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