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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.
69 lines
1.4 KiB
Go
69 lines
1.4 KiB
Go
package limiter
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import (
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"context"
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"io"
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"github.com/restic/restic/internal/restic"
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)
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// LimitBackend wraps a Backend and applies rate limiting to Load() and Save()
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// calls on the backend.
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func LimitBackend(be restic.Backend, l Limiter) restic.Backend {
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return rateLimitedBackend{
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Backend: be,
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limiter: l,
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}
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}
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type rateLimitedBackend struct {
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restic.Backend
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limiter Limiter
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}
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func (r rateLimitedBackend) Save(ctx context.Context, h restic.Handle, rd restic.RewindReader) error {
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limited := limitedRewindReader{
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RewindReader: rd,
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limited: r.limiter.Upstream(rd),
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}
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return r.Backend.Save(ctx, h, limited)
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}
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type limitedRewindReader struct {
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restic.RewindReader
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limited io.Reader
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}
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func (l limitedRewindReader) Read(b []byte) (int, error) {
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return l.limited.Read(b)
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}
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func (r rateLimitedBackend) Load(ctx context.Context, h restic.Handle, length int, offset int64, consumer func(rd io.Reader) error) error {
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return r.Backend.Load(ctx, h, length, offset, func(rd io.Reader) error {
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lrd := limitedReadCloser{
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limited: r.limiter.Downstream(rd),
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}
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return consumer(lrd)
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})
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}
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type limitedReadCloser struct {
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original io.ReadCloser
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limited io.Reader
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}
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func (l limitedReadCloser) Read(b []byte) (n int, err error) {
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return l.limited.Read(b)
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}
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func (l limitedReadCloser) Close() error {
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if l.original == nil {
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return nil
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}
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return l.original.Close()
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}
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var _ restic.Backend = (*rateLimitedBackend)(nil)
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