From aac6fe5a4aa83356da871a8871c7766eef55075f Mon Sep 17 00:00:00 2001
From: Stefan Penner <stefan.penner@gmail.com>
Date: Sat, 2 Mar 2019 15:41:36 -0800
Subject: [PATCH] memoize existsSync calls on the fastboot instance itself

In large applications with many nested addons and engines, this can do
excessive work.

Luckily it is perfectly consistent for us to cache this on the addon
instance state. In-fact it is incoherent for this to change from the
perspective of one fastboot addon instance
---
 index.js | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/index.js b/index.js
index 29d7ff55f..465e1058c 100644
--- a/index.js
+++ b/index.js
@@ -39,6 +39,18 @@ module.exports = {
 
   init() {
     this._super.init && this._super.init.apply(this, arguments);
+    this._existsCache = new Map();
+  },
+
+  existsSync(path) {
+    if (this._existsCache.has(path)) {
+      return this._existsCache.get(path);
+    }
+
+    const exists = existsSync(path);
+
+    this._existsCache.set(path, exists);
+    return exists;
   },
 
   /**
@@ -139,7 +151,7 @@ module.exports = {
     const currentAddonFastbootPath = path.join(addon.root, 'fastboot');
 
     let fastbootTree;
-    if (existsSync(currentAddonFastbootPath)) {
+    if (this.existsSync(currentAddonFastbootPath)) {
       fastbootTree = this.treeGenerator(currentAddonFastbootPath);
     }
 
@@ -168,7 +180,7 @@ module.exports = {
 
     // check the parent containing the fastboot directory
     const projectFastbootPath = path.join(this.project.root, 'fastboot');
-    if (existsSync(projectFastbootPath)) {
+    if (this.existsSync(projectFastbootPath)) {
       let fastbootTree = this.treeGenerator(projectFastbootPath);
       fastbootTrees.push(fastbootTree);
     }