rename PromiseCanceller to AbortSignalListener (#4282)

src/execution/AbortSignalListener.ts

@@ -0,0 +1,91 @@
+import { promiseWithResolvers } from '../jsutils/promiseWithResolvers.js';
+
+/**
+ * A AbortSignalListener object can be used to trigger multiple responses
+ * in response to a single AbortSignal.
+ *
+ * @internal
+ */
+export class AbortSignalListener {
+  abortSignal: AbortSignal;
+  abort: () => void;
+
+  private _onAborts: Set<() => void>;
+
+  constructor(abortSignal: AbortSignal) {
+    this.abortSignal = abortSignal;
+    this._onAborts = new Set<() => void>();
+    this.abort = () => {
+      for (const abort of this._onAborts) {
+        abort();
+      }
+    };
+
+    abortSignal.addEventListener('abort', this.abort);
+  }
+
+  add(onAbort: () => void): void {
+    this._onAborts.add(onAbort);
+  }
+
+  delete(onAbort: () => void): void {
+    this._onAborts.delete(onAbort);
+  }
+
+  disconnect(): void {
+    this.abortSignal.removeEventListener('abort', this.abort);
+  }
+}
+
+export function cancellablePromise<T>(
+  originalPromise: Promise<T>,
+  abortSignalListener: AbortSignalListener,
+): Promise<T> {
+  const abortSignal = abortSignalListener.abortSignal;
+  if (abortSignal.aborted) {
+    // eslint-disable-next-line @typescript-eslint/prefer-promise-reject-errors
+    return Promise.reject(abortSignal.reason);
+  }
+
+  const { promise, resolve, reject } = promiseWithResolvers<T>();
+  const onAbort = () => reject(abortSignal.reason);
+  abortSignalListener.add(onAbort);
+  originalPromise.then(
+    (resolved) => {
+      abortSignalListener.delete(onAbort);
+      resolve(resolved);
+    },
+    (error: unknown) => {
+      abortSignalListener.delete(onAbort);
+      reject(error);
+    },
+  );
+
+  return promise;
+}
+
+export function cancellableIterable<T>(
+  iterable: AsyncIterable<T>,
+  abortSignalListener: AbortSignalListener,
+): AsyncIterable<T> {
+  const iterator = iterable[Symbol.asyncIterator]();
+
+  const _next = iterator.next.bind(iterator);
+
+  if (iterator.return) {
+    const _return = iterator.return.bind(iterator);
+
+    return {
+      [Symbol.asyncIterator]: () => ({
+        next: () => cancellablePromise(_next(), abortSignalListener),
+        return: () => cancellablePromise(_return(), abortSignalListener),
+      }),
+    };
+  }
+
+  return {
+    [Symbol.asyncIterator]: () => ({
+      next: () => cancellablePromise(_next(), abortSignalListener),
+    }),
+  };
+}

src/execution/IncrementalPublisher.ts

@@ -4,8 +4,8 @@ import { pathToArray } from '../jsutils/Path.js';
 
 import type { GraphQLError } from '../error/GraphQLError.js';
 
+import type { AbortSignalListener } from './AbortSignalListener.js';
 import { IncrementalGraph } from './IncrementalGraph.js';
-import type { PromiseCanceller } from './PromiseCanceller.js';
 import type {
   CancellableStreamRecord,
   CompletedExecutionGroup,
@@ -44,7 +44,7 @@ export function buildIncrementalResponse(
 }
 
 interface IncrementalPublisherContext {
-  promiseCanceller: PromiseCanceller | undefined;
+  abortSignalListener: AbortSignalListener | undefined;
   cancellableStreams: Set<CancellableStreamRecord> | undefined;
 }
 
@@ -127,7 +127,7 @@ class IncrementalPublisher {
       IteratorResult<SubsequentIncrementalExecutionResult, void>
     > => {
       if (isDone) {
-        this._context.promiseCanceller?.disconnect();
+        this._context.abortSignalListener?.disconnect();
         await this._returnAsyncIteratorsIgnoringErrors();
         return { value: undefined, done: true };
       }
@@ -176,7 +176,7 @@ class IncrementalPublisher {
 
       // TODO: add test for this case
       /* c8 ignore next */
-      this._context.promiseCanceller?.disconnect();
+      this._context.abortSignalListener?.disconnect();
       await this._returnAsyncIteratorsIgnoringErrors();
       return { value: undefined, done: true };
     };

src/execution/__tests__/AbortSignalListener-test.ts

@@ -0,0 +1,170 @@
+import { expect } from 'chai';
+import { describe, it } from 'mocha';
+
+import { expectPromise } from '../../__testUtils__/expectPromise.js';
+
+import {
+  AbortSignalListener,
+  cancellableIterable,
+  cancellablePromise,
+} from '../AbortSignalListener.js';
+
+describe('AbortSignalListener', () => {
+  it('works to add a listener', () => {
+    const abortController = new AbortController();
+
+    const abortSignalListener = new AbortSignalListener(abortController.signal);
+
+    let called = false;
+    const onAbort = () => {
+      called = true;
+    };
+    abortSignalListener.add(onAbort);
+
+    abortController.abort();
+
+    expect(called).to.equal(true);
+  });
+
+  it('works to delete a listener', () => {
+    const abortController = new AbortController();
+
+    const abortSignalListener = new AbortSignalListener(abortController.signal);
+
+    let called = false;
+    /* c8 ignore next 3 */
+    const onAbort = () => {
+      called = true;
+    };
+    abortSignalListener.add(onAbort);
+    abortSignalListener.delete(onAbort);
+
+    abortController.abort();
+
+    expect(called).to.equal(false);
+  });
+
+  it('works to disconnect a listener from the abortSignal', () => {
+    const abortController = new AbortController();
+
+    const abortSignalListener = new AbortSignalListener(abortController.signal);
+
+    let called = false;
+    /* c8 ignore next 3 */
+    const onAbort = () => {
+      called = true;
+    };
+    abortSignalListener.add(onAbort);
+
+    abortSignalListener.disconnect();
+
+    abortController.abort();
+
+    expect(called).to.equal(false);
+  });
+});
+
+describe('cancellablePromise', () => {
+  it('works to cancel an already resolved promise', async () => {
+    const abortController = new AbortController();
+
+    const abortSignalListener = new AbortSignalListener(abortController.signal);
+
+    const promise = Promise.resolve(1);
+
+    const withCancellation = cancellablePromise(promise, abortSignalListener);
+
+    abortController.abort(new Error('Cancelled!'));
+
+    await expectPromise(withCancellation).toRejectWith('Cancelled!');
+  });
+
+  it('works to cancel an already resolved promise after abort signal triggered', async () => {
+    const abortController = new AbortController();
+    const abortSignalListener = new AbortSignalListener(abortController.signal);
+
+    abortController.abort(new Error('Cancelled!'));
+
+    const promise = Promise.resolve(1);
+
+    const withCancellation = cancellablePromise(promise, abortSignalListener);
+
+    await expectPromise(withCancellation).toRejectWith('Cancelled!');
+  });
+
+  it('works to cancel a hanging promise', async () => {
+    const abortController = new AbortController();
+    const abortSignalListener = new AbortSignalListener(abortController.signal);
+
+    const promise = new Promise(() => {
+      /* never resolves */
+    });
+
+    const withCancellation = cancellablePromise(promise, abortSignalListener);
+
+    abortController.abort(new Error('Cancelled!'));
+
+    await expectPromise(withCancellation).toRejectWith('Cancelled!');
+  });
+
+  it('works to cancel a hanging promise created after abort signal triggered', async () => {
+    const abortController = new AbortController();
+    const abortSignalListener = new AbortSignalListener(abortController.signal);
+
+    abortController.abort(new Error('Cancelled!'));
+
+    const promise = new Promise(() => {
+      /* never resolves */
+    });
+
+    const withCancellation = cancellablePromise(promise, abortSignalListener);
+
+    await expectPromise(withCancellation).toRejectWith('Cancelled!');
+  });
+});
+
+describe('cancellableAsyncIterable', () => {
+  it('works to abort a next call', async () => {
+    const abortController = new AbortController();
+    const abortSignalListener = new AbortSignalListener(abortController.signal);
+
+    const asyncIterable = {
+      [Symbol.asyncIterator]: () => ({
+        next: () => Promise.resolve({ value: 1, done: false }),
+      }),
+    };
+
+    const withCancellation = cancellableIterable(
+      asyncIterable,
+      abortSignalListener,
+    );
+
+    const nextPromise = withCancellation[Symbol.asyncIterator]().next();
+
+    abortController.abort(new Error('Cancelled!'));
+
+    await expectPromise(nextPromise).toRejectWith('Cancelled!');
+  });
+
+  it('works to abort a next call when already aborted', async () => {
+    const abortController = new AbortController();
+    const abortSignalListener = new AbortSignalListener(abortController.signal);
+
+    abortController.abort(new Error('Cancelled!'));
+
+    const asyncIterable = {
+      [Symbol.asyncIterator]: () => ({
+        next: () => Promise.resolve({ value: 1, done: false }),
+      }),
+    };
+
+    const withCancellation = cancellableIterable(
+      asyncIterable,
+      abortSignalListener,
+    );
+
+    const nextPromise = withCancellation[Symbol.asyncIterator]().next();
+
+    await expectPromise(nextPromise).toRejectWith('Cancelled!');
+  });
+});