From 915d9de91dcbb2a3d8757e97f6e5f2c59a141b35 Mon Sep 17 00:00:00 2001
From: Cuong Manh Le <cuong@orijtech.com>
Date: Tue, 1 Jun 2021 23:38:36 +0700
Subject: [PATCH] p2p/pex: reuse hash.Hasher per addrbook for speed (#6509)
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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
---
 CHANGELOG_PENDING.md  |  1 +
 p2p/pex/addrbook.go   | 26 +++++++++++++-------------
 p2p/pex/bench_test.go | 24 ++++++++++++++++++++++++
 3 files changed, 38 insertions(+), 13 deletions(-)
 create mode 100644 p2p/pex/bench_test.go

diff --git a/CHANGELOG_PENDING.md b/CHANGELOG_PENDING.md
index 4d76de6a5..38b0954e6 100644
--- a/CHANGELOG_PENDING.md
+++ b/CHANGELOG_PENDING.md
@@ -114,6 +114,7 @@ Friendly reminder: We have a [bug bounty program](https://hackerone.com/tendermi
 - [node/state] \#6370 graceful shutdown in the consensus reactor (@JayT106)
 - [crypto/merkle] \#6443 Improve HashAlternatives performance (@cuonglm)
 - [crypto/merkle] \#6513 Optimize HashAlternatives (@marbar3778)
+- [p2p/pex] \#6509 Improve addrBook.hash performance (@cuonglm)
 
 ### BUG FIXES
 
diff --git a/p2p/pex/addrbook.go b/p2p/pex/addrbook.go
index 831848915..dd8922bce 100644
--- a/p2p/pex/addrbook.go
+++ b/p2p/pex/addrbook.go
@@ -5,9 +5,9 @@
 package pex
 
 import (
-	crand "crypto/rand"
 	"encoding/binary"
 	"fmt"
+	"hash"
 	"math"
 	mrand "math/rand"
 	"net"
@@ -101,15 +101,18 @@ 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.
@@ -122,7 +125,6 @@ func NewAddrBook(filePath string, routabilityStrict bool) AddrBook {
 		badPeers:          make(map[p2p.NodeID]*knownAddress),
 		filePath:          filePath,
 		routabilityStrict: routabilityStrict,
-		hashKey:           newHashKey(),
 	}
 	am.init()
 	am.BaseService = *service.NewBaseService(nil, "AddrBook", am)
@@ -143,6 +145,7 @@ 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
 }
diff --git a/p2p/pex/bench_test.go b/p2p/pex/bench_test.go
new file mode 100644
index 000000000..7d2b636f1
--- /dev/null
+++ b/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.NodeID]struct{}),
+		addrLookup:        make(map[p2p.NodeID]*knownAddress),
+		badPeers:          make(map[p2p.NodeID]*knownAddress),
+		filePath:          "",
+		routabilityStrict: true,
+	}
+	book.init()
+	msg := []byte(`foobar`)
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_, _ = book.hash(msg)
+	}
+}