multipart: Code cleanup

- More locking cleanup. Fix naming convention.
- Simplify concatenation and blocking calls.

pkg/fs/fs-multipart.go

@@ -44,6 +44,8 @@ import (
 
 // isValidUploadID - is upload id.
 func (fs Filesystem) isValidUploadID(object, uploadID string) bool {
+	fs.rwLock.RLock()
+	defer fs.rwLock.RUnlock()
 	s, ok := fs.multiparts.ActiveSession[object]
 	if !ok {
 		return false
@@ -56,9 +58,6 @@ func (fs Filesystem) isValidUploadID(object, uploadID string) bool {
 
 // ListMultipartUploads - list incomplete multipart sessions for a given BucketMultipartResourcesMetadata
 func (fs Filesystem) ListMultipartUploads(bucket string, resources BucketMultipartResourcesMetadata) (BucketMultipartResourcesMetadata, *probe.Error) {
-	fs.rwLock.RLock()
-	defer fs.rwLock.RUnlock()
-
 	// Input validation.
 	if !IsValidBucketName(bucket) {
 		return BucketMultipartResourcesMetadata{}, probe.NewError(BucketNameInvalid{Bucket: bucket})
@@ -73,6 +72,8 @@ func (fs Filesystem) ListMultipartUploads(bucket string, resources BucketMultipa
 		return BucketMultipartResourcesMetadata{}, probe.NewError(e)
 	}
 	var uploads []*UploadMetadata
+	fs.rwLock.RLock()
+	defer fs.rwLock.RUnlock()
 	for object, session := range fs.multiparts.ActiveSession {
 		if strings.HasPrefix(object, resources.Prefix) {
 			if len(uploads) > resources.MaxUploads {
@@ -117,34 +118,81 @@ func (fs Filesystem) ListMultipartUploads(bucket string, resources BucketMultipa
 	return resources, nil
 }
 
-// concatenate parts.
-func (fs Filesystem) concatParts(parts *CompleteMultipartUpload, objectPath string, mw io.Writer) *probe.Error {
-	for _, part := range parts.Part {
-		partFile, e := os.OpenFile(objectPath+fmt.Sprintf("$%d-$multiparts", part.PartNumber), os.O_RDONLY, 0600)
-		defer partFile.Close()
+// verify if parts sent over the network do really match with what we
+// have for the session.
+func doPartsMatch(parts []CompletePart, savedParts []*PartMetadata) bool {
+	if parts == nil || savedParts == nil {
+		return false
+	}
+	// Range of incoming parts and compare them with saved parts.
+	for i, part := range parts {
+		if strings.Trim(part.ETag, "\"") != savedParts[i].ETag {
+			return false
+		}
+	}
+	return true
+}
+
+type multiCloser struct {
+	Closers []io.Closer
+}
+
+func (m multiCloser) Close() error {
+	for _, c := range m.Closers {
+		if e := c.Close(); e != nil {
+			return e
+		}
+	}
+	return nil
+}
+
+// MultiCloser - returns a Closer that's the logical
+// concatenation of the provided input closers. They're closed
+// sequentially. If any of the closers return a non-nil error, Close
+// will return that error.
+func MultiCloser(closers ...io.Closer) io.Closer {
+	return multiCloser{closers}
+}
+
+// removeParts - remove all parts.
+func removeParts(partPathPrefix string, parts []*PartMetadata) *probe.Error {
+	for _, part := range parts {
+		if e := os.Remove(partPathPrefix + fmt.Sprintf("$%d-$multiparts", part.PartNumber)); e != nil {
+			return probe.NewError(e)
+		}
+	}
+	if e := os.Remove(partPathPrefix + "$multiparts"); e != nil {
+		return probe.NewError(e)
+	}
+	return nil
+}
+
+// saveParts - concantenate and save all parts.
+func saveParts(partPathPrefix string, mw io.Writer, parts []CompletePart) *probe.Error {
+	var partReaders []io.Reader
+	var partClosers []io.Closer
+	for _, part := range parts {
+		partFile, e := os.OpenFile(partPathPrefix+fmt.Sprintf("$%d-$multiparts", part.PartNumber), os.O_RDONLY, 0600)
 		if e != nil {
 			return probe.NewError(e)
 		}
+		partReaders = append(partReaders, partFile)
+		partClosers = append(partClosers, partFile)
+	}
+	// Concatenate a list of closers and close upon return.
+	closer := MultiCloser(partClosers...)
+	defer closer.Close()
 
-		recvMD5 := part.ETag
-		// Complete multipart request header md5sum per part is hex
-		// encoded trim it and decode if possible.
-		if _, e = hex.DecodeString(strings.Trim(recvMD5, "\"")); e != nil {
-			return probe.NewError(InvalidDigest{Md5: recvMD5})
-		}
-
-		if _, e = io.Copy(mw, partFile); e != nil {
-			return probe.NewError(e)
-		}
+	reader := io.MultiReader(partReaders...)
+	readBuffer := make([]byte, 4*1024*1024)
+	if _, e := io.CopyBuffer(mw, reader, readBuffer); e != nil {
+		return probe.NewError(e)
 	}
 	return nil
 }
 
 // NewMultipartUpload - initiate a new multipart session
 func (fs Filesystem) NewMultipartUpload(bucket, object string) (string, *probe.Error) {
-	fs.rwLock.Lock()
-	defer fs.rwLock.Unlock()
-
 	di, e := disk.GetInfo(fs.path)
 	if e != nil {
 		return "", probe.NewError(e)
@@ -192,12 +240,6 @@ func (fs Filesystem) NewMultipartUpload(bucket, object string) (string, *probe.E
 	uploadIDSum := sha512.Sum512(id)
 	uploadID := base64.URLEncoding.EncodeToString(uploadIDSum[:])[:47]
 
-	multiPartfile, e := os.OpenFile(objectPath+"$multiparts", os.O_WRONLY|os.O_CREATE, 0600)
-	if e != nil {
-		return "", probe.NewError(e)
-	}
-	defer multiPartfile.Close()
-
 	// Initialize multipart session.
 	mpartSession := &MultipartSession{}
 	mpartSession.TotalParts = 0
@@ -205,14 +247,23 @@ func (fs Filesystem) NewMultipartUpload(bucket, object string) (string, *probe.E
 	mpartSession.Initiated = time.Now().UTC()
 	var parts []*PartMetadata
 	mpartSession.Parts = parts
-	fs.multiparts.ActiveSession[object] = mpartSession
 
-	encoder := json.NewEncoder(multiPartfile)
-	if e = encoder.Encode(mpartSession); e != nil {
+	fs.rwLock.Lock()
+	fs.multiparts.ActiveSession[object] = mpartSession
+	fs.rwLock.Unlock()
+
+	mpartSessionBytes, e := json.Marshal(mpartSession)
+	if e != nil {
 		return "", probe.NewError(e)
 	}
-	if err := saveMultipartsSession(fs.multiparts); err != nil {
-		return "", err.Trace()
+
+	partPathPrefix := objectPath + uploadID
+	if e = ioutil.WriteFile(partPathPrefix+"$multiparts", mpartSessionBytes, 0600); e != nil {
+		return "", probe.NewError(e)
+	}
+
+	if err := saveMultipartsSession(*fs.multiparts); err != nil {
+		return "", err.Trace(partPathPrefix)
 	}
 	return uploadID, nil
 }
@@ -226,9 +277,6 @@ func (a partNumber) Less(i, j int) bool { return a[i].PartNumber < a[j].PartNumb
 
 // CreateObjectPart - create a part in a multipart session
 func (fs Filesystem) CreateObjectPart(bucket, object, uploadID, expectedMD5Sum string, partID int, size int64, data io.Reader, signature *Signature) (string, *probe.Error) {
-	fs.rwLock.Lock()
-	defer fs.rwLock.Unlock()
-
 	di, err := disk.GetInfo(fs.path)
 	if err != nil {
 		return "", probe.NewError(err)
@@ -266,7 +314,7 @@ func (fs Filesystem) CreateObjectPart(bucket, object, uploadID, expectedMD5Sum s
 		expectedMD5SumBytes, err = base64.StdEncoding.DecodeString(strings.TrimSpace(expectedMD5Sum))
 		if err != nil {
 			// Pro-actively close the connection
-			return "", probe.NewError(InvalidDigest{Md5: expectedMD5Sum})
+			return "", probe.NewError(InvalidDigest{MD5: expectedMD5Sum})
 		}
 		expectedMD5Sum = hex.EncodeToString(expectedMD5SumBytes)
 	}
@@ -282,29 +330,32 @@ func (fs Filesystem) CreateObjectPart(bucket, object, uploadID, expectedMD5Sum s
 	}
 
 	objectPath := filepath.Join(bucketPath, object)
-	partPath := objectPath + fmt.Sprintf("$%d-$multiparts", partID)
+	partPathPrefix := objectPath + uploadID
+	partPath := partPathPrefix + fmt.Sprintf("$%d-$multiparts", partID)
 	partFile, e := atomic.FileCreateWithPrefix(partPath, "$multiparts")
 	if e != nil {
 		return "", probe.NewError(e)
 	}
-	h := md5.New()
-	sh := sha256.New()
-	mw := io.MultiWriter(partFile, h, sh)
-	if _, e = io.CopyN(mw, data, size); e != nil {
+
+	md5Hasher := md5.New()
+	sha256Hasher := sha256.New()
+	partWriter := io.MultiWriter(partFile, md5Hasher, sha256Hasher)
+	if _, e = io.CopyN(partWriter, data, size); e != nil {
 		partFile.CloseAndPurge()
 		return "", probe.NewError(e)
 	}
-	md5sum := hex.EncodeToString(h.Sum(nil))
+
+	md5sum := hex.EncodeToString(md5Hasher.Sum(nil))
 	// Verify if the written object is equal to what is expected, only
 	// if it is requested as such.
 	if strings.TrimSpace(expectedMD5Sum) != "" {
 		if !isMD5SumEqual(strings.TrimSpace(expectedMD5Sum), md5sum) {
 			partFile.CloseAndPurge()
-			return "", probe.NewError(BadDigest{Md5: expectedMD5Sum, Bucket: bucket, Object: object})
+			return "", probe.NewError(BadDigest{MD5: expectedMD5Sum, Bucket: bucket, Object: object})
 		}
 	}
 	if signature != nil {
-		ok, err := signature.DoesSignatureMatch(hex.EncodeToString(sh.Sum(nil)))
+		ok, err := signature.DoesSignatureMatch(hex.EncodeToString(sha256Hasher.Sum(nil)))
 		if err != nil {
 			partFile.CloseAndPurge()
 			return "", err.Trace()
@@ -326,24 +377,30 @@ func (fs Filesystem) CreateObjectPart(bucket, object, uploadID, expectedMD5Sum s
 	partMetadata.Size = fi.Size()
 	partMetadata.LastModified = fi.ModTime()
 
-	multiPartfile, e := os.OpenFile(objectPath+"$multiparts", os.O_RDWR|os.O_APPEND, 0600)
+	multipartSessionBytes, e := ioutil.ReadFile(partPathPrefix + "$multiparts")
 	if e != nil {
 		return "", probe.NewError(e)
 	}
-	defer multiPartfile.Close()
 
 	var deserializedMultipartSession MultipartSession
-	decoder := json.NewDecoder(multiPartfile)
-	if e = decoder.Decode(&deserializedMultipartSession); e != nil {
+	if e = json.Unmarshal(multipartSessionBytes, &deserializedMultipartSession); e != nil {
 		return "", probe.NewError(e)
 	}
 	deserializedMultipartSession.Parts = append(deserializedMultipartSession.Parts, &partMetadata)
 	deserializedMultipartSession.TotalParts++
-	fs.multiparts.ActiveSession[object] = &deserializedMultipartSession
 
+	fs.rwLock.Lock()
+	fs.multiparts.ActiveSession[object] = &deserializedMultipartSession
+	fs.rwLock.Unlock()
+
+	// Sort by part number before saving.
 	sort.Sort(partNumber(deserializedMultipartSession.Parts))
-	encoder := json.NewEncoder(multiPartfile)
-	if e = encoder.Encode(&deserializedMultipartSession); e != nil {
+
+	multipartSessionBytes, e = json.Marshal(deserializedMultipartSession)
+	if e != nil {
+		return "", probe.NewError(e)
+	}
+	if e = ioutil.WriteFile(partPathPrefix+"$multiparts", multipartSessionBytes, 0600); e != nil {
 		return "", probe.NewError(e)
 	}
 	return partMetadata.ETag, nil
@@ -351,9 +408,6 @@ func (fs Filesystem) CreateObjectPart(bucket, object, uploadID, expectedMD5Sum s
 
 // CompleteMultipartUpload - complete a multipart upload and persist the data
 func (fs Filesystem) CompleteMultipartUpload(bucket, object, uploadID string, data io.Reader, signature *Signature) (ObjectMetadata, *probe.Error) {
-	fs.rwLock.Lock()
-	defer fs.rwLock.Unlock()
-
 	// Check bucket name is valid.
 	if !IsValidBucketName(bucket) {
 		return ObjectMetadata{}, probe.NewError(BucketNameInvalid{Bucket: bucket})
@@ -384,8 +438,8 @@ func (fs Filesystem) CompleteMultipartUpload(bucket, object, uploadID string, da
 	if e != nil {
 		return ObjectMetadata{}, probe.NewError(e)
 	}
-	h := md5.New()
-	mw := io.MultiWriter(file, h)
+	md5Hasher := md5.New()
+	objectWriter := io.MultiWriter(file, md5Hasher)
 
 	partBytes, e := ioutil.ReadAll(data)
 	if e != nil {
@@ -405,35 +459,45 @@ func (fs Filesystem) CompleteMultipartUpload(bucket, object, uploadID string, da
 			return ObjectMetadata{}, probe.NewError(SignatureDoesNotMatch{})
 		}
 	}
-	parts := &CompleteMultipartUpload{}
-	if e := xml.Unmarshal(partBytes, parts); e != nil {
+	completeMultipartUpload := &CompleteMultipartUpload{}
+	if e := xml.Unmarshal(partBytes, completeMultipartUpload); e != nil {
 		file.CloseAndPurge()
 		return ObjectMetadata{}, probe.NewError(MalformedXML{})
 	}
-	if !sort.IsSorted(completedParts(parts.Part)) {
+	if !sort.IsSorted(completedParts(completeMultipartUpload.Part)) {
 		file.CloseAndPurge()
 		return ObjectMetadata{}, probe.NewError(InvalidPartOrder{})
 	}
 
-	if err := fs.concatParts(parts, objectPath, mw); err != nil {
+	// Save parts for verification.
+	parts := completeMultipartUpload.Part
+
+	fs.rwLock.RLock()
+	savedParts := fs.multiparts.ActiveSession[object].Parts
+	fs.rwLock.RUnlock()
+
+	if !doPartsMatch(parts, savedParts) {
 		file.CloseAndPurge()
-		return ObjectMetadata{}, err.Trace()
+		return ObjectMetadata{}, probe.NewError(InvalidPart{})
 	}
 
+	partPathPrefix := objectPath + uploadID
+	if err := saveParts(partPathPrefix, objectWriter, parts); err != nil {
+		file.CloseAndPurge()
+		return ObjectMetadata{}, err.Trace(partPathPrefix)
+	}
+	if err := removeParts(partPathPrefix, savedParts); err != nil {
+		file.CloseAndPurge()
+		return ObjectMetadata{}, err.Trace(partPathPrefix)
+	}
+
+	fs.rwLock.Lock()
 	delete(fs.multiparts.ActiveSession, object)
-	for _, part := range parts.Part {
-		if e = os.Remove(objectPath + fmt.Sprintf("$%d-$multiparts", part.PartNumber)); e != nil {
-			file.CloseAndPurge()
-			return ObjectMetadata{}, probe.NewError(e)
-		}
-	}
-	if e := os.Remove(objectPath + "$multiparts"); e != nil {
+	fs.rwLock.Unlock()
+
+	if err := saveMultipartsSession(*fs.multiparts); err != nil {
 		file.CloseAndPurge()
-		return ObjectMetadata{}, probe.NewError(e)
-	}
-	if e := saveMultipartsSession(fs.multiparts); e != nil {
-		file.CloseAndPurge()
-		return ObjectMetadata{}, e.Trace()
+		return ObjectMetadata{}, err.Trace(partPathPrefix)
 	}
 	file.Close()
 
@@ -451,16 +515,13 @@ func (fs Filesystem) CompleteMultipartUpload(bucket, object, uploadID string, da
 		Created:     st.ModTime(),
 		Size:        st.Size(),
 		ContentType: contentType,
-		Md5:         hex.EncodeToString(h.Sum(nil)),
+		MD5:         hex.EncodeToString(md5Hasher.Sum(nil)),
 	}
 	return newObject, nil
 }
 
 // ListObjectParts - list parts from incomplete multipart session for a given ObjectResourcesMetadata
 func (fs Filesystem) ListObjectParts(bucket, object string, resources ObjectResourcesMetadata) (ObjectResourcesMetadata, *probe.Error) {
-	fs.rwLock.Lock()
-	defer fs.rwLock.Unlock()
-
 	// Check bucket name is valid.
 	if !IsValidBucketName(bucket) {
 		return ObjectResourcesMetadata{}, probe.NewError(BucketNameInvalid{Bucket: bucket})
@@ -498,17 +559,16 @@ func (fs Filesystem) ListObjectParts(bucket, object string, resources ObjectReso
 	}
 
 	objectPath := filepath.Join(bucketPath, object)
-	multiPartfile, e := os.OpenFile(objectPath+"$multiparts", os.O_RDONLY, 0600)
+	partPathPrefix := objectPath + resources.UploadID
+	multipartSessionBytes, e := ioutil.ReadFile(partPathPrefix + "$multiparts")
 	if e != nil {
 		return ObjectResourcesMetadata{}, probe.NewError(e)
 	}
-	defer multiPartfile.Close()
-
 	var deserializedMultipartSession MultipartSession
-	decoder := json.NewDecoder(multiPartfile)
-	if e = decoder.Decode(&deserializedMultipartSession); e != nil {
+	if e = json.Unmarshal(multipartSessionBytes, &deserializedMultipartSession); e != nil {
 		return ObjectResourcesMetadata{}, probe.NewError(e)
 	}
+
 	var parts []*PartMetadata
 	for i := startPartNumber; i <= deserializedMultipartSession.TotalParts; i++ {
 		if len(parts) > objectResourcesMetadata.MaxParts {
@@ -527,9 +587,6 @@ func (fs Filesystem) ListObjectParts(bucket, object string, resources ObjectReso
 
 // AbortMultipartUpload - abort an incomplete multipart session
 func (fs Filesystem) AbortMultipartUpload(bucket, object, uploadID string) *probe.Error {
-	fs.rwLock.Lock()
-	defer fs.rwLock.Unlock()
-
 	// Check bucket name valid.
 	if !IsValidBucketName(bucket) {
 		return probe.NewError(BucketNameInvalid{Bucket: bucket})
@@ -555,15 +612,20 @@ func (fs Filesystem) AbortMultipartUpload(bucket, object, uploadID string) *prob
 	}
 
 	objectPath := filepath.Join(bucketPath, object)
-	for _, part := range fs.multiparts.ActiveSession[object].Parts {
-		e := os.RemoveAll(objectPath + fmt.Sprintf("$%d-$multiparts", part.PartNumber))
-		if e != nil {
-			return probe.NewError(e)
-		}
+	partPathPrefix := objectPath + uploadID
+	fs.rwLock.RLock()
+	savedParts := fs.multiparts.ActiveSession[object].Parts
+	fs.rwLock.RUnlock()
+
+	if err := removeParts(partPathPrefix, savedParts); err != nil {
+		return err.Trace(partPathPrefix)
 	}
+
+	fs.rwLock.Lock()
 	delete(fs.multiparts.ActiveSession, object)
-	if e := os.RemoveAll(objectPath + "$multiparts"); e != nil {
-		return probe.NewError(e)
+	fs.rwLock.Unlock()
+	if err := saveMultipartsSession(*fs.multiparts); err != nil {
+		return err.Trace(partPathPrefix)
 	}
 	return nil
 }