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de010910e2
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 <charlie.vieth@gmail.com>
31 lines
608 B
Go
31 lines
608 B
Go
package cache
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import "github.com/miekg/dns"
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// filterRRSlice filters out OPT RRs, and sets all RR TTLs to ttl.
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// If dup is true the RRs in rrs are _copied_ before adjusting their
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// TTL and the slice of copied RRs is returned.
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func filterRRSlice(rrs []dns.RR, ttl uint32, dup bool) []dns.RR {
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n := 0
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for _, r := range rrs {
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if r.Header().Rrtype != dns.TypeOPT {
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n++
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}
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}
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rs := make([]dns.RR, n)
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j := 0
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for _, r := range rrs {
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if r.Header().Rrtype == dns.TypeOPT {
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continue
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}
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if dup {
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rs[j] = dns.Copy(r)
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} else {
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rs[j] = r
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}
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rs[j].Header().Ttl = ttl
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j++
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}
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return rs
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}
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