From cfab887062cf82ddff281cec6a7917318f4a8dff Mon Sep 17 00:00:00 2001
From: Jasper De Moor <jasperdemoor@gmail.com>
Date: Sat, 21 Jul 2018 19:43:58 -0700
Subject: [PATCH] Split cache into subdirs for faster fs (#1322)

---
 packages/core/parcel/src/FSCache.js | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/packages/core/parcel/src/FSCache.js b/packages/core/parcel/src/FSCache.js
index 8043b43e66f..fee757bfcec 100644
--- a/packages/core/parcel/src/FSCache.js
+++ b/packages/core/parcel/src/FSCache.js
@@ -23,13 +23,24 @@ class FSCache {
   }
 
   async ensureDirExists() {
+    if (this.dirExists) {
+      return;
+    }
+
     await fs.mkdirp(this.dir);
+
+    // Create sub-directories for every possible hex value
+    // This speeds up large caches on many file systems since there are fewer files in a single directory.
+    for (let i = 0; i < 256; i++) {
+      await fs.mkdirp(path.join(this.dir, ('00' + i.toString(16)).slice(-2)));
+    }
+
     this.dirExists = true;
   }
 
   getCacheFile(filename) {
     let hash = md5(this.optionsHash + filename);
-    return path.join(this.dir, hash + '.json');
+    return path.join(this.dir, hash.slice(0, 2), hash.slice(2) + '.json');
   }
 
   async getLastModified(filename) {