lib: initial experimental AbortController implementation

AbortController impl based very closely on:
 https://github.com/mysticatea/abort-controller

Marked experimental.
Not currently used by any of the existing promise apis.

Signed-off-by: James M Snell <jasnell@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/33527
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1 files changed, 83 insertions, 0 deletions

diff --git a/lib/internal/abort_controller.js b/lib/internal/abort_controller.js
new file mode 100644
index 00000000000..b4ba6dd4f87
--- /dev/null
+++ b/lib/internal/abort_controller.js
@@ -0,0 +1,83 @@
+'use strict';
+
+// Modeled very closely on the AbortController implementation
+// in https://github.com/mysticatea/abort-controller (MIT license)
+
+const {
+  Object,
+  Symbol,
+} = primordials;
+
+const {
+  EventTarget,
+  Event
+} = require('internal/event_target');
+const {
+  customInspectSymbol,
+  emitExperimentalWarning
+} = require('internal/util');
+const { inspect } = require('internal/util/inspect');
+
+const kAborted = Symbol('kAborted');
+
+function customInspect(self, obj, depth, options) {
+  if (depth < 0)
+    return self;
+
+  const opts = Object.assign({}, options, {
+    depth: options.depth === null ? null : options.depth - 1
+  });
+
+  return `${self.constructor.name} ${inspect(obj, opts)}`;
+}
+
+class AbortSignal extends EventTarget {
+  get aborted() { return !!this[kAborted]; }
+
+  [customInspectSymbol](depth, options) {
+    return customInspect(this, {
+      aborted: this.aborted
+    }, depth, options);
+  }
+}
+
+Object.defineProperties(AbortSignal.prototype, {
+  aborted: { enumerable: true }
+});
+
+function abortSignal(signal) {
+  if (signal[kAborted]) return;
+  signal[kAborted] = true;
+  const event = new Event('abort');
+  if (typeof signal.onabort === 'function') {
+    signal.onabort(event);
+  }
+  signal.dispatchEvent(event);
+}
+
+class AbortController {
+  #signal = new AbortSignal();
+
+  constructor() {
+    emitExperimentalWarning('AbortController');
+  }
+
+  get signal() { return this.#signal; }
+  abort() { abortSignal(this.#signal); }
+
+  [customInspectSymbol](depth, options) {
+    return customInspect(this, {
+      signal: this.signal
+    }, depth, options);
+  }
+}
+
+Object.defineProperties(AbortController.prototype, {
+  signal: { enumerable: true },
+  abort: { enumerable: true }
+});
+
+module.exports = {
+  AbortController,
+  AbortSignal,
+};