From a89bdbd19b3b15739e7cc39fefa7506e55c3606b Mon Sep 17 00:00:00 2001
From: Marvin Hagemeister <hello@marvinh.dev>
Date: Tue, 10 Jan 2023 15:18:46 +0100
Subject: [PATCH] perf: avoid unnecessary fs.statSync calls

Only resolve a module dir when we now that the mapped path is a
directory. This improves linting time by about 18% in projects
with many files.
---
 .changeset/mean-seals-tease.md |  5 +++++
 src/index.ts                   | 21 ++++++++++++++++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/mean-seals-tease.md

diff --git a/.changeset/mean-seals-tease.md b/.changeset/mean-seals-tease.md
new file mode 100644
index 00000000..173c1c2f
--- /dev/null
+++ b/.changeset/mean-seals-tease.md
@@ -0,0 +1,5 @@
+---
+'eslint-import-resolver-typescript': patch
+---
+
+Only try to resolve a module directory when we know that the path is a directory. This can lead to a 15% speedup on projects with many files.
diff --git a/src/index.ts b/src/index.ts
index b7656f96..54d17cc9 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -287,7 +287,26 @@ function getMappedPath(
         ]),
       )
       .flat(2)
-      .filter(mappedPath => isFile(mappedPath) || isModule(mappedPath))
+      .filter(mappedPath => {
+        if (mappedPath === undefined) {
+          return false
+        }
+
+        try {
+          const stat = fs.statSync(mappedPath, { throwIfNoEntry: false })
+          if (stat === undefined) return false
+          if (stat.isFile()) return true
+
+          // Maybe this is a module dir?
+          if (stat.isDirectory()) {
+            return isModule(mappedPath)
+          }
+        } catch {
+          return false
+        }
+
+        return false
+      })
   }
 
   if (retry && paths.length === 0) {