Golang util.BytesToUint32函數代碼示例

func LoadNeedleMap(file *os.File) (*NeedleMap, error) {
	nm := NewNeedleMap(file)
	bytes := make([]byte, 16*RowsToRead)
	count, e := nm.indexFile.Read(bytes)
	for count > 0 && e == nil {
		for i := 0; i < count; i += 16 {
			key := util.BytesToUint64(bytes[i : i+8])
			offset := util.BytesToUint32(bytes[i+8 : i+12])
			size := util.BytesToUint32(bytes[i+12 : i+16])
			nm.fileCounter++
			nm.fileByteCounter = nm.fileByteCounter + uint64(size)
			if offset > 0 {
				oldSize := nm.m.Set(Key(key), offset, size)
				//log.Println("reading key", key, "offset", offset, "size", size, "oldSize", oldSize)
				if oldSize > 0 {
					nm.deletionCounter++
					nm.deletionByteCounter = nm.deletionByteCounter + uint64(oldSize)
				}
			} else {
				oldSize := nm.m.Delete(Key(key))
				//log.Println("removing key", key, "offset", offset, "size", size, "oldSize", oldSize)
				nm.deletionCounter++
				nm.deletionByteCounter = nm.deletionByteCounter + uint64(oldSize)
			}
		}

		count, e = nm.indexFile.Read(bytes)
	}
	return nm, e
}

func (m cdbMap) Visit(visit func(NeedleValue) error) (err error) {
	fh, err := os.Open(m.fn1)
	if err != nil {
		return fmt.Errorf("cannot open %s: %s", m.fn1, err)
	}
	defer fh.Close()
	walk := func(elt cdb.Element) error {
		if len(elt.Key) != 8 {
			return nil
		}
		return visit(NeedleValue{Key: Key(util.BytesToUint64(elt.Key)),
			Offset: util.BytesToUint32(elt.Data[:4]),
			Size:   util.BytesToUint32(elt.Data[4:8])})
	}
	if err = cdb.DumpMap(fh, walk); err != nil {
		return err
	}
	if m.c2 == nil {
		return nil
	}
	fh.Close()
	if fh, err = os.Open(m.fn2); err != nil {
		return fmt.Errorf("cannot open %s: %s", m.fn2, err)
	}
	return cdb.DumpMap(fh, walk)
}

// walks through the index file, calls fn function with each key, offset, size
// stops with the error returned by the fn function
func WalkIndexFile(r *os.File, fn func(key uint64, offset, size uint32) error) error {
	var readerOffset int64
	bytes := make([]byte, 16*RowsToRead)
	count, e := r.ReadAt(bytes, readerOffset)
	glog.V(3).Infoln("file", r.Name(), "readerOffset", readerOffset, "count", count, "e", e)
	readerOffset += int64(count)
	var (
		key          uint64
		offset, size uint32
		i            int
	)

	for count > 0 && e == nil || e == io.EOF {
		for i = 0; i+16 <= count; i += 16 {
			key = util.BytesToUint64(bytes[i : i+8])
			offset = util.BytesToUint32(bytes[i+8 : i+12])
			size = util.BytesToUint32(bytes[i+12 : i+16])
			if e = fn(key, offset, size); e != nil {
				return e
			}
		}
		if e == io.EOF {
			return nil
		}
		count, e = r.ReadAt(bytes, readerOffset)
		glog.V(3).Infoln("file", r.Name(), "readerOffset", readerOffset, "count", count, "e", e)
		readerOffset += int64(count)
	}
	return e
}

// walks through the index file, calls fn function with each key, offset, size
// stops with the error returned by the fn function
func walkIndexFile(r io.Reader, fn func(key uint64, offset, size uint32) error) error {
	br := bufio.NewReaderSize(r, 1024*1024)
	bytes := make([]byte, 16*RowsToRead)
	count, e := br.Read(bytes)
	var (
		key          uint64
		offset, size uint32
		i            int
	)

	for count > 0 && e == nil {
		for i = 0; i+16 <= count; i += 16 {
			key = util.BytesToUint64(bytes[i : i+8])
			offset = util.BytesToUint32(bytes[i+8 : i+12])
			size = util.BytesToUint32(bytes[i+12 : i+16])
			if e = fn(key, offset, size); e != nil {
				return e
			}
		}
		if count%16 != 0 {
			copy(bytes[:count-i], bytes[i:count])
			i = count - i
			count, e = br.Read(bytes[i:])
			count += i
		} else {
			count, e = br.Read(bytes)
		}
	}
	if e == io.EOF {
		return nil
	}
	return e
}

func (n *Needle) readNeedleDataVersion2(bytes []byte) {
	index, lenBytes := 0, len(bytes)
	if index < lenBytes {
		n.DataSize = util.BytesToUint32(bytes[index : index+4])
		index = index + 4
		n.Data = bytes[index : index+int(n.DataSize)]
		index = index + int(n.DataSize)
		n.Flags = bytes[index]
		index = index + 1
	}
	if index < lenBytes && n.HasName() {
		n.NameSize = uint8(bytes[index])
		index = index + 1
		n.Name = bytes[index : index+int(n.NameSize)]
		index = index + int(n.NameSize)
	}
	if index < lenBytes && n.HasMime() {
		n.MimeSize = uint8(bytes[index])
		index = index + 1
		n.Mime = bytes[index : index+int(n.MimeSize)]
		index = index + int(n.MimeSize)
	}
	if index < lenBytes && n.HasLastModifiedDate() {
		n.LastModified = util.BytesToUint64(bytes[index : index+LastModifiedBytesLength])
		index = index + LastModifiedBytesLength
	}
}

func (m cdbMap) Get(key uint64) (element *NeedleValue, ok bool) {
	var (
		data []byte
		k    []byte = make([]byte, 8)
		err  error
	)
	util.Uint64toBytes(k, key)
	if data, err = m.c1.Data(k); err != nil || data == nil {
		if m.c2 == nil {
			return nil, false
		}
		if data, err = m.c2.Data(k); err != nil || data == nil {
			return nil, false
		}
	}
	return &NeedleValue{Key: Key(key), Offset: util.BytesToUint32(data[:4]),
		Size: util.BytesToUint32(data[4:])}, true
}

func (n *Needle) Read(r io.Reader, size uint32, version Version) (ret int, err error) {
	switch version {
	case Version1:
		bytes := make([]byte, NeedleHeaderSize+size+NeedleChecksumSize)
		if ret, err = r.Read(bytes); err != nil {
			return
		}
		n.readNeedleHeader(bytes)
		n.Data = bytes[NeedleHeaderSize : NeedleHeaderSize+size]
		checksum := util.BytesToUint32(bytes[NeedleHeaderSize+size : NeedleHeaderSize+size+NeedleChecksumSize])
		newChecksum := NewCRC(n.Data)
		if checksum != newChecksum.Value() {
			return 0, errors.New("CRC error! Data On Disk Corrupted!")
		}
		n.Checksum = newChecksum
		return
	case Version2:
		if size == 0 {
			return 0, nil
		}
		bytes := make([]byte, NeedleHeaderSize+size+NeedleChecksumSize)
		if ret, err = r.Read(bytes); err != nil {
			return
		}
		if ret != int(NeedleHeaderSize+size+NeedleChecksumSize) {
			return 0, errors.New("File Entry Not Found!")
		}
		n.readNeedleHeader(bytes)
		if n.Size != size {
			return 0, fmt.Errorf("File Entry Not Found! Needle %d Memory %d", n.Size, size)
		}
		n.readNeedleDataVersion2(bytes[NeedleHeaderSize : NeedleHeaderSize+int(n.Size)])
		checksum := util.BytesToUint32(bytes[NeedleHeaderSize+n.Size : NeedleHeaderSize+n.Size+NeedleChecksumSize])
		newChecksum := NewCRC(n.Data)
		if checksum != newChecksum.Value() {
			return 0, errors.New("CRC error! Data On Disk Corrupted!")
		}
		n.Checksum = newChecksum
		return
	}
	return 0, fmt.Errorf("Unsupported Version! (%d)", version)
}

func ParseKeyHash(key_hash_string string) (uint64, uint32) {
	key_hash_bytes, khe := hex.DecodeString(key_hash_string)
	key_hash_len := len(key_hash_bytes)
	if khe != nil || key_hash_len <= 4 {
		glog.V(0).Infoln("Invalid key_hash", key_hash_string, "length:", key_hash_len, "error", khe)
		return 0, 0
	}
	key := util.BytesToUint64(key_hash_bytes[0 : key_hash_len-4])
	hash := util.BytesToUint32(key_hash_bytes[key_hash_len-4 : key_hash_len])
	return key, hash
}

func (n *Needle) readNeedleHeader(bytes []byte) {
	n.Cookie = util.BytesToUint32(bytes[0:4])
	n.Id = util.BytesToUint64(bytes[4:12])
	n.Size = util.BytesToUint32(bytes[12:NeedleHeaderSize])
}