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backend: Improve Save()

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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.
This commit is contained in:
Alexander Neumann 2018-03-03 14:20:54 +01:00
parent 58306bfabb
commit 99f7fd74e3
29 changed files with 387 additions and 204 deletions
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41
internal/backend/backend_retry_test.go
View file

@ -13,48 +13,11 @@ import (
"github.com/restic/restic/internal/test"
)
func TestBackendRetrySeeker(t *testing.T) {
be := &mock.Backend{
SaveFn: func(ctx context.Context, h restic.Handle, rd io.Reader) error {
return nil
},
}
retryBackend := RetryBackend{
Backend: be,
}
data := test.Random(24, 23*14123)
type wrapReader struct {
io.Reader
}
var rd io.Reader
rd = wrapReader{bytes.NewReader(data)}
err := retryBackend.Save(context.TODO(), restic.Handle{}, rd)
if err == nil {
t.Fatal("did not get expected error for retry backend with non-seeker reader")
}
rd = bytes.NewReader(data)
_, err = io.CopyN(ioutil.Discard, rd, 5)
if err != nil {
t.Fatal(err)
}
err = retryBackend.Save(context.TODO(), restic.Handle{}, rd)
if err == nil {
t.Fatal("did not get expected error for partial reader")
}
}
func TestBackendSaveRetry(t *testing.T) {
buf := bytes.NewBuffer(nil)
errcount := 0
be := &mock.Backend{
SaveFn: func(ctx context.Context, h restic.Handle, rd io.Reader) error {
SaveFn: func(ctx context.Context, h restic.Handle, rd restic.RewindReader) error {
if errcount == 0 {
errcount++
_, err := io.CopyN(ioutil.Discard, rd, 120)
@ -75,7 +38,7 @@ func TestBackendSaveRetry(t *testing.T) {
}
data := test.Random(23, 5*1024*1024+11241)
err := retryBackend.Save(context.TODO(), restic.Handle{}, bytes.NewReader(data))
err := retryBackend.Save(context.TODO(), restic.Handle{}, restic.NewByteReader(data))
if err != nil {
t.Fatal(err)
}