perf: Add schema caching to parameter validation

parameters/cookie_parameters.go

@@ -4,7 +4,6 @@
 package parameters
 
 import (
-	"encoding/json"
 	"fmt"
 	"net/http"
 	"strconv"
@@ -70,13 +69,8 @@ func (v *paramValidator) ValidateCookieParamsWithPathItem(request *http.Request,
 				sch = p.Schema.Schema()
 			}
 
-			// Render schema once for ReferenceSchema field in errors
-			var renderedSchema string
-			if sch != nil {
-				rendered, _ := sch.RenderInline()
-				schemaBytes, _ := json.Marshal(rendered)
-				renderedSchema = string(schemaBytes)
-			}
+			// Get rendered schema for ReferenceSchema field in errors (uses cache if available)
+			renderedSchema := GetRenderedSchema(sch, v.options)
 
 			pType := sch.Type
 

parameters/header_parameters.go

@@ -4,7 +4,6 @@
 package parameters
 
 import (
-	"encoding/json"
 	"fmt"
 	"net/http"
 	"strconv"
@@ -60,13 +59,8 @@ func (v *paramValidator) ValidateHeaderParamsWithPathItem(request *http.Request,
 					sch = p.Schema.Schema()
 				}
 
-				// Render schema once for ReferenceSchema field in errors
-				var renderedSchema string
-				if sch != nil {
-					rendered, _ := sch.RenderInline()
-					schemaBytes, _ := json.Marshal(rendered)
-					renderedSchema = string(schemaBytes)
-				}
+				// Get rendered schema for ReferenceSchema field in errors (uses cache if available)
+				renderedSchema := GetRenderedSchema(sch, v.options)
 
 				pType := sch.Type
 
@@ -204,15 +198,10 @@ func (v *paramValidator) ValidateHeaderParamsWithPathItem(request *http.Request,
 				}
 			} else {
 				if p.Required != nil && *p.Required {
-					// Render schema for missing required parameter
+					// Get rendered schema for missing required parameter (uses cache if available)
 					var renderedSchema string
 					if p.Schema != nil {
-						sch := p.Schema.Schema()
-						if sch != nil {
-							rendered, _ := sch.RenderInline()
-							schemaBytes, _ := json.Marshal(rendered)
-							renderedSchema = string(schemaBytes)
-						}
+						renderedSchema = GetRenderedSchema(p.Schema.Schema(), v.options)
 					}
 					validationErrors = append(validationErrors, errors.HeaderParameterMissing(p, pathValue, operation, renderedSchema))
 				}

parameters/path_parameters.go

@@ -4,7 +4,6 @@
 package parameters
 
 import (
-	"encoding/json"
 	"fmt"
 	"net/http"
 	"net/url"
@@ -142,13 +141,8 @@ func (v *paramValidator) ValidatePathParamsWithPathItem(request *http.Request, p
 					// extract the schema from the parameter
 					sch := p.Schema.Schema()
 
-					// Render schema once for ReferenceSchema field in errors
-					var renderedSchema string
-					if sch != nil {
-						rendered, _ := sch.RenderInline()
-						schemaBytes, _ := json.Marshal(rendered)
-						renderedSchema = string(schemaBytes)
-					}
+					// Get rendered schema for ReferenceSchema field in errors (uses cache if available)
+					renderedSchema := GetRenderedSchema(sch, v.options)
 
 					// check enum (if present)
 					enumCheck := func(decodedValue string) {
@@ -309,13 +303,8 @@ func (v *paramValidator) ValidatePathParamsWithPathItem(request *http.Request, p
 								if sch.Items != nil && sch.Items.IsA() {
 									iSch := sch.Items.A.Schema()
 
-									// Render items schema once for ReferenceSchema field in array errors
-									var renderedItemsSchema string
-									if iSch != nil {
-										rendered, _ := iSch.RenderInline()
-										schemaBytes, _ := json.Marshal(rendered)
-										renderedItemsSchema = string(schemaBytes)
-									}
+									// Get rendered items schema for ReferenceSchema field in errors (uses cache if available)
+									renderedItemsSchema := GetRenderedSchema(iSch, v.options)
 
 									for n := range iSch.Type {
 										// determine how to explode the array

parameters/query_parameters.go

@@ -121,13 +121,8 @@ doneLooking:
 						}
 					}
 
-					// Render schema once for ReferenceSchema field in errors
-					var renderedSchema string
-					if sch != nil {
-						rendered, _ := sch.RenderInline()
-						schemaBytes, _ := json.Marshal(rendered)
-						renderedSchema = string(schemaBytes)
-					}
+					// Get rendered schema for ReferenceSchema field in errors (uses cache if available)
+					renderedSchema := GetRenderedSchema(sch, v.options)
 
 					pType := sch.Type
 
@@ -263,12 +258,8 @@ doneLooking:
 							break
 						}
 					}
-					var renderedSchema string
-					if sch != nil {
-						rendered, _ := sch.RenderInline()
-						schemaBytes, _ := json.Marshal(rendered)
-						renderedSchema = string(schemaBytes)
-					}
+					// Get rendered schema for ReferenceSchema field in errors (uses cache if available)
+					renderedSchema := GetRenderedSchema(sch, v.options)
 					validationErrors = append(validationErrors, errors.QueryParameterMissing(params[p], pathValue, operation, renderedSchema))
 				}
 			}

parameters/validate_parameter.go

@@ -18,6 +18,7 @@ import (
 
 	stdError "errors"
 
+	"github.com/pb33f/libopenapi-validator/cache"
 	"github.com/pb33f/libopenapi-validator/config"
 	"github.com/pb33f/libopenapi-validator/errors"
 	"github.com/pb33f/libopenapi-validator/helpers"
@@ -35,16 +36,41 @@ func ValidateSingleParameterSchema(
 	pathTemplate string,
 	operation string,
 ) (validationErrors []*errors.ValidationError) {
-	// Get the JSON Schema for the parameter definition.
-	jsonSchema, err := buildJsonRender(schema)
-	if err != nil {
-		return validationErrors
+	var jsch *jsonschema.Schema
+	var jsonSchema []byte
+
+	// Try cache lookup first - avoids expensive schema compilation on each request
+	if o != nil && o.SchemaCache != nil && schema != nil && schema.GoLow() != nil {
+		hash := schema.GoLow().Hash()
+		if cached, ok := o.SchemaCache.Load(hash); ok && cached != nil && cached.CompiledSchema != nil {
+			jsch = cached.CompiledSchema
+		}
 	}
 
-	// Attempt to compile the JSON Schema
-	jsch, err := helpers.NewCompiledSchema(name, jsonSchema, o)
-	if err != nil {
-		return validationErrors
+	// Cache miss - compile the schema
+	if jsch == nil {
+		// Get the JSON Schema for the parameter definition.
+		var err error
+		jsonSchema, err = buildJsonRender(schema)
+		if err != nil {
+			return validationErrors
+		}
+
+		// Attempt to compile the JSON Schema
+		jsch, err = helpers.NewCompiledSchema(name, jsonSchema, o)
+		if err != nil {
+			return validationErrors
+		}
+
+		// Store in cache for future requests
+		if o != nil && o.SchemaCache != nil && schema != nil && schema.GoLow() != nil {
+			hash := schema.GoLow().Hash()
+			o.SchemaCache.Store(hash, &cache.SchemaCacheEntry{
+				Schema:         schema,
+				RenderedJSON:   jsonSchema,
+				CompiledSchema: jsch,
+			})
+		}
 	}
 
 	// Validate the object and report any errors.
@@ -71,6 +97,28 @@ func buildJsonRender(schema *base.Schema) ([]byte, error) {
 	return utils.ConvertYAMLtoJSON(renderedSchema)
 }
 
+// GetRenderedSchema returns a JSON string representation of the schema for error messages.
+// It first checks the schema cache for a pre-rendered version, falling back to fresh rendering.
+// This avoids expensive re-rendering on each validation when the cache is available.
+func GetRenderedSchema(schema *base.Schema, opts *config.ValidationOptions) string {
+	if schema == nil {
+		return ""
+	}
+
+	// Try cache lookup first
+	if opts != nil && opts.SchemaCache != nil && schema.GoLow() != nil {
+		hash := schema.GoLow().Hash()
+		if cached, ok := opts.SchemaCache.Load(hash); ok && cached != nil && len(cached.RenderedJSON) > 0 {
+			return string(cached.RenderedJSON)
+		}
+	}
+
+	// Cache miss - render fresh
+	rendered, _ := schema.RenderInline()
+	schemaBytes, _ := json.Marshal(rendered)
+	return string(schemaBytes)
+}
+
 // ValidateParameterSchema will validate a parameter against a raw object, or a blob of json/yaml.
 // It will return a list of validation errors, if any.
 //
@@ -94,13 +142,59 @@ func ValidateParameterSchema(
 	validationOptions *config.ValidationOptions,
 ) []*errors.ValidationError {
 	var validationErrors []*errors.ValidationError
+	var jsch *jsonschema.Schema
+	var jsonSchema []byte
 
-	// 1. build a JSON render of the schema.
-	renderCtx := base.NewInlineRenderContextForValidation()
-	renderedSchema, _ := schema.RenderInlineWithContext(renderCtx)
-	jsonSchema, _ := utils.ConvertYAMLtoJSON(renderedSchema)
+	// Try cache lookup first - avoids expensive schema compilation on each request
+	if validationOptions != nil && validationOptions.SchemaCache != nil && schema != nil && schema.GoLow() != nil {
+		hash := schema.GoLow().Hash()
+		if cached, ok := validationOptions.SchemaCache.Load(hash); ok && cached != nil && cached.CompiledSchema != nil {
+			jsch = cached.CompiledSchema
+		}
+	}
 
-	// 2. decode the object into a json blob.
+	// Cache miss - render and compile the schema
+	if jsch == nil {
+		// 1. build a JSON render of the schema.
+		renderCtx := base.NewInlineRenderContextForValidation()
+		renderedSchema, _ := schema.RenderInlineWithContext(renderCtx)
+		referenceSchema := string(renderedSchema)
+		jsonSchema, _ = utils.ConvertYAMLtoJSON(renderedSchema)
+
+		// 2. create a new json schema compiler and add the schema to it
+		var err error
+		jsch, err = helpers.NewCompiledSchema(name, jsonSchema, validationOptions)
+		if err != nil {
+			// schema compilation failed, return validation error instead of panicking
+			validationErrors = append(validationErrors, &errors.ValidationError{
+				ValidationType:    validationType,
+				ValidationSubType: subValType,
+				Message:           fmt.Sprintf("%s '%s' failed schema compilation", entity, name),
+				Reason: fmt.Sprintf("%s '%s' schema compilation failed: %s",
+					reasonEntity, name, err.Error()),
+				SpecLine:      1,
+				SpecCol:       0,
+				ParameterName: name,
+				HowToFix:      "check the parameter schema for invalid JSON Schema syntax, complex regex patterns, or unsupported schema constructs",
+				Context:       string(jsonSchema),
+			})
+			return validationErrors
+		}
+
+		// Store in cache for future requests
+		if validationOptions != nil && validationOptions.SchemaCache != nil && schema != nil && schema.GoLow() != nil {
+			hash := schema.GoLow().Hash()
+			validationOptions.SchemaCache.Store(hash, &cache.SchemaCacheEntry{
+				Schema:          schema,
+				RenderedInline:  renderedSchema,
+				ReferenceSchema: referenceSchema,
+				RenderedJSON:    jsonSchema,
+				CompiledSchema:  jsch,
+			})
+		}
+	}
+
+	// 3. decode the object into a json blob.
 	var decodedObj interface{}
 	rawIsMap := false
 	validEncoding := false
@@ -125,24 +219,6 @@ func ValidateParameterSchema(
 		}
 		validEncoding = true
 	}
-	// 3. create a new json schema compiler and add the schema to it
-	jsch, err := helpers.NewCompiledSchema(name, jsonSchema, validationOptions)
-	if err != nil {
-		// schema compilation failed, return validation error instead of panicking
-		validationErrors = append(validationErrors, &errors.ValidationError{
-			ValidationType:    validationType,
-			ValidationSubType: subValType,
-			Message:           fmt.Sprintf("%s '%s' failed schema compilation", entity, name),
-			Reason: fmt.Sprintf("%s '%s' schema compilation failed: %s",
-				reasonEntity, name, err.Error()),
-			SpecLine:      1,
-			SpecCol:       0,
-			ParameterName: name,
-			HowToFix:      "check the parameter schema for invalid JSON Schema syntax, complex regex patterns, or unsupported schema constructs",
-			Context:       string(jsonSchema),
-		})
-		return validationErrors
-	}
 
 	// 4. validate the object against the schema
 	var scErrs error