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io.go
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/
io.go
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// SPDX-License-Identifier: AGPL-3.0-only
// Provenance-includes-location: https://github.com/thanos-io/thanos/blob/main/pkg/store/io.go
// Provenance-includes-license: Apache-2.0
// Provenance-includes-copyright: The Thanos Authors.
package storegateway
import (
"bufio"
"fmt"
"io"
)
type offsetTrackingReader struct {
offset uint64
r *bufio.Reader
}
// SkipTo skips to the provided offset.
func (r *offsetTrackingReader) SkipTo(at uint64) error {
if diff := int(at - r.offset); diff < 0 {
return fmt.Errorf("cannot reverse reader: offset %d, at %d", r.offset, at)
} else if diff > 0 {
n, err := r.r.Discard(diff)
r.offset += uint64(n)
if err != nil {
return fmt.Errorf("discarding sequence reader: %w", err)
}
}
return nil
}
// ReadByte implement io.ByteReader for compatibility with binary.ReadUvarint.
func (r *offsetTrackingReader) ReadByte() (byte, error) {
r.offset++
return r.r.ReadByte()
}
// Read implements io.Reader.
func (r *offsetTrackingReader) Read(p []byte) (int, error) {
n, err := r.r.Read(p)
r.offset += uint64(n)
return n, err
}
func (r *offsetTrackingReader) Reset(offset uint64, reader io.Reader) {
r.r.Reset(reader)
r.offset = offset
}
// Release removes the reference to the underlying reader
func (r *offsetTrackingReader) Release() {
r.Reset(0, nil)
}