deno/ext/web/03_abort_signal.js

// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.

// @ts-check
/// <reference path="../../core/internal.d.ts" />

import { core, primordials } from "ext:core/mod.js";
const {
  ArrayPrototypeEvery,
  ArrayPrototypePush,
  FunctionPrototypeApply,
  ObjectPrototypeIsPrototypeOf,
  SafeSet,
  SafeSetIterator,
  SafeWeakRef,
  SafeWeakSet,
  SetPrototypeAdd,
  SetPrototypeDelete,
  Symbol,
  SymbolFor,
  TypeError,
  WeakRefPrototypeDeref,
  WeakSetPrototypeAdd,
  WeakSetPrototypeHas,
} = primordials;

import * as webidl from "ext:deno_webidl/00_webidl.js";
import { assert } from "./00_infra.js";
import { createFilteredInspectProxy } from "ext:deno_console/01_console.js";
import {
  defineEventHandler,
  Event,
  EventTarget,
  listenerCount,
  setIsTrusted,
} from "./02_event.js";
import { clearTimeout, refTimer, unrefTimer } from "./02_timers.js";

// Since WeakSet is not a iterable, WeakRefSet class is provided to store and
// iterate objects.
// To create an AsyncIterable using GeneratorFunction in the internal code,
// there are many primordial considerations, so we simply implement the
// toArray method.
class WeakRefSet {
  #weakSet = new SafeWeakSet();
  #refs = [];

  add(value) {
    if (WeakSetPrototypeHas(this.#weakSet, value)) {
      return;
    }
    WeakSetPrototypeAdd(this.#weakSet, value);
    ArrayPrototypePush(this.#refs, new SafeWeakRef(value));
  }

  has(value) {
    return WeakSetPrototypeHas(this.#weakSet, value);
  }

  toArray() {
    const ret = [];
    for (let i = 0; i < this.#refs.length; ++i) {
      const value = WeakRefPrototypeDeref(this.#refs[i]);
      if (value !== undefined) {
        ArrayPrototypePush(ret, value);
      }
    }
    return ret;
  }
}

const add = Symbol("[[add]]");
const signalAbort = Symbol("[[signalAbort]]");
const remove = Symbol("[[remove]]");
const abortReason = Symbol("[[abortReason]]");
const abortAlgos = Symbol("[[abortAlgos]]");
const dependent = Symbol("[[dependent]]");
const sourceSignals = Symbol("[[sourceSignals]]");
const dependentSignals = Symbol("[[dependentSignals]]");
const signal = Symbol("[[signal]]");
const timerId = Symbol("[[timerId]]");

const illegalConstructorKey = Symbol("illegalConstructorKey");

class AbortSignal extends EventTarget {
  [abortReason] = undefined;
  [abortAlgos] = null;
  [dependent] = false;
  [sourceSignals] = null;
  [dependentSignals] = null;
  [timerId] = null;
  [webidl.brand] = webidl.brand;

  static any(signals) {
    const prefix = "Failed to execute 'AbortSignal.any'";
    webidl.requiredArguments(arguments.length, 1, prefix);
    return createDependentAbortSignal(signals, prefix);
  }

  static abort(reason = undefined) {
    if (reason !== undefined) {
      reason = webidl.converters.any(reason);
    }
    const signal = new AbortSignal(illegalConstructorKey);
    signal[signalAbort](reason);
    return signal;
  }

  static timeout(millis) {
    const prefix = "Failed to execute 'AbortSignal.timeout'";
    webidl.requiredArguments(arguments.length, 1, prefix);
    millis = webidl.converters["unsigned long long"](
      millis,
      prefix,
      "Argument 1",
      {
        enforceRange: true,
      },
    );

    const signal = new AbortSignal(illegalConstructorKey);
    signal[timerId] = core.queueSystemTimer(
      undefined,
      false,
      millis,
      () => {
        clearTimeout(signal[timerId]);
        signal[timerId] = null;
        signal[signalAbort](
          new DOMException("Signal timed out.", "TimeoutError"),
        );
      },
    );
    unrefTimer(signal[timerId]);
    return signal;
  }

  [add](algorithm) {
    if (this.aborted) {
      return;
    }
    this[abortAlgos] ??= new SafeSet();
    SetPrototypeAdd(this[abortAlgos], algorithm);
  }

  [signalAbort](
    reason = new DOMException("The signal has been aborted", "AbortError"),
  ) {
    if (this.aborted) {
      return;
    }
    this[abortReason] = reason;
    const algos = this[abortAlgos];
    this[abortAlgos] = null;

    if (listenerCount(this, "abort") > 0) {
      const event = new Event("abort");
      setIsTrusted(event, true);
      super.dispatchEvent(event);
    }
    if (algos !== null) {
      for (const algorithm of new SafeSetIterator(algos)) {
        algorithm();
      }
    }

    if (this[dependentSignals] !== null) {
      const dependentSignalArray = this[dependentSignals].toArray();
      for (let i = 0; i < dependentSignalArray.length; ++i) {
        const dependentSignal = dependentSignalArray[i];
        dependentSignal[signalAbort](reason);
      }
    }
  }

  [remove](algorithm) {
    this[abortAlgos] && SetPrototypeDelete(this[abortAlgos], algorithm);
  }

  constructor(key = null) {
    if (key !== illegalConstructorKey) {
      throw new TypeError("Illegal constructor.");
    }
    super();
  }

  get aborted() {
    webidl.assertBranded(this, AbortSignalPrototype);
    return this[abortReason] !== undefined;
  }

  get reason() {
    webidl.assertBranded(this, AbortSignalPrototype);
    return this[abortReason];
  }

  throwIfAborted() {
    webidl.assertBranded(this, AbortSignalPrototype);
    if (this[abortReason] !== undefined) {
      throw this[abortReason];
    }
  }

  // `addEventListener` and `removeEventListener` have to be overridden in
  // order to have the timer block the event loop while there are listeners.
  // `[add]` and `[remove]` don't ref and unref the timer because they can
  // only be used by Deno internals, which use it to essentially cancel async
  // ops which would block the event loop.
  addEventListener() {
    FunctionPrototypeApply(super.addEventListener, this, arguments);
    if (listenerCount(this, "abort") > 0) {
      if (this[timerId] !== null) {
        refTimer(this[timerId]);
      } else if (this[sourceSignals] !== null) {
        const sourceSignalArray = this[sourceSignals].toArray();
        for (let i = 0; i < sourceSignalArray.length; ++i) {
          const sourceSignal = sourceSignalArray[i];
          if (sourceSignal[timerId] !== null) {
            refTimer(sourceSignal[timerId]);
          }
        }
      }
    }
  }

  removeEventListener() {
    FunctionPrototypeApply(super.removeEventListener, this, arguments);
    if (listenerCount(this, "abort") === 0) {
      if (this[timerId] !== null) {
        unrefTimer(this[timerId]);
      } else if (this[sourceSignals] !== null) {
        const sourceSignalArray = this[sourceSignals].toArray();
        for (let i = 0; i < sourceSignalArray.length; ++i) {
          const sourceSignal = sourceSignalArray[i];
          if (sourceSignal[timerId] !== null) {
            // Check that all dependent signals of the timer signal do not have listeners
            if (
              ArrayPrototypeEvery(
                sourceSignal[dependentSignals].toArray(),
                (dependentSignal) =>
                  dependentSignal === this ||
                  listenerCount(dependentSignal, "abort") === 0,
              )
            ) {
              unrefTimer(sourceSignal[timerId]);
            }
          }
        }
      }
    }
  }

  [SymbolFor("Deno.privateCustomInspect")](inspect, inspectOptions) {
    return inspect(
      createFilteredInspectProxy({
        object: this,
        evaluate: ObjectPrototypeIsPrototypeOf(AbortSignalPrototype, this),
        keys: [
          "aborted",
          "reason",
          "onabort",
        ],
      }),
      inspectOptions,
    );
  }
}
defineEventHandler(AbortSignal.prototype, "abort");

webidl.configureInterface(AbortSignal);
const AbortSignalPrototype = AbortSignal.prototype;

class AbortController {
  [signal] = new AbortSignal(illegalConstructorKey);

  constructor() {
    this[webidl.brand] = webidl.brand;
  }

  get signal() {
    webidl.assertBranded(this, AbortControllerPrototype);
    return this[signal];
  }

  abort(reason) {
    webidl.assertBranded(this, AbortControllerPrototype);
    this[signal][signalAbort](reason);
  }

  [SymbolFor("Deno.privateCustomInspect")](inspect, inspectOptions) {
    return inspect(
      createFilteredInspectProxy({
        object: this,
        evaluate: ObjectPrototypeIsPrototypeOf(AbortControllerPrototype, this),
        keys: [
          "signal",
        ],
      }),
      inspectOptions,
    );
  }
}

webidl.configureInterface(AbortController);
const AbortControllerPrototype = AbortController.prototype;

webidl.converters.AbortSignal = webidl.createInterfaceConverter(
  "AbortSignal",
  AbortSignal.prototype,
);
webidl.converters["sequence<AbortSignal>"] = webidl.createSequenceConverter(
  webidl.converters.AbortSignal,
);

function newSignal() {
  return new AbortSignal(illegalConstructorKey);
}

function createDependentAbortSignal(signals, prefix) {
  signals = webidl.converters["sequence<AbortSignal>"](
    signals,
    prefix,
    "Argument 1",
  );

  const resultSignal = new AbortSignal(illegalConstructorKey);
  for (let i = 0; i < signals.length; ++i) {
    const signal = signals[i];
    if (signal[abortReason] !== undefined) {
      resultSignal[abortReason] = signal[abortReason];
      return resultSignal;
    }
  }

  resultSignal[dependent] = true;
  resultSignal[sourceSignals] = new WeakRefSet();
  for (let i = 0; i < signals.length; ++i) {
    const signal = signals[i];
    if (!signal[dependent]) {
      signal[dependentSignals] ??= new WeakRefSet();
      resultSignal[sourceSignals].add(signal);
      signal[dependentSignals].add(resultSignal);
    } else {
      const sourceSignalArray = signal[sourceSignals].toArray();
      for (let j = 0; j < sourceSignalArray.length; ++j) {
        const sourceSignal = sourceSignalArray[j];
        assert(sourceSignal[abortReason] === undefined);
        assert(!sourceSignal[dependent]);

        if (resultSignal[sourceSignals].has(sourceSignal)) {
          continue;
        }
        resultSignal[sourceSignals].add(sourceSignal);
        sourceSignal[dependentSignals].add(resultSignal);
      }
    }
  }

  return resultSignal;
}

export {
  AbortController,
  AbortSignal,
  AbortSignalPrototype,
  add,
  createDependentAbortSignal,
  newSignal,
  remove,
  signalAbort,
  timerId,
};