88 lines
1.9 KiB
Go
88 lines
1.9 KiB
Go
package files
|
|
|
|
import (
|
|
"errors"
|
|
"fmt"
|
|
"strconv"
|
|
"strings"
|
|
)
|
|
|
|
// ChunkSpec is a wrapper around an uncompressed array of chunk identifiers
|
|
type ChunkSpec []uint64
|
|
|
|
// CreateChunkSpec given a full list of chunks with their downloaded status (true for downloaded, false otherwise)
|
|
// derives a list of identifiers of chunks that have not been downloaded yet
|
|
func CreateChunkSpec(progress []bool) ChunkSpec {
|
|
chunks := ChunkSpec{}
|
|
for i, p := range progress {
|
|
if !p {
|
|
chunks = append(chunks, uint64(i))
|
|
}
|
|
}
|
|
return chunks
|
|
}
|
|
|
|
// Deserialize takes in a compressed chunk spec and returns an uncompressed ChunkSpec or an error
|
|
// if the serialized chunk spec has format errors
|
|
func Deserialize(serialized string) (*ChunkSpec, error) {
|
|
|
|
var chunkSpec ChunkSpec
|
|
|
|
if len(serialized) == 0 {
|
|
return &chunkSpec, nil
|
|
}
|
|
|
|
ranges := strings.Split(serialized, ",")
|
|
for _, r := range ranges {
|
|
parts := strings.Split(r, ":")
|
|
if len(parts) == 1 {
|
|
single, err := strconv.Atoi(r)
|
|
if err != nil {
|
|
return nil, errors.New("invalid chunk spec")
|
|
}
|
|
chunkSpec = append(chunkSpec, uint64(single))
|
|
} else if len(parts) == 2 {
|
|
start, err1 := strconv.Atoi(parts[0])
|
|
end, err2 := strconv.Atoi(parts[1])
|
|
if err1 != nil || err2 != nil {
|
|
return nil, errors.New("invalid chunk spec")
|
|
}
|
|
for i := start; i <= end; i++ {
|
|
chunkSpec = append(chunkSpec, uint64(i))
|
|
}
|
|
} else {
|
|
return nil, errors.New("invalid chunk spec")
|
|
}
|
|
}
|
|
return &chunkSpec, nil
|
|
}
|
|
|
|
// Serialize compresses the ChunkSpec into a list of inclusive ranges e.g. 1,2,3,5,6,7 becomes "1:3,5:7"
|
|
func (cs ChunkSpec) Serialize() string {
|
|
result := ""
|
|
|
|
i := 0
|
|
|
|
for {
|
|
if i >= len(cs) {
|
|
break
|
|
}
|
|
j := i + 1
|
|
for ; j < len(cs) && cs[j] == cs[j-1]+1; j++ {
|
|
}
|
|
|
|
if result != "" {
|
|
result += ","
|
|
}
|
|
|
|
if j == i+1 {
|
|
result += fmt.Sprintf("%d", cs[i])
|
|
} else {
|
|
result += fmt.Sprintf("%d:%d", cs[i], cs[j-1])
|
|
}
|
|
i = j
|
|
}
|
|
|
|
return result
|
|
}
|