feat: add AbortController and AbortSignal (#2025)

Author: edusperoni

docs/README.md

@@ -8,6 +8,11 @@
   timing, performance timeline with `PerformanceObserver`), per-isolate time
   origins for workers, the native clock hook that future `requestAnimationFrame`
   work must share, and the documented spec deviations.
+- [AbortController / AbortSignal](abort-signal.md) — the DOM abort primitives
+  (`AbortController`, `AbortSignal` with the `abort`/`timeout`/`any` statics)
+  layered on the runtime's `EventTarget`, the GC contract (weak timers and
+  `any()` links, listener-driven persistence), and the `DOMException`
+  stand-in (name-patched `Error` reasons).
 - [Error handling](error-handling.md) — global `error`/`unhandledrejection` events, `reportError`, catching Java exceptions in JS (`error.nativeException`), forwarding JS throws to Java callers (`interop.escapeException`), JS stacks on Java exceptions (`com.tns.JavaScriptStackTrace`), configuration flags, and crash-reporter integration.
 - [structuredClone](structured-clone.md) — the WHATWG `structuredClone(value, { transfer })` global: what clones, how graph identity and cycles are preserved, `ArrayBuffer` transfer, and the `DataCloneError`-named `Error` that stands in for `DOMException`.
 - [Implementing additional Chrome DevTools protocol Domains](extending-inspector.md)

docs/abort-signal.md

@@ -0,0 +1,72 @@
+# AbortController / AbortSignal
+
+The runtime installs the DOM Standard's abort primitives as globals in every
+isolate (main and workers): `AbortController`, and `AbortSignal` with the
+`abort`, `timeout` and `any` statics. The implementation is
+`test-app/runtime/src/main/cpp/js/abort-signal.js`, evaluated during `Events::Init`
+right after the `Event`/`EventTarget` builtin it is layered on, so the
+interfaces exist before any user code runs. `AbortSignal` extends the
+runtime's `EventTarget`; `new AbortSignal()` throws `TypeError: Illegal
+constructor` — instances come from a controller or one of the statics.
+
+## Surface
+
+- `new AbortController()` — `controller.signal` (stable identity) and
+  `controller.abort(reason?)`.
+- `signal.aborted`, `signal.reason`, `signal.throwIfAborted()`, and the
+  `abort` event (`addEventListener("abort", …)` or the `onabort` handler
+  attribute with HTML event-handler semantics).
+- `AbortSignal.abort(reason?)` — an already-aborted signal; no event fires.
+- `AbortSignal.timeout(delay)` — aborts with a `TimeoutError`-named reason
+  after `delay` ms. `delay` must be an integer in `[0, 2^32 − 1]`
+  (`TypeError` for non-numbers, `RangeError` otherwise), matching Node's
+  validation.
+- `AbortSignal.any(signals)` — a composite signal that aborts with the first
+  source's reason. Accepts any iterable whose members are all `AbortSignal`s
+  (`TypeError` otherwise). Composites are flattened: `any([any([a]), b])`
+  follows `a` and `b` directly. Per spec, every affected signal's
+  `aborted`/`reason` flips before the first `abort` event fires.
+
+## GC contract
+
+The implementation is GC-transparent the way Node's is: internal references
+never keep an unobservable signal alive, and never let an observable abort
+be dropped.
+
+- A `timeout()` timer closes over a `WeakRef`, so a signal nobody can
+  observe is collectable before it fires; a `FinalizationRegistry` cancels
+  the pending native timer when that happens.
+- `any()` links are `WeakRef`s in both directions (source → dependent and
+  dependent → source), with prune registries clearing dead entries — so
+  per-request composites never accumulate on a long-lived source, and a
+  collected source leaves its composites' source lists (a composite whose
+  sources are all gone can never abort and stops being retained).
+- Weakness alone would silently drop the abort of a signal that is
+  listened-to but otherwise unreachable, so a strong `gcPersistentSignals`
+  set holds exactly the signals whose abort someone can still observe: live
+  timeout signals and live non-empty composites while they have `abort`
+  listeners (`onabort` counts — it registers a real listener), plus timeout
+  sources a composite follows, until their timer fires. The listener
+  accounting comes from an internal symbol-keyed hook the events builtin
+  calls from every listener-list mutation path (add, remove, and `once`
+  removal during dispatch); the key travels only through the builtin-only
+  `internals` object (see `test-app/runtime/src/main/cpp/js/README.md`) and
+  never reaches app code, so the accounting cannot be bypassed via a
+  captured `EventTarget.prototype.addEventListener`.
+
+Entries leave the persistent set on abort, on the last abort-listener
+removal, or when a composite loses its last source.
+
+## Deviations from Node / the web
+
+- **No `DOMException`.** As with [structuredClone](structured-clone.md) and
+  the [Performance API](performance.md), default reasons are `Error`
+  instances with `name` patched: `"AbortError"` (default abort) and
+  `"TimeoutError"` (timeout). `instanceof DOMException` checks cannot work;
+  match on `reason.name`.
+- Abort events carry no `isTrusted` flag (the runtime's `Event` doesn't
+  model it).
+
+Listener errors during the abort dispatch go through the runtime's standard
+listener-error pipeline (see [error handling](error-handling.md)); a throwing
+listener never prevents the remaining listeners from running.

eslint.config.mjs

@@ -1,7 +1,7 @@
 // Lint setup for the runtime's builtin JavaScript
 // (test-app/runtime/src/main/cpp/js). Each file is compiled by BuiltinLoader
 // as a FUNCTION BODY with the fixed parameters `exports`, `require`, `module`,
-// `binding` and `primordials` (see that directory's README.md), which are
+// `binding`, `primordials` and `internals` (see that directory's README.md), which are
 // declared as globals here. no-undef is the typo net for binding-bag destructures and
 // native-global usage alike; no-restricted-properties keeps the captured
 // intrinsics from being read off the live globals again.
@@ -16,6 +16,7 @@ const capturedStatics = [
   ['ArrayBuffer', 'isView', 'ArrayBufferIsView'],
   ['JSON', 'stringify', 'JSONStringify'],
   ['Number', 'isFinite', 'NumberIsFinite'],
+  ['Number', 'isInteger', 'NumberIsInteger'],
   ['Number', 'isNaN', 'NumberIsNaN'],
   ['Number', 'parseFloat', 'NumberParseFloat'],
   ['Number', 'parseInt', 'NumberParseInt'],
@@ -31,7 +32,7 @@ const capturedStatics = [
 
 // Captured constructors. A destructure from `primordials` shadows the global,
 // so these only fire on the unguarded reference.
-const restrictedGlobals = ['Date', 'Map', 'Number', 'Proxy', 'Set', 'String', 'TypeError'].map((name) => ({
+const restrictedGlobals = ['Date', 'FinalizationRegistry', 'Map', 'Number', 'Proxy', 'RangeError', 'Set', 'String', 'TypeError', 'WeakRef'].map((name) => ({
   name,
   message: `Destructure ${name} from primordials — builtins must not read intrinsics off globals user code can replace.`,
 }));
@@ -55,6 +56,7 @@ export default [
         module: 'readonly',
         binding: 'readonly',
         primordials: 'readonly',
+        internals: 'readonly',
         global: 'readonly',
         console: 'readonly',
         URL: 'readonly',

test-app/app/src/main/assets/app/mainpage.js

@@ -80,6 +80,8 @@ require('./tests/testURLSearchParamsImpl.js');
 require('./tests/testQueueMicrotask');
 require('./tests/testErrorEvents');
 require('./tests/testUnhandledRejections');
+// AbortController/AbortSignal (abort/timeout/any) on top of EventTarget
+require('./tests/testAbortSignal');
 require('./tests/testEscapeException');
 require('./tests/testUncaughtErrorPolicy');
 // Runtime builtins keep working when app code replaces the intrinsics they use