From da5347580dc3853532927655dc9245793cc4acbc Mon Sep 17 00:00:00 2001
From: Danny Browning <bdbrowning2@gmail.com>
Date: Wed, 15 May 2024 11:32:35 -0600
Subject: [PATCH] fix: cache ajv schemas rather than ajv objects for schema
 validation (#3228)

* fix: cache ajv schemas rather than ajv objects for schema validation

* fix: remove lru cache and use ajv caching properly
---
 .../package.json                              |  1 -
 .../src/schema-utils.ts                       | 20 +++++++++----------
 2 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/packages/stream-model-instance-handler/package.json b/packages/stream-model-instance-handler/package.json
index 995676b33f..87bc57e64b 100644
--- a/packages/stream-model-instance-handler/package.json
+++ b/packages/stream-model-instance-handler/package.json
@@ -46,7 +46,6 @@
     "ajv": "^8.8.2",
     "ajv-formats": "^2.1.1",
     "fast-json-patch": "^3.1.0",
-    "least-recent": "^1.0.3",
     "lodash.clonedeep": "^4.5.0",
     "uint8arrays": "^5.0.1"
   },
diff --git a/packages/stream-model-instance-handler/src/schema-utils.ts b/packages/stream-model-instance-handler/src/schema-utils.ts
index 378f89f3ca..db25426d05 100644
--- a/packages/stream-model-instance-handler/src/schema-utils.ts
+++ b/packages/stream-model-instance-handler/src/schema-utils.ts
@@ -1,8 +1,5 @@
 import Ajv, { SchemaObject } from 'ajv/dist/2020.js'
 import addFormats from 'ajv-formats'
-import { LRUCache } from 'least-recent'
-
-const AJV_CACHE_SIZE = 500
 
 function buildAjv(): Ajv {
   const validator = new Ajv({
@@ -21,22 +18,23 @@ function buildAjv(): Ajv {
  * TODO: Move schema stream loading out of this.
  */
 export class SchemaValidation {
-  readonly validators: LRUCache<string, Ajv>
+  readonly ajv: Ajv
 
   constructor() {
-    this.validators = new LRUCache(AJV_CACHE_SIZE)
+    this.ajv = buildAjv()
   }
 
   public validateSchema(content: Record<string, any>, schema: SchemaObject, schemaId: string) {
-    let validator = this.validators.get(schemaId)
-    if (!validator) {
-      validator = buildAjv()
-      this.validators.set(schemaId, validator)
+    let existingSchema = this.ajv.getSchema(schemaId)
+    if (!existingSchema) {
+      this.ajv.addSchema(schema, schemaId)
+      //we've added the schema above, so ajv will have it
+      existingSchema = this.ajv.getSchema(schemaId)!
     }
-    const isValid = validator.validate(schema, content)
+    const isValid = existingSchema(content)
 
     if (!isValid) {
-      const errorMessages = validator.errorsText()
+      const errorMessages = this.ajv.errorsText(existingSchema.errors)
       throw new Error(`Validation Error: ${errorMessages}`)
     }
   }