From 00bdb72b6ec20a4f9f8366378f49319b4805c2b7 Mon Sep 17 00:00:00 2001
From: Joyee Cheung <joyeec9h3@gmail.com>
Date: Wed, 14 Dec 2022 00:02:51 +0100
Subject: [PATCH] lib: add getLazy() method to internal/util

This patch adds a getLazy() method to facilitate initialize-once
lazy loading in the internals.

PR-URL: https://github.com/nodejs/node/pull/45849
Backport-PR-URL: https://github.com/nodejs/node/pull/46425
Reviewed-By: Geoffrey Booth <webadmin@geoffreybooth.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
---
 lib/internal/util.js | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/lib/internal/util.js b/lib/internal/util.js
index 4d72783617dd03..be4e60051d8319 100644
--- a/lib/internal/util.js
+++ b/lib/internal/util.js
@@ -691,6 +691,24 @@ function isArrayBufferDetached(value) {
   return false;
 }
 
+/**
+ * Helper function to lazy-load an initialize-once value.
+ * @template T Return value of initializer
+ * @param {()=>T} initializer Initializer of the lazily loaded value.
+ * @returns {()=>T}
+ */
+function getLazy(initializer) {
+  let value;
+  let initialized = false;
+  return function() {
+    if (initialized === false) {
+      value = initializer();
+      initialized = true;
+    }
+    return value;
+  };
+}
+
 // Setup user-facing NODE_V8_COVERAGE environment variable that writes
 // ScriptCoverage objects to a specified directory.
 function setupCoverageHooks(dir) {
@@ -713,6 +731,7 @@ function setupCoverageHooks(dir) {
 }
 
 module.exports = {
+  getLazy,
   assertCrypto,
   cachedResult,
   convertToValidSignal,