From 87889abfb06ca3e240292da5a7ece1904e20c7b6 Mon Sep 17 00:00:00 2001
From: cjihrig <cjihrig@gmail.com>
Date: Tue, 26 Jan 2021 23:15:56 -0500
Subject: [PATCH] util: add internal createDeferredPromise()
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The pattern of resolving/rejecting a Promise from outside of its
executor happens numerous times throughout the codebase (more than
what is updated here in fact). This commit abstracts that logic
into an internal utility function.

PR-URL: https://github.com/nodejs/node/pull/37095
Backport-PR-URL: https://github.com/nodejs/node/pull/39704
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Zijian Liu <lxxyxzj@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 lib/child_process.js |  9 ++-------
 lib/internal/blob.js | 13 ++-----------
 lib/internal/util.js | 12 ++++++++++++
 3 files changed, 16 insertions(+), 18 deletions(-)

diff --git a/lib/child_process.js b/lib/child_process.js
index 09369316de52f1..8c10ce36cc7d74 100644
--- a/lib/child_process.js
+++ b/lib/child_process.js
@@ -28,12 +28,12 @@ const {
   ObjectAssign,
   ObjectDefineProperty,
   ObjectPrototypeHasOwnProperty,
-  Promise,
 } = primordials;
 
 const {
   promisify,
   convertToValidSignal,
+  createDeferredPromise,
   getSystemErrorName
 } = require('internal/util');
 const { isArrayBufferView } = require('internal/util/types');
@@ -215,12 +215,7 @@ function exec(command, options, callback) {
 
 const customPromiseExecFunction = (orig) => {
   return (...args) => {
-    let resolve;
-    let reject;
-    const promise = new Promise((res, rej) => {
-      resolve = res;
-      reject = rej;
-    });
+    const { promise, resolve, reject } = createDeferredPromise();
 
     promise.child = orig(...args, (err, stdout, stderr) => {
       if (err !== null) {
diff --git a/lib/internal/blob.js b/lib/internal/blob.js
index f0220552256737..accfdf9539c1d2 100644
--- a/lib/internal/blob.js
+++ b/lib/internal/blob.js
@@ -3,7 +3,6 @@
 const {
   ArrayFrom,
   ObjectSetPrototypeOf,
-  Promise,
   PromiseResolve,
   RegExpPrototypeTest,
   StringPrototypeToLowerCase,
@@ -31,6 +30,7 @@ const {
 } = require('internal/util/types');
 
 const {
+  createDeferredPromise,
   customInspectSymbol: kInspect,
   emitExperimentalWarning,
 } = require('internal/util');
@@ -58,15 +58,6 @@ const kLength = Symbol('kLength');
 
 let Buffer;
 
-function deferred() {
-  let res, rej;
-  const promise = new Promise((resolve, reject) => {
-    res = resolve;
-    rej = reject;
-  });
-  return { promise, resolve: res, reject: rej };
-}
-
 function lazyBuffer() {
   if (Buffer === undefined)
     Buffer = require('buffer').Buffer;
@@ -212,7 +203,7 @@ class Blob extends JSTransferable {
       promise,
       resolve,
       reject
-    } = deferred();
+    } = createDeferredPromise();
     job.ondone = (err, ab) => {
       if (err !== undefined)
         return reject(new AbortError());
diff --git a/lib/internal/util.js b/lib/internal/util.js
index 9127c5a83e278e..be3a4eef644469 100644
--- a/lib/internal/util.js
+++ b/lib/internal/util.js
@@ -420,11 +420,23 @@ function sleep(msec) {
   _sleep(msec);
 }
 
+function createDeferredPromise() {
+  let resolve;
+  let reject;
+  const promise = new Promise((res, rej) => {
+    resolve = res;
+    reject = rej;
+  });
+
+  return { promise, resolve, reject };
+}
+
 module.exports = {
   assertCrypto,
   cachedResult,
   convertToValidSignal,
   createClassWrapper,
+  createDeferredPromise,
   decorateErrorStack,
   deprecate,
   emitExperimentalWarning,