From 8892a8c1d0b54965501dd03113873ac66a50f74f Mon Sep 17 00:00:00 2001
From: Thomas Dy <thatsmydoing@gmail.com>
Date: Sat, 13 Aug 2022 07:50:10 +0900
Subject: [PATCH] perf: add filesystem caching support (#166)

Co-authored-by: JounQin <admin@1stg.me>
---
 .changeset/nasty-points-speak.md | 5 +++++
 src/index.ts                     | 7 +++++--
 2 files changed, 10 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/nasty-points-speak.md

diff --git a/.changeset/nasty-points-speak.md b/.changeset/nasty-points-speak.md
new file mode 100644
index 0000000..dbd14cc
--- /dev/null
+++ b/.changeset/nasty-points-speak.md
@@ -0,0 +1,5 @@
+---
+"eslint-import-resolver-typescript": patch
+---
+
+perf: add filesystem caching support
diff --git a/src/index.ts b/src/index.ts
index 6ca26a9..3a80169 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -5,6 +5,7 @@ import { fileURLToPath } from 'node:url'
 import debug from 'debug'
 import {
   FileSystem,
+  CachedInputFileSystem,
   ResolveOptions,
   Resolver,
   ResolverFactory,
@@ -113,6 +114,7 @@ const fileSystem = fs as FileSystem
 const JS_EXT_PATTERN = /\.(?:[cm]js|jsx?)$/
 const RELATIVE_PATH_PATTERN = /^\.{1,2}(?:\/.*)?$/
 
+let previousOptions: TsResolverOptions | null | undefined
 let cachedOptions: InternalResolverOptions | undefined
 
 let mappersCachedOptions: InternalResolverOptions
@@ -135,14 +137,15 @@ export function resolve(
   found: boolean
   path?: string | null
 } {
-  if (!cachedOptions || cachedOptions !== options) {
+  if (!cachedOptions || previousOptions !== options) {
+    previousOptions = options
     cachedOptions = {
       ...options,
       conditionNames: options?.conditionNames ?? defaultConditionNames,
       extensions: options?.extensions ?? defaultExtensions,
       extensionAlias: options?.extensionAlias ?? defaultExtensionAlias,
       mainFields: options?.mainFields ?? defaultMainFields,
-      fileSystem,
+      fileSystem: new CachedInputFileSystem(fileSystem, 5 * 1000),
       useSyncFileSystemCalls: true,
     }
   }