p2p/pex: reuse hash.Hasher per addrbook for speed (#6509) (#9445)

Cherry-picking PR #6509

By pre-creating the hasher, instead of creating new one everytime addrbook.hash is called.

```
name             old time/op    new time/op    delta
AddrBook_hash-8     181ns ±13%      80ns ± 1%  -56.08%  (p=0.000 n=10+10)

name             old alloc/op   new alloc/op   delta
AddrBook_hash-8      216B ± 0%        8B ± 0%  -96.30%  (p=0.000 n=10+10)

name             old allocs/op  new allocs/op  delta
AddrBook_hash-8      2.00 ± 0%      1.00 ± 0%  -50.00%  (p=0.000 n=10+10)
```

Fixed #6508



---

#### PR checklist

- [x] Tests written/updated, or no tests needed
- [x] `CHANGELOG_PENDING.md` updated, or no changelog entry needed
- [x] Updated relevant documentation (`docs/`) and code comments, or no
      documentation updates needed

p2p/pex/addrbook.go

@@ -5,9 +5,9 @@
 package pex
 
 import (
-	crand "crypto/rand"
 	"encoding/binary"
 	"fmt"
+	"hash"
 	"math"
 	"math/rand"
 	"net"
@@ -104,15 +104,18 @@ type addrBook struct {
 	filePath          string
 	key               string // random prefix for bucket placement
 	routabilityStrict bool
-	hashKey           []byte
+	hasher            hash.Hash64
 
 	wg sync.WaitGroup
 }
 
-func newHashKey() []byte {
-	result := make([]byte, highwayhash.Size)
-	crand.Read(result) //nolint:errcheck // ignore error
-	return result
+func mustNewHasher() hash.Hash64 {
+	key := crypto.CRandBytes(highwayhash.Size)
+	hasher, err := highwayhash.New64(key)
+	if err != nil {
+		panic(err)
+	}
+	return hasher
 }
 
 // NewAddrBook creates a new address book.
@@ -126,7 +129,6 @@ func NewAddrBook(filePath string, routabilityStrict bool) AddrBook {
 		badPeers:          make(map[p2p.ID]*knownAddress),
 		filePath:          filePath,
 		routabilityStrict: routabilityStrict,
-		hashKey:           newHashKey(),
 	}
 	am.init()
 	am.BaseService = *service.NewBaseService(nil, "AddrBook", am)
@@ -147,6 +149,7 @@ func (a *addrBook) init() {
 	for i := range a.bucketsOld {
 		a.bucketsOld[i] = make(map[string]*knownAddress)
 	}
+	a.hasher = mustNewHasher()
 }
 
 // OnStart implements Service.
@@ -938,10 +941,7 @@ func groupKeyFor(na *p2p.NetAddress, routabilityStrict bool) string {
 }
 
 func (a *addrBook) hash(b []byte) ([]byte, error) {
-	hasher, err := highwayhash.New64(a.hashKey)
-	if err != nil {
-		return nil, err
-	}
-	hasher.Write(b)
-	return hasher.Sum(nil), nil
+	a.hasher.Reset()
+	a.hasher.Write(b)
+	return a.hasher.Sum(nil), nil
 }

p2p/pex/bench_test.go

@@ -0,0 +1,24 @@
+package pex
+
+import (
+	"testing"
+
+	"github.com/tendermint/tendermint/p2p"
+)
+
+func BenchmarkAddrBook_hash(b *testing.B) {
+	book := &addrBook{
+		ourAddrs:          make(map[string]struct{}),
+		privateIDs:        make(map[p2p.ID]struct{}),
+		addrLookup:        make(map[p2p.ID]*knownAddress),
+		badPeers:          make(map[p2p.ID]*knownAddress),
+		filePath:          "",
+		routabilityStrict: true,
+	}
+	book.init()
+	msg := []byte(`foobar`)
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_, _ = book.hash(msg)
+	}
+}