lib: use indexed appends for dependent signals

Avoid a primordial push call for each dependent signal.

Signed-off-by: Roberto Bianchi <roberto.bianchi@spendesk.com>

Author: rozzilla

benchmark/abort_controller/abort-controller-abort-fanout.js

@@ -0,0 +1,31 @@
+'use strict';
+const common = require('../common.js');
+const assert = require('node:assert');
+
+const bench = common.createBenchmark(main, {
+  n: [1000],
+  fanout: [0, 1, 16, 64],
+});
+
+function main({ n, fanout }) {
+  const reason = new Error('reason');
+  const controllers = [];
+  const signals = [];
+
+  for (let i = 0; i < n; i++) {
+    const controller = new AbortController();
+    controllers[i] = controller;
+    for (let j = 0; j < fanout; j++) {
+      signals[signals.length] = AbortSignal.any([controller.signal]);
+    }
+  }
+
+  bench.start();
+  for (const controller of controllers) {
+    controller.abort(reason);
+  }
+  bench.end(n);
+
+  assert.strictEqual(signals.length, n * fanout);
+  assert(signals.every((signal) => signal.aborted));
+}

lib/internal/abort_controller.js

@@ -4,7 +4,6 @@
 // in https://github.com/mysticatea/abort-controller (MIT license)
 
 const {
-  ArrayPrototypePush,
   FunctionPrototypeCall,
   ObjectAssign,
   ObjectDefineProperties,
@@ -577,7 +576,7 @@ function abortSignal(signal, reason) {
         dependentSignal[kReason] = reason;
         dependentSignal[kAborted] = true;
         // 2. Append dependentSignal to dependentSignalsToAbort.
-        ArrayPrototypePush(dependentSignalsToAbort, dependentSignal);
+        dependentSignalsToAbort[dependentSignalsToAbort.length] = dependentSignal;
       }
     });
   }