From 7dea3409d4944b0d61108f9bd1b553d8cfed7e9c Mon Sep 17 00:00:00 2001
From: Antoine Pelisse <apelisse@gmail.com>
Date: Mon, 30 Jan 2023 10:02:57 -0800
Subject: [PATCH] apiextensions: Pool schemas in SchemaHas
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Using a `sync.Pool` to re-use the buffers that have to escape in the
predicate significantly reduces the number of allocations needed to run
the SchemaHas method, as shown in the following example:

```
> benchstat old.bench new.bench
name         old time/op    new time/op    delta
SchemaHas-8    11.0ms ± 0%     2.1ms ± 1%   -80.60%  (p=0.008 n=5+5)

name         old alloc/op   new alloc/op   delta
SchemaHas-8    37.5MB ± 0%     0.0MB ± 0%  -100.00%  (p=0.008 n=5+5)

name         old allocs/op  new allocs/op  delta
SchemaHas-8     73.1k ± 0%      0.0k       -100.00%  (p=0.008 n=5+5)
```
---
 .../apiextensions/validation/validation.go    | 41 +++++++++++++------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation.go b/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation.go
index be4252c14c4..d93cc932490 100644
--- a/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation.go
+++ b/staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation.go
@@ -23,6 +23,7 @@ import (
 	"reflect"
 	"regexp"
 	"strings"
+	"sync"
 	"unicode"
 	"unicode/utf8"
 
@@ -1364,6 +1365,22 @@ func HasSchemaWith(spec *apiextensions.CustomResourceDefinitionSpec, pred func(s
 	return false
 }
 
+var schemaPool = sync.Pool{
+	New: func() any {
+		return new(apiextensions.JSONSchemaProps)
+	},
+}
+
+func schemaHasRecurse(s *apiextensions.JSONSchemaProps, pred func(s *apiextensions.JSONSchemaProps) bool) bool {
+	if s == nil {
+		return false
+	}
+	schema := schemaPool.Get().(*apiextensions.JSONSchemaProps)
+	defer schemaPool.Put(schema)
+	*schema = *s
+	return SchemaHas(schema, pred)
+}
+
 func SchemaHas(s *apiextensions.JSONSchemaProps, pred func(s *apiextensions.JSONSchemaProps) bool) bool {
 	if s == nil {
 		return false
@@ -1374,60 +1391,60 @@ func SchemaHas(s *apiextensions.JSONSchemaProps, pred func(s *apiextensions.JSON
 	}
 
 	if s.Items != nil {
-		if s.Items != nil && SchemaHas(s.Items.Schema, pred) {
+		if s.Items != nil && schemaHasRecurse(s.Items.Schema, pred) {
 			return true
 		}
 		for i := range s.Items.JSONSchemas {
-			if SchemaHas(&s.Items.JSONSchemas[i], pred) {
+			if schemaHasRecurse(&s.Items.JSONSchemas[i], pred) {
 				return true
 			}
 		}
 	}
 	for i := range s.AllOf {
-		if SchemaHas(&s.AllOf[i], pred) {
+		if schemaHasRecurse(&s.AllOf[i], pred) {
 			return true
 		}
 	}
 	for i := range s.AnyOf {
-		if SchemaHas(&s.AnyOf[i], pred) {
+		if schemaHasRecurse(&s.AnyOf[i], pred) {
 			return true
 		}
 	}
 	for i := range s.OneOf {
-		if SchemaHas(&s.OneOf[i], pred) {
+		if schemaHasRecurse(&s.OneOf[i], pred) {
 			return true
 		}
 	}
-	if SchemaHas(s.Not, pred) {
+	if schemaHasRecurse(s.Not, pred) {
 		return true
 	}
 	for _, s := range s.Properties {
-		if SchemaHas(&s, pred) {
+		if schemaHasRecurse(&s, pred) {
 			return true
 		}
 	}
 	if s.AdditionalProperties != nil {
-		if SchemaHas(s.AdditionalProperties.Schema, pred) {
+		if schemaHasRecurse(s.AdditionalProperties.Schema, pred) {
 			return true
 		}
 	}
 	for _, s := range s.PatternProperties {
-		if SchemaHas(&s, pred) {
+		if schemaHasRecurse(&s, pred) {
 			return true
 		}
 	}
 	if s.AdditionalItems != nil {
-		if SchemaHas(s.AdditionalItems.Schema, pred) {
+		if schemaHasRecurse(s.AdditionalItems.Schema, pred) {
 			return true
 		}
 	}
 	for _, s := range s.Definitions {
-		if SchemaHas(&s, pred) {
+		if schemaHasRecurse(&s, pred) {
 			return true
 		}
 	}
 	for _, d := range s.Dependencies {
-		if SchemaHas(d.Schema, pred) {
+		if schemaHasRecurse(d.Schema, pred) {
 			return true
 		}
 	}