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Merged
merged 3 commits into from
Oct 13, 2025
Merged

p2p/enode: optimize DistCmp #32888

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bacd81e
p2p/enode: opt DistCmp
cuiweixie Oct 12, 2025
39f5232
simplify DistCmp
fjl Oct 13, 2025
1029acb
p2p/enode: fmt file
cuiweixie Oct 13, 2025
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8 changes: 5 additions & 3 deletions p2p/enode/node.go
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ package enode
import (
"crypto/ecdsa"
"encoding/base64"
"encoding/binary"
"encoding/hex"
"errors"
"fmt"
Expand Down Expand Up @@ -358,9 +359,10 @@ func ParseID(in string) (ID, error) {
// Returns -1 if a is closer to target, 1 if b is closer to target
// and 0 if they are equal.
func DistCmp(target, a, b ID) int {
for i := range target {
da := a[i] ^ target[i]
db := b[i] ^ target[i]
for i := 0; i < len(target); i += 8 {
tn := binary.BigEndian.Uint64(target[i : i+8])
da := tn ^ binary.BigEndian.Uint64(a[i:i+8])
db := tn ^ binary.BigEndian.Uint64(b[i:i+8])
if da > db {
return 1
} else if da < db {
Expand Down
10 changes: 10 additions & 0 deletions p2p/enode/node_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -368,6 +368,16 @@ func TestID_distcmpEqual(t *testing.T) {
}
}

func BenchmarkDistCmp(b *testing.B) {
base := ID{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}
aID := ID{15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0}
bID := ID{15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 1}
b.ResetTimer()
for i := 0; i < b.N; i++ {
_ = DistCmp(base, aID, bID)
}
}

func TestID_logdist(t *testing.T) {
logdistBig := func(a, b ID) int {
abig, bbig := new(big.Int).SetBytes(a[:]), new(big.Int).SetBytes(b[:])
Expand Down