190d8e2f51
This inlines the io.LimitedReader into the LimitedReadCloser body to achieve fewer allocations. Results on linux/amd64: name old time/op new time/op delta Backend/BenchmarkLoadPartialFile-8 412µs ± 4% 413µs ± 4% ~ (p=0.634 n=17+17) Backend/BenchmarkLoadPartialFileOffset-8 455µs ±13% 441µs ±10% ~ (p=0.072 n=20+18) name old speed new speed delta Backend/BenchmarkLoadPartialFile-8 10.2GB/s ± 3% 10.2GB/s ± 4% ~ (p=0.817 n=16+17) Backend/BenchmarkLoadPartialFileOffset-8 9.25GB/s ±12% 9.54GB/s ± 9% ~ (p=0.072 n=20+18) name old alloc/op new alloc/op delta Backend/BenchmarkLoadPartialFile-8 888B ± 0% 872B ± 0% -1.80% (p=0.000 n=15+15) Backend/BenchmarkLoadPartialFileOffset-8 888B ± 0% 872B ± 0% -1.80% (p=0.000 n=15+15) name old allocs/op new allocs/op delta Backend/BenchmarkLoadPartialFile-8 18.0 ± 0% 17.0 ± 0% -5.56% (p=0.000 n=15+15) Backend/BenchmarkLoadPartialFileOffset-8 18.0 ± 0% 17.0 ± 0% -5.56% (p=0.000 n=15+15)
59 lines
1.6 KiB
Go
59 lines
1.6 KiB
Go
package backend
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import (
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"bytes"
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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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// LoadAll reads all data stored in the backend for the handle into the given
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// buffer, which is truncated. If the buffer is not large enough or nil, a new
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// one is allocated.
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func LoadAll(ctx context.Context, buf []byte, be restic.Backend, h restic.Handle) ([]byte, error) {
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err := be.Load(ctx, h, 0, 0, func(rd io.Reader) error {
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// make sure this is idempotent, in case an error occurs this function may be called multiple times!
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wr := bytes.NewBuffer(buf[:0])
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_, cerr := io.Copy(wr, rd)
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if cerr != nil {
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return cerr
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}
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buf = wr.Bytes()
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return nil
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})
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if err != nil {
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return nil, err
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}
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return buf, nil
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}
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// LimitedReadCloser wraps io.LimitedReader and exposes the Close() method.
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type LimitedReadCloser struct {
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io.Closer
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io.LimitedReader
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}
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// LimitReadCloser returns a new reader wraps r in an io.LimitedReader, but also
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// exposes the Close() method.
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func LimitReadCloser(r io.ReadCloser, n int64) *LimitedReadCloser {
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return &LimitedReadCloser{Closer: r, LimitedReader: io.LimitedReader{R: r, N: n}}
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}
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// DefaultLoad implements Backend.Load using lower-level openReader func
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func DefaultLoad(ctx context.Context, h restic.Handle, length int, offset int64,
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openReader func(ctx context.Context, h restic.Handle, length int, offset int64) (io.ReadCloser, error),
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fn func(rd io.Reader) error) error {
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rd, err := openReader(ctx, h, length, offset)
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if err != nil {
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return err
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}
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err = fn(rd)
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if err != nil {
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rd.Close() // ignore secondary errors closing the reader
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return err
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}
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return rd.Close()
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}
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