export class ManualPromise<T = void> extends Promise<T> {
private readonly _resolve!: (t: T) => void;
private readonly _reject!: (e: Error) => void;
private _isDone: boolean;
constructor() {
let resolve!: (t: T) => void;
let reject!: (e: Error) => void;
super((res, rej) => {
resolve = res;
reject = rej;
});
this._isDone = false;
this._resolve = resolve;
this._reject = reject;
}
isDone() {
return this._isDone;
}
resolve(t: T) {
this._isDone = true;
this._resolve(t);
}
reject(e: Error) {
this._isDone = true;
this._reject(e);
}
static override get [Symbol.species]() {
return Promise;
}
override get [Symbol.toStringTag]() {
return 'ManualPromise';
}
}
export class LongStandingScope {
private _terminateError: Error | undefined;
private _closeError: Error | undefined;
private readonly _terminatePromises = new Map<
ManualPromise<Error>,
string[]
>();
private _isClosed = false;
reject(error: Error) {
this._isClosed = true;
this._terminateError = error;
for (const p of this._terminatePromises.keys()) {
p.resolve(error);
}
}
close(error: Error) {
this._isClosed = true;
this._closeError = error;
for (const [p, frames] of this._terminatePromises) {
p.resolve(cloneError(error, frames));
}
}
isClosed() {
return this._isClosed;
}
static raceMultiple<T>(
scopes: LongStandingScope[],
promise: Promise<T>
): Promise<T> {
return Promise.race(scopes.map((s) => s.race(promise)));
}
race<T>(promise: Promise<T> | Promise<T>[]): Promise<T> {
return this._race(Array.isArray(promise) ? promise : [promise], false);
}
safeRace<T>(promise: Promise<T>, defaultValue?: T): Promise<T> {
return this._race([promise], true, defaultValue);
}
private async _race<T>(
promises: Promise<T>[],
safe: boolean,
defaultValue?: T
): Promise<T> {
const terminatePromise = new ManualPromise<Error>();
const frames = captureRawStack();
if (this._terminateError) {
terminatePromise.resolve(this._terminateError);
}
if (this._closeError) {
terminatePromise.resolve(cloneError(this._closeError, frames));
}
this._terminatePromises.set(terminatePromise, frames);
try {
return await Promise.race([
terminatePromise.then((e) =>
safe ? (defaultValue as T) : Promise.reject(e)
),
...promises,
]);
} finally {
this._terminatePromises.delete(terminatePromise);
}
}
}
function cloneError(error: Error, frames: string[]) {
const clone = new Error(error.message);
clone.name = error.name;
clone.stack = [`${error.name}:${error.message}`, ...frames].join('\n');
return clone;
}
function captureRawStack(): string[] {
const stackTraceLimit = Error.stackTraceLimit;
Error.stackTraceLimit = 50;
const error = new Error('Stack trace capture');
const stack = error.stack ?? '';
Error.stackTraceLimit = stackTraceLimit;
return stack.split('\n');
}
