1 files changed, 213 insertions, 0 deletions
diff --git a/weed/operation/chunked_file.go b/weed/operation/chunked_file.go
new file mode 100644
index 000000000..52086514a
--- /dev/null
+++ b/weed/operation/chunked_file.go
@@ -0,0 +1,213 @@
+package operation
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"sort"
+
+	"sync"
+
+	"github.com/chrislusf/seaweedfs/weed/glog"
+	"github.com/chrislusf/seaweedfs/weed/util"
+)
+
+var (
+	// when the remote server does not allow range requests (Accept-Ranges was not set)
+	ErrRangeRequestsNotSupported = errors.New("Range requests are not supported by the remote server")
+	// ErrInvalidRange is returned by Read when trying to read past the end of the file
+	ErrInvalidRange = errors.New("Invalid range")
+)
+
+type ChunkInfo struct {
+	Fid    string `json:"fid"`
+	Offset int64  `json:"offset"`
+	Size   int64  `json:"size"`
+}
+
+type ChunkList []*ChunkInfo
+
+type ChunkManifest struct {
+	Name   string    `json:"name,omitempty"`
+	Mime   string    `json:"mime,omitempty"`
+	Size   int64     `json:"size,omitempty"`
+	Chunks ChunkList `json:"chunks,omitempty"`
+}
+
+// seekable chunked file reader
+type ChunkedFileReader struct {
+	Manifest *ChunkManifest
+	Master   string
+	pos      int64
+	pr       *io.PipeReader
+	pw       *io.PipeWriter
+	mutex    sync.Mutex
+}
+
+func (s ChunkList) Len() int           { return len(s) }
+func (s ChunkList) Less(i, j int) bool { return s[i].Offset < s[j].Offset }
+func (s ChunkList) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
+
+func LoadChunkManifest(buffer []byte, isGzipped bool) (*ChunkManifest, error) {
+	if isGzipped {
+		var err error
+		if buffer, err = UnGzipData(buffer); err != nil {
+			return nil, err
+		}
+	}
+	cm := ChunkManifest{}
+	if e := json.Unmarshal(buffer, &cm); e != nil {
+		return nil, e
+	}
+	sort.Sort(cm.Chunks)
+	return &cm, nil
+}
+
+func (cm *ChunkManifest) Marshal() ([]byte, error) {
+	return json.Marshal(cm)
+}
+
+func (cm *ChunkManifest) DeleteChunks(master string) error {
+	deleteError := 0
+	for _, ci := range cm.Chunks {
+		if e := DeleteFile(master, ci.Fid, ""); e != nil {
+			deleteError++
+			glog.V(0).Infof("Delete %s error: %v, master: %s", ci.Fid, e, master)
+		}
+	}
+	if deleteError > 0 {
+		return errors.New("Not all chunks deleted.")
+	}
+	return nil
+}
+
+func readChunkNeedle(fileUrl string, w io.Writer, offset int64) (written int64, e error) {
+	req, err := http.NewRequest("GET", fileUrl, nil)
+	if err != nil {
+		return written, err
+	}
+	if offset > 0 {
+		req.Header.Set("Range", fmt.Sprintf("bytes=%d-", offset))
+	}
+
+	resp, err := util.Do(req)
+	if err != nil {
+		return written, err
+	}
+	defer resp.Body.Close()
+
+	switch resp.StatusCode {
+	case http.StatusRequestedRangeNotSatisfiable:
+		return written, ErrInvalidRange
+	case http.StatusOK:
+		if offset > 0 {
+			return written, ErrRangeRequestsNotSupported
+		}
+	case http.StatusPartialContent:
+		break
+	default:
+		return written, fmt.Errorf("Read chunk needle error: [%d] %s", resp.StatusCode, fileUrl)
+
+	}
+	return io.Copy(w, resp.Body)
+}
+
+func (cf *ChunkedFileReader) Seek(offset int64, whence int) (int64, error) {
+	var err error
+	switch whence {
+	case 0:
+	case 1:
+		offset += cf.pos
+	case 2:
+		offset = cf.Manifest.Size - offset
+	}
+	if offset > cf.Manifest.Size {
+		err = ErrInvalidRange
+	}
+	if cf.pos != offset {
+		cf.Close()
+	}
+	cf.pos = offset
+	return cf.pos, err
+}
+
+func (cf *ChunkedFileReader) WriteTo(w io.Writer) (n int64, err error) {
+	cm := cf.Manifest
+	chunkIndex := -1
+	chunkStartOffset := int64(0)
+	for i, ci := range cm.Chunks {
+		if cf.pos >= ci.Offset && cf.pos < ci.Offset+ci.Size {
+			chunkIndex = i
+			chunkStartOffset = cf.pos - ci.Offset
+			break
+		}
+	}
+	if chunkIndex < 0 {
+		return n, ErrInvalidRange
+	}
+	for ; chunkIndex < cm.Chunks.Len(); chunkIndex++ {
+		ci := cm.Chunks[chunkIndex]
+		// if we need read date from local volume server first?
+		fileUrl, lookupError := LookupFileId(cf.Master, ci.Fid)
+		if lookupError != nil {
+			return n, lookupError
+		}
+		if wn, e := readChunkNeedle(fileUrl, w, chunkStartOffset); e != nil {
+			return n, e
+		} else {
+			n += wn
+			cf.pos += wn
+		}
+
+		chunkStartOffset = 0
+	}
+	return n, nil
+}
+
+func (cf *ChunkedFileReader) ReadAt(p []byte, off int64) (n int, err error) {
+	cf.Seek(off, 0)
+	return cf.Read(p)
+}
+
+func (cf *ChunkedFileReader) Read(p []byte) (int, error) {
+	return cf.getPipeReader().Read(p)
+}
+
+func (cf *ChunkedFileReader) Close() (e error) {
+	cf.mutex.Lock()
+	defer cf.mutex.Unlock()
+	return cf.closePipe()
+}
+
+func (cf *ChunkedFileReader) closePipe() (e error) {
+	if cf.pr != nil {
+		if err := cf.pr.Close(); err != nil {
+			e = err
+		}
+	}
+	cf.pr = nil
+	if cf.pw != nil {
+		if err := cf.pw.Close(); err != nil {
+			e = err
+		}
+	}
+	cf.pw = nil
+	return e
+}
+
+func (cf *ChunkedFileReader) getPipeReader() io.Reader {
+	cf.mutex.Lock()
+	defer cf.mutex.Unlock()
+	if cf.pr != nil && cf.pw != nil {
+		return cf.pr
+	}
+	cf.closePipe()
+	cf.pr, cf.pw = io.Pipe()
+	go func(pw *io.PipeWriter) {
+		_, e := cf.WriteTo(pw)
+		pw.CloseWithError(e)
+	}(cf.pw)
+	return cf.pr
+}