From 6bb47458123bc7b3fa2c4bf0e4fb8c76db21558e Mon Sep 17 00:00:00 2001
From: Zach Hamm <zach.hamm@reddit.com>
Date: Tue, 20 Jan 2026 15:00:09 -0800
Subject: [PATCH] Cache YAML Nodes

---
 cache/cache.go                 |  2 ++
 requests/validate_request.go   | 11 ++++++++---
 responses/validate_response.go | 10 +++++++---
 validator.go                   | 11 +++++++++++
 4 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/cache/cache.go b/cache/cache.go
index deedc6b..005b474 100644
--- a/cache/cache.go
+++ b/cache/cache.go
@@ -6,6 +6,7 @@ package cache
 import (
 	"github.com/pb33f/libopenapi/datamodel/high/base"
 	"github.com/santhosh-tekuri/jsonschema/v6"
+	"go.yaml.in/yaml/v4"
 )
 
 // SchemaCacheEntry holds a compiled schema and its intermediate representations.
@@ -16,6 +17,7 @@ type SchemaCacheEntry struct {
 	ReferenceSchema string // String version of RenderedInline
 	RenderedJSON    []byte
 	CompiledSchema  *jsonschema.Schema
+	RenderedNode    *yaml.Node
 }
 
 // SchemaCache defines the interface for schema caching implementations.
diff --git a/requests/validate_request.go b/requests/validate_request.go
index 1e7d828..f1ce93c 100644
--- a/requests/validate_request.go
+++ b/requests/validate_request.go
@@ -47,6 +47,7 @@ func ValidateRequestSchema(input *ValidateRequestSchemaInput) (bool, []*errors.V
 	var renderedSchema, jsonSchema []byte
 	var referenceSchema string
 	var compiledSchema *jsonschema.Schema
+	var cachedNode *yaml.Node
 
 	if input.Schema == nil {
 		return false, []*errors.ValidationError{{
@@ -71,6 +72,7 @@ func ValidateRequestSchema(input *ValidateRequestSchemaInput) (bool, []*errors.V
 			referenceSchema = cached.ReferenceSchema
 			jsonSchema = cached.RenderedJSON
 			compiledSchema = cached.CompiledSchema
+			cachedNode = cached.RenderedNode
 		}
 	}
 
@@ -229,9 +231,12 @@ func ValidateRequestSchema(input *ValidateRequestSchemaInput) (bool, []*errors.V
 		schFlatErrs := jk.BasicOutput().Errors
 		var schemaValidationErrors []*errors.SchemaValidationFailure
 
-		// re-encode the schema.
-		var renderedNode yaml.Node
-		_ = yaml.Unmarshal(renderedSchema, &renderedNode)
+		// Use cached node if available, otherwise parse
+		renderedNode := cachedNode
+		if renderedNode == nil {
+			renderedNode = new(yaml.Node)
+			_ = yaml.Unmarshal(renderedSchema, renderedNode)
+		}
 		for q := range schFlatErrs {
 			er := schFlatErrs[q]
 
diff --git a/responses/validate_response.go b/responses/validate_response.go
index 04bc78d..f63a6a3 100644
--- a/responses/validate_response.go
+++ b/responses/validate_response.go
@@ -51,6 +51,7 @@ func ValidateResponseSchema(input *ValidateResponseSchemaInput) (bool, []*errors
 	var renderedSchema, jsonSchema []byte
 	var referenceSchema string
 	var compiledSchema *jsonschema.Schema
+	var cachedNode *yaml.Node
 
 	if input.Schema == nil {
 		return false, []*errors.ValidationError{{
@@ -74,6 +75,7 @@ func ValidateResponseSchema(input *ValidateResponseSchemaInput) (bool, []*errors
 			renderedSchema = cached.RenderedInline
 			referenceSchema = cached.ReferenceSchema
 			compiledSchema = cached.CompiledSchema
+			cachedNode = cached.RenderedNode
 		}
 	}
 
@@ -247,9 +249,11 @@ func ValidateResponseSchema(input *ValidateResponseSchemaInput) (bool, []*errors
 		schFlatErrs := jk.BasicOutput().Errors
 		var schemaValidationErrors []*errors.SchemaValidationFailure
 
-		// re-encode the schema once for error reporting
-		var renderedNode yaml.Node
-		_ = yaml.Unmarshal(renderedSchema, &renderedNode)
+		renderedNode := cachedNode
+		if renderedNode == nil {
+			renderedNode = new(yaml.Node)
+			_ = yaml.Unmarshal(renderedSchema, renderedNode)
+		}
 
 		for q := range schFlatErrs {
 			er := schFlatErrs[q]
diff --git a/validator.go b/validator.go
index 29eec15..22a8f10 100644
--- a/validator.go
+++ b/validator.go
@@ -12,6 +12,7 @@ import (
 	"github.com/pb33f/libopenapi"
 	"github.com/pb33f/libopenapi/datamodel/high/base"
 	"github.com/pb33f/libopenapi/utils"
+	"go.yaml.in/yaml/v4"
 
 	v3 "github.com/pb33f/libopenapi/datamodel/high/v3"
 
@@ -491,12 +492,17 @@ func warmMediaTypeSchema(mediaType *v3.MediaType, schemaCache cache.SchemaCache,
 				if len(renderedInline) > 0 {
 					compiledSchema, _ := helpers.NewCompiledSchema(fmt.Sprintf("%x", hash), renderedJSON, options)
 
+					// Pre-parse YAML node for error reporting (avoids re-parsing on each error)
+					var renderedNode yaml.Node
+					_ = yaml.Unmarshal(renderedInline, &renderedNode)
+
 					schemaCache.Store(hash, &cache.SchemaCacheEntry{
 						Schema:          schema,
 						RenderedInline:  renderedInline,
 						ReferenceSchema: referenceSchema,
 						RenderedJSON:    renderedJSON,
 						CompiledSchema:  compiledSchema,
+						RenderedNode:    &renderedNode,
 					})
 				}
 			}
@@ -539,6 +545,10 @@ func warmParameterSchema(param *v3.Parameter, schemaCache cache.SchemaCache, opt
 				if len(renderedInline) > 0 {
 					compiledSchema, _ := helpers.NewCompiledSchema(fmt.Sprintf("%x", hash), renderedJSON, options)
 
+					// Pre-parse YAML node for error reporting (avoids re-parsing on each error)
+					var renderedNode yaml.Node
+					_ = yaml.Unmarshal(renderedInline, &renderedNode)
+
 					// Store in cache using the shared SchemaCache type
 					schemaCache.Store(hash, &cache.SchemaCacheEntry{
 						Schema:          schema,
@@ -546,6 +556,7 @@ func warmParameterSchema(param *v3.Parameter, schemaCache cache.SchemaCache, opt
 						ReferenceSchema: referenceSchema,
 						RenderedJSON:    renderedJSON,
 						CompiledSchema:  compiledSchema,
+						RenderedNode:    &renderedNode,
 					})
 				}
 			}