lib: add getLazy() method to internal/util

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

PR-URL: #45849
Backport-PR-URL: #46425
Reviewed-By: Geoffrey Booth <[email protected]>
Reviewed-By: Chengzhong Wu <[email protected]>

Author: joyeecheung

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,