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google.go
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google.go
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package gcs
import (
"context"
"fmt"
"io"
"math/rand"
"strconv"
"strings"
"time"
gcs "cloud.google.com/go/storage"
"google.golang.org/api/iterator"
"google.golang.org/api/option"
"github.com/hemantthanna/cas/storage"
"github.com/hemantthanna/cas/types"
)
var (
_ storage.Storage = (*Storage)(nil)
)
const (
dirBlobs = "cas/blobs/"
dirPins = "cas/pins/"
dirTmp = "cas/tmp/"
metaRef = "cas:ref"
)
var rnd = rand.New(rand.NewSource(time.Now().UnixNano()))
func init() {
storage.RegisterConfig("gcs:ClientConfig", &Config{})
}
type Config struct {
Bucket string `json:"bucket"`
}
func (c *Config) References() []types.Ref {
return nil
}
func (c *Config) OpenStorage(ctx context.Context) (storage.Storage, error) {
cli, err := New(ctx, c.Bucket)
if err != nil {
return nil, err
}
return cli, nil
}
func New(ctx context.Context, bucket string, opts ...option.ClientOption) (*Storage, error) {
cli, err := gcs.NewClient(ctx, opts...)
if err != nil {
return nil, err
}
b := cli.Bucket(bucket)
return &Storage{cli: cli, b: b}, nil
}
type Storage struct {
cli *gcs.Client
b *gcs.BucketHandle
}
func (s *Storage) Close() error {
return s.cli.Close()
}
func (s *Storage) blobObject(ref types.Ref) *gcs.ObjectHandle {
return s.b.Object(dirBlobs + ref.String())
}
func (s *Storage) pinObject(name string) *gcs.ObjectHandle {
return s.b.Object(dirPins + name)
}
func (s *Storage) StatBlob(ctx context.Context, ref types.Ref) (uint64, error) {
if ref.Zero() {
return 0, storage.ErrInvalidRef
}
info, err := s.blobObject(ref).Attrs(ctx)
if err == gcs.ErrObjectNotExist {
return 0, storage.ErrNotFound
} else if err != nil {
return 0, err
}
return uint64(info.Size), nil
}
func (s *Storage) FetchBlob(ctx context.Context, ref types.Ref) (io.ReadCloser, uint64, error) {
if ref.Zero() {
return nil, 0, storage.ErrInvalidRef
}
r, err := s.blobObject(ref).NewReader(ctx)
if err == gcs.ErrObjectNotExist {
return nil, 0, storage.ErrNotFound
} else if err != nil {
return nil, 0, err
}
return r, uint64(r.Attrs.Size), nil
}
func (s *Storage) iterate(ctx context.Context, pref string) objectsIterator {
it := s.b.Objects(ctx, &gcs.Query{Delimiter: "/", Prefix: pref})
return objectsIterator{
it: it, pref: pref,
}
}
func (s *Storage) IterateBlobs(ctx context.Context) storage.Iterator {
return &blobIterator{
objectsIterator: s.iterate(ctx, dirBlobs),
}
}
func (s *Storage) BeginBlob(ctx context.Context) (storage.BlobWriter, error) {
for {
name := dirTmp + strconv.FormatUint(rnd.Uint64(), 16)
_, err := s.b.Object(name).Attrs(ctx)
if err == nil {
continue
} else if err != gcs.ErrObjectNotExist {
return nil, err
}
ctx, discard := context.WithCancel(ctx)
w := s.b.Object(name).If(gcs.Conditions{DoesNotExist: true}).NewWriter(ctx)
return &blobWriter{s: s, ctx: ctx, w: w, discard: discard, hw: storage.Hash()}, nil
}
}
func (s *Storage) SetPin(ctx context.Context, name string, ref types.Ref) error {
w := s.pinObject(name).NewWriter(ctx)
w.ObjectAttrs.Metadata = map[string]string{
metaRef: ref.String(),
}
return w.Close()
}
func (s *Storage) DeletePin(ctx context.Context, name string) error {
return s.pinObject(name).Delete(ctx)
}
func (s *Storage) GetPin(ctx context.Context, name string) (types.Ref, error) {
if strings.ContainsAny(name, "/?&") {
return types.Ref{}, fmt.Errorf("invalid pin name: %q", name)
}
info, err := s.pinObject(name).Attrs(ctx)
if err == gcs.ErrObjectNotExist {
return types.Ref{}, storage.ErrNotFound
} else if err != nil {
return types.Ref{}, err
}
ref, err := types.ParseRef(info.Metadata[metaRef])
if err != nil {
return types.Ref{}, err
}
return ref, nil
}
func (s *Storage) IteratePins(ctx context.Context) storage.PinIterator {
return &pinsIterator{
objectsIterator: s.iterate(ctx, dirPins),
}
}
type blobWriter struct {
s *Storage
ctx context.Context
discard func()
w *gcs.Writer
hw storage.BlobWriter
sr types.SizedRef
}
func (w *blobWriter) Write(p []byte) (int, error) {
if _, err := w.hw.Write(p); err != nil {
return 0, err
}
return w.w.Write(p)
}
func (w *blobWriter) Size() uint64 {
return w.hw.Size()
}
func (w *blobWriter) Complete() (types.SizedRef, error) {
sr, err := w.hw.Complete()
if err != nil {
return types.SizedRef{}, err
}
w.sr = sr
err = w.w.Close()
if err != nil {
w.Close()
return types.SizedRef{}, err
}
return sr, nil
}
func (w *blobWriter) Close() error {
w.discard()
if err := w.hw.Close(); err != nil {
return err
}
return w.w.Close()
}
func (w *blobWriter) Commit() error {
if err := w.hw.Commit(); err != nil {
return err
}
src := w.s.b.Object(w.w.Name)
dst := w.s.blobObject(w.sr.Ref).If(gcs.Conditions{DoesNotExist: true})
_, err := dst.CopierFrom(src).Run(w.ctx)
_ = src.Delete(w.ctx)
w.discard()
return err
}
type objectsIterator struct {
it *gcs.ObjectIterator
pref string
cur *gcs.ObjectAttrs
err error
}
func (it *objectsIterator) Next() bool {
it.cur, it.err = it.it.Next()
if it.err == iterator.Done {
it.err = nil
return false
}
if it.cur != nil {
it.cur.Name = strings.TrimPrefix(it.cur.Name, it.pref)
}
return it.err == nil
}
func (it *objectsIterator) Err() error {
return it.err
}
func (it *objectsIterator) Close() error {
return nil
}
type blobIterator struct {
objectsIterator
sr types.SizedRef
}
func (it *blobIterator) SizedRef() types.SizedRef {
return it.sr
}
func (it *blobIterator) Next() bool {
if !it.objectsIterator.Next() || it.cur == nil {
return false
}
it.sr.Size = uint64(it.cur.Size)
it.sr.Ref, it.err = types.ParseRef(it.cur.Name)
return it.err == nil
}
type pinsIterator struct {
objectsIterator
pin types.Pin
}
func (it *pinsIterator) Pin() types.Pin {
return it.pin
}
func (it *pinsIterator) Next() bool {
if !it.objectsIterator.Next() || it.cur == nil {
return false
}
it.pin.Name = it.cur.Name
it.pin.Ref, it.err = types.ParseRef(it.cur.Metadata[metaRef])
return it.err == nil
}