restic/internal/backend/utils.go
Michael Eischer 3d29083e60 copy/find/ls/recover/stats: Memorize snapshot listing before index
These commands filter the snapshots according to some criteria which
essentially requires loading the index before filtering the snapshots.
Thus create a copy of the snapshots list beforehand and use it later on.
2022-04-09 12:26:30 +02:00

97 lines
2.4 KiB
Go

package backend
import (
"bytes"
"context"
"fmt"
"io"
"github.com/restic/restic/internal/restic"
)
// LoadAll reads all data stored in the backend for the handle into the given
// buffer, which is truncated. If the buffer is not large enough or nil, a new
// one is allocated.
func LoadAll(ctx context.Context, buf []byte, be restic.Backend, h restic.Handle) ([]byte, error) {
err := be.Load(ctx, h, 0, 0, func(rd io.Reader) error {
// make sure this is idempotent, in case an error occurs this function may be called multiple times!
wr := bytes.NewBuffer(buf[:0])
_, cerr := io.Copy(wr, rd)
if cerr != nil {
return cerr
}
buf = wr.Bytes()
return nil
})
if err != nil {
return nil, err
}
return buf, nil
}
// LimitedReadCloser wraps io.LimitedReader and exposes the Close() method.
type LimitedReadCloser struct {
io.Closer
io.LimitedReader
}
// LimitReadCloser returns a new reader wraps r in an io.LimitedReader, but also
// exposes the Close() method.
func LimitReadCloser(r io.ReadCloser, n int64) *LimitedReadCloser {
return &LimitedReadCloser{Closer: r, LimitedReader: io.LimitedReader{R: r, N: n}}
}
// DefaultLoad implements Backend.Load using lower-level openReader func
func DefaultLoad(ctx context.Context, h restic.Handle, length int, offset int64,
openReader func(ctx context.Context, h restic.Handle, length int, offset int64) (io.ReadCloser, error),
fn func(rd io.Reader) error) error {
rd, err := openReader(ctx, h, length, offset)
if err != nil {
return err
}
err = fn(rd)
if err != nil {
_ = rd.Close() // ignore secondary errors closing the reader
return err
}
return rd.Close()
}
type memorizedLister struct {
fileInfos []restic.FileInfo
tpe restic.FileType
}
func (m *memorizedLister) List(ctx context.Context, t restic.FileType, fn func(restic.FileInfo) error) error {
if t != m.tpe {
return fmt.Errorf("filetype mismatch, expected %s got %s", m.tpe, t)
}
for _, fi := range m.fileInfos {
if ctx.Err() != nil {
break
}
err := fn(fi)
if err != nil {
return err
}
}
return ctx.Err()
}
func MemorizeList(ctx context.Context, be restic.Lister, t restic.FileType) (restic.Lister, error) {
var fileInfos []restic.FileInfo
err := be.List(ctx, t, func(fi restic.FileInfo) error {
fileInfos = append(fileInfos, fi)
return nil
})
if err != nil {
return nil, err
}
return &memorizedLister{
fileInfos: fileInfos,
tpe: t,
}, nil
}