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restic/internal/hashing/writer.go
greatroar 41fee11f66 Micro-optimization for hashing.Writer/PackerManager
name             old time/op    new time/op    delta
PackerManager-8     247ms ± 1%     246ms ± 1%  -0.43%  (p=0.001 n=18+18)

name             old speed      new speed      delta
PackerManager-8   213MB/s ± 1%   214MB/s ± 1%  +0.43%  (p=0.001 n=18+18)

name             old alloc/op   new alloc/op   delta
PackerManager-8    92.2kB ± 0%    91.5kB ± 0%  -0.82%  (p=0.000 n=19+20)

name             old allocs/op  new allocs/op  delta
PackerManager-8     1.43k ± 0%     1.41k ± 0%  -1.67%  (p=0.000 n=20+20)
2020-03-05 22:30:04 +01:00

33 lines
644 B
Go

package hashing
import (
"hash"
"io"
)
// Writer transparently hashes all data while writing it to the underlying writer.
type Writer struct {
w io.Writer
h hash.Hash
}
// NewWriter wraps the writer w and feeds all data written to the hash h.
func NewWriter(w io.Writer, h hash.Hash) *Writer {
return &Writer{
h: h,
w: w,
}
}
// Write wraps the write method of the underlying writer and also hashes all data.
func (h *Writer) Write(p []byte) (int, error) {
n, err := h.w.Write(p)
h.h.Write(p[:n])
return n, err
}
// Sum returns the hash of all data written so far.
func (h *Writer) Sum(d []byte) []byte {
return h.h.Sum(d)
}