Event loop resolving prematurely
It looks like event loop clears on
Can anyone help with that?
Execution result
await it.return?.();await it.return?.(); call which is really strange. I can't figure out whats happening here and where the problem is.Can anyone help with that?
import { assert } from 'jsr:@std/assert@^1.0.0';
async function* abortable(
p: ReadableStream<Uint8Array>,
signal: AbortSignal,
): AsyncGenerator<Uint8Array> {
signal.throwIfAborted();
const { promise, reject } = Promise.withResolvers<never>();
const abort = () => reject(signal.reason);
signal.addEventListener("abort", abort, { once: true });
const it = p[Symbol.asyncIterator]();
try{
while (true) {
const race = Promise.race([promise, it.next()]);
race.catch(() => {
signal.removeEventListener("abort", abort);
});
const { done, value } = await race;
if (done) {
signal.removeEventListener("abort", abort);
return;
}
yield value;
}
}catch(e){
await it.return?.();
throw e;
}
}
Deno.test('aborting streams', async () => {
let streamClosed = false;
const stream = new ReadableStream<Uint8Array>({
cancel() {
streamClosed = true;
console.log('Stream closed');
}
});
console.log('stream created');
const signalController = new AbortController();
setTimeout(() => signalController.abort(), 1000);
try{
for await (const _ of abortable(stream, signalController.signal)) {
console.log('Got data');
}
}catch(e){
console.error(e);
}
console.log('Stream closed');
assert(streamClosed);
});import { assert } from 'jsr:@std/assert@^1.0.0';
async function* abortable(
p: ReadableStream<Uint8Array>,
signal: AbortSignal,
): AsyncGenerator<Uint8Array> {
signal.throwIfAborted();
const { promise, reject } = Promise.withResolvers<never>();
const abort = () => reject(signal.reason);
signal.addEventListener("abort", abort, { once: true });
const it = p[Symbol.asyncIterator]();
try{
while (true) {
const race = Promise.race([promise, it.next()]);
race.catch(() => {
signal.removeEventListener("abort", abort);
});
const { done, value } = await race;
if (done) {
signal.removeEventListener("abort", abort);
return;
}
yield value;
}
}catch(e){
await it.return?.();
throw e;
}
}
Deno.test('aborting streams', async () => {
let streamClosed = false;
const stream = new ReadableStream<Uint8Array>({
cancel() {
streamClosed = true;
console.log('Stream closed');
}
});
console.log('stream created');
const signalController = new AbortController();
setTimeout(() => signalController.abort(), 1000);
try{
for await (const _ of abortable(stream, signalController.signal)) {
console.log('Got data');
}
}catch(e){
console.error(e);
}
console.log('Stream closed');
assert(streamClosed);
});Execution result
❯ deno test -A strange.test.ts
running 1 test from ./oko.test.ts
aborting streams ...
------- output -------
stream created
----- output end -----
ok | 0 passed | 0 failed (1s)
error: Promise resolution is still pending but the event loop has already resolved.❯ deno test -A strange.test.ts
running 1 test from ./oko.test.ts
aborting streams ...
------- output -------
stream created
----- output end -----
ok | 0 passed | 0 failed (1s)
error: Promise resolution is still pending but the event loop has already resolved.
