From 190d8e2f510c251cf93b582de1c0cbd842fa4d09 Mon Sep 17 00:00:00 2001
From: greatroar <@>
Date: Tue, 26 May 2020 13:35:07 +0200
Subject: [PATCH] Flatten backend.LimitedReadCloser structure
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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)
---
internal/backend/utils.go | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)
diff --git a/internal/backend/utils.go b/internal/backend/utils.go
index 1665aedc6..e6dc7a549 100644
--- a/internal/backend/utils.go
+++ b/internal/backend/utils.go
@@ -32,19 +32,14 @@ func LoadAll(ctx context.Context, buf []byte, be restic.Backend, h restic.Handle
// LimitedReadCloser wraps io.LimitedReader and exposes the Close() method.
type LimitedReadCloser struct {
- io.ReadCloser
- io.Reader
+ io.Closer
+ io.LimitedReader
}
-// Read reads data from the limited reader.
-func (l *LimitedReadCloser) Read(p []byte) (int, error) {
- return l.Reader.Read(p)
-}
-
-// LimitReadCloser returns a new reader wraps r in an io.LimitReader, but also
+// 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{ReadCloser: r, Reader: io.LimitReader(r, n)}
+ return &LimitedReadCloser{Closer: r, LimitedReader: io.LimitedReader{R: r, N: n}}
}
// DefaultLoad implements Backend.Load using lower-level openReader func