refactor(shares): use more efficient make([]byte, N) not bytes.Repeat([]byte{0}, N) #42
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odeke-em
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ramin,
staheri14 and
distractedm1nd
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…, N)
This change uses Go's memory model guarantees that the zero value memory
shall be zeroed and hence to create a slice of 0 bytes aka padding,
we can simply use make([]byte, N) which is much more efficient than
bytes.Repeat([]byte{0}, N) and the benchmarks show this improvement:
```shell
$ benchstat before.txt after.txt
name old time/op new time/op delta
PaddingVsRepeat-8 674ns ± 1% 538ns ± 0% -20.22% (p=0.000 n=9+9)
name old alloc/op new alloc/op delta
PaddingVsRepeat-8 1.31kB ± 0% 0.83kB ± 0% -36.59% (p=0.000 n=10+10)
name old allocs/op new allocs/op delta
PaddingVsRepeat-8 12.0 ± 0% 11.0 ± 0% -8.33% (p=0.000 n=10+10)
```
Fixes celestiaorg#41
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rootulp
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rootulp
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Feb 29, 2024
| @@ -31,8 +31,7 @@ func zeroPadIfNecessary(share []byte, width int) (padded []byte, bytesOfPadding | |||
| } | |||
|
|
|||
| missingBytes := width - oldLen | |||
| padByte := []byte{0} | |||
| padding := bytes.Repeat(padByte, missingBytes) | |||
| padding := make([]byte, missingBytes) | |||
There was a problem hiding this comment.
LGTM because Test_zeroPadIfNecessary still passes
| @@ -20,7 +19,7 @@ func NamespacePaddingShare(ns namespace.Namespace, shareVersion uint8) (Share, e | |||
| if err := b.WriteSequenceLen(0); err != nil { | |||
| return Share{}, err | |||
| } | |||
| padding := bytes.Repeat([]byte{0}, FirstSparseShareContentSize) | |||
| padding := make([]byte, FirstSparseShareContentSize) | |||
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LGTM b/c TestNamespacePaddingShare still passes
liamsi
approved these changes
Feb 29, 2024
odeke-em
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|
Thank you for the review and merge! |
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This change uses Go's memory model guarantees that the zero value memory shall be zeroed and hence to create a slice of 0 bytes aka padding, we can simply use make([]byte, N) which is much more efficient than bytes.Repeat([]byte{0}, N) and the benchmarks show this improvement:
Fixes #41