func (n *FileId) String() string {
bytes := make([]byte, 12)
util.Uint64toBytes(bytes[0:8], n.Key)
util.Uint32toBytes(bytes[8:12], n.Hashcode)
nonzero_index := 0
for ; bytes[nonzero_index] == 0; nonzero_index++ {
}
return n.VolumeId.String() + "," + hex.EncodeToString(bytes[nonzero_index:])
}
// dumps a NeedleMap into a cdb
func DumpNeedleMapToCdb(cdbName string, nm *NeedleMap) error {
tempnam := cdbName + "t"
fnames := make([]string, 1, 2)
adder, closer, err := openTempCdb(tempnam)
if err != nil {
return fmt.Errorf("error creating factory: %s", err)
}
fnames[0] = tempnam
elt := cdb.Element{Key: make([]byte, 8), Data: make([]byte, 8)}
fcount := uint64(0)
walk := func(key uint64, offset, size uint32) error {
//如果写入1失败则写入2中
if fcount >= maxCdbRecCount {
if err = closer(); err != nil {
return err
}
tempnam = cdbName + "t2"
if adder, closer, err = openTempCdb(tempnam); err != nil {
return fmt.Errorf("error creating second factory: %s", err)
}
fnames = append(fnames, tempnam)
fcount = 0
}
util.Uint64toBytes(elt.Key, key)
util.Uint32toBytes(elt.Data[:4], offset)
util.Uint32toBytes(elt.Data[4:], size)
fcount++
return adder(elt)
}
// and write out the cdb from there
err = nm.Visit(func(nv NeedleValue) error {
return walk(uint64(nv.Key), nv.Offset, nv.Size)
})
if err != nil {
closer()
return fmt.Errorf("error walking index %v: %s", nm, err)
}
// store fileBytes
//写入metric数据
data, e := json.Marshal(nm.mapMetric)
if e != nil {
return fmt.Errorf("error marshaling metric %v: %s", nm.mapMetric, e)
}
if err = adder(cdb.Element{Key: []byte{'M'}, Data: data}); err != nil {
return err
}
if err = closer(); err != nil {
return err
}
os.Remove(cdbName)
//如果只有一个文件就叫base.cdb如果有2个则叫base.1/2.cdb
if len(fnames) == 1 {
return os.Rename(fnames[0], cdbName)
}
bn, ext := baseFilename(cdbName)
if err = os.Rename(fnames[0], bn+".1"+ext); err != nil {
return err
}
return os.Rename(fnames[1], bn+".2"+ext)
}
func (n *Needle) Append(w io.Writer, version Version) (size uint32, err error) {
if s, ok := w.(io.Seeker); ok {
if end, e := s.Seek(0, 1); e == nil {
defer func(s io.Seeker, off int64) {
if err != nil {
if _, e = s.Seek(off, 0); e != nil {
glog.V(0).Infof("Failed to seek %s back to %d with error: %v", w, off, e)
}
}
}(s, end)
} else {
err = fmt.Errorf("Cannot Read Current Volume Position: %v", e)
return
}
}
switch version {
case Version1:
header := make([]byte, NeedleHeaderSize)
util.Uint32toBytes(header[0:4], n.Cookie)
util.Uint64toBytes(header[4:12], n.Id)
n.Size = uint32(len(n.Data))
size = n.Size
util.Uint32toBytes(header[12:16], n.Size)
if _, err = w.Write(header); err != nil {
return
}
if _, err = w.Write(n.Data); err != nil {
return
}
padding := NeedlePaddingSize - ((NeedleHeaderSize + n.Size + NeedleChecksumSize) % NeedlePaddingSize)
util.Uint32toBytes(header[0:NeedleChecksumSize], n.Checksum.Value())
_, err = w.Write(header[0 : NeedleChecksumSize+padding])
return
case Version2:
header := make([]byte, NeedleHeaderSize)
util.Uint32toBytes(header[0:4], n.Cookie)
util.Uint64toBytes(header[4:12], n.Id)
n.DataSize, n.NameSize, n.MimeSize = uint32(len(n.Data)), uint8(len(n.Name)), uint8(len(n.Mime))
if n.DataSize > 0 {
n.Size = 4 + n.DataSize + 1
if n.HasName() {
n.Size = n.Size + 1 + uint32(n.NameSize)
}
if n.HasMime() {
n.Size = n.Size + 1 + uint32(n.MimeSize)
}
if n.HasLastModifiedDate() {
n.Size = n.Size + LastModifiedBytesLength
}
if n.HasTtl() {
n.Size = n.Size + TtlBytesLength
}
}
size = n.DataSize
util.Uint32toBytes(header[12:16], n.Size)
if _, err = w.Write(header); err != nil {
return
}
if n.DataSize > 0 {
util.Uint32toBytes(header[0:4], n.DataSize)
if _, err = w.Write(header[0:4]); err != nil {
return
}
if _, err = w.Write(n.Data); err != nil {
return
}
util.Uint8toBytes(header[0:1], n.Flags)
if _, err = w.Write(header[0:1]); err != nil {
return
}
if n.HasName() {
util.Uint8toBytes(header[0:1], n.NameSize)
if _, err = w.Write(header[0:1]); err != nil {
return
}
if _, err = w.Write(n.Name); err != nil {
return
}
}
if n.HasMime() {
util.Uint8toBytes(header[0:1], n.MimeSize)
if _, err = w.Write(header[0:1]); err != nil {
return
}
if _, err = w.Write(n.Mime); err != nil {
return
}
}
if n.HasLastModifiedDate() {
util.Uint64toBytes(header[0:8], n.LastModified)
if _, err = w.Write(header[8-LastModifiedBytesLength : 8]); err != nil {
return
}
}
if n.HasTtl() {
n.Ttl.ToBytes(header[0:TtlBytesLength])
if _, err = w.Write(header[0:TtlBytesLength]); err != nil {
return
}
}
}
padding := NeedlePaddingSize - ((NeedleHeaderSize + n.Size + NeedleChecksumSize) % NeedlePaddingSize)
util.Uint32toBytes(header[0:NeedleChecksumSize], n.Checksum.Value())
_, err = w.Write(header[0 : NeedleChecksumSize+padding])
return n.DataSize, err
}
return 0, fmt.Errorf("Unsupported Version! (%d)", version)
}
//此处的etag即为Needle的checksum
func (n *Needle) Etag() string {
bits := make([]byte, 4)
util.Uint32toBytes(bits, uint32(n.Checksum))
return fmt.Sprintf("\"%x\"", bits)
}