containerd/content/local/readerat.go
Stephen J Day 8be340e37b
content: remove Provider.Reader
After some analysis, it was found that Content.Reader was generally
redudant to an io.ReaderAt. This change removes `Content.Reader` in
favor of a `Content.ReaderAt`. In general, `ReaderAt` can perform better
over interfaces with indeterminant latency because it avoids remote
state for reads. Where a reader is required, a helper is provided to
convert it into an `io.SectionReader`.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
2017-08-09 14:32:28 -07:00

25 lines
441 B
Go

package local
import (
"os"
)
// readerat implements io.ReaderAt in a completely stateless manner by opening
// the referenced file for each call to ReadAt.
type sizeReaderAt struct {
size int64
fp *os.File
}
func (ra sizeReaderAt) ReadAt(p []byte, offset int64) (int, error) {
return ra.fp.ReadAt(p, offset)
}
func (ra sizeReaderAt) Size() int64 {
return ra.size
}
func (ra sizeReaderAt) Close() error {
return ra.fp.Close()
}