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mirror of https://github.com/octoleo/restic.git synced 2024-12-23 19:38:57 +00:00
restic/internal/backend/b2/b2.go
Alexander Neumann 99f7fd74e3 backend: Improve Save()
As mentioned in issue [#1560](https://github.com/restic/restic/pull/1560#issuecomment-364689346)
this changes the signature for `backend.Save()`. It now takes a
parameter of interface type `RewindReader`, so that the backend
implementations or our `RetryBackend` middleware can reset the reader to
the beginning and then retry an upload operation.

The `RewindReader` interface also provides a `Length()` method, which is
used in the backend to get the size of the data to be saved. This
removes several ugly hacks we had to do to pull the size back out of the
`io.Reader` passed to `Save()` before. In the `s3` and `rest` backend
this is actively used.
2018-03-03 15:49:44 +01:00

364 lines
8.1 KiB
Go

package b2
import (
"context"
"io"
"net/http"
"path"
"strings"
"github.com/restic/restic/internal/backend"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/restic"
"github.com/kurin/blazer/b2"
)
// b2Backend is a backend which stores its data on Backblaze B2.
type b2Backend struct {
client *b2.Client
bucket *b2.Bucket
cfg Config
listMaxItems int
backend.Layout
sem *backend.Semaphore
}
const defaultListMaxItems = 1000
// ensure statically that *b2Backend implements restic.Backend.
var _ restic.Backend = &b2Backend{}
func newClient(ctx context.Context, cfg Config, rt http.RoundTripper) (*b2.Client, error) {
opts := []b2.ClientOption{b2.Transport(rt)}
c, err := b2.NewClient(ctx, cfg.AccountID, cfg.Key, opts...)
if err != nil {
return nil, errors.Wrap(err, "b2.NewClient")
}
return c, nil
}
// Open opens a connection to the B2 service.
func Open(ctx context.Context, cfg Config, rt http.RoundTripper) (restic.Backend, error) {
debug.Log("cfg %#v", cfg)
ctx, cancel := context.WithCancel(ctx)
defer cancel()
client, err := newClient(ctx, cfg, rt)
if err != nil {
return nil, err
}
bucket, err := client.Bucket(ctx, cfg.Bucket)
if err != nil {
return nil, errors.Wrap(err, "Bucket")
}
sem, err := backend.NewSemaphore(cfg.Connections)
if err != nil {
return nil, err
}
be := &b2Backend{
client: client,
bucket: bucket,
cfg: cfg,
Layout: &backend.DefaultLayout{
Join: path.Join,
Path: cfg.Prefix,
},
listMaxItems: defaultListMaxItems,
sem: sem,
}
return be, nil
}
// Create opens a connection to the B2 service. If the bucket does not exist yet,
// it is created.
func Create(ctx context.Context, cfg Config, rt http.RoundTripper) (restic.Backend, error) {
debug.Log("cfg %#v", cfg)
ctx, cancel := context.WithCancel(ctx)
defer cancel()
client, err := newClient(ctx, cfg, rt)
if err != nil {
return nil, err
}
attr := b2.BucketAttrs{
Type: b2.Private,
}
bucket, err := client.NewBucket(ctx, cfg.Bucket, &attr)
if err != nil {
return nil, errors.Wrap(err, "NewBucket")
}
sem, err := backend.NewSemaphore(cfg.Connections)
if err != nil {
return nil, err
}
be := &b2Backend{
client: client,
bucket: bucket,
cfg: cfg,
Layout: &backend.DefaultLayout{
Join: path.Join,
Path: cfg.Prefix,
},
listMaxItems: defaultListMaxItems,
sem: sem,
}
present, err := be.Test(ctx, restic.Handle{Type: restic.ConfigFile})
if err != nil {
return nil, err
}
if present {
return nil, errors.New("config already exists")
}
return be, nil
}
// SetListMaxItems sets the number of list items to load per request.
func (be *b2Backend) SetListMaxItems(i int) {
be.listMaxItems = i
}
// Location returns the location for the backend.
func (be *b2Backend) Location() string {
return be.cfg.Bucket
}
// IsNotExist returns true if the error is caused by a non-existing file.
func (be *b2Backend) IsNotExist(err error) bool {
return b2.IsNotExist(errors.Cause(err))
}
// Load runs fn with a reader that yields the contents of the file at h at the
// given offset.
func (be *b2Backend) Load(ctx context.Context, h restic.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
return backend.DefaultLoad(ctx, h, length, offset, be.openReader, fn)
}
func (be *b2Backend) openReader(ctx context.Context, h restic.Handle, length int, offset int64) (io.ReadCloser, error) {
debug.Log("Load %v, length %v, offset %v from %v", h, length, offset, be.Filename(h))
if err := h.Valid(); err != nil {
return nil, err
}
if offset < 0 {
return nil, errors.New("offset is negative")
}
if length < 0 {
return nil, errors.Errorf("invalid length %d", length)
}
ctx, cancel := context.WithCancel(ctx)
be.sem.GetToken()
name := be.Layout.Filename(h)
obj := be.bucket.Object(name)
if offset == 0 && length == 0 {
rd := obj.NewReader(ctx)
return be.sem.ReleaseTokenOnClose(rd, cancel), nil
}
// pass a negative length to NewRangeReader so that the remainder of the
// file is read.
if length == 0 {
length = -1
}
rd := obj.NewRangeReader(ctx, offset, int64(length))
return be.sem.ReleaseTokenOnClose(rd, cancel), nil
}
// Save stores data in the backend at the handle.
func (be *b2Backend) Save(ctx context.Context, h restic.Handle, rd restic.RewindReader) error {
ctx, cancel := context.WithCancel(ctx)
defer cancel()
if err := h.Valid(); err != nil {
return err
}
be.sem.GetToken()
defer be.sem.ReleaseToken()
name := be.Filename(h)
debug.Log("Save %v, name %v", h, name)
obj := be.bucket.Object(name)
w := obj.NewWriter(ctx)
n, err := io.Copy(w, rd)
debug.Log(" saved %d bytes, err %v", n, err)
if err != nil {
_ = w.Close()
return errors.Wrap(err, "Copy")
}
return errors.Wrap(w.Close(), "Close")
}
// Stat returns information about a blob.
func (be *b2Backend) Stat(ctx context.Context, h restic.Handle) (bi restic.FileInfo, err error) {
debug.Log("Stat %v", h)
be.sem.GetToken()
defer be.sem.ReleaseToken()
name := be.Filename(h)
obj := be.bucket.Object(name)
info, err := obj.Attrs(ctx)
if err != nil {
debug.Log("Attrs() err %v", err)
return restic.FileInfo{}, errors.Wrap(err, "Stat")
}
return restic.FileInfo{Size: info.Size, Name: h.Name}, nil
}
// Test returns true if a blob of the given type and name exists in the backend.
func (be *b2Backend) Test(ctx context.Context, h restic.Handle) (bool, error) {
debug.Log("Test %v", h)
be.sem.GetToken()
defer be.sem.ReleaseToken()
found := false
name := be.Filename(h)
obj := be.bucket.Object(name)
info, err := obj.Attrs(ctx)
if err == nil && info != nil && info.Status == b2.Uploaded {
found = true
}
return found, nil
}
// Remove removes the blob with the given name and type.
func (be *b2Backend) Remove(ctx context.Context, h restic.Handle) error {
debug.Log("Remove %v", h)
be.sem.GetToken()
defer be.sem.ReleaseToken()
obj := be.bucket.Object(be.Filename(h))
return errors.Wrap(obj.Delete(ctx), "Delete")
}
// List returns a channel that yields all names of blobs of type t. A
// goroutine is started for this. If the channel done is closed, sending
// stops.
func (be *b2Backend) List(ctx context.Context, t restic.FileType, fn func(restic.FileInfo) error) error {
debug.Log("List %v", t)
prefix, _ := be.Basedir(t)
cur := &b2.Cursor{Prefix: prefix}
ctx, cancel := context.WithCancel(ctx)
defer cancel()
for {
be.sem.GetToken()
objs, c, err := be.bucket.ListCurrentObjects(ctx, be.listMaxItems, cur)
be.sem.ReleaseToken()
if err != nil && err != io.EOF {
debug.Log("List: %v", err)
return err
}
debug.Log("returned %v items", len(objs))
for _, obj := range objs {
// Skip objects returned that do not have the specified prefix.
if !strings.HasPrefix(obj.Name(), prefix) {
continue
}
m := path.Base(obj.Name())
if m == "" {
continue
}
if ctx.Err() != nil {
return ctx.Err()
}
if ctx.Err() != nil {
return ctx.Err()
}
attrs, err := obj.Attrs(ctx)
if err != nil {
return err
}
fi := restic.FileInfo{
Name: m,
Size: attrs.Size,
}
err = fn(fi)
if err != nil {
return err
}
if ctx.Err() != nil {
return ctx.Err()
}
}
if err == io.EOF {
return ctx.Err()
}
cur = c
}
return ctx.Err()
}
// Remove keys for a specified backend type.
func (be *b2Backend) removeKeys(ctx context.Context, t restic.FileType) error {
debug.Log("removeKeys %v", t)
return be.List(ctx, t, func(fi restic.FileInfo) error {
return be.Remove(ctx, restic.Handle{Type: t, Name: fi.Name})
})
}
// Delete removes all restic keys in the bucket. It will not remove the bucket itself.
func (be *b2Backend) Delete(ctx context.Context) error {
alltypes := []restic.FileType{
restic.DataFile,
restic.KeyFile,
restic.LockFile,
restic.SnapshotFile,
restic.IndexFile}
for _, t := range alltypes {
err := be.removeKeys(ctx, t)
if err != nil {
return nil
}
}
err := be.Remove(ctx, restic.Handle{Type: restic.ConfigFile})
if err != nil && b2.IsNotExist(errors.Cause(err)) {
err = nil
}
return err
}
// Close does nothing
func (be *b2Backend) Close() error { return nil }