timers: add helper fn for async init

There are currently 3 places in Timers where the exact same code
appears. Instead create a helper function that does the same job
of setting asyncId & triggerAsyncId, as well as calling emitInit.

PR-URL: #18825
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/internal/timers.js

@@ -24,6 +24,7 @@ module.exports = {
   async_id_symbol,
   trigger_async_id_symbol,
   Timeout,
+  initAsyncResource,
   refreshFnSymbol,
   setUnrefTimeout,
   validateTimerDuration
@@ -37,6 +38,14 @@ function getTimers() {
   return timers;
 }
 
+function initAsyncResource(resource, type) {
+  const asyncId = resource[async_id_symbol] = newAsyncId();
+  const triggerAsyncId =
+    resource[trigger_async_id_symbol] = getDefaultTriggerAsyncId();
+  if (initHooksExist())
+    emitInit(asyncId, type, triggerAsyncId, resource);
+}
+
 // Timer constructor function.
 // The entire prototype is defined in lib/timers.js
 function Timeout(callback, after, args, isRepeat, isUnrefed) {
@@ -66,14 +75,7 @@ function Timeout(callback, after, args, isRepeat, isUnrefed) {
 
   this[unrefedSymbol] = isUnrefed;
 
-  this[async_id_symbol] = newAsyncId();
-  this[trigger_async_id_symbol] = getDefaultTriggerAsyncId();
-  if (initHooksExist()) {
-    emitInit(this[async_id_symbol],
-             'Timeout',
-             this[trigger_async_id_symbol],
-             this);
-  }
+  initAsyncResource(this, 'Timeout');
 }
 
 Timeout.prototype[refreshFnSymbol] = function refresh() {

lib/timers.js

@@ -30,6 +30,7 @@ const {
   async_id_symbol,
   trigger_async_id_symbol,
   Timeout,
+  initAsyncResource,
   validateTimerDuration
 } = require('internal/timers');
 const internalUtil = require('internal/util');
@@ -39,12 +40,8 @@ const util = require('util');
 const errors = require('internal/errors');
 const debug = util.debuglog('timer');
 const {
-  getDefaultTriggerAsyncId,
-  newAsyncId,
-  initHooksExist,
   destroyHooksExist,
   // The needed emit*() functions.
-  emitInit,
   emitBefore,
   emitAfter,
   emitDestroy
@@ -188,14 +185,7 @@ function insert(item, unrefed, start) {
 
   if (!item[async_id_symbol] || item._destroyed) {
     item._destroyed = false;
-    item[async_id_symbol] = newAsyncId();
-    item[trigger_async_id_symbol] = getDefaultTriggerAsyncId();
-    if (initHooksExist()) {
-      emitInit(item[async_id_symbol],
-               'Timeout',
-               item[trigger_async_id_symbol],
-               item);
-    }
+    initAsyncResource(item, 'Timeout');
   }
 
   L.append(list, item);
@@ -720,14 +710,7 @@ const Immediate = class Immediate {
     this._destroyed = false;
     this[kRefed] = false;
 
-    this[async_id_symbol] = newAsyncId();
-    this[trigger_async_id_symbol] = getDefaultTriggerAsyncId();
-    if (initHooksExist()) {
-      emitInit(this[async_id_symbol],
-               'Immediate',
-               this[trigger_async_id_symbol],
-               this);
-    }
+    initAsyncResource(this, 'Immediate');
 
     this.ref();
     immediateInfo[kCount]++;