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package super_block
import (
"github.com/golang/protobuf/proto"
"github.com/chrislusf/seaweedfs/weed/util/log"
"github.com/chrislusf/seaweedfs/weed/pb/master_pb"
"github.com/chrislusf/seaweedfs/weed/storage/needle"
"github.com/chrislusf/seaweedfs/weed/util"
)
const (
SuperBlockSize = 8
)
/*
* Super block currently has 8 bytes allocated for each volume.
* Byte 0: version, 1 or 2
* Byte 1: Replica Placement strategy, 000, 001, 002, 010, etc
* Byte 2 and byte 3: Time to live. See TTL for definition
* Byte 4 and byte 5: The number of times the volume has been compacted.
* Rest bytes: Reserved
*/
type SuperBlock struct {
Version needle.Version
ReplicaPlacement *ReplicaPlacement
Ttl *needle.TTL
CompactionRevision uint16
Extra *master_pb.SuperBlockExtra
ExtraSize uint16
}
func (s *SuperBlock) BlockSize() int {
switch s.Version {
case needle.Version2, needle.Version3:
return SuperBlockSize + int(s.ExtraSize)
}
return SuperBlockSize
}
func (s *SuperBlock) Bytes() []byte {
header := make([]byte, SuperBlockSize)
header[0] = byte(s.Version)
header[1] = s.ReplicaPlacement.Byte()
s.Ttl.ToBytes(header[2:4])
util.Uint16toBytes(header[4:6], s.CompactionRevision)
if s.Extra != nil {
extraData, err := proto.Marshal(s.Extra)
if err != nil {
log.Fatalf("cannot marshal super block extra %+v: %v", s.Extra, err)
}
extraSize := len(extraData)
if extraSize > 256*256-2 {
// reserve a couple of bits for future extension
log.Fatalf("super block extra size is %d bigger than %d", extraSize, 256*256-2)
}
s.ExtraSize = uint16(extraSize)
util.Uint16toBytes(header[6:8], s.ExtraSize)
header = append(header, extraData...)
}
return header
}
func (s *SuperBlock) Initialized() bool {
return s.ReplicaPlacement != nil && s.Ttl != nil
}
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