @@
+donut
+build-constants.go

pkg/donut/LICENSE

@@ -0,0 +1,202 @@
+
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+                        http://www.apache.org/licenses/
+
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+      Contributor provides its Contributions) on an "AS IS" BASIS,
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pkg/donut/README.md

@@ -0,0 +1,3 @@
+# Donut
+
+donut - Donut (do not delete) on disk format implementation released under [Apache license v2](./LICENSE).

pkg/donut/bucket.go

@@ -0,0 +1,544 @@
+/*
+ * 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 (
+	"bytes"
+	"fmt"
+	"hash"
+	"io"
+	"path/filepath"
+	"sort"
+	"strings"
+	"sync"
+	"time"
+
+	"crypto/md5"
+	"encoding/hex"
+	"encoding/json"
+
+	"github.com/minio/minio/pkg/iodine"
+	"github.com/minio/minio/pkg/utils/crypto/sha512"
+	"github.com/minio/minio/pkg/utils/split"
+)
+
+const (
+	blockSize = 10 * 1024 * 1024
+)
+
+// internal struct carrying bucket specific information
+type bucket struct {
+	name      string
+	acl       string
+	time      time.Time
+	donutName string
+	nodes     map[string]node
+	lock      *sync.RWMutex
+}
+
+// newBucket - instantiate a new bucket
+func newBucket(bucketName, aclType, donutName string, nodes map[string]node) (bucket, BucketMetadata, error) {
+	errParams := map[string]string{
+		"bucketName": bucketName,
+		"donutName":  donutName,
+		"aclType":    aclType,
+	}
+
+	if strings.TrimSpace(bucketName) == "" || strings.TrimSpace(donutName) == "" {
+		return bucket{}, BucketMetadata{}, iodine.New(InvalidArgument{}, errParams)
+	}
+
+	b := bucket{}
+	t := time.Now().UTC()
+	b.name = bucketName
+	b.acl = aclType
+	b.time = t
+	b.donutName = donutName
+	b.nodes = nodes
+	b.lock = new(sync.RWMutex)
+
+	metadata := BucketMetadata{}
+	metadata.Version = bucketMetadataVersion
+	metadata.Name = bucketName
+	metadata.ACL = BucketACL(aclType)
+	metadata.Created = t
+	metadata.Metadata = make(map[string]string)
+	metadata.BucketObjects = make(map[string]interface{})
+
+	return b, metadata, nil
+}
+
+func (b bucket) getBucketName() string {
+	return b.name
+}
+func (b bucket) getBucketMetadataReaders() ([]io.ReadCloser, error) {
+	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)
+}
+
+// GetObjectMetadata - get metadata for an object
+func (b bucket) GetObjectMetadata(objectName string) (ObjectMetadata, error) {
+	b.lock.RLock()
+	defer b.lock.RUnlock()
+	return b.readObjectMetadata(objectName)
+}
+
+// ListObjects - list all objects
+func (b bucket) ListObjects(prefix, marker, delimiter string, maxkeys int) (ListObjectsResults, error) {
+	b.lock.RLock()
+	defer b.lock.RUnlock()
+	if maxkeys <= 0 {
+		maxkeys = 1000
+	}
+	var isTruncated bool
+	var objects []string
+	bucketMetadata, err := b.getBucketMetadata()
+	if err != nil {
+		return ListObjectsResults{}, iodine.New(err, nil)
+	}
+	for objectName := range bucketMetadata.Buckets[b.getBucketName()].BucketObjects {
+		if strings.HasPrefix(objectName, strings.TrimSpace(prefix)) {
+			if objectName > marker {
+				objects = append(objects, objectName)
+			}
+		}
+	}
+	if strings.TrimSpace(prefix) != "" {
+		objects = TrimPrefix(objects, prefix)
+	}
+	var prefixes []string
+	var filteredObjects []string
+	if strings.TrimSpace(delimiter) != "" {
+		filteredObjects = HasNoDelimiter(objects, delimiter)
+		prefixes = HasDelimiter(objects, delimiter)
+		prefixes = SplitDelimiter(prefixes, delimiter)
+		prefixes = SortU(prefixes)
+	} else {
+		filteredObjects = objects
+	}
+	var results []string
+	var commonPrefixes []string
+
+	for _, commonPrefix := range prefixes {
+		commonPrefixes = append(commonPrefixes, prefix+commonPrefix)
+	}
+	filteredObjects = RemoveDuplicates(filteredObjects)
+	sort.Strings(filteredObjects)
+	for _, objectName := range filteredObjects {
+		if len(results) >= maxkeys {
+			isTruncated = true
+			break
+		}
+		results = append(results, prefix+objectName)
+	}
+	results = RemoveDuplicates(results)
+	commonPrefixes = RemoveDuplicates(commonPrefixes)
+	sort.Strings(commonPrefixes)
+
+	listObjects := ListObjectsResults{}
+	listObjects.Objects = make(map[string]ObjectMetadata)
+	listObjects.CommonPrefixes = commonPrefixes
+	listObjects.IsTruncated = isTruncated
+
+	for _, objectName := range results {
+		objMetadata, err := b.readObjectMetadata(normalizeObjectName(objectName))
+		if err != nil {
+			return ListObjectsResults{}, iodine.New(err, nil)
+		}
+		listObjects.Objects[objectName] = objMetadata
+	}
+	return listObjects, nil
+}
+
+// ReadObject - open an object to read
+func (b bucket) ReadObject(objectName string) (reader io.ReadCloser, size int64, err error) {
+	b.lock.RLock()
+	defer b.lock.RUnlock()
+	reader, writer := io.Pipe()
+	// get list of objects
+	bucketMetadata, err := b.getBucketMetadata()
+	if err != nil {
+		return nil, 0, iodine.New(err, nil)
+	}
+	// check if object exists
+	if _, ok := bucketMetadata.Buckets[b.getBucketName()].BucketObjects[objectName]; !ok {
+		return nil, 0, iodine.New(ObjectNotFound{Object: objectName}, nil)
+	}
+	objMetadata, err := b.readObjectMetadata(normalizeObjectName(objectName))
+	if err != nil {
+		return nil, 0, iodine.New(err, nil)
+	}
+	// read and reply back to GetObject() request in a go-routine
+	go b.readObjectData(normalizeObjectName(objectName), writer, objMetadata)
+	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) (ObjectMetadata, error) {
+	b.lock.Lock()
+	defer b.lock.Unlock()
+	if objectName == "" || objectData == nil {
+		return ObjectMetadata{}, iodine.New(InvalidArgument{}, nil)
+	}
+	writers, err := b.getWriters(normalizeObjectName(objectName), "data")
+	if err != nil {
+		return ObjectMetadata{}, iodine.New(err, nil)
+	}
+	sumMD5 := md5.New()
+	sum512 := sha512.New()
+	objMetadata := ObjectMetadata{}
+	objMetadata.Version = objectMetadataVersion
+	objMetadata.Created = time.Now().UTC()
+	// 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.Copy(mw, objectData)
+		if 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 ObjectMetadata{}, iodine.New(err, nil)
+		}
+		// write encoded data with k, m and writers
+		chunkCount, totalLength, err := b.writeObjectData(k, m, writers, objectData, sumMD5, sum512)
+		if err != nil {
+			return ObjectMetadata{}, iodine.New(err, nil)
+		}
+		/// donutMetadata section
+		objMetadata.BlockSize = blockSize
+		objMetadata.ChunkCount = chunkCount
+		objMetadata.DataDisks = k
+		objMetadata.ParityDisks = m
+		objMetadata.ErasureTechnique = "Cauchy"
+		objMetadata.Size = int64(totalLength)
+	}
+	objMetadata.Bucket = b.getBucketName()
+	objMetadata.Object = objectName
+	dataMD5sum := sumMD5.Sum(nil)
+	dataSHA512sum := sum512.Sum(nil)
+
+	objMetadata.MD5Sum = hex.EncodeToString(dataMD5sum)
+	objMetadata.SHA512Sum = hex.EncodeToString(dataSHA512sum)
+
+	// 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 ObjectMetadata{}, iodine.New(err, nil)
+		}
+	}
+	objMetadata.Metadata = metadata
+	// write object specific metadata
+	if err := b.writeObjectMetadata(normalizeObjectName(objectName), objMetadata); err != nil {
+		return ObjectMetadata{}, iodine.New(err, nil)
+	}
+	// close all writers, when control flow reaches here
+	for _, writer := range writers {
+		writer.Close()
+	}
+	return objMetadata, nil
+}
+
+// isMD5SumEqual - returns error if md5sum mismatches, other its `nil`
+func (b bucket) isMD5SumEqual(expectedMD5Sum, actualMD5Sum string) error {
+	if strings.TrimSpace(expectedMD5Sum) != "" && strings.TrimSpace(actualMD5Sum) != "" {
+		expectedMD5SumBytes, err := hex.DecodeString(expectedMD5Sum)
+		if err != nil {
+			return iodine.New(err, nil)
+		}
+		actualMD5SumBytes, err := hex.DecodeString(actualMD5Sum)
+		if err != nil {
+			return iodine.New(err, nil)
+		}
+		if !bytes.Equal(expectedMD5SumBytes, actualMD5SumBytes) {
+			return iodine.New(BadDigest{}, nil)
+		}
+		return nil
+	}
+	return iodine.New(InvalidArgument{}, nil)
+}
+
+// writeObjectMetadata - write additional object metadata
+func (b bucket) writeObjectMetadata(objectName string, objMetadata ObjectMetadata) error {
+	if objMetadata.Object == "" {
+		return iodine.New(InvalidArgument{}, nil)
+	}
+	objMetadataWriters, err := b.getWriters(objectName, objectMetadataConfig)
+	if err != nil {
+		return iodine.New(err, nil)
+	}
+	for _, objMetadataWriter := range objMetadataWriters {
+		defer objMetadataWriter.Close()
+	}
+	for _, objMetadataWriter := range objMetadataWriters {
+		jenc := json.NewEncoder(objMetadataWriter)
+		if err := jenc.Encode(&objMetadata); err != nil {
+			return iodine.New(err, nil)
+		}
+	}
+	return nil
+}
+
+// readObjectMetadata - read object metadata
+func (b bucket) readObjectMetadata(objectName string) (ObjectMetadata, error) {
+	objMetadata := ObjectMetadata{}
+	if objectName == "" {
+		return ObjectMetadata{}, iodine.New(InvalidArgument{}, nil)
+	}
+	objMetadataReaders, err := b.getReaders(objectName, objectMetadataConfig)
+	if err != nil {
+		return ObjectMetadata{}, iodine.New(err, nil)
+	}
+	for _, objMetadataReader := range objMetadataReaders {
+		defer objMetadataReader.Close()
+	}
+	for _, objMetadataReader := range objMetadataReaders {
+		jdec := json.NewDecoder(objMetadataReader)
+		if err := jdec.Decode(&objMetadata); err != nil {
+			return ObjectMetadata{}, iodine.New(err, nil)
+		}
+		break
+	}
+	return objMetadata, nil
+}
+
+// TODO - This a temporary normalization of objectNames, need to find a better way
+//
+// normalizedObjectName - all objectNames with "/" get normalized to a simple objectName
+//
+// example:
+// user provided value - "this/is/my/deep/directory/structure"
+// donut normalized value - "this-is-my-deep-directory-structure"
+//
+func normalizeObjectName(objectName string) string {
+	// replace every '/' with '-'
+	return strings.Replace(objectName, "/", "-", -1)
+}
+
+// getDataAndParity - calculate k, m (data and parity) values from number of disks
+func (b bucket) getDataAndParity(totalWriters int) (k uint8, m uint8, err error) {
+	if totalWriters <= 1 {
+		return 0, 0, iodine.New(InvalidArgument{}, nil)
+	}
+	quotient := totalWriters / 2 // not using float or abs to let integer round off to lower value
+	// quotient cannot be bigger than (255 / 2) = 127
+	if quotient > 127 {
+		return 0, 0, iodine.New(ParityOverflow{}, nil)
+	}
+	remainder := totalWriters % 2 // will be 1 for odd and 0 for even numbers
+	k = uint8(quotient + remainder)
+	m = uint8(quotient)
+	return k, m, nil
+}
+
+// writeObjectData -
+func (b bucket) writeObjectData(k, m uint8, writers []io.WriteCloser, objectData io.Reader, sumMD5, sum512 hash.Hash) (int, int, error) {
+	encoder, err := newEncoder(k, m, "Cauchy")
+	if err != nil {
+		return 0, 0, iodine.New(err, nil)
+	}
+	chunkCount := 0
+	totalLength := 0
+	for chunk := range split.Stream(objectData, 10*1024*1024) {
+		if chunk.Err != nil {
+			return 0, 0, iodine.New(err, nil)
+		}
+		totalLength = totalLength + len(chunk.Data)
+		encodedBlocks, _ := encoder.Encode(chunk.Data)
+		sumMD5.Write(chunk.Data)
+		sum512.Write(chunk.Data)
+		for blockIndex, block := range encodedBlocks {
+			_, err := io.Copy(writers[blockIndex], bytes.NewBuffer(block))
+			if err != nil {
+				return 0, 0, iodine.New(err, nil)
+			}
+		}
+		chunkCount = chunkCount + 1
+	}
+	return chunkCount, totalLength, nil
+}
+
+// readObjectData -
+func (b bucket) readObjectData(objectName string, writer *io.PipeWriter, objMetadata ObjectMetadata) {
+	readers, err := b.getReaders(objectName, "data")
+	if err != nil {
+		writer.CloseWithError(iodine.New(err, nil))
+		return
+	}
+	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 objMetadata.ErasureTechnique == "" {
+			writer.CloseWithError(iodine.New(MissingErasureTechnique{}, nil))
+			return
+		}
+		encoder, err := newEncoder(objMetadata.DataDisks, objMetadata.ParityDisks, objMetadata.ErasureTechnique)
+		if err != nil {
+			writer.CloseWithError(iodine.New(err, nil))
+			return
+		}
+		totalLeft := objMetadata.Size
+		for i := 0; i < objMetadata.ChunkCount; i++ {
+			decodedData, err := b.decodeEncodedData(totalLeft, int64(objMetadata.BlockSize), readers, encoder, writer)
+			if err != nil {
+				writer.CloseWithError(iodine.New(err, nil))
+				return
+			}
+			_, err = io.Copy(mwriter, bytes.NewBuffer(decodedData))
+			if err != nil {
+				writer.CloseWithError(iodine.New(err, nil))
+				return
+			}
+			totalLeft = totalLeft - int64(objMetadata.BlockSize)
+		}
+	case true:
+		_, err := io.Copy(writer, readers[0])
+		if err != nil {
+			writer.CloseWithError(iodine.New(err, nil))
+			return
+		}
+	}
+	// check if decodedData md5sum matches
+	if !bytes.Equal(expectedMd5sum, hasher.Sum(nil)) {
+		writer.CloseWithError(iodine.New(ChecksumMismatch{}, nil))
+		return
+	}
+	writer.Close()
+	return
+}
+
+// decodeEncodedData -
+func (b bucket) decodeEncodedData(totalLeft, blockSize int64, readers []io.ReadCloser, encoder encoder, writer *io.PipeWriter) ([]byte, error) {
+	var curBlockSize int64
+	if blockSize < totalLeft {
+		curBlockSize = blockSize
+	} else {
+		curBlockSize = totalLeft // cast is safe, blockSize in if protects
+	}
+	curChunkSize, err := encoder.GetEncodedBlockLen(int(curBlockSize))
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	encodedBytes := make([][]byte, len(readers))
+	for i, reader := range readers {
+		var bytesBuffer bytes.Buffer
+		_, err := io.CopyN(&bytesBuffer, reader, int64(curChunkSize))
+		if err != nil {
+			return nil, iodine.New(err, nil)
+		}
+		encodedBytes[i] = bytesBuffer.Bytes()
+	}
+	decodedData, err := encoder.Decode(encodedBytes, int(curBlockSize))
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	return decodedData, nil
+}
+
+// getReaders -
+func (b bucket) getReaders(objectName, objectMeta string) ([]io.ReadCloser, error) {
+	var readers []io.ReadCloser
+	nodeSlice := 0
+	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 {
+			bucketSlice := fmt.Sprintf("%s$%d$%d", b.name, nodeSlice, order)
+			objectPath := filepath.Join(b.donutName, bucketSlice, objectName, objectMeta)
+			objectSlice, err := disk.OpenFile(objectPath)
+			if err != nil {
+				return nil, iodine.New(err, nil)
+			}
+			readers[order] = objectSlice
+		}
+		nodeSlice = nodeSlice + 1
+	}
+	return readers, nil
+}
+
+// getWriters -
+func (b bucket) getWriters(objectName, objectMeta string) ([]io.WriteCloser, error) {
+	var writers []io.WriteCloser
+	nodeSlice := 0
+	for _, node := range b.nodes {
+		disks, err := node.ListDisks()
+		if err != nil {
+			return nil, iodine.New(err, nil)
+		}
+		writers = make([]io.WriteCloser, len(disks))
+		for order, disk := range disks {
+			bucketSlice := fmt.Sprintf("%s$%d$%d", b.name, nodeSlice, order)
+			objectPath := filepath.Join(b.donutName, bucketSlice, objectName, objectMeta)
+			objectSlice, err := disk.CreateFile(objectPath)
+			if err != nil {
+				return nil, iodine.New(err, nil)
+			}
+			writers[order] = objectSlice
+		}
+		nodeSlice = nodeSlice + 1
+	}
+	return writers, nil
+}

pkg/donut/common.go

@@ -0,0 +1,123 @@
+/*
+ * 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 (
+	"bufio"
+	"bytes"
+	"io"
+	"sort"
+	"strings"
+)
+
+// ProxyWriter implements io.Writer to trap written bytes
+type ProxyWriter struct {
+	writer       io.Writer
+	writtenBytes []byte
+}
+
+func (r *ProxyWriter) Write(p []byte) (n int, err error) {
+	n, err = r.writer.Write(p)
+	if err != nil {
+		return
+	}
+	r.writtenBytes = append(r.writtenBytes, p[0:n]...)
+	return
+}
+
+// NewProxyWriter - wrap around a given writer with ProxyWriter
+func NewProxyWriter(w io.Writer) *ProxyWriter {
+	return &ProxyWriter{writer: w, writtenBytes: nil}
+}
+
+// Delimiter delims the string at delimiter
+func Delimiter(object, delimiter string) string {
+	readBuffer := bytes.NewBufferString(object)
+	reader := bufio.NewReader(readBuffer)
+	stringReader := strings.NewReader(delimiter)
+	delimited, _ := stringReader.ReadByte()
+	delimitedStr, _ := reader.ReadString(delimited)
+	return delimitedStr
+}
+
+// RemoveDuplicates removes duplicate elements from a slice
+func RemoveDuplicates(slice []string) []string {
+	newSlice := []string{}
+	seen := make(map[string]struct{})
+	for _, val := range slice {
+		if _, ok := seen[val]; !ok {
+			newSlice = append(newSlice, val)
+			seen[val] = struct{}{} // avoiding byte allocation
+		}
+	}
+	return newSlice
+}
+
+// TrimPrefix trims off a prefix string from all the elements in a given slice
+func TrimPrefix(objects []string, prefix string) []string {
+	var results []string
+	for _, object := range objects {
+		results = append(results, strings.TrimPrefix(object, prefix))
+	}
+	return results
+}
+
+// HasNoDelimiter provides a new slice from an input slice which has elements without delimiter
+func HasNoDelimiter(objects []string, delim string) []string {
+	var results []string
+	for _, object := range objects {
+		if !strings.Contains(object, delim) {
+			results = append(results, object)
+		}
+	}
+	return results
+}
+
+// HasDelimiter provides a new slice from an input slice which has elements with a delimiter
+func HasDelimiter(objects []string, delim string) []string {
+	var results []string
+	for _, object := range objects {
+		if strings.Contains(object, delim) {
+			results = append(results, object)
+		}
+	}
+	return results
+}
+
+// SplitDelimiter provides a new slice from an input slice by splitting a delimiter
+func SplitDelimiter(objects []string, delim string) []string {
+	var results []string
+	for _, object := range objects {
+		parts := strings.Split(object, delim)
+		results = append(results, parts[0]+delim)
+	}
+	return results
+}
+
+// SortU sort a slice in lexical order, removing duplicate elements
+func SortU(objects []string) []string {
+	objectMap := make(map[string]string)
+	for _, v := range objects {
+		objectMap[v] = v
+	}
+	var results []string
+	for k := range objectMap {
+		results = append(results, k)
+	}
+	sort.Strings(results)
+	return results
+}

pkg/donut/config.go

@@ -0,0 +1,87 @@
+/*
+ * 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 (
+	"os/user"
+	"path/filepath"
+	"time"
+
+	"github.com/minio/minio/pkg/iodine"
+	"github.com/minio/minio/pkg/quick"
+)
+
+// getDonutConfigPath get donut config file path
+func getDonutConfigPath() (string, error) {
+	u, err := user.Current()
+	if err != nil {
+		return "", iodine.New(err, nil)
+	}
+	donutConfigPath := filepath.Join(u.HomeDir, ".minio", "donut.json")
+	return donutConfigPath, nil
+}
+
+// SaveConfig save donut config
+func SaveConfig(a *Config) error {
+	donutConfigPath, err := getDonutConfigPath()
+	if err != nil {
+		return iodine.New(err, nil)
+	}
+	qc, err := quick.New(a)
+	if err != nil {
+		return iodine.New(err, nil)
+	}
+	if err := qc.Save(donutConfigPath); err != nil {
+		return iodine.New(err, nil)
+	}
+	return nil
+}
+
+// LoadConfig load donut config
+func LoadConfig() (*Config, error) {
+	donutConfigPath, err := getDonutConfigPath()
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	a := &Config{}
+	a.Version = "0.0.1"
+	qc, err := quick.New(a)
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	if err := qc.Load(donutConfigPath); err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	return qc.Data().(*Config), nil
+}
+
+// LoadDonut load donut from config
+func LoadDonut() (Interface, error) {
+	conf, err := LoadConfig()
+	if err != nil {
+		conf = &Config{
+			Version:    "0.0.1",
+			MaxSize:    512000000,
+			Expiration: 1 * time.Hour,
+		}
+	}
+	donut, err := New(conf)
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	return donut, nil
+}

pkg/donut/date.go

@@ -0,0 +1,78 @@
+/*
+ * 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 (
+	"errors"
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+// Date - [0000-00-00]
+type Date struct {
+	Year  int16
+	Month byte
+	Day   byte
+}
+
+// String output in yyyy-mm-dd format
+func (d Date) String() string {
+	return fmt.Sprintf("%04d-%02d-%02d", d.Year, d.Month, d.Day)
+}
+
+// IsZero true if date is 0000-00-00
+func (d Date) IsZero() bool {
+	return d.Day == 0 && d.Month == 0 && d.Year == 0
+}
+
+// Convert string date in format YYYY-MM-DD to Date.
+// Leading and trailing spaces are ignored. If format is invalid returns zero.
+func parseDate(str string) (d Date, err error) {
+	str = strings.TrimSpace(str)
+	if str == "0000-00-00" {
+		return
+	}
+	var (
+		y, m, n int
+	)
+	if len(str) != 10 || str[4] != '-' || str[7] != '-' {
+		err = errors.New("Invalid 0000-00-000 style DATE string: " + str)
+		return
+	}
+	if y, err = strconv.Atoi(str[0:4]); err != nil {
+		return
+	}
+	if m, err = strconv.Atoi(str[5:7]); err != nil {
+		return
+	}
+	if m < 1 || m > 12 {
+		err = errors.New("Invalid 0000-00-000 style DATE string: " + str)
+		return
+	}
+	if n, err = strconv.Atoi(str[8:10]); err != nil {
+		return
+	}
+	if n < 1 || n > 31 {
+		err = errors.New("Invalid 0000-00-000 style DATE string: " + str)
+		return
+	}
+	d.Year = int16(y)
+	d.Month = byte(m)
+	d.Day = byte(n)
+	return
+}

pkg/donut/definitions.go

@@ -0,0 +1,73 @@
+/*
+ * 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 "time"
+
+// ObjectMetadata container for object on donut system
+type ObjectMetadata struct {
+	// version
+	Version string `json:"version"`
+
+	// object metadata
+	Created time.Time `json:"created"`
+	Bucket  string    `json:"bucket"`
+	Object  string    `json:"object"`
+	Size    int64     `json:"size"`
+
+	// erasure
+	DataDisks        uint8  `json:"sys.erasureK"`
+	ParityDisks      uint8  `json:"sys.erasureM"`
+	ErasureTechnique string `json:"sys.erasureTechnique"`
+	BlockSize        int    `json:"sys.blockSize"`
+	ChunkCount       int    `json:"sys.chunkCount"`
+
+	// checksums
+	MD5Sum    string `json:"sys.md5sum"`
+	SHA512Sum string `json:"sys.sha512sum"`
+
+	// metadata
+	Metadata map[string]string `json:"metadata"`
+}
+
+// Metadata container for donut metadata
+type Metadata struct {
+	Version string `json:"version"`
+}
+
+// AllBuckets container for all buckets
+type AllBuckets struct {
+	Version string                    `json:"version"`
+	Buckets map[string]BucketMetadata `json:"buckets"`
+}
+
+// BucketMetadata container for bucket level metadata
+type BucketMetadata struct {
+	Version       string                 `json:"version"`
+	Name          string                 `json:"name"`
+	ACL           BucketACL              `json:"acl"`
+	Created       time.Time              `json:"created"`
+	Metadata      map[string]string      `json:"metadata"`
+	BucketObjects map[string]interface{} `json:"objects"`
+}
+
+// ListObjectsResults container for list objects response
+type ListObjectsResults struct {
+	Objects        map[string]ObjectMetadata `json:"objects"`
+	CommonPrefixes []string                  `json:"commonPrefixes"`
+	IsTruncated    bool                      `json:"isTruncated"`
+}

pkg/donut/disk/disk.go

@@ -0,0 +1,177 @@
+/*
+ * 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 impliedisk.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package disk
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"syscall"
+
+	"github.com/minio/minio/pkg/iodine"
+)
+
+// Disk container for disk parameters
+type Disk struct {
+	path   string
+	fsInfo map[string]string
+}
+
+// New - instantiate new disk
+func New(diskPath string) (Disk, error) {
+	if diskPath == "" {
+		return Disk{}, iodine.New(InvalidArgument{}, nil)
+	}
+	s := syscall.Statfs_t{}
+	err := syscall.Statfs(diskPath, &s)
+	if err != nil {
+		return Disk{}, iodine.New(err, nil)
+	}
+	st, err := os.Stat(diskPath)
+	if err != nil {
+		return Disk{}, iodine.New(err, nil)
+	}
+	if !st.IsDir() {
+		return Disk{}, iodine.New(syscall.ENOTDIR, nil)
+	}
+	disk := Disk{
+		path:   diskPath,
+		fsInfo: make(map[string]string),
+	}
+	if fsType := getFSType(s.Type); fsType != "UNKNOWN" {
+		disk.fsInfo["FSType"] = fsType
+		disk.fsInfo["MountPoint"] = disk.path
+		return disk, nil
+	}
+	return Disk{}, iodine.New(UnsupportedFilesystem{Type: strconv.FormatInt(s.Type, 10)},
+		map[string]string{"Type": strconv.FormatInt(s.Type, 10)})
+}
+
+// GetPath - get root disk path
+func (disk Disk) GetPath() string {
+	return disk.path
+}
+
+// GetFSInfo - get disk filesystem and its usage information
+func (disk Disk) GetFSInfo() map[string]string {
+	s := syscall.Statfs_t{}
+	err := syscall.Statfs(disk.path, &s)
+	if err != nil {
+		return nil
+	}
+	disk.fsInfo["Total"] = formatBytes(s.Bsize * int64(s.Blocks))
+	disk.fsInfo["Free"] = formatBytes(s.Bsize * int64(s.Bfree))
+	disk.fsInfo["TotalB"] = strconv.FormatInt(s.Bsize*int64(s.Blocks), 10)
+	disk.fsInfo["FreeB"] = strconv.FormatInt(s.Bsize*int64(s.Bfree), 10)
+	return disk.fsInfo
+}
+
+// MakeDir - make a directory inside disk root path
+func (disk Disk) MakeDir(dirname string) error {
+	return os.MkdirAll(filepath.Join(disk.path, dirname), 0700)
+}
+
+// ListDir - list a directory inside disk root path, get only directories
+func (disk Disk) ListDir(dirname string) ([]os.FileInfo, error) {
+	dir, err := os.Open(filepath.Join(disk.path, dirname))
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	defer dir.Close()
+	contents, err := dir.Readdir(-1)
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	var directories []os.FileInfo
+	for _, content := range contents {
+		// Include only directories, ignore everything else
+		if content.IsDir() {
+			directories = append(directories, content)
+		}
+	}
+	return directories, nil
+}
+
+// ListFiles - list a directory inside disk root path, get only files
+func (disk Disk) ListFiles(dirname string) ([]os.FileInfo, error) {
+	dir, err := os.Open(filepath.Join(disk.path, dirname))
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	defer dir.Close()
+	contents, err := dir.Readdir(-1)
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	var files []os.FileInfo
+	for _, content := range contents {
+		// Include only regular files, ignore everything else
+		if content.Mode().IsRegular() {
+			files = append(files, content)
+		}
+	}
+	return files, nil
+}
+
+// CreateFile - create a file inside disk root path
+func (disk Disk) CreateFile(filename string) (*os.File, error) {
+	if filename == "" {
+		return nil, iodine.New(InvalidArgument{}, nil)
+	}
+	filePath := filepath.Join(disk.path, filename)
+	// Create directories if they don't exist
+	if err := os.MkdirAll(filepath.Dir(filePath), 0700); err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	dataFile, err := os.OpenFile(filePath, os.O_WRONLY|os.O_CREATE, 0600)
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	return dataFile, nil
+}
+
+// OpenFile - read a file inside disk root path
+func (disk Disk) OpenFile(filename string) (*os.File, error) {
+	if filename == "" {
+		return nil, iodine.New(InvalidArgument{}, nil)
+	}
+	dataFile, err := os.Open(filepath.Join(disk.path, filename))
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	return dataFile, nil
+}
+
+// formatBytes - Convert bytes to human readable string. Like a 2 MB, 64.2 KB, 52 B
+func formatBytes(i int64) (result string) {
+	switch {
+	case i > (1024 * 1024 * 1024 * 1024):
+		result = fmt.Sprintf("%.02f TB", float64(i)/1024/1024/1024/1024)
+	case i > (1024 * 1024 * 1024):
+		result = fmt.Sprintf("%.02f GB", float64(i)/1024/1024/1024)
+	case i > (1024 * 1024):
+		result = fmt.Sprintf("%.02f MB", float64(i)/1024/1024)
+	case i > 1024:
+		result = fmt.Sprintf("%.02f KB", float64(i)/1024)
+	default:
+		result = fmt.Sprintf("%d B", i)
+	}
+	result = strings.Trim(result, " ")
+	return
+}

pkg/donut/disk/disk_darwin.go

@@ -0,0 +1,34 @@
+/*
+ * 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 disk
+
+import "strconv"
+
+// fsType2StrinMap - list of filesystems supported by donut
+var fsType2StringMap = map[string]string{
+	"11": "HFS",
+}
+
+// getFSType - get filesystem type
+func getFSType(fsType uint32) string {
+	fsTypeHex := strconv.FormatUint(uint64(fsType), 16)
+	fsTypeString, ok := fsType2StringMap[fsTypeHex]
+	if ok == false {
+		return "UNKNOWN"
+	}
+	return fsTypeString
+}

pkg/donut/disk/disk_linux.go

@@ -0,0 +1,44 @@
+/*
+ * 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 disk
+
+import "strconv"
+
+// fsType2StringMap - list of filesystems supported by donut on linux
+var fsType2StringMap = map[string]string{
+	"1021994":  "TMPFS",
+	"137d":     "EXT",
+	"4244":     "HFS",
+	"4d44":     "MSDOS",
+	"52654973": "REISERFS",
+	"5346544e": "NTFS",
+	"58465342": "XFS",
+	"61756673": "AUFS",
+	"6969":     "NFS",
+	"ef51":     "EXT2OLD",
+	"ef53":     "EXT4",
+}
+
+// getFSType - get filesystem type
+func getFSType(fsType int64) string {
+	fsTypeHex := strconv.FormatInt(fsType, 16)
+	fsTypeString, ok := fsType2StringMap[fsTypeHex]
+	if ok == false {
+		return "UNKNOWN"
+	}
+	return fsTypeString
+}

pkg/donut/disk/disk_test.go

@@ -0,0 +1,78 @@
+/*
+ * 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 impliedisk.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package disk
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+
+	. "github.com/minio/check"
+)
+
+func TestDisk(t *testing.T) { TestingT(t) }
+
+type MyDiskSuite struct {
+	path string
+	disk Disk
+}
+
+var _ = Suite(&MyDiskSuite{})
+
+func (s *MyDiskSuite) SetUpSuite(c *C) {
+	path, err := ioutil.TempDir(os.TempDir(), "disk-")
+	c.Assert(err, IsNil)
+	s.path = path
+	d, err := New(s.path)
+	c.Assert(err, IsNil)
+	s.disk = d
+}
+
+func (s *MyDiskSuite) TearDownSuite(c *C) {
+	os.RemoveAll(s.path)
+}
+
+func (s *MyDiskSuite) TestDiskInfo(c *C) {
+	c.Assert(s.path, Equals, s.disk.GetPath())
+	fsInfo := s.disk.GetFSInfo()
+	c.Assert(fsInfo["MountPoint"], Equals, s.disk.GetPath())
+	c.Assert(fsInfo["FSType"], Not(Equals), "UNKNOWN")
+}
+
+func (s *MyDiskSuite) TestDiskCreateDir(c *C) {
+	c.Assert(s.disk.MakeDir("hello"), IsNil)
+}
+
+func (s *MyDiskSuite) TestDiskCreateFile(c *C) {
+	f, err := s.disk.CreateFile("hello1")
+	c.Assert(err, IsNil)
+	c.Assert(f.Name(), Equals, filepath.Join(s.path, "hello1"))
+	defer f.Close()
+}
+
+func (s *MyDiskSuite) TestDiskOpenFile(c *C) {
+	f, err := s.disk.CreateFile("hello2")
+	c.Assert(err, IsNil)
+	c.Assert(f.Name(), Equals, filepath.Join(s.path, "hello2"))
+	defer f.Close()
+
+	f, err = s.disk.OpenFile("hello2")
+	c.Assert(err, IsNil)
+	c.Assert(f.Name(), Equals, filepath.Join(s.path, "hello2"))
+	defer f.Close()
+}

pkg/donut/disk/errors.go

@@ -0,0 +1,33 @@
+/*
+ * 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 impliedisk.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package disk
+
+// InvalidArgument invalid argument
+type InvalidArgument struct{}
+
+func (e InvalidArgument) Error() string {
+	return "Invalid argument"
+}
+
+// UnsupportedFilesystem unsupported filesystem type
+type UnsupportedFilesystem struct {
+	Type string
+}
+
+func (e UnsupportedFilesystem) Error() string {
+	return "Unsupported filesystem: " + e.Type
+}

pkg/donut/donut-v1.go

@@ -0,0 +1,375 @@
+/*
+ * 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"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/minio/minio/pkg/iodine"
+)
+
+// config files used inside Donut
+const (
+	// donut system config
+	donutConfig = "donutConfig.json"
+
+	// bucket, object metadata
+	bucketMetadataConfig = "bucketMetadata.json"
+	objectMetadataConfig = "objectMetadata.json"
+
+	// versions
+	objectMetadataVersion = "1.0.0"
+	bucketMetadataVersion = "1.0.0"
+)
+
+// makeBucket - make a new bucket
+func (donut API) makeBucket(bucket string, acl BucketACL) error {
+	donut.lock.Lock()
+	defer donut.lock.Unlock()
+	if bucket == "" || strings.TrimSpace(bucket) == "" {
+		return iodine.New(InvalidArgument{}, nil)
+	}
+	return donut.makeDonutBucket(bucket, acl.String())
+}
+
+// getBucketMetadata - get bucket metadata
+func (donut API) getBucketMetadata(bucketName string) (BucketMetadata, error) {
+	donut.lock.RLock()
+	defer donut.lock.RUnlock()
+	if err := donut.listDonutBuckets(); err != nil {
+		return BucketMetadata{}, iodine.New(err, nil)
+	}
+	if _, ok := donut.buckets[bucketName]; !ok {
+		return BucketMetadata{}, iodine.New(BucketNotFound{Bucket: bucketName}, nil)
+	}
+	metadata, err := donut.getDonutBucketMetadata()
+	if err != nil {
+		return BucketMetadata{}, iodine.New(err, nil)
+	}
+	return metadata.Buckets[bucketName], nil
+}
+
+// setBucketMetadata - set bucket metadata
+func (donut API) setBucketMetadata(bucketName string, bucketMetadata map[string]string) error {
+	donut.lock.Lock()
+	defer donut.lock.Unlock()
+	if err := donut.listDonutBuckets(); err != nil {
+		return iodine.New(err, nil)
+	}
+	metadata, err := donut.getDonutBucketMetadata()
+	if err != nil {
+		return iodine.New(err, nil)
+	}
+	oldBucketMetadata := metadata.Buckets[bucketName]
+	acl, ok := bucketMetadata["acl"]
+	if !ok {
+		return iodine.New(InvalidArgument{}, nil)
+	}
+	oldBucketMetadata.ACL = BucketACL(acl)
+	metadata.Buckets[bucketName] = oldBucketMetadata
+	return donut.setDonutBucketMetadata(metadata)
+}
+
+// listBuckets - return list of buckets
+func (donut API) listBuckets() (map[string]BucketMetadata, error) {
+	donut.lock.RLock()
+	defer donut.lock.RUnlock()
+	if err := donut.listDonutBuckets(); err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	metadata, err := donut.getDonutBucketMetadata()
+	if err != nil {
+		// intentionally left out the error when Donut is empty
+		// but we need to revisit this area in future - since we need
+		// to figure out between acceptable and unacceptable errors
+		return make(map[string]BucketMetadata), nil
+	}
+	return metadata.Buckets, nil
+}
+
+// listObjects - return list of objects
+func (donut API) listObjects(bucket, prefix, marker, delimiter string, maxkeys int) (ListObjectsResults, error) {
+	donut.lock.RLock()
+	defer donut.lock.RUnlock()
+	errParams := map[string]string{
+		"bucket":    bucket,
+		"prefix":    prefix,
+		"marker":    marker,
+		"delimiter": delimiter,
+		"maxkeys":   strconv.Itoa(maxkeys),
+	}
+	if err := donut.listDonutBuckets(); err != nil {
+		return ListObjectsResults{}, iodine.New(err, errParams)
+	}
+	if _, ok := donut.buckets[bucket]; !ok {
+		return ListObjectsResults{}, iodine.New(BucketNotFound{Bucket: bucket}, errParams)
+	}
+	listObjects, err := donut.buckets[bucket].ListObjects(prefix, marker, delimiter, maxkeys)
+	if err != nil {
+		return ListObjectsResults{}, iodine.New(err, errParams)
+	}
+	return listObjects, nil
+}
+
+// putObject - put object
+func (donut API) putObject(bucket, object, expectedMD5Sum string, reader io.Reader, metadata map[string]string) (ObjectMetadata, error) {
+	donut.lock.Lock()
+	defer donut.lock.Unlock()
+	errParams := map[string]string{
+		"bucket": bucket,
+		"object": object,
+	}
+	if bucket == "" || strings.TrimSpace(bucket) == "" {
+		return ObjectMetadata{}, iodine.New(InvalidArgument{}, errParams)
+	}
+	if object == "" || strings.TrimSpace(object) == "" {
+		return ObjectMetadata{}, iodine.New(InvalidArgument{}, errParams)
+	}
+	if err := donut.listDonutBuckets(); err != nil {
+		return ObjectMetadata{}, iodine.New(err, errParams)
+	}
+	if _, ok := donut.buckets[bucket]; !ok {
+		return ObjectMetadata{}, iodine.New(BucketNotFound{Bucket: bucket}, nil)
+	}
+	bucketMeta, err := donut.getDonutBucketMetadata()
+	if err != nil {
+		return ObjectMetadata{}, iodine.New(err, errParams)
+	}
+	if _, ok := bucketMeta.Buckets[bucket].BucketObjects[object]; ok {
+		return ObjectMetadata{}, iodine.New(ObjectExists{Object: object}, errParams)
+	}
+	objMetadata, err := donut.buckets[bucket].WriteObject(object, reader, expectedMD5Sum, metadata)
+	if err != nil {
+		return ObjectMetadata{}, iodine.New(err, errParams)
+	}
+	bucketMeta.Buckets[bucket].BucketObjects[object] = 1
+	if err := donut.setDonutBucketMetadata(bucketMeta); err != nil {
+		return ObjectMetadata{}, iodine.New(err, errParams)
+	}
+	return objMetadata, nil
+}
+
+// getObject - get object
+func (donut API) getObject(bucket, object string) (reader io.ReadCloser, size int64, err error) {
+	donut.lock.RLock()
+	defer donut.lock.RUnlock()
+	errParams := map[string]string{
+		"bucket": bucket,
+		"object": object,
+	}
+	if bucket == "" || strings.TrimSpace(bucket) == "" {
+		return nil, 0, iodine.New(InvalidArgument{}, errParams)
+	}
+	if object == "" || strings.TrimSpace(object) == "" {
+		return nil, 0, iodine.New(InvalidArgument{}, errParams)
+	}
+	if err := donut.listDonutBuckets(); err != nil {
+		return nil, 0, iodine.New(err, nil)
+	}
+	if _, ok := donut.buckets[bucket]; !ok {
+		return nil, 0, iodine.New(BucketNotFound{Bucket: bucket}, errParams)
+	}
+	return donut.buckets[bucket].ReadObject(object)
+}
+
+// getObjectMetadata - get object metadata
+func (donut API) getObjectMetadata(bucket, object string) (ObjectMetadata, error) {
+	donut.lock.RLock()
+	defer donut.lock.RUnlock()
+	errParams := map[string]string{
+		"bucket": bucket,
+		"object": object,
+	}
+	if err := donut.listDonutBuckets(); err != nil {
+		return ObjectMetadata{}, iodine.New(err, errParams)
+	}
+	if _, ok := donut.buckets[bucket]; !ok {
+		return ObjectMetadata{}, iodine.New(BucketNotFound{Bucket: bucket}, errParams)
+	}
+	bucketMeta, err := donut.getDonutBucketMetadata()
+	if err != nil {
+		return ObjectMetadata{}, iodine.New(err, errParams)
+	}
+	if _, ok := bucketMeta.Buckets[bucket].BucketObjects[object]; !ok {
+		return ObjectMetadata{}, iodine.New(ObjectNotFound{Object: object}, errParams)
+	}
+	objectMetadata, err := donut.buckets[bucket].GetObjectMetadata(object)
+	if err != nil {
+		return ObjectMetadata{}, iodine.New(err, nil)
+	}
+	return objectMetadata, nil
+}
+
+// getDiskWriters -
+func (donut API) getBucketMetadataWriters() ([]io.WriteCloser, error) {
+	var writers []io.WriteCloser
+	for _, node := range donut.nodes {
+		disks, err := node.ListDisks()
+		if err != nil {
+			return nil, iodine.New(err, nil)
+		}
+		writers = make([]io.WriteCloser, len(disks))
+		for order, d := range disks {
+			bucketMetaDataWriter, err := d.CreateFile(filepath.Join(donut.config.DonutName, bucketMetadataConfig))
+			if err != nil {
+				return nil, iodine.New(err, nil)
+			}
+			writers[order] = bucketMetaDataWriter
+		}
+	}
+	return writers, nil
+}
+
+func (donut API) getBucketMetadataReaders() ([]io.ReadCloser, error) {
+	var readers []io.ReadCloser
+	for _, node := range donut.nodes {
+		disks, err := node.ListDisks()
+		if err != nil {
+			return nil, iodine.New(err, nil)
+		}
+		readers = make([]io.ReadCloser, len(disks))
+		for order, d := range disks {
+			bucketMetaDataReader, err := d.OpenFile(filepath.Join(donut.config.DonutName, bucketMetadataConfig))
+			if err != nil {
+				return nil, iodine.New(err, nil)
+			}
+			readers[order] = bucketMetaDataReader
+		}
+	}
+	return readers, nil
+}
+
+//
+func (donut API) setDonutBucketMetadata(metadata *AllBuckets) error {
+	writers, err := donut.getBucketMetadataWriters()
+	if err != nil {
+		return iodine.New(err, nil)
+	}
+	for _, writer := range writers {
+		defer writer.Close()
+	}
+	for _, writer := range writers {
+		jenc := json.NewEncoder(writer)
+		if err := jenc.Encode(metadata); err != nil {
+			return iodine.New(err, nil)
+		}
+	}
+	return nil
+}
+
+func (donut API) getDonutBucketMetadata() (*AllBuckets, error) {
+	metadata := new(AllBuckets)
+	readers, err := donut.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)
+}
+
+func (donut API) makeDonutBucket(bucketName, acl string) error {
+	if err := donut.listDonutBuckets(); err != nil {
+		return iodine.New(err, nil)
+	}
+	if _, ok := donut.buckets[bucketName]; ok {
+		return iodine.New(BucketExists{Bucket: bucketName}, nil)
+	}
+	bucket, bucketMetadata, err := newBucket(bucketName, acl, donut.config.DonutName, donut.nodes)
+	if err != nil {
+		return iodine.New(err, nil)
+	}
+	nodeNumber := 0
+	donut.buckets[bucketName] = bucket
+	for _, node := range donut.nodes {
+		disks, err := node.ListDisks()
+		if err != nil {
+			return iodine.New(err, nil)
+		}
+		for order, disk := range disks {
+			bucketSlice := fmt.Sprintf("%s$%d$%d", bucketName, nodeNumber, order)
+			err := disk.MakeDir(filepath.Join(donut.config.DonutName, bucketSlice))
+			if err != nil {
+				return iodine.New(err, nil)
+			}
+		}
+		nodeNumber = nodeNumber + 1
+	}
+	metadata, err := donut.getDonutBucketMetadata()
+	if err != nil {
+		if os.IsNotExist(iodine.ToError(err)) {
+			metadata := new(AllBuckets)
+			metadata.Buckets = make(map[string]BucketMetadata)
+			metadata.Buckets[bucketName] = bucketMetadata
+			err = donut.setDonutBucketMetadata(metadata)
+			if err != nil {
+				return iodine.New(err, nil)
+			}
+			return nil
+		}
+		return iodine.New(err, nil)
+	}
+	metadata.Buckets[bucketName] = bucketMetadata
+	err = donut.setDonutBucketMetadata(metadata)
+	if err != nil {
+		return iodine.New(err, nil)
+	}
+	return nil
+}
+
+func (donut API) listDonutBuckets() error {
+	for _, node := range donut.nodes {
+		disks, err := node.ListDisks()
+		if err != nil {
+			return iodine.New(err, nil)
+		}
+		for _, disk := range disks {
+			dirs, err := disk.ListDir(donut.config.DonutName)
+			if err != nil {
+				return iodine.New(err, nil)
+			}
+			for _, dir := range dirs {
+				splitDir := strings.Split(dir.Name(), "$")
+				if len(splitDir) < 3 {
+					return iodine.New(CorruptedBackend{Backend: dir.Name()}, nil)
+				}
+				bucketName := splitDir[0]
+				// we dont need this once we cache from makeDonutBucket()
+				bucket, _, err := newBucket(bucketName, "private", donut.config.DonutName, donut.nodes)
+				if err != nil {
+					return iodine.New(err, nil)
+				}
+				donut.buckets[bucketName] = bucket
+			}
+		}
+	}
+	return nil
+}

pkg/donut/donut-v1_test.go

@@ -0,0 +1,288 @@
+/*
+ * 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 impliedd.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package donut
+
+import (
+	"bytes"
+	"crypto/md5"
+	"encoding/base64"
+	"encoding/hex"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strconv"
+	"testing"
+	"time"
+
+	. "github.com/minio/check"
+)
+
+func TestDonut(t *testing.T) { TestingT(t) }
+
+type MyDonutSuite struct {
+	root string
+}
+
+var _ = Suite(&MyDonutSuite{})
+
+// create a dummy TestNodeDiskMap
+func createTestNodeDiskMap(p string) map[string][]string {
+	nodes := make(map[string][]string)
+	nodes["localhost"] = make([]string, 16)
+	for i := 0; i < len(nodes["localhost"]); i++ {
+		diskPath := filepath.Join(p, strconv.Itoa(i))
+		if _, err := os.Stat(diskPath); err != nil {
+			if os.IsNotExist(err) {
+				os.MkdirAll(diskPath, 0700)
+			}
+		}
+		nodes["localhost"][i] = diskPath
+	}
+	return nodes
+}
+
+var dd Interface
+
+func (s *MyDonutSuite) SetUpSuite(c *C) {
+	root, err := ioutil.TempDir(os.TempDir(), "donut-")
+	c.Assert(err, IsNil)
+	s.root = root
+
+	conf := new(Config)
+	conf.DonutName = "test"
+	conf.NodeDiskMap = createTestNodeDiskMap(root)
+	conf.Expiration = time.Duration(1 * time.Hour)
+	conf.MaxSize = 100000
+
+	dd, err = New(conf)
+	c.Assert(err, IsNil)
+
+	// testing empty donut
+	buckets, err := dd.ListBuckets()
+	c.Assert(err, IsNil)
+	c.Assert(len(buckets), Equals, 0)
+}
+
+func (s *MyDonutSuite) TearDownSuite(c *C) {
+	os.RemoveAll(s.root)
+}
+
+// test make bucket without name
+func (s *MyDonutSuite) TestBucketWithoutNameFails(c *C) {
+	// fail to create new bucket without a name
+	err := dd.MakeBucket("", "private")
+	c.Assert(err, Not(IsNil))
+
+	err = dd.MakeBucket(" ", "private")
+	c.Assert(err, Not(IsNil))
+}
+
+// test empty bucket
+func (s *MyDonutSuite) TestEmptyBucket(c *C) {
+	c.Assert(dd.MakeBucket("foo1", "private"), IsNil)
+	// check if bucket is empty
+	var resources BucketResourcesMetadata
+	resources.Maxkeys = 1
+	objectsMetadata, resources, err := dd.ListObjects("foo1", resources)
+	c.Assert(err, IsNil)
+	c.Assert(len(objectsMetadata), Equals, 0)
+	c.Assert(resources.CommonPrefixes, DeepEquals, []string{})
+	c.Assert(resources.IsTruncated, Equals, false)
+}
+
+// test bucket list
+func (s *MyDonutSuite) TestMakeBucketAndList(c *C) {
+	// create bucket
+	err := dd.MakeBucket("foo2", "private")
+	c.Assert(err, IsNil)
+
+	// check bucket exists
+	buckets, err := dd.ListBuckets()
+	c.Assert(err, IsNil)
+	c.Assert(len(buckets), Equals, 5)
+	c.Assert(buckets[0].ACL, Equals, BucketACL("private"))
+}
+
+// test re-create bucket
+func (s *MyDonutSuite) TestMakeBucketWithSameNameFails(c *C) {
+	err := dd.MakeBucket("foo3", "private")
+	c.Assert(err, IsNil)
+
+	err = dd.MakeBucket("foo3", "private")
+	c.Assert(err, Not(IsNil))
+}
+
+// test make multiple buckets
+func (s *MyDonutSuite) TestCreateMultipleBucketsAndList(c *C) {
+	// add a second bucket
+	err := dd.MakeBucket("foo4", "private")
+	c.Assert(err, IsNil)
+
+	err = dd.MakeBucket("bar1", "private")
+	c.Assert(err, IsNil)
+
+	buckets, err := dd.ListBuckets()
+	c.Assert(err, IsNil)
+
+	c.Assert(len(buckets), Equals, 2)
+	c.Assert(buckets[0].Name, Equals, "bar1")
+	c.Assert(buckets[1].Name, Equals, "foo4")
+
+	err = dd.MakeBucket("foobar1", "private")
+	c.Assert(err, IsNil)
+
+	buckets, err = dd.ListBuckets()
+	c.Assert(err, IsNil)
+
+	c.Assert(len(buckets), Equals, 3)
+	c.Assert(buckets[2].Name, Equals, "foobar1")
+}
+
+// test object create without bucket
+func (s *MyDonutSuite) TestNewObjectFailsWithoutBucket(c *C) {
+	_, err := dd.CreateObject("unknown", "obj", "", 0, nil, nil)
+	c.Assert(err, Not(IsNil))
+}
+
+// test create object metadata
+func (s *MyDonutSuite) TestNewObjectMetadata(c *C) {
+	data := "Hello World"
+	hasher := md5.New()
+	hasher.Write([]byte(data))
+	expectedMd5Sum := base64.StdEncoding.EncodeToString(hasher.Sum(nil))
+	reader := ioutil.NopCloser(bytes.NewReader([]byte(data)))
+
+	err := dd.MakeBucket("foo6", "private")
+	c.Assert(err, IsNil)
+
+	objectMetadata, err := dd.CreateObject("foo6", "obj", expectedMd5Sum, int64(len(data)), reader, map[string]string{"contentType": "application/json"})
+	c.Assert(err, IsNil)
+	c.Assert(objectMetadata.MD5Sum, Equals, hex.EncodeToString(hasher.Sum(nil)))
+	c.Assert(objectMetadata.Metadata["contentType"], Equals, "application/json")
+}
+
+// test create object fails without name
+func (s *MyDonutSuite) TestNewObjectFailsWithEmptyName(c *C) {
+	_, err := dd.CreateObject("foo", "", "", 0, nil, nil)
+	c.Assert(err, Not(IsNil))
+}
+
+// test create object
+func (s *MyDonutSuite) TestNewObjectCanBeWritten(c *C) {
+	err := dd.MakeBucket("foo", "private")
+	c.Assert(err, IsNil)
+
+	data := "Hello World"
+
+	hasher := md5.New()
+	hasher.Write([]byte(data))
+	expectedMd5Sum := base64.StdEncoding.EncodeToString(hasher.Sum(nil))
+	reader := ioutil.NopCloser(bytes.NewReader([]byte(data)))
+
+	actualMetadata, err := dd.CreateObject("foo", "obj", expectedMd5Sum, int64(len(data)), reader, map[string]string{"contentType": "application/octet-stream"})
+	c.Assert(err, IsNil)
+	c.Assert(actualMetadata.MD5Sum, Equals, hex.EncodeToString(hasher.Sum(nil)))
+
+	var buffer bytes.Buffer
+	size, err := dd.GetObject(&buffer, "foo", "obj")
+	c.Assert(err, IsNil)
+	c.Assert(size, Equals, int64(len(data)))
+	c.Assert(buffer.Bytes(), DeepEquals, []byte(data))
+
+	actualMetadata, err = dd.GetObjectMetadata("foo", "obj")
+	c.Assert(err, IsNil)
+	c.Assert(hex.EncodeToString(hasher.Sum(nil)), Equals, actualMetadata.MD5Sum)
+	c.Assert(int64(len(data)), Equals, actualMetadata.Size)
+}
+
+// test list objects
+func (s *MyDonutSuite) TestMultipleNewObjects(c *C) {
+	c.Assert(dd.MakeBucket("foo5", "private"), IsNil)
+
+	one := ioutil.NopCloser(bytes.NewReader([]byte("one")))
+
+	_, err := dd.CreateObject("foo5", "obj1", "", int64(len("one")), one, nil)
+	c.Assert(err, IsNil)
+
+	two := ioutil.NopCloser(bytes.NewReader([]byte("two")))
+	_, err = dd.CreateObject("foo5", "obj2", "", int64(len("two")), two, nil)
+	c.Assert(err, IsNil)
+
+	var buffer1 bytes.Buffer
+	size, err := dd.GetObject(&buffer1, "foo5", "obj1")
+	c.Assert(err, IsNil)
+	c.Assert(size, Equals, int64(len([]byte("one"))))
+	c.Assert(buffer1.Bytes(), DeepEquals, []byte("one"))
+
+	var buffer2 bytes.Buffer
+	size, err = dd.GetObject(&buffer2, "foo5", "obj2")
+	c.Assert(err, IsNil)
+	c.Assert(size, Equals, int64(len([]byte("two"))))
+
+	c.Assert(buffer2.Bytes(), DeepEquals, []byte("two"))
+
+	/// test list of objects
+
+	// test list objects with prefix and delimiter
+	var resources BucketResourcesMetadata
+	resources.Prefix = "o"
+	resources.Delimiter = "1"
+	resources.Maxkeys = 10
+	objectsMetadata, resources, err := dd.ListObjects("foo5", resources)
+	c.Assert(err, IsNil)
+	c.Assert(resources.IsTruncated, Equals, false)
+	c.Assert(resources.CommonPrefixes[0], Equals, "obj1")
+
+	// test list objects with only delimiter
+	resources.Prefix = ""
+	resources.Delimiter = "1"
+	resources.Maxkeys = 10
+	objectsMetadata, resources, err = dd.ListObjects("foo5", resources)
+	c.Assert(err, IsNil)
+	c.Assert(objectsMetadata[0].Object, Equals, "obj2")
+	c.Assert(resources.IsTruncated, Equals, false)
+	c.Assert(resources.CommonPrefixes[0], Equals, "obj1")
+
+	// test list objects with only prefix
+	resources.Prefix = "o"
+	resources.Delimiter = ""
+	resources.Maxkeys = 10
+	objectsMetadata, resources, err = dd.ListObjects("foo5", resources)
+	c.Assert(err, IsNil)
+	c.Assert(resources.IsTruncated, Equals, false)
+	c.Assert(objectsMetadata[0].Object, Equals, "obj1")
+	c.Assert(objectsMetadata[1].Object, Equals, "obj2")
+
+	three := ioutil.NopCloser(bytes.NewReader([]byte("three")))
+	_, err = dd.CreateObject("foo5", "obj3", "", int64(len("three")), three, nil)
+	c.Assert(err, IsNil)
+
+	var buffer bytes.Buffer
+	size, err = dd.GetObject(&buffer, "foo5", "obj3")
+	c.Assert(err, IsNil)
+	c.Assert(size, Equals, int64(len([]byte("three"))))
+	c.Assert(buffer.Bytes(), DeepEquals, []byte("three"))
+
+	// test list objects with maxkeys
+	resources.Prefix = "o"
+	resources.Delimiter = ""
+	resources.Maxkeys = 2
+	objectsMetadata, resources, err = dd.ListObjects("foo5", resources)
+	c.Assert(err, IsNil)
+	c.Assert(resources.IsTruncated, Equals, true)
+	c.Assert(len(objectsMetadata), Equals, 2)
+}

pkg/donut/donut-v2.go

@@ -0,0 +1,638 @@
+/*
+ * 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 (
+	"bytes"
+	"crypto/md5"
+	"encoding/base64"
+	"encoding/hex"
+	"errors"
+	"io"
+	"io/ioutil"
+	"log"
+	"runtime/debug"
+	"sort"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/minio/minio/pkg/donut/trove"
+	"github.com/minio/minio/pkg/iodine"
+	"github.com/minio/minio/pkg/quick"
+)
+
+// total Number of buckets allowed
+const (
+	totalBuckets = 100
+)
+
+// Config donut config
+type Config struct {
+	Version     string              `json:"version"`
+	MaxSize     uint64              `json:"max-size"`
+	Expiration  time.Duration       `json:"expiration"`
+	DonutName   string              `json:"donut-name"`
+	NodeDiskMap map[string][]string `json:"node-disk-map"`
+}
+
+// API - local variables
+type API struct {
+	config           *Config
+	lock             *sync.RWMutex
+	objects          *trove.Cache
+	multiPartObjects *trove.Cache
+	storedBuckets    map[string]storedBucket
+	nodes            map[string]node
+	buckets          map[string]bucket
+}
+
+// storedBucket saved bucket
+type storedBucket struct {
+	bucketMetadata   BucketMetadata
+	objectMetadata   map[string]ObjectMetadata
+	partMetadata     map[string]PartMetadata
+	multiPartSession map[string]multiPartSession
+}
+
+// multiPartSession multipart session
+type multiPartSession struct {
+	totalParts int
+	uploadID   string
+	initiated  time.Time
+}
+
+// New instantiate a new donut
+func New(c *Config) (Interface, error) {
+	if err := quick.CheckData(c); err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	a := API{config: c}
+	a.storedBuckets = make(map[string]storedBucket)
+	a.nodes = make(map[string]node)
+	a.buckets = make(map[string]bucket)
+	a.objects = trove.NewCache(a.config.MaxSize, a.config.Expiration)
+	a.multiPartObjects = trove.NewCache(0, time.Duration(0))
+	a.objects.OnExpired = a.expiredObject
+	a.multiPartObjects.OnExpired = a.expiredPart
+	a.lock = new(sync.RWMutex)
+
+	// set up cache expiration
+	a.objects.ExpireObjects(time.Second * 5)
+
+	if len(a.config.NodeDiskMap) > 0 {
+		for k, v := range a.config.NodeDiskMap {
+			if len(v) == 0 {
+				return nil, iodine.New(InvalidDisksArgument{}, nil)
+			}
+			err := a.AttachNode(k, v)
+			if err != nil {
+				return nil, iodine.New(err, nil)
+			}
+		}
+		/// Initialization, populate all buckets into memory
+		buckets, err := a.listBuckets()
+		if err != nil {
+			return nil, iodine.New(err, nil)
+		}
+		for k, v := range buckets {
+			storedBucket := a.storedBuckets[k]
+			storedBucket.bucketMetadata = v
+			a.storedBuckets[k] = storedBucket
+		}
+	}
+	return a, nil
+}
+
+// GetObject - GET object from cache buffer
+func (donut API) GetObject(w io.Writer, bucket string, object string) (int64, error) {
+	donut.lock.RLock()
+	if !IsValidBucket(bucket) {
+		donut.lock.RUnlock()
+		return 0, iodine.New(BucketNameInvalid{Bucket: bucket}, nil)
+	}
+	if !IsValidObjectName(object) {
+		donut.lock.RUnlock()
+		return 0, iodine.New(ObjectNameInvalid{Object: object}, nil)
+	}
+	if _, ok := donut.storedBuckets[bucket]; ok == false {
+		donut.lock.RUnlock()
+		return 0, iodine.New(BucketNotFound{Bucket: bucket}, nil)
+	}
+	objectKey := bucket + "/" + object
+	data, ok := donut.objects.Get(objectKey)
+	if !ok {
+		if len(donut.config.NodeDiskMap) > 0 {
+			reader, size, err := donut.getObject(bucket, object)
+			if err != nil {
+				donut.lock.RUnlock()
+				return 0, iodine.New(err, nil)
+			}
+			// new proxy writer to capture data read from disk
+			pw := NewProxyWriter(w)
+			written, err := io.CopyN(pw, reader, size)
+			if err != nil {
+				donut.lock.RUnlock()
+				return 0, iodine.New(err, nil)
+			}
+			donut.lock.RUnlock()
+			/// cache object read from disk
+			{
+				donut.lock.Lock()
+				ok := donut.objects.Set(objectKey, pw.writtenBytes)
+				donut.lock.Unlock()
+				pw.writtenBytes = nil
+				go debug.FreeOSMemory()
+				if !ok {
+					return 0, iodine.New(InternalError{}, nil)
+				}
+			}
+			return written, nil
+		}
+		donut.lock.RUnlock()
+		return 0, iodine.New(ObjectNotFound{Object: object}, nil)
+	}
+	written, err := io.CopyN(w, bytes.NewBuffer(data), int64(donut.objects.Len(objectKey)))
+	if err != nil {
+		return 0, iodine.New(err, nil)
+	}
+	donut.lock.RUnlock()
+	return written, nil
+}
+
+// GetPartialObject - GET object from cache buffer range
+func (donut API) GetPartialObject(w io.Writer, bucket, object string, start, length int64) (int64, error) {
+	errParams := map[string]string{
+		"bucket": bucket,
+		"object": object,
+		"start":  strconv.FormatInt(start, 10),
+		"length": strconv.FormatInt(length, 10),
+	}
+	donut.lock.RLock()
+	if !IsValidBucket(bucket) {
+		donut.lock.RUnlock()
+		return 0, iodine.New(BucketNameInvalid{Bucket: bucket}, errParams)
+	}
+	if !IsValidObjectName(object) {
+		donut.lock.RUnlock()
+		return 0, iodine.New(ObjectNameInvalid{Object: object}, errParams)
+	}
+	if start < 0 {
+		donut.lock.RUnlock()
+		return 0, iodine.New(InvalidRange{
+			Start:  start,
+			Length: length,
+		}, errParams)
+	}
+	objectKey := bucket + "/" + object
+	data, ok := donut.objects.Get(objectKey)
+	if !ok {
+		if len(donut.config.NodeDiskMap) > 0 {
+			reader, _, err := donut.getObject(bucket, object)
+			if err != nil {
+				donut.lock.RUnlock()
+				return 0, iodine.New(err, nil)
+			}
+			if _, err := io.CopyN(ioutil.Discard, reader, start); err != nil {
+				donut.lock.RUnlock()
+				return 0, iodine.New(err, nil)
+			}
+			pw := NewProxyWriter(w)
+			written, err := io.CopyN(w, reader, length)
+			if err != nil {
+				donut.lock.RUnlock()
+				return 0, iodine.New(err, nil)
+			}
+			donut.lock.RUnlock()
+			{
+				donut.lock.Lock()
+				ok := donut.objects.Set(objectKey, pw.writtenBytes)
+				donut.lock.Unlock()
+				pw.writtenBytes = nil
+				go debug.FreeOSMemory()
+				if !ok {
+					return 0, iodine.New(InternalError{}, nil)
+				}
+			}
+			return written, nil
+		}
+		donut.lock.RUnlock()
+		return 0, iodine.New(ObjectNotFound{Object: object}, nil)
+	}
+	written, err := io.CopyN(w, bytes.NewBuffer(data[start:]), length)
+	if err != nil {
+		return 0, iodine.New(err, nil)
+	}
+	donut.lock.RUnlock()
+	return written, nil
+}
+
+// GetBucketMetadata -
+func (donut API) GetBucketMetadata(bucket string) (BucketMetadata, error) {
+	donut.lock.RLock()
+	if !IsValidBucket(bucket) {
+		donut.lock.RUnlock()
+		return BucketMetadata{}, iodine.New(BucketNameInvalid{Bucket: bucket}, nil)
+	}
+	if _, ok := donut.storedBuckets[bucket]; ok == false {
+		if len(donut.config.NodeDiskMap) > 0 {
+			bucketMetadata, err := donut.getBucketMetadata(bucket)
+			if err != nil {
+				donut.lock.RUnlock()
+				return BucketMetadata{}, iodine.New(err, nil)
+			}
+			storedBucket := donut.storedBuckets[bucket]
+			donut.lock.RUnlock()
+			{
+				donut.lock.Lock()
+				storedBucket.bucketMetadata = bucketMetadata
+				donut.storedBuckets[bucket] = storedBucket
+				donut.lock.Unlock()
+			}
+		}
+		return BucketMetadata{}, iodine.New(BucketNotFound{Bucket: bucket}, nil)
+	}
+	donut.lock.RUnlock()
+	return donut.storedBuckets[bucket].bucketMetadata, nil
+}
+
+// SetBucketMetadata -
+func (donut API) SetBucketMetadata(bucket string, metadata map[string]string) error {
+	donut.lock.RLock()
+	if !IsValidBucket(bucket) {
+		donut.lock.RUnlock()
+		return iodine.New(BucketNameInvalid{Bucket: bucket}, nil)
+	}
+	if _, ok := donut.storedBuckets[bucket]; ok == false {
+		donut.lock.RUnlock()
+		return iodine.New(BucketNotFound{Bucket: bucket}, nil)
+	}
+	donut.lock.RUnlock()
+	donut.lock.Lock()
+	{
+		if len(donut.config.NodeDiskMap) > 0 {
+			if err := donut.setBucketMetadata(bucket, metadata); err != nil {
+				return iodine.New(err, nil)
+			}
+		}
+		storedBucket := donut.storedBuckets[bucket]
+		storedBucket.bucketMetadata.ACL = BucketACL(metadata["acl"])
+		donut.storedBuckets[bucket] = storedBucket
+	}
+	donut.lock.Unlock()
+	return nil
+}
+
+// isMD5SumEqual - returns error if md5sum mismatches, success its `nil`
+func isMD5SumEqual(expectedMD5Sum, actualMD5Sum string) error {
+	if strings.TrimSpace(expectedMD5Sum) != "" && strings.TrimSpace(actualMD5Sum) != "" {
+		expectedMD5SumBytes, err := hex.DecodeString(expectedMD5Sum)
+		if err != nil {
+			return iodine.New(err, nil)
+		}
+		actualMD5SumBytes, err := hex.DecodeString(actualMD5Sum)
+		if err != nil {
+			return iodine.New(err, nil)
+		}
+		if !bytes.Equal(expectedMD5SumBytes, actualMD5SumBytes) {
+			return iodine.New(errors.New("bad digest, md5sum mismatch"), nil)
+		}
+		return nil
+	}
+	return iodine.New(errors.New("invalid argument"), nil)
+}
+
+// CreateObject -
+func (donut API) CreateObject(bucket, key, expectedMD5Sum string, size int64, data io.Reader, metadata map[string]string) (ObjectMetadata, error) {
+	if size > int64(donut.config.MaxSize) {
+		generic := GenericObjectError{Bucket: bucket, Object: key}
+		return ObjectMetadata{}, iodine.New(EntityTooLarge{
+			GenericObjectError: generic,
+			Size:               strconv.FormatInt(size, 10),
+			MaxSize:            strconv.FormatUint(donut.config.MaxSize, 10),
+		}, nil)
+	}
+	contentType := metadata["contentType"]
+	objectMetadata, err := donut.createObject(bucket, key, contentType, expectedMD5Sum, size, data)
+	// free
+	debug.FreeOSMemory()
+	return objectMetadata, iodine.New(err, nil)
+}
+
+// createObject - PUT object to cache buffer
+func (donut API) createObject(bucket, key, contentType, expectedMD5Sum string, size int64, data io.Reader) (ObjectMetadata, error) {
+	donut.lock.RLock()
+	if !IsValidBucket(bucket) {
+		donut.lock.RUnlock()
+		return ObjectMetadata{}, iodine.New(BucketNameInvalid{Bucket: bucket}, nil)
+	}
+	if !IsValidObjectName(key) {
+		donut.lock.RUnlock()
+		return ObjectMetadata{}, iodine.New(ObjectNameInvalid{Object: key}, nil)
+	}
+	if _, ok := donut.storedBuckets[bucket]; ok == false {
+		donut.lock.RUnlock()
+		return ObjectMetadata{}, iodine.New(BucketNotFound{Bucket: bucket}, nil)
+	}
+	storedBucket := donut.storedBuckets[bucket]
+	// get object key
+	objectKey := bucket + "/" + key
+	if _, ok := storedBucket.objectMetadata[objectKey]; ok == true {
+		donut.lock.RUnlock()
+		return ObjectMetadata{}, iodine.New(ObjectExists{Object: key}, nil)
+	}
+	donut.lock.RUnlock()
+
+	if contentType == "" {
+		contentType = "application/octet-stream"
+	}
+	contentType = strings.TrimSpace(contentType)
+	if strings.TrimSpace(expectedMD5Sum) != "" {
+		expectedMD5SumBytes, err := base64.StdEncoding.DecodeString(strings.TrimSpace(expectedMD5Sum))
+		if err != nil {
+			// pro-actively close the connection
+			return ObjectMetadata{}, iodine.New(InvalidDigest{Md5: expectedMD5Sum}, nil)
+		}
+		expectedMD5Sum = hex.EncodeToString(expectedMD5SumBytes)
+	}
+
+	if len(donut.config.NodeDiskMap) > 0 {
+		objMetadata, err := donut.putObject(bucket, key, expectedMD5Sum, data, map[string]string{"contentType": contentType})
+		if err != nil {
+			return ObjectMetadata{}, iodine.New(err, nil)
+		}
+		donut.lock.Lock()
+		storedBucket.objectMetadata[objectKey] = objMetadata
+		donut.storedBuckets[bucket] = storedBucket
+		donut.lock.Unlock()
+		return objMetadata, nil
+	}
+	// calculate md5
+	hash := md5.New()
+
+	var err error
+	var totalLength int
+	for err == nil {
+		var length int
+		byteBuffer := make([]byte, 1024*1024)
+		length, err = data.Read(byteBuffer)
+		// While hash.Write() wouldn't mind a Nil byteBuffer
+		// It is necessary for us to verify this and break
+		if length == 0 {
+			break
+		}
+		hash.Write(byteBuffer[0:length])
+		//donut.lock.Lock()
+		ok := donut.objects.Append(objectKey, byteBuffer[0:length])
+		//donut.lock.Unlock()
+		if !ok {
+			return ObjectMetadata{}, iodine.New(InternalError{}, nil)
+		}
+		totalLength += length
+		go debug.FreeOSMemory()
+	}
+	if err != io.EOF {
+		return ObjectMetadata{}, iodine.New(err, nil)
+	}
+
+	md5SumBytes := hash.Sum(nil)
+	md5Sum := hex.EncodeToString(md5SumBytes)
+	// Verify if the written object is equal to what is expected, only if it is requested as such
+	if strings.TrimSpace(expectedMD5Sum) != "" {
+		if err := isMD5SumEqual(strings.TrimSpace(expectedMD5Sum), md5Sum); err != nil {
+			return ObjectMetadata{}, iodine.New(BadDigest{}, nil)
+		}
+	}
+
+	m := make(map[string]string)
+	m["contentType"] = contentType
+	newObject := ObjectMetadata{
+		Bucket: bucket,
+		Object: key,
+
+		Metadata: m,
+		Created:  time.Now().UTC(),
+		MD5Sum:   md5Sum,
+		Size:     int64(totalLength),
+	}
+
+	//donut.lock.Lock()
+	storedBucket.objectMetadata[objectKey] = newObject
+	donut.storedBuckets[bucket] = storedBucket
+	//donut.lock.Unlock()
+	return newObject, nil
+}
+
+// MakeBucket - create bucket in cache
+func (donut API) MakeBucket(bucketName, acl string) error {
+	donut.lock.RLock()
+	if len(donut.storedBuckets) == totalBuckets {
+		donut.lock.RUnlock()
+		return iodine.New(TooManyBuckets{Bucket: bucketName}, nil)
+	}
+	if !IsValidBucket(bucketName) {
+		donut.lock.RUnlock()
+		return iodine.New(BucketNameInvalid{Bucket: bucketName}, nil)
+	}
+	if !IsValidBucketACL(acl) {
+		donut.lock.RUnlock()
+		return iodine.New(InvalidACL{ACL: acl}, nil)
+	}
+	if _, ok := donut.storedBuckets[bucketName]; ok == true {
+		donut.lock.RUnlock()
+		return iodine.New(BucketExists{Bucket: bucketName}, nil)
+	}
+	donut.lock.RUnlock()
+
+	if strings.TrimSpace(acl) == "" {
+		// default is private
+		acl = "private"
+	}
+	if len(donut.config.NodeDiskMap) > 0 {
+		if err := donut.makeBucket(bucketName, BucketACL(acl)); err != nil {
+			return iodine.New(err, nil)
+		}
+	}
+	var newBucket = storedBucket{}
+	newBucket.objectMetadata = make(map[string]ObjectMetadata)
+	newBucket.multiPartSession = make(map[string]multiPartSession)
+	newBucket.partMetadata = make(map[string]PartMetadata)
+	newBucket.bucketMetadata = BucketMetadata{}
+	newBucket.bucketMetadata.Name = bucketName
+	newBucket.bucketMetadata.Created = time.Now().UTC()
+	newBucket.bucketMetadata.ACL = BucketACL(acl)
+	//donut.lock.Lock()
+	donut.storedBuckets[bucketName] = newBucket
+	//donut.lock.Unlock()
+	return nil
+}
+
+// ListObjects - list objects from cache
+func (donut API) ListObjects(bucket string, resources BucketResourcesMetadata) ([]ObjectMetadata, BucketResourcesMetadata, error) {
+	donut.lock.RLock()
+	defer donut.lock.RUnlock()
+	if !IsValidBucket(bucket) {
+		return nil, BucketResourcesMetadata{IsTruncated: false}, iodine.New(BucketNameInvalid{Bucket: bucket}, nil)
+	}
+	if !IsValidPrefix(resources.Prefix) {
+		return nil, BucketResourcesMetadata{IsTruncated: false}, iodine.New(ObjectNameInvalid{Object: resources.Prefix}, nil)
+	}
+	if _, ok := donut.storedBuckets[bucket]; ok == false {
+		return nil, BucketResourcesMetadata{IsTruncated: false}, iodine.New(BucketNotFound{Bucket: bucket}, nil)
+	}
+	var results []ObjectMetadata
+	var keys []string
+	if len(donut.config.NodeDiskMap) > 0 {
+		listObjects, err := donut.listObjects(
+			bucket,
+			resources.Prefix,
+			resources.Marker,
+			resources.Delimiter,
+			resources.Maxkeys,
+		)
+		if err != nil {
+			return nil, BucketResourcesMetadata{IsTruncated: false}, iodine.New(err, nil)
+		}
+		resources.CommonPrefixes = listObjects.CommonPrefixes
+		resources.IsTruncated = listObjects.IsTruncated
+		if resources.IsTruncated && resources.IsDelimiterSet() {
+			resources.NextMarker = results[len(results)-1].Object
+		}
+		for key := range listObjects.Objects {
+			keys = append(keys, key)
+		}
+		sort.Strings(keys)
+		for _, key := range keys {
+			results = append(results, listObjects.Objects[key])
+		}
+		return results, resources, nil
+	}
+	storedBucket := donut.storedBuckets[bucket]
+	for key := range storedBucket.objectMetadata {
+		if strings.HasPrefix(key, bucket+"/") {
+			key = key[len(bucket)+1:]
+			if strings.HasPrefix(key, resources.Prefix) {
+				if key > resources.Marker {
+					keys = append(keys, key)
+				}
+			}
+		}
+	}
+	if strings.TrimSpace(resources.Prefix) != "" {
+		keys = TrimPrefix(keys, resources.Prefix)
+	}
+	var prefixes []string
+	var filteredKeys []string
+	if strings.TrimSpace(resources.Delimiter) != "" {
+		filteredKeys = HasNoDelimiter(keys, resources.Delimiter)
+		prefixes = HasDelimiter(keys, resources.Delimiter)
+		prefixes = SplitDelimiter(prefixes, resources.Delimiter)
+		prefixes = SortU(prefixes)
+	} else {
+		filteredKeys = keys
+	}
+	for _, commonPrefix := range prefixes {
+		resources.CommonPrefixes = append(resources.CommonPrefixes, resources.Prefix+commonPrefix)
+	}
+	filteredKeys = RemoveDuplicates(filteredKeys)
+	sort.Strings(filteredKeys)
+
+	for _, key := range filteredKeys {
+		if len(results) == resources.Maxkeys {
+			resources.IsTruncated = true
+			if resources.IsTruncated && resources.IsDelimiterSet() {
+				resources.NextMarker = results[len(results)-1].Object
+			}
+			return results, resources, nil
+		}
+		object := storedBucket.objectMetadata[bucket+"/"+resources.Prefix+key]
+		results = append(results, object)
+	}
+	resources.CommonPrefixes = RemoveDuplicates(resources.CommonPrefixes)
+	sort.Strings(resources.CommonPrefixes)
+	return results, resources, nil
+}
+
+// byBucketName is a type for sorting bucket metadata by bucket name
+type byBucketName []BucketMetadata
+
+func (b byBucketName) Len() int           { return len(b) }
+func (b byBucketName) Swap(i, j int)      { b[i], b[j] = b[j], b[i] }
+func (b byBucketName) Less(i, j int) bool { return b[i].Name < b[j].Name }
+
+// ListBuckets - List buckets from cache
+func (donut API) ListBuckets() ([]BucketMetadata, error) {
+	donut.lock.RLock()
+	defer donut.lock.RUnlock()
+	var results []BucketMetadata
+	for _, bucket := range donut.storedBuckets {
+		results = append(results, bucket.bucketMetadata)
+	}
+	sort.Sort(byBucketName(results))
+	return results, nil
+}
+
+// GetObjectMetadata - get object metadata from cache
+func (donut API) GetObjectMetadata(bucket, key string) (ObjectMetadata, error) {
+	donut.lock.RLock()
+	// check if bucket exists
+	if !IsValidBucket(bucket) {
+		donut.lock.RUnlock()
+		return ObjectMetadata{}, iodine.New(BucketNameInvalid{Bucket: bucket}, nil)
+	}
+	if !IsValidObjectName(key) {
+		donut.lock.RUnlock()
+		return ObjectMetadata{}, iodine.New(ObjectNameInvalid{Object: key}, nil)
+	}
+	if _, ok := donut.storedBuckets[bucket]; ok == false {
+		donut.lock.RUnlock()
+		return ObjectMetadata{}, iodine.New(BucketNotFound{Bucket: bucket}, nil)
+	}
+	storedBucket := donut.storedBuckets[bucket]
+	objectKey := bucket + "/" + key
+	if objMetadata, ok := storedBucket.objectMetadata[objectKey]; ok == true {
+		donut.lock.RUnlock()
+		return objMetadata, nil
+	}
+	if len(donut.config.NodeDiskMap) > 0 {
+		objMetadata, err := donut.getObjectMetadata(bucket, key)
+		donut.lock.RUnlock()
+		if err != nil {
+			return ObjectMetadata{}, iodine.New(err, nil)
+		}
+		// update
+		donut.lock.Lock()
+		storedBucket.objectMetadata[objectKey] = objMetadata
+		donut.lock.Unlock()
+		return objMetadata, nil
+	}
+	donut.lock.RUnlock()
+	return ObjectMetadata{}, iodine.New(ObjectNotFound{Object: key}, nil)
+}
+
+func (donut API) expiredObject(a ...interface{}) {
+	cacheStats := donut.objects.Stats()
+	log.Printf("CurrentSize: %d, CurrentItems: %d, TotalExpirations: %d",
+		cacheStats.Bytes, cacheStats.Items, cacheStats.Expired)
+	key := a[0].(string)
+	// loop through all buckets
+	for _, storedBucket := range donut.storedBuckets {
+		delete(storedBucket.objectMetadata, key)
+	}
+	debug.FreeOSMemory()
+}

pkg/donut/donut-v2_test.go

@@ -0,0 +1,261 @@
+/*
+ * 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 impliedc.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package donut
+
+import (
+	"bytes"
+	"crypto/md5"
+	"encoding/base64"
+	"encoding/hex"
+	"io/ioutil"
+	"testing"
+	"time"
+
+	. "github.com/minio/check"
+)
+
+func TestCache(t *testing.T) { TestingT(t) }
+
+type MyCacheSuite struct{}
+
+var _ = Suite(&MyCacheSuite{})
+
+var dc Interface
+
+func (s *MyCacheSuite) SetUpSuite(c *C) {
+	// test only cache
+	conf := new(Config)
+	conf.DonutName = ""
+	conf.NodeDiskMap = nil
+	conf.Expiration = time.Duration(1 * time.Hour)
+	conf.MaxSize = 100000
+
+	var err error
+	dc, err = New(conf)
+	c.Assert(err, IsNil)
+
+	// testing empty cache
+	buckets, err := dc.ListBuckets()
+	c.Assert(err, IsNil)
+	c.Assert(len(buckets), Equals, 0)
+}
+
+// test make bucket without name
+func (s *MyCacheSuite) TestBucketWithoutNameFails(c *C) {
+	// fail to create new bucket without a name
+	err := dc.MakeBucket("", "private")
+	c.Assert(err, Not(IsNil))
+
+	err = dc.MakeBucket(" ", "private")
+	c.Assert(err, Not(IsNil))
+}
+
+// test empty bucket
+func (s *MyCacheSuite) TestEmptyBucket(c *C) {
+	c.Assert(dc.MakeBucket("foo1", "private"), IsNil)
+	// check if bucket is empty
+	var resources BucketResourcesMetadata
+	resources.Maxkeys = 1
+	objectsMetadata, resources, err := dc.ListObjects("foo1", resources)
+	c.Assert(err, IsNil)
+	c.Assert(len(objectsMetadata), Equals, 0)
+	c.Assert(resources.CommonPrefixes, DeepEquals, []string{})
+	c.Assert(resources.IsTruncated, Equals, false)
+}
+
+// test bucket list
+func (s *MyCacheSuite) TestMakeBucketAndList(c *C) {
+	// create bucket
+	err := dc.MakeBucket("foo2", "private")
+	c.Assert(err, IsNil)
+
+	// check bucket exists
+	buckets, err := dc.ListBuckets()
+	c.Assert(err, IsNil)
+	c.Assert(len(buckets), Equals, 5)
+	c.Assert(buckets[0].ACL, Equals, BucketACL("private"))
+}
+
+// test re-create bucket
+func (s *MyCacheSuite) TestMakeBucketWithSameNameFails(c *C) {
+	err := dc.MakeBucket("foo3", "private")
+	c.Assert(err, IsNil)
+
+	err = dc.MakeBucket("foo3", "private")
+	c.Assert(err, Not(IsNil))
+}
+
+// test make multiple buckets
+func (s *MyCacheSuite) TestCreateMultipleBucketsAndList(c *C) {
+	// add a second bucket
+	err := dc.MakeBucket("foo4", "private")
+	c.Assert(err, IsNil)
+
+	err = dc.MakeBucket("bar1", "private")
+	c.Assert(err, IsNil)
+
+	buckets, err := dc.ListBuckets()
+	c.Assert(err, IsNil)
+
+	c.Assert(len(buckets), Equals, 2)
+	c.Assert(buckets[0].Name, Equals, "bar1")
+	c.Assert(buckets[1].Name, Equals, "foo4")
+
+	err = dc.MakeBucket("foobar1", "private")
+	c.Assert(err, IsNil)
+
+	buckets, err = dc.ListBuckets()
+	c.Assert(err, IsNil)
+
+	c.Assert(len(buckets), Equals, 3)
+	c.Assert(buckets[2].Name, Equals, "foobar1")
+}
+
+// test object create without bucket
+func (s *MyCacheSuite) TestNewObjectFailsWithoutBucket(c *C) {
+	_, err := dc.CreateObject("unknown", "obj", "", 0, nil, nil)
+	c.Assert(err, Not(IsNil))
+}
+
+// test create object metadata
+func (s *MyCacheSuite) TestNewObjectMetadata(c *C) {
+	data := "Hello World"
+	hasher := md5.New()
+	hasher.Write([]byte(data))
+	expectedMd5Sum := base64.StdEncoding.EncodeToString(hasher.Sum(nil))
+	reader := ioutil.NopCloser(bytes.NewReader([]byte(data)))
+
+	err := dc.MakeBucket("foo6", "private")
+	c.Assert(err, IsNil)
+
+	objectMetadata, err := dc.CreateObject("foo6", "obj", expectedMd5Sum, int64(len(data)), reader, map[string]string{"contentType": "application/json"})
+	c.Assert(err, IsNil)
+	c.Assert(objectMetadata.MD5Sum, Equals, hex.EncodeToString(hasher.Sum(nil)))
+	c.Assert(objectMetadata.Metadata["contentType"], Equals, "application/json")
+}
+
+// test create object fails without name
+func (s *MyCacheSuite) TestNewObjectFailsWithEmptyName(c *C) {
+	_, err := dc.CreateObject("foo", "", "", 0, nil, nil)
+	c.Assert(err, Not(IsNil))
+}
+
+// test create object
+func (s *MyCacheSuite) TestNewObjectCanBeWritten(c *C) {
+	err := dc.MakeBucket("foo", "private")
+	c.Assert(err, IsNil)
+
+	data := "Hello World"
+
+	hasher := md5.New()
+	hasher.Write([]byte(data))
+	expectedMd5Sum := base64.StdEncoding.EncodeToString(hasher.Sum(nil))
+	reader := ioutil.NopCloser(bytes.NewReader([]byte(data)))
+
+	actualMetadata, err := dc.CreateObject("foo", "obj", expectedMd5Sum, int64(len(data)), reader, map[string]string{"contentType": "application/octet-stream"})
+	c.Assert(err, IsNil)
+	c.Assert(actualMetadata.MD5Sum, Equals, hex.EncodeToString(hasher.Sum(nil)))
+
+	var buffer bytes.Buffer
+	size, err := dc.GetObject(&buffer, "foo", "obj")
+	c.Assert(err, IsNil)
+	c.Assert(size, Equals, int64(len(data)))
+	c.Assert(buffer.Bytes(), DeepEquals, []byte(data))
+
+	actualMetadata, err = dc.GetObjectMetadata("foo", "obj")
+	c.Assert(err, IsNil)
+	c.Assert(hex.EncodeToString(hasher.Sum(nil)), Equals, actualMetadata.MD5Sum)
+	c.Assert(int64(len(data)), Equals, actualMetadata.Size)
+}
+
+// test list objects
+func (s *MyCacheSuite) TestMultipleNewObjects(c *C) {
+	c.Assert(dc.MakeBucket("foo5", "private"), IsNil)
+
+	one := ioutil.NopCloser(bytes.NewReader([]byte("one")))
+
+	_, err := dc.CreateObject("foo5", "obj1", "", int64(len("one")), one, nil)
+	c.Assert(err, IsNil)
+
+	two := ioutil.NopCloser(bytes.NewReader([]byte("two")))
+	_, err = dc.CreateObject("foo5", "obj2", "", int64(len("two")), two, nil)
+	c.Assert(err, IsNil)
+
+	var buffer1 bytes.Buffer
+	size, err := dc.GetObject(&buffer1, "foo5", "obj1")
+	c.Assert(err, IsNil)
+	c.Assert(size, Equals, int64(len([]byte("one"))))
+	c.Assert(buffer1.Bytes(), DeepEquals, []byte("one"))
+
+	var buffer2 bytes.Buffer
+	size, err = dc.GetObject(&buffer2, "foo5", "obj2")
+	c.Assert(err, IsNil)
+	c.Assert(size, Equals, int64(len([]byte("two"))))
+
+	c.Assert(buffer2.Bytes(), DeepEquals, []byte("two"))
+
+	/// test list of objects
+
+	// test list objects with prefix and delimiter
+	var resources BucketResourcesMetadata
+	resources.Prefix = "o"
+	resources.Delimiter = "1"
+	resources.Maxkeys = 10
+	objectsMetadata, resources, err := dc.ListObjects("foo5", resources)
+	c.Assert(err, IsNil)
+	c.Assert(resources.IsTruncated, Equals, false)
+	c.Assert(resources.CommonPrefixes[0], Equals, "obj1")
+
+	// test list objects with only delimiter
+	resources.Prefix = ""
+	resources.Delimiter = "1"
+	resources.Maxkeys = 10
+	objectsMetadata, resources, err = dc.ListObjects("foo5", resources)
+	c.Assert(err, IsNil)
+	c.Assert(objectsMetadata[0].Object, Equals, "obj2")
+	c.Assert(resources.IsTruncated, Equals, false)
+	c.Assert(resources.CommonPrefixes[0], Equals, "obj1")
+
+	// test list objects with only prefix
+	resources.Prefix = "o"
+	resources.Delimiter = ""
+	resources.Maxkeys = 10
+	objectsMetadata, resources, err = dc.ListObjects("foo5", resources)
+	c.Assert(err, IsNil)
+	c.Assert(resources.IsTruncated, Equals, false)
+	c.Assert(objectsMetadata[0].Object, Equals, "obj1")
+	c.Assert(objectsMetadata[1].Object, Equals, "obj2")
+
+	three := ioutil.NopCloser(bytes.NewReader([]byte("three")))
+	_, err = dc.CreateObject("foo5", "obj3", "", int64(len("three")), three, nil)
+	c.Assert(err, IsNil)
+
+	var buffer bytes.Buffer
+	size, err = dc.GetObject(&buffer, "foo5", "obj3")
+	c.Assert(err, IsNil)
+	c.Assert(size, Equals, int64(len([]byte("three"))))
+	c.Assert(buffer.Bytes(), DeepEquals, []byte("three"))
+
+	// test list objects with maxkeys
+	resources.Prefix = "o"
+	resources.Delimiter = ""
+	resources.Maxkeys = 2
+	objectsMetadata, resources, err = dc.ListObjects("foo5", resources)
+	c.Assert(err, IsNil)
+	c.Assert(resources.IsTruncated, Equals, true)
+	c.Assert(len(objectsMetadata), Equals, 2)
+}

pkg/donut/encoder.go

@@ -0,0 +1,96 @@
+/*
+ * 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 (
+	"strconv"
+
+	encoding "github.com/minio/minio/pkg/erasure"
+	"github.com/minio/minio/pkg/iodine"
+)
+
+// encoder internal struct
+type encoder struct {
+	encoder   *encoding.Erasure
+	k, m      uint8
+	technique encoding.Technique
+}
+
+// getErasureTechnique - convert technique string into Technique type
+func getErasureTechnique(technique string) (encoding.Technique, error) {
+	switch true {
+	case technique == "Cauchy":
+		return encoding.Cauchy, nil
+	case technique == "Vandermonde":
+		return encoding.Cauchy, nil
+	default:
+		return encoding.None, iodine.New(InvalidErasureTechnique{Technique: technique}, nil)
+	}
+}
+
+// newEncoder - instantiate a new encoder
+func newEncoder(k, m uint8, technique string) (encoder, error) {
+	errParams := map[string]string{
+		"k":         strconv.FormatUint(uint64(k), 10),
+		"m":         strconv.FormatUint(uint64(m), 10),
+		"technique": technique,
+	}
+	e := encoder{}
+	t, err := getErasureTechnique(technique)
+	if err != nil {
+		return encoder{}, iodine.New(err, errParams)
+	}
+	params, err := encoding.ValidateParams(k, m, t)
+	if err != nil {
+		return encoder{}, iodine.New(err, errParams)
+	}
+	e.encoder = encoding.NewErasure(params)
+	e.k = k
+	e.m = m
+	e.technique = t
+	return e, nil
+}
+
+// TODO - think again if this is needed
+// GetEncodedBlockLen - wrapper around erasure function with the same name
+func (e encoder) GetEncodedBlockLen(dataLength int) (int, error) {
+	if dataLength <= 0 {
+		return 0, iodine.New(InvalidArgument{}, nil)
+	}
+	return encoding.GetEncodedBlockLen(dataLength, e.k), nil
+}
+
+// Encode - erasure code input bytes
+func (e encoder) Encode(data []byte) (encodedData [][]byte, err error) {
+	if data == nil {
+		return nil, iodine.New(InvalidArgument{}, nil)
+	}
+	encodedData, err = e.encoder.Encode(data)
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	return encodedData, nil
+}
+
+// Decode - erasure decode input encoded bytes
+func (e encoder) Decode(encodedData [][]byte, dataLength int) (data []byte, err error) {
+	decodedData, err := e.encoder.Decode(encodedData, dataLength)
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	return decodedData, nil
+}

pkg/donut/errors.go

@@ -0,0 +1,311 @@
+/*
+ * 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 "fmt"
+
+// InvalidArgument invalid argument
+type InvalidArgument struct{}
+
+func (e InvalidArgument) Error() string {
+	return "Invalid argument"
+}
+
+// UnsupportedFilesystem unsupported filesystem type
+type UnsupportedFilesystem struct {
+	Type string
+}
+
+func (e UnsupportedFilesystem) Error() string {
+	return "Unsupported filesystem: " + e.Type
+}
+
+// BucketNotFound bucket does not exist
+type BucketNotFound struct {
+	Bucket string
+}
+
+func (e BucketNotFound) Error() string {
+	return "Bucket not found: " + e.Bucket
+}
+
+// ObjectExists object exists
+type ObjectExists struct {
+	Object string
+}
+
+func (e ObjectExists) Error() string {
+	return "Object exists: " + e.Object
+}
+
+// ObjectNotFound object does not exist
+type ObjectNotFound struct {
+	Object string
+}
+
+func (e ObjectNotFound) Error() string {
+	return "Object not found: " + e.Object
+}
+
+// ObjectCorrupted object found to be corrupted
+type ObjectCorrupted struct {
+	Object string
+}
+
+func (e ObjectCorrupted) Error() string {
+	return "Object found corrupted: " + e.Object
+}
+
+// BucketExists bucket exists
+type BucketExists struct {
+	Bucket string
+}
+
+func (e BucketExists) Error() string {
+	return "Bucket exists: " + e.Bucket
+}
+
+// CorruptedBackend backend found to be corrupted
+type CorruptedBackend struct {
+	Backend string
+}
+
+func (e CorruptedBackend) Error() string {
+	return "Corrupted backend: " + e.Backend
+}
+
+// NotImplemented function not implemented
+type NotImplemented struct {
+	Function string
+}
+
+func (e NotImplemented) Error() string {
+	return "Not implemented: " + e.Function
+}
+
+// InvalidDisksArgument invalid number of disks per node
+type InvalidDisksArgument struct{}
+
+func (e InvalidDisksArgument) Error() string {
+	return "Invalid number of disks per node"
+}
+
+// BadDigest bad md5sum
+type BadDigest struct{}
+
+func (e BadDigest) Error() string {
+	return "Bad digest"
+}
+
+// ParityOverflow parity over flow
+type ParityOverflow struct{}
+
+func (e ParityOverflow) Error() string {
+	return "Parity overflow"
+}
+
+// ChecksumMismatch checksum mismatch
+type ChecksumMismatch struct{}
+
+func (e ChecksumMismatch) Error() string {
+	return "Checksum mismatch"
+}
+
+// MissingErasureTechnique missing erasure technique
+type MissingErasureTechnique struct{}
+
+func (e MissingErasureTechnique) Error() string {
+	return "Missing erasure technique"
+}
+
+// InvalidErasureTechnique invalid erasure technique
+type InvalidErasureTechnique struct {
+	Technique string
+}
+
+func (e InvalidErasureTechnique) Error() string {
+	return "Invalid erasure technique: " + e.Technique
+}
+
+// InternalError - generic internal error
+type InternalError struct {
+}
+
+// BackendError - generic disk backend error
+type BackendError struct {
+	Path string
+}
+
+// BackendCorrupted - path has corrupted data
+type BackendCorrupted BackendError
+
+// APINotImplemented - generic API not implemented error
+type APINotImplemented struct {
+	API string
+}
+
+// GenericBucketError - generic bucket error
+type GenericBucketError struct {
+	Bucket string
+}
+
+// GenericObjectError - generic object error
+type GenericObjectError struct {
+	Bucket string
+	Object string
+}
+
+// ImplementationError - generic implementation error
+type ImplementationError struct {
+	Bucket string
+	Object string
+	Err    error
+}
+
+// DigestError - Generic Md5 error
+type DigestError struct {
+	Bucket string
+	Key    string
+	Md5    string
+}
+
+/// ACL related errors
+
+// InvalidACL - acl invalid
+type InvalidACL struct {
+	ACL string
+}
+
+func (e InvalidACL) Error() string {
+	return "Requested ACL is " + e.ACL + " invalid"
+}
+
+/// Bucket related errors
+
+// BucketNameInvalid - bucketname provided is invalid
+type BucketNameInvalid GenericBucketError
+
+// TooManyBuckets - total buckets exceeded
+type TooManyBuckets GenericBucketError
+
+/// Object related errors
+
+// EntityTooLarge - object size exceeds maximum limit
+type EntityTooLarge struct {
+	GenericObjectError
+	Size    string
+	MaxSize string
+}
+
+// ObjectNameInvalid - object name provided is invalid
+type ObjectNameInvalid GenericObjectError
+
+// InvalidDigest - md5 in request header invalid
+type InvalidDigest DigestError
+
+// Return string an error formatted as the given text
+func (e ImplementationError) Error() string {
+	error := ""
+	if e.Bucket != "" {
+		error = error + "Bucket: " + e.Bucket + " "
+	}
+	if e.Object != "" {
+		error = error + "Object: " + e.Object + " "
+	}
+	error = error + "Error: " + e.Err.Error()
+	return error
+}
+
+// EmbedError - wrapper function for error object
+func EmbedError(bucket, object string, err error) ImplementationError {
+	return ImplementationError{
+		Bucket: bucket,
+		Object: object,
+		Err:    err,
+	}
+}
+
+// Return string an error formatted as the given text
+func (e InternalError) Error() string {
+	return "Internal error occured"
+}
+
+// Return string an error formatted as the given text
+func (e APINotImplemented) Error() string {
+	return "Api not implemented: " + e.API
+}
+
+// Return string an error formatted as the given text
+func (e BucketNameInvalid) Error() string {
+	return "Bucket name invalid: " + e.Bucket
+}
+
+// Return string an error formatted as the given text
+func (e TooManyBuckets) Error() string {
+	return "Bucket limit exceeded beyond 100, cannot create bucket: " + e.Bucket
+}
+
+// Return string an error formatted as the given text
+func (e ObjectNameInvalid) Error() string {
+	return "Object name invalid: " + e.Bucket + "#" + e.Object
+}
+
+// Return string an error formatted as the given text
+func (e EntityTooLarge) Error() string {
+	return e.Bucket + "#" + e.Object + "with " + e.Size + "reached maximum allowed size limit " + e.MaxSize
+}
+
+// Return string an error formatted as the given text
+func (e BackendCorrupted) Error() string {
+	return "Backend corrupted: " + e.Path
+}
+
+// Return string an error formatted as the given text
+func (e InvalidDigest) Error() string {
+	return "Md5 provided " + e.Md5 + " is invalid"
+}
+
+// OperationNotPermitted - operation not permitted
+type OperationNotPermitted struct {
+	Op     string
+	Reason string
+}
+
+func (e OperationNotPermitted) Error() string {
+	return "Operation " + e.Op + " not permitted for reason: " + e.Reason
+}
+
+// InvalidRange - invalid range
+type InvalidRange struct {
+	Start  int64
+	Length int64
+}
+
+func (e InvalidRange) Error() string {
+	return fmt.Sprintf("Invalid range start:%d length:%d", e.Start, e.Length)
+}
+
+/// Multipart related errors
+
+// InvalidUploadID invalid upload id
+type InvalidUploadID struct {
+	UploadID string
+}
+
+func (e InvalidUploadID) Error() string {
+	return "Invalid upload id " + e.UploadID
+}

pkg/donut/interfaces.go

@@ -0,0 +1,70 @@
+/*
+ * 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 "io"
+
+// Collection of Donut specification interfaces
+
+// Interface is a collection of object storage and management interface
+type Interface interface {
+	ObjectStorage
+	Management
+}
+
+// ObjectStorage is a donut object storage interface
+type ObjectStorage interface {
+	// Storage service operations
+	GetBucketMetadata(bucket string) (BucketMetadata, error)
+	SetBucketMetadata(bucket string, metadata map[string]string) error
+	ListBuckets() ([]BucketMetadata, error)
+	MakeBucket(bucket string, ACL string) error
+
+	// Bucket operations
+	ListObjects(bucket string, resources BucketResourcesMetadata) ([]ObjectMetadata, BucketResourcesMetadata, error)
+
+	// Object operations
+	GetObject(w io.Writer, bucket, object string) (int64, error)
+	GetPartialObject(w io.Writer, bucket, object string, start, length int64) (int64, error)
+	GetObjectMetadata(bucket, object string) (ObjectMetadata, error)
+	CreateObject(bucket, object, expectedMD5Sum string, size int64, reader io.Reader, metadata map[string]string) (ObjectMetadata, error)
+
+	Multipart
+}
+
+// Multipart API
+type Multipart interface {
+	NewMultipartUpload(bucket, key, contentType string) (string, error)
+	AbortMultipartUpload(bucket, key, uploadID string) error
+	CreateObjectPart(bucket, key, uploadID string, partID int, contentType, expectedMD5Sum string, size int64, data io.Reader) (string, error)
+	CompleteMultipartUpload(bucket, key, uploadID string, parts map[int]string) (ObjectMetadata, error)
+	ListMultipartUploads(bucket string, resources BucketMultipartResourcesMetadata) (BucketMultipartResourcesMetadata, error)
+	ListObjectParts(bucket, key string, resources ObjectResourcesMetadata) (ObjectResourcesMetadata, error)
+}
+
+// Management is a donut management system interface
+type Management interface {
+	Heal() error
+	Rebalance() error
+	Info() (map[string][]string, error)
+
+	AttachNode(hostname string, disks []string) error
+	DetachNode(hostname string) error
+
+	SaveConfig() error
+	LoadConfig() error
+}

pkg/donut/management.go

@@ -0,0 +1,108 @@
+/*
+ * 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"
+	"path/filepath"
+
+	"github.com/minio/minio/pkg/donut/disk"
+	"github.com/minio/minio/pkg/iodine"
+)
+
+// Heal - heal a donut and fix bad data blocks
+func (donut API) Heal() error {
+	return iodine.New(NotImplemented{Function: "Heal"}, nil)
+}
+
+// Info - return info about donut configuration
+func (donut API) Info() (nodeDiskMap map[string][]string, err error) {
+	nodeDiskMap = make(map[string][]string)
+	for nodeName, node := range donut.nodes {
+		disks, err := node.ListDisks()
+		if err != nil {
+			return nil, iodine.New(err, nil)
+		}
+		diskList := make([]string, len(disks))
+		for diskOrder, disk := range disks {
+			diskList[diskOrder] = disk.GetPath()
+		}
+		nodeDiskMap[nodeName] = diskList
+	}
+	return nodeDiskMap, nil
+}
+
+// AttachNode - attach node
+func (donut API) AttachNode(hostname string, disks []string) error {
+	if hostname == "" || len(disks) == 0 {
+		return iodine.New(InvalidArgument{}, nil)
+	}
+	node, err := newNode(hostname)
+	if err != nil {
+		return iodine.New(err, nil)
+	}
+	donut.nodes[hostname] = node
+	for i, d := range disks {
+		newDisk, err := disk.New(d)
+		if err != nil {
+			return iodine.New(err, nil)
+		}
+		if err := newDisk.MakeDir(donut.config.DonutName); err != nil {
+			return iodine.New(err, nil)
+		}
+		if err := node.AttachDisk(newDisk, i); err != nil {
+			return iodine.New(err, nil)
+		}
+	}
+	return nil
+}
+
+// DetachNode - detach node
+func (donut API) DetachNode(hostname string) error {
+	delete(donut.nodes, hostname)
+	return nil
+}
+
+// SaveConfig - save donut configuration
+func (donut API) SaveConfig() error {
+	nodeDiskMap := make(map[string][]string)
+	for hostname, node := range donut.nodes {
+		disks, err := node.ListDisks()
+		if err != nil {
+			return iodine.New(err, nil)
+		}
+		for order, disk := range disks {
+			donutConfigPath := filepath.Join(donut.config.DonutName, donutConfig)
+			donutConfigWriter, err := disk.CreateFile(donutConfigPath)
+			defer donutConfigWriter.Close()
+			if err != nil {
+				return iodine.New(err, nil)
+			}
+			nodeDiskMap[hostname][order] = disk.GetPath()
+			jenc := json.NewEncoder(donutConfigWriter)
+			if err := jenc.Encode(nodeDiskMap); err != nil {
+				return iodine.New(err, nil)
+			}
+		}
+	}
+	return nil
+}
+
+// LoadConfig - load configuration
+func (donut API) LoadConfig() error {
+	return iodine.New(NotImplemented{Function: "LoadConfig"}, nil)
+}

pkg/donut/multipart.go

@@ -0,0 +1,405 @@
+/*
+ * 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 (
+	"bytes"
+	"crypto/md5"
+	"crypto/sha512"
+	"encoding/base64"
+	"encoding/hex"
+	"errors"
+	"io"
+	"math/rand"
+	"runtime/debug"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/minio/minio/pkg/iodine"
+)
+
+// NewMultipartUpload -
+func (donut API) NewMultipartUpload(bucket, key, contentType string) (string, error) {
+	donut.lock.RLock()
+	if !IsValidBucket(bucket) {
+		donut.lock.RUnlock()
+		return "", iodine.New(BucketNameInvalid{Bucket: bucket}, nil)
+	}
+	if !IsValidObjectName(key) {
+		donut.lock.RUnlock()
+		return "", iodine.New(ObjectNameInvalid{Object: key}, nil)
+	}
+	if _, ok := donut.storedBuckets[bucket]; ok == false {
+		donut.lock.RUnlock()
+		return "", iodine.New(BucketNotFound{Bucket: bucket}, nil)
+	}
+	storedBucket := donut.storedBuckets[bucket]
+	objectKey := bucket + "/" + key
+	if _, ok := storedBucket.objectMetadata[objectKey]; ok == true {
+		donut.lock.RUnlock()
+		return "", iodine.New(ObjectExists{Object: key}, nil)
+	}
+	donut.lock.RUnlock()
+
+	//donut.lock.Lock()
+	id := []byte(strconv.FormatInt(rand.Int63(), 10) + bucket + key + time.Now().String())
+	uploadIDSum := sha512.Sum512(id)
+	uploadID := base64.URLEncoding.EncodeToString(uploadIDSum[:])[:47]
+
+	donut.storedBuckets[bucket].multiPartSession[key] = multiPartSession{
+		uploadID:   uploadID,
+		initiated:  time.Now(),
+		totalParts: 0,
+	}
+	//donut.lock.Unlock()
+
+	return uploadID, nil
+}
+
+// AbortMultipartUpload -
+func (donut API) AbortMultipartUpload(bucket, key, uploadID string) error {
+	donut.lock.RLock()
+	storedBucket := donut.storedBuckets[bucket]
+	if storedBucket.multiPartSession[key].uploadID != uploadID {
+		donut.lock.RUnlock()
+		return iodine.New(InvalidUploadID{UploadID: uploadID}, nil)
+	}
+	donut.lock.RUnlock()
+
+	donut.cleanupMultiparts(bucket, key, uploadID)
+	donut.cleanupMultipartSession(bucket, key, uploadID)
+	return nil
+}
+
+func getMultipartKey(key string, uploadID string, partNumber int) string {
+	return key + "?uploadId=" + uploadID + "&partNumber=" + strconv.Itoa(partNumber)
+}
+
+// CreateObjectPart -
+func (donut API) CreateObjectPart(bucket, key, uploadID string, partID int, contentType, expectedMD5Sum string, size int64, data io.Reader) (string, error) {
+	// Verify upload id
+	donut.lock.RLock()
+	storedBucket := donut.storedBuckets[bucket]
+	if storedBucket.multiPartSession[key].uploadID != uploadID {
+		donut.lock.RUnlock()
+		return "", iodine.New(InvalidUploadID{UploadID: uploadID}, nil)
+	}
+	donut.lock.RUnlock()
+
+	etag, err := donut.createObjectPart(bucket, key, uploadID, partID, "", expectedMD5Sum, size, data)
+	if err != nil {
+		return "", iodine.New(err, nil)
+	}
+	// free
+	debug.FreeOSMemory()
+	return etag, nil
+}
+
+// createObject - PUT object to cache buffer
+func (donut API) createObjectPart(bucket, key, uploadID string, partID int, contentType, expectedMD5Sum string, size int64, data io.Reader) (string, error) {
+	donut.lock.RLock()
+	if !IsValidBucket(bucket) {
+		donut.lock.RUnlock()
+		return "", iodine.New(BucketNameInvalid{Bucket: bucket}, nil)
+	}
+	if !IsValidObjectName(key) {
+		donut.lock.RUnlock()
+		return "", iodine.New(ObjectNameInvalid{Object: key}, nil)
+	}
+	if _, ok := donut.storedBuckets[bucket]; ok == false {
+		donut.lock.RUnlock()
+		return "", iodine.New(BucketNotFound{Bucket: bucket}, nil)
+	}
+	storedBucket := donut.storedBuckets[bucket]
+	// get object key
+	partKey := bucket + "/" + getMultipartKey(key, uploadID, partID)
+	if _, ok := storedBucket.partMetadata[partKey]; ok == true {
+		donut.lock.RUnlock()
+		return storedBucket.partMetadata[partKey].ETag, nil
+	}
+	donut.lock.RUnlock()
+
+	if contentType == "" {
+		contentType = "application/octet-stream"
+	}
+	contentType = strings.TrimSpace(contentType)
+	if strings.TrimSpace(expectedMD5Sum) != "" {
+		expectedMD5SumBytes, err := base64.StdEncoding.DecodeString(strings.TrimSpace(expectedMD5Sum))
+		if err != nil {
+			// pro-actively close the connection
+			return "", iodine.New(InvalidDigest{Md5: expectedMD5Sum}, nil)
+		}
+		expectedMD5Sum = hex.EncodeToString(expectedMD5SumBytes)
+	}
+
+	// calculate md5
+	hash := md5.New()
+	var readBytes []byte
+
+	var err error
+	var length int
+	for err == nil {
+		byteBuffer := make([]byte, 1024*1024)
+		length, err = data.Read(byteBuffer)
+		// While hash.Write() wouldn't mind a Nil byteBuffer
+		// It is necessary for us to verify this and break
+		if length == 0 {
+			break
+		}
+		hash.Write(byteBuffer[0:length])
+		readBytes = append(readBytes, byteBuffer[0:length]...)
+	}
+	if err != io.EOF {
+		return "", iodine.New(err, nil)
+	}
+	go debug.FreeOSMemory()
+	md5SumBytes := hash.Sum(nil)
+	totalLength := int64(len(readBytes))
+
+	//donut.lock.Lock()
+	donut.multiPartObjects.Set(partKey, readBytes)
+	//donut.lock.Unlock()
+	// setting up for de-allocation
+	readBytes = nil
+
+	md5Sum := hex.EncodeToString(md5SumBytes)
+	// Verify if the written object is equal to what is expected, only if it is requested as such
+	if strings.TrimSpace(expectedMD5Sum) != "" {
+		if err := isMD5SumEqual(strings.TrimSpace(expectedMD5Sum), md5Sum); err != nil {
+			return "", iodine.New(BadDigest{}, nil)
+		}
+	}
+	newPart := PartMetadata{
+		PartNumber:   partID,
+		LastModified: time.Now().UTC(),
+		ETag:         md5Sum,
+		Size:         totalLength,
+	}
+
+	//donut.lock.Lock()
+	storedBucket.partMetadata[partKey] = newPart
+	multiPartSession := storedBucket.multiPartSession[key]
+	multiPartSession.totalParts++
+	storedBucket.multiPartSession[key] = multiPartSession
+	donut.storedBuckets[bucket] = storedBucket
+	//donut.lock.Unlock()
+
+	return md5Sum, nil
+}
+
+func (donut API) cleanupMultipartSession(bucket, key, uploadID string) {
+	//	donut.lock.Lock()
+	//	defer donut.lock.Unlock()
+	delete(donut.storedBuckets[bucket].multiPartSession, key)
+}
+
+func (donut API) cleanupMultiparts(bucket, key, uploadID string) {
+	for i := 1; i <= donut.storedBuckets[bucket].multiPartSession[key].totalParts; i++ {
+		objectKey := bucket + "/" + getMultipartKey(key, uploadID, i)
+		donut.multiPartObjects.Delete(objectKey)
+	}
+}
+
+// CompleteMultipartUpload -
+func (donut API) CompleteMultipartUpload(bucket, key, uploadID string, parts map[int]string) (ObjectMetadata, error) {
+	if !IsValidBucket(bucket) {
+		return ObjectMetadata{}, iodine.New(BucketNameInvalid{Bucket: bucket}, nil)
+	}
+	if !IsValidObjectName(key) {
+		return ObjectMetadata{}, iodine.New(ObjectNameInvalid{Object: key}, nil)
+	}
+	// Verify upload id
+	donut.lock.RLock()
+	if _, ok := donut.storedBuckets[bucket]; ok == false {
+		donut.lock.RUnlock()
+		return ObjectMetadata{}, iodine.New(BucketNotFound{Bucket: bucket}, nil)
+	}
+	storedBucket := donut.storedBuckets[bucket]
+	if storedBucket.multiPartSession[key].uploadID != uploadID {
+		donut.lock.RUnlock()
+		return ObjectMetadata{}, iodine.New(InvalidUploadID{UploadID: uploadID}, nil)
+	}
+	donut.lock.RUnlock()
+
+	//donut.lock.Lock()
+	var size int64
+	var fullObject bytes.Buffer
+	for i := 1; i <= len(parts); i++ {
+		recvMD5 := parts[i]
+		object, ok := donut.multiPartObjects.Get(bucket + "/" + getMultipartKey(key, uploadID, i))
+		if ok == false {
+			donut.lock.Unlock()
+			return ObjectMetadata{}, iodine.New(errors.New("missing part: "+strconv.Itoa(i)), nil)
+		}
+		size += int64(len(object))
+		calcMD5Bytes := md5.Sum(object)
+		// complete multi part request header md5sum per part is hex encoded
+		recvMD5Bytes, err := hex.DecodeString(strings.Trim(recvMD5, "\""))
+		if err != nil {
+			return ObjectMetadata{}, iodine.New(InvalidDigest{Md5: recvMD5}, nil)
+		}
+		if !bytes.Equal(recvMD5Bytes, calcMD5Bytes[:]) {
+			return ObjectMetadata{}, iodine.New(BadDigest{}, nil)
+		}
+		_, err = io.Copy(&fullObject, bytes.NewBuffer(object))
+		if err != nil {
+			return ObjectMetadata{}, iodine.New(err, nil)
+		}
+		object = nil
+		go debug.FreeOSMemory()
+	}
+	//donut.lock.Unlock()
+
+	md5sumSlice := md5.Sum(fullObject.Bytes())
+	// this is needed for final verification inside CreateObject, do not convert this to hex
+	md5sum := base64.StdEncoding.EncodeToString(md5sumSlice[:])
+	objectMetadata, err := donut.CreateObject(bucket, key, md5sum, size, &fullObject, nil)
+	if err != nil {
+		// No need to call internal cleanup functions here, caller will call AbortMultipartUpload()
+		// which would in-turn cleanup properly in accordance with S3 Spec
+		return ObjectMetadata{}, iodine.New(err, nil)
+	}
+	fullObject.Reset()
+	donut.cleanupMultiparts(bucket, key, uploadID)
+	donut.cleanupMultipartSession(bucket, key, uploadID)
+	return objectMetadata, nil
+}
+
+// byKey is a sortable interface for UploadMetadata slice
+type byKey []*UploadMetadata
+
+func (a byKey) Len() int           { return len(a) }
+func (a byKey) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a byKey) Less(i, j int) bool { return a[i].Key < a[j].Key }
+
+// ListMultipartUploads -
+func (donut API) ListMultipartUploads(bucket string, resources BucketMultipartResourcesMetadata) (BucketMultipartResourcesMetadata, error) {
+	// TODO handle delimiter
+	donut.lock.RLock()
+	defer donut.lock.RUnlock()
+	if _, ok := donut.storedBuckets[bucket]; ok == false {
+		return BucketMultipartResourcesMetadata{}, iodine.New(BucketNotFound{Bucket: bucket}, nil)
+	}
+	storedBucket := donut.storedBuckets[bucket]
+	var uploads []*UploadMetadata
+
+	for key, session := range storedBucket.multiPartSession {
+		if strings.HasPrefix(key, resources.Prefix) {
+			if len(uploads) > resources.MaxUploads {
+				sort.Sort(byKey(uploads))
+				resources.Upload = uploads
+				resources.NextKeyMarker = key
+				resources.NextUploadIDMarker = session.uploadID
+				resources.IsTruncated = true
+				return resources, nil
+			}
+			// uploadIDMarker is ignored if KeyMarker is empty
+			switch {
+			case resources.KeyMarker != "" && resources.UploadIDMarker == "":
+				if key > resources.KeyMarker {
+					upload := new(UploadMetadata)
+					upload.Key = key
+					upload.UploadID = session.uploadID
+					upload.Initiated = session.initiated
+					uploads = append(uploads, upload)
+				}
+			case resources.KeyMarker != "" && resources.UploadIDMarker != "":
+				if session.uploadID > resources.UploadIDMarker {
+					if key >= resources.KeyMarker {
+						upload := new(UploadMetadata)
+						upload.Key = key
+						upload.UploadID = session.uploadID
+						upload.Initiated = session.initiated
+						uploads = append(uploads, upload)
+					}
+				}
+			default:
+				upload := new(UploadMetadata)
+				upload.Key = key
+				upload.UploadID = session.uploadID
+				upload.Initiated = session.initiated
+				uploads = append(uploads, upload)
+			}
+		}
+	}
+	sort.Sort(byKey(uploads))
+	resources.Upload = uploads
+	return resources, nil
+}
+
+// partNumber is a sortable interface for Part slice
+type partNumber []*PartMetadata
+
+func (a partNumber) Len() int           { return len(a) }
+func (a partNumber) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+func (a partNumber) Less(i, j int) bool { return a[i].PartNumber < a[j].PartNumber }
+
+// ListObjectParts -
+func (donut API) ListObjectParts(bucket, key string, resources ObjectResourcesMetadata) (ObjectResourcesMetadata, error) {
+	// Verify upload id
+	donut.lock.RLock()
+	defer donut.lock.RUnlock()
+	if _, ok := donut.storedBuckets[bucket]; ok == false {
+		return ObjectResourcesMetadata{}, iodine.New(BucketNotFound{Bucket: bucket}, nil)
+	}
+	storedBucket := donut.storedBuckets[bucket]
+	if _, ok := storedBucket.multiPartSession[key]; ok == false {
+		return ObjectResourcesMetadata{}, iodine.New(ObjectNotFound{Object: key}, nil)
+	}
+	if storedBucket.multiPartSession[key].uploadID != resources.UploadID {
+		return ObjectResourcesMetadata{}, iodine.New(InvalidUploadID{UploadID: resources.UploadID}, nil)
+	}
+	objectResourcesMetadata := resources
+	objectResourcesMetadata.Bucket = bucket
+	objectResourcesMetadata.Key = key
+	var parts []*PartMetadata
+	var startPartNumber int
+	switch {
+	case objectResourcesMetadata.PartNumberMarker == 0:
+		startPartNumber = 1
+	default:
+		startPartNumber = objectResourcesMetadata.PartNumberMarker
+	}
+	for i := startPartNumber; i <= storedBucket.multiPartSession[key].totalParts; i++ {
+		if len(parts) > objectResourcesMetadata.MaxParts {
+			sort.Sort(partNumber(parts))
+			objectResourcesMetadata.IsTruncated = true
+			objectResourcesMetadata.Part = parts
+			objectResourcesMetadata.NextPartNumberMarker = i
+			return objectResourcesMetadata, nil
+		}
+		part, ok := storedBucket.partMetadata[bucket+"/"+getMultipartKey(key, resources.UploadID, i)]
+		if !ok {
+			return ObjectResourcesMetadata{}, iodine.New(errors.New("missing part: "+strconv.Itoa(i)), nil)
+		}
+		parts = append(parts, &part)
+	}
+	sort.Sort(partNumber(parts))
+	objectResourcesMetadata.Part = parts
+	return objectResourcesMetadata, nil
+}
+
+func (donut API) expiredPart(a ...interface{}) {
+	key := a[0].(string)
+	// loop through all buckets
+	for _, storedBucket := range donut.storedBuckets {
+		delete(storedBucket.partMetadata, key)
+	}
+	debug.FreeOSMemory()
+}

pkg/donut/node.go

@@ -0,0 +1,76 @@
+/*
+ * 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 (
+	"github.com/minio/minio/pkg/donut/disk"
+	"github.com/minio/minio/pkg/iodine"
+)
+
+// node struct internal
+type node struct {
+	hostname string
+	disks    map[int]disk.Disk
+}
+
+// newNode - instantiates a new node
+func newNode(hostname string) (node, error) {
+	if hostname == "" {
+		return node{}, iodine.New(InvalidArgument{}, nil)
+	}
+	disks := make(map[int]disk.Disk)
+	n := node{
+		hostname: hostname,
+		disks:    disks,
+	}
+	return n, nil
+}
+
+// GetHostname - return hostname
+func (n node) GetHostname() string {
+	return n.hostname
+}
+
+// ListDisks - return number of disks
+func (n node) ListDisks() (map[int]disk.Disk, error) {
+	return n.disks, nil
+}
+
+// AttachDisk - attach a disk
+func (n node) AttachDisk(disk disk.Disk, diskOrder int) error {
+	if diskOrder < 0 {
+		return iodine.New(InvalidArgument{}, nil)
+	}
+	n.disks[diskOrder] = disk
+	return nil
+}
+
+// DetachDisk - detach a disk
+func (n node) DetachDisk(diskOrder int) error {
+	delete(n.disks, diskOrder)
+	return nil
+}
+
+// SaveConfig - save node configuration
+func (n node) SaveConfig() error {
+	return iodine.New(NotImplemented{Function: "SaveConfig"}, nil)
+}
+
+// LoadConfig - load node configuration from saved configs
+func (n node) LoadConfig() error {
+	return iodine.New(NotImplemented{Function: "LoadConfig"}, nil)
+}

pkg/donut/rebalance.go

@@ -0,0 +1,57 @@
+/*
+ * 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 (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/minio/minio/pkg/donut/disk"
+	"github.com/minio/minio/pkg/iodine"
+)
+
+// Rebalance -
+func (donut API) Rebalance() error {
+	var totalOffSetLength int
+	var newDisks []disk.Disk
+	var existingDirs []os.FileInfo
+	for _, node := range donut.nodes {
+		disks, err := node.ListDisks()
+		if err != nil {
+			return iodine.New(err, nil)
+		}
+		totalOffSetLength = len(disks)
+		fmt.Println(totalOffSetLength)
+		for _, disk := range disks {
+			dirs, err := disk.ListDir(donut.config.DonutName)
+			if err != nil {
+				return iodine.New(err, nil)
+			}
+			if len(dirs) == 0 {
+				newDisks = append(newDisks, disk)
+			}
+			existingDirs = append(existingDirs, dirs...)
+		}
+	}
+	for _, dir := range existingDirs {
+		splits := strings.Split(dir.Name(), "$")
+		bucketName, segment, offset := splits[0], splits[1], splits[2]
+		fmt.Println(bucketName, segment, offset)
+	}
+	return nil
+}

pkg/donut/trove/trove.go

@@ -0,0 +1,226 @@
+/*
+ * 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 trove implements in memory caching methods
+package trove
+
+import (
+	"sync"
+	"time"
+)
+
+var noExpiration = time.Duration(0)
+
+// Cache holds the required variables to compose an in memory cache system
+// which also provides expiring key mechanism and also maxSize
+type Cache struct {
+	// Mutex is used for handling the concurrent
+	// read/write requests for cache
+	sync.Mutex
+
+	// items hold the cached objects
+	items map[string][]byte
+
+	// updatedAt holds the time that related item's updated at
+	updatedAt map[string]time.Time
+
+	// expiration is a duration for a cache key to expire
+	expiration time.Duration
+
+	// stopExpireTimer channel to quit the timer thread
+	stopExpireTimer chan struct{}
+
+	// maxSize is a total size for overall cache
+	maxSize uint64
+
+	// currentSize is a current size in memory
+	currentSize uint64
+
+	// OnExpired - callback function for eviction
+	OnExpired func(a ...interface{})
+
+	// totalExpired counter to keep track of total expirations
+	totalExpired uint64
+}
+
+// Stats current cache statistics
+type Stats struct {
+	Bytes   uint64
+	Items   uint64
+	Expired uint64
+}
+
+// NewCache creates an inmemory cache
+//
+// maxSize is used for expiring objects before we run out of memory
+// expiration is used for expiration of a key from cache
+func NewCache(maxSize uint64, expiration time.Duration) *Cache {
+	return &Cache{
+		items:      make(map[string][]byte),
+		updatedAt:  map[string]time.Time{},
+		expiration: expiration,
+		maxSize:    maxSize,
+	}
+}
+
+// Stats get current cache statistics
+func (r *Cache) Stats() Stats {
+	return Stats{
+		Bytes:   r.currentSize,
+		Items:   uint64(len(r.items)),
+		Expired: r.totalExpired,
+	}
+}
+
+// ExpireObjects expire objects in go routine
+func (r *Cache) ExpireObjects(gcInterval time.Duration) {
+	r.stopExpireTimer = make(chan struct{})
+	ticker := time.NewTicker(gcInterval)
+	go func() {
+		for {
+			select {
+			case <-ticker.C:
+				r.Expire()
+			case <-r.stopExpireTimer:
+				ticker.Stop()
+				return
+			}
+
+		}
+	}()
+}
+
+// Get returns a value of a given key if it exists
+func (r *Cache) Get(key string) ([]byte, bool) {
+	r.Lock()
+	defer r.Unlock()
+	value, ok := r.items[key]
+	if !ok {
+		return nil, false
+	}
+	r.updatedAt[key] = time.Now()
+	return value, true
+}
+
+// Len returns length of the value of a given key, returns zero if key doesn't exist
+func (r *Cache) Len(key string) int {
+	r.Lock()
+	defer r.Unlock()
+	_, ok := r.items[key]
+	if !ok {
+		return 0
+	}
+	return len(r.items[key])
+}
+
+// Append will append new data to an existing key,
+// if key doesn't exist it behaves like Set()
+func (r *Cache) Append(key string, value []byte) bool {
+	r.Lock()
+	defer r.Unlock()
+	valueLen := uint64(len(value))
+	if r.maxSize > 0 {
+		// check if the size of the object is not bigger than the
+		// capacity of the cache
+		if valueLen > r.maxSize {
+			return false
+		}
+		// remove random key if only we reach the maxSize threshold
+		for (r.currentSize + valueLen) > r.maxSize {
+			for randomKey := range r.items {
+				r.doDelete(randomKey)
+				break
+			}
+		}
+	}
+	_, ok := r.items[key]
+	if !ok {
+		r.items[key] = value
+		r.currentSize += valueLen
+		r.updatedAt[key] = time.Now()
+		return true
+	}
+	r.items[key] = append(r.items[key], value...)
+	r.currentSize += valueLen
+	r.updatedAt[key] = time.Now()
+	return true
+}
+
+// Set will persist a value to the cache
+func (r *Cache) Set(key string, value []byte) bool {
+	r.Lock()
+	defer r.Unlock()
+	valueLen := uint64(len(value))
+	if r.maxSize > 0 {
+		// check if the size of the object is not bigger than the
+		// capacity of the cache
+		if valueLen > r.maxSize {
+			return false
+		}
+		// remove random key if only we reach the maxSize threshold
+		for (r.currentSize + valueLen) > r.maxSize {
+			for randomKey := range r.items {
+				r.doDelete(randomKey)
+				break
+			}
+		}
+	}
+	r.items[key] = value
+	r.currentSize += valueLen
+	r.updatedAt[key] = time.Now()
+	return true
+}
+
+// Expire expires keys which have expired
+func (r *Cache) Expire() {
+	r.Lock()
+	defer r.Unlock()
+	for key := range r.items {
+		if !r.isValid(key) {
+			r.doDelete(key)
+		}
+	}
+}
+
+// Delete deletes a given key if exists
+func (r *Cache) Delete(key string) {
+	r.Lock()
+	defer r.Unlock()
+	r.doDelete(key)
+}
+
+func (r *Cache) doDelete(key string) {
+	if _, ok := r.items[key]; ok {
+		r.currentSize -= uint64(len(r.items[key]))
+		delete(r.items, key)
+		delete(r.updatedAt, key)
+		r.totalExpired++
+		if r.OnExpired != nil {
+			r.OnExpired(key)
+		}
+	}
+}
+
+func (r *Cache) isValid(key string) bool {
+	updatedAt, ok := r.updatedAt[key]
+	if !ok {
+		return false
+	}
+	if r.expiration == noExpiration {
+		return true
+	}
+	return updatedAt.Add(r.expiration).After(time.Now())
+}

pkg/donut/trove/trove_test.go

@@ -0,0 +1,45 @@
+/*
+ * 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 trove
+
+import (
+	"testing"
+
+	. "github.com/minio/check"
+)
+
+func Test(t *testing.T) { TestingT(t) }
+
+type MySuite struct{}
+
+var _ = Suite(&MySuite{})
+
+func (s *MySuite) TestCache(c *C) {
+	cache := NewCache(1000, 0)
+	data := []byte("Hello, world!")
+	ok := cache.Set("filename", data)
+
+	c.Assert(ok, Equals, true)
+	storedata, ok := cache.Get("filename")
+
+	c.Assert(ok, Equals, true)
+	c.Assert(data, DeepEquals, storedata)
+
+	cache.Delete("filename")
+	_, ok = cache.Get("filename")
+	c.Assert(ok, Equals, false)
+}

pkg/donut/utils.go

@@ -0,0 +1,201 @@
+package donut
+
+import (
+	"regexp"
+	"strings"
+	"time"
+	"unicode/utf8"
+)
+
+// BucketACL - bucket level access control
+type BucketACL string
+
+// different types of ACL's currently supported for buckets
+const (
+	BucketPrivate         = BucketACL("private")
+	BucketPublicRead      = BucketACL("public-read")
+	BucketPublicReadWrite = BucketACL("public-read-write")
+)
+
+func (b BucketACL) String() string {
+	return string(b)
+}
+
+// IsPrivate - is acl Private
+func (b BucketACL) IsPrivate() bool {
+	return b == BucketACL("private")
+}
+
+// IsPublicRead - is acl PublicRead
+func (b BucketACL) IsPublicRead() bool {
+	return b == BucketACL("public-read")
+}
+
+// IsPublicReadWrite - is acl PublicReadWrite
+func (b BucketACL) IsPublicReadWrite() bool {
+	return b == BucketACL("public-read-write")
+}
+
+// FilterMode type
+type FilterMode int
+
+// FilterMode list
+const (
+	DelimiterPrefixMode FilterMode = iota
+	DelimiterMode
+	PrefixMode
+	DefaultMode
+)
+
+// PartMetadata - various types of individual part resources
+type PartMetadata struct {
+	PartNumber   int
+	LastModified time.Time
+	ETag         string
+	Size         int64
+}
+
+// ObjectResourcesMetadata - various types of object resources
+type ObjectResourcesMetadata struct {
+	Bucket               string
+	EncodingType         string
+	Key                  string
+	UploadID             string
+	StorageClass         string
+	PartNumberMarker     int
+	NextPartNumberMarker int
+	MaxParts             int
+	IsTruncated          bool
+
+	Part []*PartMetadata
+}
+
+// UploadMetadata container capturing metadata on in progress multipart upload in a given bucket
+type UploadMetadata struct {
+	Key          string
+	UploadID     string
+	StorageClass string
+	Initiated    time.Time
+}
+
+// BucketMultipartResourcesMetadata - various types of bucket resources for inprogress multipart uploads
+type BucketMultipartResourcesMetadata struct {
+	KeyMarker          string
+	UploadIDMarker     string
+	NextKeyMarker      string
+	NextUploadIDMarker string
+	EncodingType       string
+	MaxUploads         int
+	IsTruncated        bool
+	Upload             []*UploadMetadata
+	Prefix             string
+	Delimiter          string
+	CommonPrefixes     []string
+}
+
+// BucketResourcesMetadata - various types of bucket resources
+type BucketResourcesMetadata struct {
+	Prefix         string
+	Marker         string
+	NextMarker     string
+	Maxkeys        int
+	EncodingType   string
+	Delimiter      string
+	IsTruncated    bool
+	CommonPrefixes []string
+	Mode           FilterMode
+}
+
+// GetMode - Populate filter mode
+func GetMode(resources BucketResourcesMetadata) FilterMode {
+	var f FilterMode
+	switch true {
+	case resources.Delimiter != "" && resources.Prefix != "":
+		f = DelimiterPrefixMode
+	case resources.Delimiter != "" && resources.Prefix == "":
+		f = DelimiterMode
+	case resources.Delimiter == "" && resources.Prefix != "":
+		f = PrefixMode
+	case resources.Delimiter == "" && resources.Prefix == "":
+		f = DefaultMode
+	}
+
+	return f
+}
+
+// IsValidBucketACL - is provided acl string supported
+func IsValidBucketACL(acl string) bool {
+	switch acl {
+	case "private":
+		fallthrough
+	case "public-read":
+		fallthrough
+	case "public-read-write":
+		return true
+	case "":
+		// by default its "private"
+		return true
+	default:
+		return false
+	}
+}
+
+// IsDelimiterPrefixSet Delimiter and Prefix set
+func (b BucketResourcesMetadata) IsDelimiterPrefixSet() bool {
+	return b.Mode == DelimiterPrefixMode
+}
+
+// IsDelimiterSet Delimiter set
+func (b BucketResourcesMetadata) IsDelimiterSet() bool {
+	return b.Mode == DelimiterMode
+}
+
+// IsPrefixSet Prefix set
+func (b BucketResourcesMetadata) IsPrefixSet() bool {
+	return b.Mode == PrefixMode
+}
+
+// IsDefault No query values
+func (b BucketResourcesMetadata) IsDefault() bool {
+	return b.Mode == DefaultMode
+}
+
+// IsValidBucket - verify bucket name in accordance with
+//  - http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingBucket.html
+func IsValidBucket(bucket string) bool {
+	if len(bucket) < 3 || len(bucket) > 63 {
+		return false
+	}
+	if bucket[0] == '.' || bucket[len(bucket)-1] == '.' {
+		return false
+	}
+	if match, _ := regexp.MatchString("\\.\\.", bucket); match == true {
+		return false
+	}
+	// We don't support buckets with '.' in them
+	match, _ := regexp.MatchString("^[a-zA-Z][a-zA-Z0-9\\-]+[a-zA-Z0-9]$", bucket)
+	return match
+}
+
+// IsValidObjectName - verify object name in accordance with
+//   - http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingMetadata.html
+func IsValidObjectName(object string) bool {
+	if strings.TrimSpace(object) == "" {
+		return false
+	}
+	if len(object) > 1024 || len(object) == 0 {
+		return false
+	}
+	if !utf8.ValidString(object) {
+		return false
+	}
+	return true
+}
+
+// IsValidPrefix - verify prefix name is correct, an empty prefix is valid
+func IsValidPrefix(prefix string) bool {
+	if strings.TrimSpace(prefix) == "" {
+		return true
+	}
+	return IsValidObjectName(prefix)
+}