From 8d2379bcb3ca4c5fdf6b9322bbe05e42b7a81bca Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B8rn=20Erik=20Pedersen?=
 <bjorn.erik.pedersen@gmail.com>
Date: Wed, 26 Mar 2025 11:11:06 +0100
Subject: [PATCH] common/hreflect: Replace the map/RWMutex method cache with
 sync.Map
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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It's much faster when running in parallel:

```
GetMethodByName-10        125.1n ± 6%   181.7n ± 7%  +45.30% (p=0.002 n=6)
GetMethodByNamePara-10   770.10n ± 1%   24.77n ± 9%  -96.78% (p=0.002 n=6)
```
---
 common/hreflect/helpers.go      | 21 +++++----------------
 common/hreflect/helpers_test.go | 14 ++++++++++++++
 2 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/common/hreflect/helpers.go b/common/hreflect/helpers.go
index ab7883a47..545371374 100644
--- a/common/hreflect/helpers.go
+++ b/common/hreflect/helpers.go
@@ -134,12 +134,7 @@ type methodKey struct {
 	name string
 }
 
-type methods struct {
-	sync.RWMutex
-	cache map[methodKey]int
-}
-
-var methodCache = &methods{cache: make(map[methodKey]int)}
+var methodCache sync.Map
 
 // GetMethodByName is the same as reflect.Value.MethodByName, but it caches the
 // type lookup.
@@ -157,22 +152,16 @@ func GetMethodByName(v reflect.Value, name string) reflect.Value {
 // -1 if no such method exists.
 func GetMethodIndexByName(tp reflect.Type, name string) int {
 	k := methodKey{tp, name}
-	methodCache.RLock()
-	index, found := methodCache.cache[k]
-	methodCache.RUnlock()
+	v, found := methodCache.Load(k)
 	if found {
-		return index
+		return v.(int)
 	}
-
-	methodCache.Lock()
-	defer methodCache.Unlock()
-
 	m, ok := tp.MethodByName(name)
-	index = m.Index
+	index := m.Index
 	if !ok {
 		index = -1
 	}
-	methodCache.cache[k] = index
+	methodCache.Store(k, index)
 
 	if !ok {
 		return -1
diff --git a/common/hreflect/helpers_test.go b/common/hreflect/helpers_test.go
index 119722261..cbcad0f22 100644
--- a/common/hreflect/helpers_test.go
+++ b/common/hreflect/helpers_test.go
@@ -134,3 +134,17 @@ func BenchmarkGetMethodByName(b *testing.B) {
 		}
 	}
 }
+
+func BenchmarkGetMethodByNamePara(b *testing.B) {
+	v := reflect.ValueOf(&testStruct{})
+	methods := []string{"Method1", "Method2", "Method3", "Method4", "Method5"}
+
+	b.ResetTimer()
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			for _, method := range methods {
+				_ = GetMethodByName(v, method)
+			}
+		}
+	})
+}