seaweedfs/weed/storage/erasure_coding/ec_shard.go

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package erasure_coding
import (
"fmt"
"os"
"path"
"strconv"
"github.com/chrislusf/seaweedfs/weed/storage/needle"
)
type ShardId uint8
type EcVolumeShard struct {
VolumeId needle.VolumeId
ShardId ShardId
Collection string
dir string
ecdFile *os.File
ecdFileSize int64
}
func NewEcVolumeShard(dirname string, collection string, id needle.VolumeId, shardId ShardId) (v *EcVolumeShard, e error) {
v = &EcVolumeShard{dir: dirname, Collection: collection, VolumeId: id, ShardId: shardId}
baseFileName := v.FileName()
// open ecd file
if v.ecdFile, e = os.OpenFile(baseFileName+ToExt(int(shardId)), os.O_RDONLY, 0644); e != nil {
return nil, fmt.Errorf("cannot read ec volume shard %s.%s: %v", baseFileName, ToExt(int(shardId)), e)
}
ecdFi, statErr := v.ecdFile.Stat()
if statErr != nil {
return nil, fmt.Errorf("can not stat ec volume shard %s.%s: %v", baseFileName, ToExt(int(shardId)), statErr)
}
v.ecdFileSize = ecdFi.Size()
return
}
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func (shard *EcVolumeShard) Size() int64 {
return shard.ecdFileSize
}
func (shard *EcVolumeShard) String() string {
return fmt.Sprintf("ec shard %v:%v, dir:%s, Collection:%s", shard.VolumeId, shard.ShardId, shard.dir, shard.Collection)
}
func (shard *EcVolumeShard) FileName() (fileName string) {
return EcShardFileName(shard.Collection, shard.dir, int(shard.VolumeId))
}
func EcShardFileName(collection string, dir string, id int) (fileName string) {
idString := strconv.Itoa(id)
if collection == "" {
fileName = path.Join(dir, idString)
} else {
fileName = path.Join(dir, collection+"_"+idString)
}
return
}
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func EcShardBaseFileName(collection string, id int) (baseFileName string) {
baseFileName = strconv.Itoa(id)
if collection != "" {
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baseFileName = collection + "_" + baseFileName
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}
return
}
func (shard *EcVolumeShard) Close() {
if shard.ecdFile != nil {
_ = shard.ecdFile.Close()
shard.ecdFile = nil
}
}
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func (shard *EcVolumeShard) Destroy() {
os.Remove(shard.FileName() + ToExt(int(shard.ShardId)))
}
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func (shard *EcVolumeShard) ReadAt(buf []byte, offset int64) (int, error) {
return shard.ecdFile.ReadAt(buf, offset)
}