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meta.go
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meta.go
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package s3afero
import (
"encoding/hex"
"encoding/json"
"hash/fnv"
"os"
"path/filepath"
"strings"
"time"
"github.com/spf13/afero"
)
type Metadata struct {
File string
ModTime time.Time
Size int64
Hash []byte
Meta map[string]string
}
type metaPath struct {
bucket string
object string
}
func (mp metaPath) FilePath() string {
return filepath.Join(mp.bucket, mp.object)
}
type metaStore struct {
fs afero.Fs
modTimeCalc modTimeCalc
modTimeRes time.Duration
}
func newMetaStore(fs afero.Fs, modTimeCalc modTimeCalc) *metaStore {
b := &metaStore{
fs: fs,
modTimeCalc: modTimeCalc,
modTimeRes: -1,
}
return b
}
func (ms *metaStore) getModTimeRes() (dur time.Duration, err error) {
if ms.modTimeRes < 0 {
ms.modTimeRes, err = ms.modTimeCalc()
if err != nil {
return -1, err
}
}
return ms.modTimeRes, nil
}
func (ms *metaStore) metaPath(bucket string, object string) metaPath {
// FIXME: may need to add path segments but that may be a thing of the past:
// https://stackoverflow.com/questions/466521/how-many-files-can-i-put-in-a-directory
h := fnv.New128a()
h.Write([]byte(object))
object = strings.Replace(object, "/", "_", -1)
object = strings.Replace(object, "\\", "_", -1)
return metaPath{bucket, object + "-" + hex.EncodeToString(h.Sum(nil))}
}
func (ms *metaStore) loadMeta(bucket string, object string, size int64, mtime time.Time) (*Metadata, error) {
metaPath := ms.metaPath(bucket, object)
fullPath := metaPath.FilePath()
bts, err := afero.ReadFile(ms.fs, fullPath)
if err != nil && !os.IsNotExist(err) {
return nil, err
}
var meta Metadata
if len(bts) > 0 {
if err := json.Unmarshal(bts, &meta); err != nil {
return nil, err
}
}
modRes, err := ms.getModTimeRes()
if err != nil {
return nil, err
}
modDiff := mtime.Sub(meta.ModTime)
if len(meta.Hash) == 0 || meta.Size != size || modDiff < -modRes || modDiff > modRes {
meta.Size = size
meta.ModTime = mtime
meta.Hash, err = hashFile(ms.fs, fullPath)
if err != nil {
return nil, err
}
if err := ms.saveMeta(metaPath, &meta); err != nil {
return nil, err
}
}
return &meta, nil
}
func (ms *metaStore) saveMeta(path metaPath, meta *Metadata) error {
bts, err := json.Marshal(meta)
if err != nil {
return err
}
if err := ms.fs.MkdirAll(filepath.Dir(path.FilePath()), 0777); err != nil {
return err
}
return afero.WriteFile(ms.fs, path.FilePath(), bts, 0666)
}
func (ms *metaStore) deleteMeta(path metaPath) error {
if err := ms.fs.Remove(path.FilePath()); os.IsNotExist(err) {
return nil
} else {
return err
}
}
func (ms *metaStore) deleteBucket(bucket string) error {
if err := ms.fs.RemoveAll(bucket); os.IsNotExist(err) {
return nil
} else {
return err
}
}