plugin/cache: remove superfluous allocations in item.toMsg #7700
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This commit removes superfluous allocations of the Answer, Ns, and Extra
slices when copying a cached a dns.Msg. The allocations are superfluous
because we immediately overwrite the newly copied slices with
filterRRSlice. It also updates filterRRSlice to pre-calculate the size
of the slice being copied into.
Benchmark results:
goos: darwin
goarch: arm64
pkg: github.com/coredns/coredns/plugin/cache
cpu: Apple M4 Pro
│ base.10.txt │ new.10.txt │
│ sec/op │ sec/op vs base │
CacheResponse-14 471.1n ± 0% 462.9n ± 2% -1.74% (p=0.009 n=10)
│ base.10.txt │ new.10.txt │
│ B/op │ B/op vs base │
CacheResponse-14 672.0 ± 0% 656.0 ± 0% -2.38% (p=0.000 n=10)
│ base.10.txt │ new.10.txt │
│ allocs/op │ allocs/op vs base │
CacheResponse-14 13.00 ± 0% 12.00 ± 0% -7.69% (p=0.000 n=10)
Signed-off-by: Charlie Vieth <[email protected]>
Contributor
Author
|
The Go Tests / Test e2e (pull_request) appears unrelated to this PR. |
yongtang
approved these changes
Nov 21, 2025
Contributor
Author
|
@yongtang Thank you for the review and merging! |
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1. Why is this pull request needed and what does it do?
This commit removes superfluous allocations of the Answer, Ns, and Extra slices when copying a cached a dns.Msg. The allocations are superfluous because we immediately overwrite the newly copied slices with filterRRSlice. It also updates filterRRSlice to pre-calculate the size of the slice being copied into.
Benchmark results:
2. Which issues (if any) are related?
N/A
3. Which documentation changes (if any) need to be made?
N/A
4. Does this introduce a backward incompatible change or deprecation?
N/A