rclone/backend/cache/object.go

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// +build !plan9,go1.7
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package cache
import (
"encoding/json"
"io"
"os"
"path"
"sync"
"time"
"strconv"
"github.com/ncw/rclone/fs"
"github.com/ncw/rclone/fs/hash"
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"github.com/ncw/rclone/lib/readers"
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)
// Object is a generic file like object that stores basic information about it
type Object struct {
fs.Object `json:"-"`
CacheFs *Fs `json:"-"` // cache fs
Name string `json:"name"` // name of the directory
Dir string `json:"dir"` // abs path of the object
CacheModTime int64 `json:"modTime"` // modification or creation time - IsZero for unknown
CacheSize int64 `json:"size"` // size of directory and contents or -1 if unknown
CacheStorable bool `json:"storable"` // says whether this object can be stored
CacheType string `json:"cacheType"`
CacheTs time.Time `json:"cacheTs"`
cacheHashes map[hash.Type]string // all supported hashes cached
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refreshMutex sync.Mutex
}
// NewObject builds one from a generic fs.Object
func NewObject(f *Fs, remote string) *Object { //0745 379 768
fullRemote := path.Join(f.Root(), remote)
dir, name := path.Split(fullRemote)
co := &Object{
CacheFs: f,
Name: cleanPath(name),
Dir: cleanPath(dir),
CacheModTime: time.Now().UnixNano(),
CacheSize: 0,
CacheStorable: false,
CacheType: "Object",
CacheTs: time.Now(),
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}
return co
}
// MarshalJSON is needed to override the hashes map (needed to support older versions of Go)
func (o *Object) MarshalJSON() ([]byte, error) {
hashes := make(map[string]string)
for k, v := range o.cacheHashes {
hashes[strconv.Itoa(int(k))] = v
}
type Alias Object
return json.Marshal(&struct {
Hashes map[string]string `json:"hashes"`
*Alias
}{
Alias: (*Alias)(o),
Hashes: hashes,
})
}
// UnmarshalJSON is needed to override the CacheHashes map (needed to support older versions of Go)
func (o *Object) UnmarshalJSON(b []byte) error {
type Alias Object
aux := &struct {
Hashes map[string]string `json:"hashes"`
*Alias
}{
Alias: (*Alias)(o),
}
if err := json.Unmarshal(b, &aux); err != nil {
return err
}
o.cacheHashes = make(map[hash.Type]string)
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for k, v := range aux.Hashes {
ht, _ := strconv.Atoi(k)
o.cacheHashes[hash.Type(ht)] = v
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}
return nil
}
// ObjectFromOriginal builds one from a generic fs.Object
func ObjectFromOriginal(f *Fs, o fs.Object) *Object {
var co *Object
fullRemote := cleanPath(path.Join(f.Root(), o.Remote()))
dir, name := path.Split(fullRemote)
co = &Object{
CacheFs: f,
Name: cleanPath(name),
Dir: cleanPath(dir),
CacheType: "Object",
CacheTs: time.Now(),
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}
co.updateData(o)
return co
}
func (o *Object) updateData(source fs.Object) {
o.Object = source
o.CacheModTime = source.ModTime().UnixNano()
o.CacheSize = source.Size()
o.CacheStorable = source.Storable()
o.CacheTs = time.Now()
o.cacheHashes = make(map[hash.Type]string)
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}
// Fs returns its FS info
func (o *Object) Fs() fs.Info {
return o.CacheFs
}
// String returns a human friendly name for this object
func (o *Object) String() string {
if o == nil {
return "<nil>"
}
return o.Remote()
}
// Remote returns the remote path
func (o *Object) Remote() string {
p := path.Join(o.Dir, o.Name)
if o.CacheFs.Root() != "" {
p = p[len(o.CacheFs.Root()):] // trim out root
if len(p) > 0 { // remove first separator
p = p[1:]
}
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}
return p
}
// abs returns the absolute path to the object
func (o *Object) abs() string {
return path.Join(o.Dir, o.Name)
}
// parentRemote returns the absolute path parent remote
func (o *Object) parentRemote() string {
absPath := o.abs()
return cleanPath(path.Dir(absPath))
}
// parentDir returns the absolute path parent remote
func (o *Object) parentDir() *Directory {
return NewDirectory(o.CacheFs, cleanPath(path.Dir(o.Remote())))
}
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// ModTime returns the cached ModTime
func (o *Object) ModTime() time.Time {
return time.Unix(0, o.CacheModTime)
}
// Size returns the cached Size
func (o *Object) Size() int64 {
return o.CacheSize
}
// Storable returns the cached Storable
func (o *Object) Storable() bool {
return o.CacheStorable
}
// refreshFromSource requests the original FS for the object in case it comes from a cached entry
func (o *Object) refreshFromSource() error {
o.refreshMutex.Lock()
defer o.refreshMutex.Unlock()
if o.Object != nil {
return nil
}
liveObject, err := o.CacheFs.Fs.NewObject(o.Remote())
if err != nil {
fs.Errorf(o, "error refreshing object: %v", err)
return err
}
o.updateData(liveObject)
o.persist()
return nil
}
// SetModTime sets the ModTime of this object
func (o *Object) SetModTime(t time.Time) error {
if err := o.refreshFromSource(); err != nil {
return err
}
err := o.Object.SetModTime(t)
if err != nil {
return err
}
o.CacheModTime = t.UnixNano()
o.persist()
fs.Debugf(o.Fs(), "updated ModTime %v: %v", o, t)
return nil
}
// Open is used to request a specific part of the file using fs.RangeOption
func (o *Object) Open(options ...fs.OpenOption) (io.ReadCloser, error) {
if err := o.refreshFromSource(); err != nil {
return nil, err
}
var err error
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cacheReader := NewObjectHandle(o)
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var offset, limit int64
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for _, option := range options {
switch x := option.(type) {
case *fs.SeekOption:
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offset, limit = x.Offset, 0
case *fs.RangeOption:
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offset, limit = x.Decode(o.Size())
}
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_, err = cacheReader.Seek(offset, os.SEEK_SET)
if err != nil {
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return nil, err
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}
}
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return readers.NewLimitedReadCloser(cacheReader, limit), nil
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}
// Update will change the object data
func (o *Object) Update(in io.Reader, src fs.ObjectInfo, options ...fs.OpenOption) error {
if err := o.refreshFromSource(); err != nil {
return err
}
fs.Infof(o, "updating object contents with size %v", src.Size())
// deleting cached chunks and info to be replaced with new ones
_ = o.CacheFs.cache.RemoveObject(o.abs())
err := o.Object.Update(in, src, options...)
if err != nil {
fs.Errorf(o, "error updating source: %v", err)
return err
}
o.CacheModTime = src.ModTime().UnixNano()
o.CacheSize = src.Size()
o.cacheHashes = make(map[hash.Type]string)
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o.persist()
return nil
}
// Remove deletes the object from both the cache and the source
func (o *Object) Remove() error {
if err := o.refreshFromSource(); err != nil {
return err
}
err := o.Object.Remove()
if err != nil {
return err
}
fs.Infof(o, "removing object")
_ = o.CacheFs.cache.RemoveObject(o.abs())
return err
}
// Hash requests a hash of the object and stores in the cache
// since it might or might not be called, this is lazy loaded
func (o *Object) Hash(ht hash.Type) (string, error) {
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if o.cacheHashes == nil {
o.cacheHashes = make(map[hash.Type]string)
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}
cachedHash, found := o.cacheHashes[ht]
if found {
return cachedHash, nil
}
if err := o.refreshFromSource(); err != nil {
return "", err
}
liveHash, err := o.Object.Hash(ht)
if err != nil {
return "", err
}
o.cacheHashes[ht] = liveHash
o.persist()
fs.Debugf(o, "object hash cached: %v", liveHash)
return liveHash, nil
}
// persist adds this object to the persistent cache
func (o *Object) persist() *Object {
err := o.CacheFs.cache.AddObject(o)
if err != nil {
fs.Errorf(o, "failed to cache object: %v", err)
}
return o
}
var (
_ fs.Object = (*Object)(nil)
)