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|
package main
import (
"bytes"
"errors"
"fmt"
"io"
"log"
"os"
"path"
)
type Chunk interface {
Reader() io.ReadSeeker
Len() int
}
type IdentifiedChunk interface {
Chunk
GetId() *ChunkId
}
type BufferedChunk interface {
Chunk
Bytes() []byte
}
type StorerChunk interface {
Chunk
Store(path string) error
}
type ChunkId struct {
Ver int
Idx uint64
}
func (i *ChunkId) Path(repo string) string {
return path.Join(repo, fmt.Sprintf(versionFmt, i.Ver), chunksName, fmt.Sprintf(chunkIdFmt, i.Idx))
}
func (i *ChunkId) Reader(repo *Repo) io.ReadSeeker {
path := i.Path(repo.path)
f, err := os.Open(path)
if err != nil {
log.Println("Cannot open chunk: ", path)
}
return f
}
func NewLoadedChunk(id *ChunkId, value []byte) *LoadedChunk {
return &LoadedChunk{Id: id, value: value}
}
type LoadedChunk struct {
Id *ChunkId
value []byte
}
func (c *LoadedChunk) GetId() *ChunkId {
return c.Id
}
func (c *LoadedChunk) Reader() io.ReadSeeker {
// log.Printf("Chunk %d: Reading from in-memory value\n", c.id)
return bytes.NewReader(c.value)
}
func (c *LoadedChunk) Len() int {
return len(c.value)
}
func (c *LoadedChunk) Bytes() []byte {
return c.value
}
func (c *LoadedChunk) Store(path string) error {
return storeChunk(c.Reader(), c.Id.Path(path))
}
func NewStoredChunk(repo *Repo, id *ChunkId) *StoredChunk {
return &StoredChunk{repo: repo, Id: id}
}
type StoredChunk struct {
repo *Repo
Id *ChunkId
}
func (c *StoredChunk) GetId() *ChunkId {
return c.Id
}
func (c *StoredChunk) Reader() io.ReadSeeker {
// log.Printf("Chunk %d: Reading from file\n", c.id)
return c.Id.Reader(c.repo)
}
func (c *StoredChunk) Len() int {
path := c.Id.Path(c.repo.path)
info, err := os.Stat(path)
if err != nil {
log.Println("Chunk: could not stat file:", path)
}
return int(info.Size())
}
func NewTempChunk(value []byte) *TempChunk {
return &TempChunk{Value: value}
}
type TempChunk struct {
Value []byte
}
func (c *TempChunk) Reader() io.ReadSeeker {
return bytes.NewReader(c.Value)
}
func (c *TempChunk) Len() int {
return len(c.Value)
}
func (c *TempChunk) Bytes() []byte {
return c.Value
}
func (c *TempChunk) AppendFrom(r io.Reader) {
buff, err := io.ReadAll(r)
if err != nil {
println("Chunk: error appending to temp chunk:", err)
}
c.Value = append(c.Value, buff...)
}
type DeltaChunk struct {
repo *Repo
Source *ChunkId
Patch []byte
Size int
}
func (c *DeltaChunk) Reader() io.ReadSeeker {
var buff bytes.Buffer
c.repo.Patcher().Patch(c.Source.Reader(c.repo), &buff, bytes.NewReader(c.Patch))
return bytes.NewReader(buff.Bytes())
}
// TODO: Maybe return the size of the patch instead ?
func (c *DeltaChunk) Len() int {
return c.Size
}
func storeChunk(r io.Reader, path string) error {
file, err := os.Create(path)
if err != nil {
return errors.New(fmt.Sprintf("Error creating chunk for '%s'; %s\n", path, err))
}
n, err := io.Copy(file, r)
if err != nil {
return errors.New(fmt.Sprintf("Error writing chunk content for '%s', written %d bytes: %s\n", path, n, err))
}
if err := file.Close(); err != nil {
return errors.New(fmt.Sprintf("Error closing chunk for '%s': %s\n", path, err))
}
return nil
}
|
