@sussudio/base
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Internal APIs for VS Code's utilities and user interface building blocks.
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JavaScript
/*---------------------------------------------------------------------------------------------
* Copyright (c) Microsoft Corporation. All rights reserved.
* Licensed under the MIT License. See License.txt in the project root for license information.
*--------------------------------------------------------------------------------------------*/
import { CancellationTokenSource } from './cancellation.mjs';
import { CancellationError } from './errors.mjs';
import { Emitter, Event } from './event.mjs';
import { Disposable, MutableDisposable, toDisposable } from './lifecycle.mjs';
import { extUri as defaultExtUri } from './resources.mjs';
import { setTimeout0 } from './platform.mjs';
export function isThenable(obj) {
return !!obj && typeof obj.then === 'function';
}
export function createCancelablePromise(callback) {
const source = new CancellationTokenSource();
const thenable = callback(source.token);
const promise = new Promise((resolve, reject) => {
const subscription = source.token.onCancellationRequested(() => {
subscription.dispose();
source.dispose();
reject(new CancellationError());
});
Promise.resolve(thenable).then(
(value) => {
subscription.dispose();
source.dispose();
resolve(value);
},
(err) => {
subscription.dispose();
source.dispose();
reject(err);
},
);
});
return new (class {
cancel() {
source.cancel();
}
then(resolve, reject) {
return promise.then(resolve, reject);
}
catch(reject) {
return this.then(undefined, reject);
}
finally(onfinally) {
return promise.finally(onfinally);
}
})();
}
export function raceCancellation(promise, token, defaultValue) {
return new Promise((resolve, reject) => {
const ref = token.onCancellationRequested(() => {
ref.dispose();
resolve(defaultValue);
});
promise.then(resolve, reject).finally(() => ref.dispose());
});
}
/**
* Returns a promise that rejects with an {@CancellationError} as soon as the passed token is cancelled.
* @see {@link raceCancellation}
*/
export function raceCancellationError(promise, token) {
return new Promise((resolve, reject) => {
const ref = token.onCancellationRequested(() => {
ref.dispose();
reject(new CancellationError());
});
promise.then(resolve, reject).finally(() => ref.dispose());
});
}
/**
* Returns as soon as one of the promises is resolved and cancels remaining promises
*/
export async function raceCancellablePromises(cancellablePromises) {
let resolvedPromiseIndex = -1;
const promises = cancellablePromises.map((promise, index) =>
promise.then((result) => {
resolvedPromiseIndex = index;
return result;
}),
);
const result = await Promise.race(promises);
cancellablePromises.forEach((cancellablePromise, index) => {
if (index !== resolvedPromiseIndex) {
cancellablePromise.cancel();
}
});
return result;
}
export function raceTimeout(promise, timeout, onTimeout) {
let promiseResolve = undefined;
const timer = setTimeout(() => {
promiseResolve?.(undefined);
onTimeout?.();
}, timeout);
return Promise.race([
promise.finally(() => clearTimeout(timer)),
new Promise((resolve) => (promiseResolve = resolve)),
]);
}
export function asPromise(callback) {
return new Promise((resolve, reject) => {
const item = callback();
if (isThenable(item)) {
item.then(resolve, reject);
} else {
resolve(item);
}
});
}
/**
* A helper to prevent accumulation of sequential async tasks.
*
* Imagine a mail man with the sole task of delivering letters. As soon as
* a letter submitted for delivery, he drives to the destination, delivers it
* and returns to his base. Imagine that during the trip, N more letters were submitted.
* When the mail man returns, he picks those N letters and delivers them all in a
* single trip. Even though N+1 submissions occurred, only 2 deliveries were made.
*
* The throttler implements this via the queue() method, by providing it a task
* factory. Following the example:
*
* const throttler = new Throttler();
* const letters = [];
*
* function deliver() {
* const lettersToDeliver = letters;
* letters = [];
* return makeTheTrip(lettersToDeliver);
* }
*
* function onLetterReceived(l) {
* letters.push(l);
* throttler.queue(deliver);
* }
*/
export class Throttler {
activePromise;
queuedPromise;
queuedPromiseFactory;
constructor() {
this.activePromise = null;
this.queuedPromise = null;
this.queuedPromiseFactory = null;
}
queue(promiseFactory) {
if (this.activePromise) {
this.queuedPromiseFactory = promiseFactory;
if (!this.queuedPromise) {
const onComplete = () => {
this.queuedPromise = null;
const result = this.queue(this.queuedPromiseFactory);
this.queuedPromiseFactory = null;
return result;
};
this.queuedPromise = new Promise((resolve) => {
this.activePromise.then(onComplete, onComplete).then(resolve);
});
}
return new Promise((resolve, reject) => {
this.queuedPromise.then(resolve, reject);
});
}
this.activePromise = promiseFactory();
return new Promise((resolve, reject) => {
this.activePromise.then(
(result) => {
this.activePromise = null;
resolve(result);
},
(err) => {
this.activePromise = null;
reject(err);
},
);
});
}
}
export class Sequencer {
current = Promise.resolve(null);
queue(promiseTask) {
return (this.current = this.current.then(
() => promiseTask(),
() => promiseTask(),
));
}
}
export class SequencerByKey {
promiseMap = new Map();
queue(key, promiseTask) {
const runningPromise = this.promiseMap.get(key) ?? Promise.resolve();
const newPromise = runningPromise
.catch(() => {})
.then(promiseTask)
.finally(() => {
if (this.promiseMap.get(key) === newPromise) {
this.promiseMap.delete(key);
}
});
this.promiseMap.set(key, newPromise);
return newPromise;
}
}
const timeoutDeferred = (timeout, fn) => {
let scheduled = true;
const handle = setTimeout(() => {
scheduled = false;
fn();
}, timeout);
return {
isTriggered: () => scheduled,
dispose: () => {
clearTimeout(handle);
scheduled = false;
},
};
};
const microtaskDeferred = (fn) => {
let scheduled = true;
queueMicrotask(() => {
if (scheduled) {
scheduled = false;
fn();
}
});
return {
isTriggered: () => scheduled,
dispose: () => {
scheduled = false;
},
};
};
/** Can be passed into the Delayed to defer using a microtask */
export const MicrotaskDelay = Symbol('MicrotaskDelay');
/**
* A helper to delay (debounce) execution of a task that is being requested often.
*
* Following the throttler, now imagine the mail man wants to optimize the number of
* trips proactively. The trip itself can be long, so he decides not to make the trip
* as soon as a letter is submitted. Instead he waits a while, in case more
* letters are submitted. After said waiting period, if no letters were submitted, he
* decides to make the trip. Imagine that N more letters were submitted after the first
* one, all within a short period of time between each other. Even though N+1
* submissions occurred, only 1 delivery was made.
*
* The delayer offers this behavior via the trigger() method, into which both the task
* to be executed and the waiting period (delay) must be passed in as arguments. Following
* the example:
*
* const delayer = new Delayer(WAITING_PERIOD);
* const letters = [];
*
* function letterReceived(l) {
* letters.push(l);
* delayer.trigger(() => { return makeTheTrip(); });
* }
*/
export class Delayer {
defaultDelay;
deferred;
completionPromise;
doResolve;
doReject;
task;
constructor(defaultDelay) {
this.defaultDelay = defaultDelay;
this.deferred = null;
this.completionPromise = null;
this.doResolve = null;
this.doReject = null;
this.task = null;
}
trigger(task, delay = this.defaultDelay) {
this.task = task;
this.cancelTimeout();
if (!this.completionPromise) {
this.completionPromise = new Promise((resolve, reject) => {
this.doResolve = resolve;
this.doReject = reject;
}).then(() => {
this.completionPromise = null;
this.doResolve = null;
if (this.task) {
const task = this.task;
this.task = null;
return task();
}
return undefined;
});
}
const fn = () => {
this.deferred = null;
this.doResolve?.(null);
};
this.deferred = delay === MicrotaskDelay ? microtaskDeferred(fn) : timeoutDeferred(delay, fn);
return this.completionPromise;
}
isTriggered() {
return !!this.deferred?.isTriggered();
}
cancel() {
this.cancelTimeout();
if (this.completionPromise) {
this.doReject?.(new CancellationError());
this.completionPromise = null;
}
}
cancelTimeout() {
this.deferred?.dispose();
this.deferred = null;
}
dispose() {
this.cancel();
}
}
/**
* A helper to delay execution of a task that is being requested often, while
* preventing accumulation of consecutive executions, while the task runs.
*
* The mail man is clever and waits for a certain amount of time, before going
* out to deliver letters. While the mail man is going out, more letters arrive
* and can only be delivered once he is back. Once he is back the mail man will
* do one more trip to deliver the letters that have accumulated while he was out.
*/
export class ThrottledDelayer {
delayer;
throttler;
constructor(defaultDelay) {
this.delayer = new Delayer(defaultDelay);
this.throttler = new Throttler();
}
trigger(promiseFactory, delay) {
return this.delayer.trigger(() => this.throttler.queue(promiseFactory), delay);
}
isTriggered() {
return this.delayer.isTriggered();
}
cancel() {
this.delayer.cancel();
}
dispose() {
this.delayer.dispose();
}
}
/**
* A barrier that is initially closed and then becomes opened permanently.
*/
export class Barrier {
_isOpen;
_promise;
_completePromise;
constructor() {
this._isOpen = false;
this._promise = new Promise((c, e) => {
this._completePromise = c;
});
}
isOpen() {
return this._isOpen;
}
open() {
this._isOpen = true;
this._completePromise(true);
}
wait() {
return this._promise;
}
}
/**
* A barrier that is initially closed and then becomes opened permanently after a certain period of
* time or when open is called explicitly
*/
export class AutoOpenBarrier extends Barrier {
_timeout;
constructor(autoOpenTimeMs) {
super();
this._timeout = setTimeout(() => this.open(), autoOpenTimeMs);
}
open() {
clearTimeout(this._timeout);
super.open();
}
}
export function timeout(millis, token) {
if (!token) {
return createCancelablePromise((token) => timeout(millis, token));
}
return new Promise((resolve, reject) => {
const handle = setTimeout(() => {
disposable.dispose();
resolve();
}, millis);
const disposable = token.onCancellationRequested(() => {
clearTimeout(handle);
disposable.dispose();
reject(new CancellationError());
});
});
}
export function disposableTimeout(handler, timeout = 0) {
const timer = setTimeout(handler, timeout);
return toDisposable(() => clearTimeout(timer));
}
/**
* Runs the provided list of promise factories in sequential order. The returned
* promise will complete to an array of results from each promise.
*/
export function sequence(promiseFactories) {
const results = [];
let index = 0;
const len = promiseFactories.length;
function next() {
return index < len ? promiseFactories[index++]() : null;
}
function thenHandler(result) {
if (result !== undefined && result !== null) {
results.push(result);
}
const n = next();
if (n) {
return n.then(thenHandler);
}
return Promise.resolve(results);
}
return Promise.resolve(null).then(thenHandler);
}
export function first(promiseFactories, shouldStop = (t) => !!t, defaultValue = null) {
let index = 0;
const len = promiseFactories.length;
const loop = () => {
if (index >= len) {
return Promise.resolve(defaultValue);
}
const factory = promiseFactories[index++];
const promise = Promise.resolve(factory());
return promise.then((result) => {
if (shouldStop(result)) {
return Promise.resolve(result);
}
return loop();
});
};
return loop();
}
export function firstParallel(promiseList, shouldStop = (t) => !!t, defaultValue = null) {
if (promiseList.length === 0) {
return Promise.resolve(defaultValue);
}
let todo = promiseList.length;
const finish = () => {
todo = -1;
for (const promise of promiseList) {
promise.cancel?.();
}
};
return new Promise((resolve, reject) => {
for (const promise of promiseList) {
promise
.then((result) => {
if (--todo >= 0 && shouldStop(result)) {
finish();
resolve(result);
} else if (todo === 0) {
resolve(defaultValue);
}
})
.catch((err) => {
if (--todo >= 0) {
finish();
reject(err);
}
});
}
});
}
/**
* A helper to queue N promises and run them all with a max degree of parallelism. The helper
* ensures that at any time no more than M promises are running at the same time.
*/
export class Limiter {
_size = 0;
runningPromises;
maxDegreeOfParalellism;
outstandingPromises;
_onDrained;
constructor(maxDegreeOfParalellism) {
this.maxDegreeOfParalellism = maxDegreeOfParalellism;
this.outstandingPromises = [];
this.runningPromises = 0;
this._onDrained = new Emitter();
}
/**
* An event that fires when every promise in the queue
* has started to execute. In other words: no work is
* pending to be scheduled.
*
* This is NOT an event that signals when all promises
* have finished though.
*/
get onDrained() {
return this._onDrained.event;
}
get size() {
return this._size;
}
queue(factory) {
this._size++;
return new Promise((c, e) => {
this.outstandingPromises.push({ factory, c, e });
this.consume();
});
}
consume() {
while (this.outstandingPromises.length && this.runningPromises < this.maxDegreeOfParalellism) {
const iLimitedTask = this.outstandingPromises.shift();
this.runningPromises++;
const promise = iLimitedTask.factory();
promise.then(iLimitedTask.c, iLimitedTask.e);
promise.then(
() => this.consumed(),
() => this.consumed(),
);
}
}
consumed() {
this._size--;
this.runningPromises--;
if (this.outstandingPromises.length > 0) {
this.consume();
} else {
this._onDrained.fire();
}
}
dispose() {
this._onDrained.dispose();
}
}
/**
* A queue is handles one promise at a time and guarantees that at any time only one promise is executing.
*/
export class Queue extends Limiter {
constructor() {
super(1);
}
}
/**
* A helper to organize queues per resource. The ResourceQueue makes sure to manage queues per resource
* by disposing them once the queue is empty.
*/
export class ResourceQueue {
queues = new Map();
drainers = new Set();
async whenDrained() {
if (this.isDrained()) {
return;
}
const promise = new DeferredPromise();
this.drainers.add(promise);
return promise.p;
}
isDrained() {
for (const [, queue] of this.queues) {
if (queue.size > 0) {
return false;
}
}
return true;
}
queueFor(resource, extUri = defaultExtUri) {
const key = extUri.getComparisonKey(resource);
let queue = this.queues.get(key);
if (!queue) {
queue = new Queue();
Event.once(queue.onDrained)(() => {
queue?.dispose();
this.queues.delete(key);
this.onDidQueueDrain();
});
this.queues.set(key, queue);
}
return queue;
}
onDidQueueDrain() {
if (!this.isDrained()) {
return; // not done yet
}
this.releaseDrainers();
}
releaseDrainers() {
for (const drainer of this.drainers) {
drainer.complete();
}
this.drainers.clear();
}
dispose() {
for (const [, queue] of this.queues) {
queue.dispose();
}
this.queues.clear();
// Even though we might still have pending
// tasks queued, after the queues have been
// disposed, we can no longer track them, so
// we release drainers to prevent hanging
// promises when the resource queue is being
// disposed.
this.releaseDrainers();
}
}
export class TimeoutTimer {
_token;
constructor(runner, timeout) {
this._token = -1;
if (typeof runner === 'function' && typeof timeout === 'number') {
this.setIfNotSet(runner, timeout);
}
}
dispose() {
this.cancel();
}
cancel() {
if (this._token !== -1) {
clearTimeout(this._token);
this._token = -1;
}
}
cancelAndSet(runner, timeout) {
this.cancel();
this._token = setTimeout(() => {
this._token = -1;
runner();
}, timeout);
}
setIfNotSet(runner, timeout) {
if (this._token !== -1) {
// timer is already set
return;
}
this._token = setTimeout(() => {
this._token = -1;
runner();
}, timeout);
}
}
export class IntervalTimer {
_token;
constructor() {
this._token = -1;
}
dispose() {
this.cancel();
}
cancel() {
if (this._token !== -1) {
clearInterval(this._token);
this._token = -1;
}
}
cancelAndSet(runner, interval) {
this.cancel();
this._token = setInterval(() => {
runner();
}, interval);
}
}
export class RunOnceScheduler {
runner;
timeoutToken;
timeout;
timeoutHandler;
constructor(runner, delay) {
this.timeoutToken = -1;
this.runner = runner;
this.timeout = delay;
this.timeoutHandler = this.onTimeout.bind(this);
}
/**
* Dispose RunOnceScheduler
*/
dispose() {
this.cancel();
this.runner = null;
}
/**
* Cancel current scheduled runner (if any).
*/
cancel() {
if (this.isScheduled()) {
clearTimeout(this.timeoutToken);
this.timeoutToken = -1;
}
}
/**
* Cancel previous runner (if any) & schedule a new runner.
*/
schedule(delay = this.timeout) {
this.cancel();
this.timeoutToken = setTimeout(this.timeoutHandler, delay);
}
get delay() {
return this.timeout;
}
set delay(value) {
this.timeout = value;
}
/**
* Returns true if scheduled.
*/
isScheduled() {
return this.timeoutToken !== -1;
}
flush() {
if (this.isScheduled()) {
this.cancel();
this.doRun();
}
}
onTimeout() {
this.timeoutToken = -1;
if (this.runner) {
this.doRun();
}
}
doRun() {
this.runner?.();
}
}
/**
* Same as `RunOnceScheduler`, but doesn't count the time spent in sleep mode.
* > **NOTE**: Only offers 1s resolution.
*
* When calling `setTimeout` with 3hrs, and putting the computer immediately to sleep
* for 8hrs, `setTimeout` will fire **as soon as the computer wakes from sleep**. But
* this scheduler will execute 3hrs **after waking the computer from sleep**.
*/
export class ProcessTimeRunOnceScheduler {
runner;
timeout;
counter;
intervalToken;
intervalHandler;
constructor(runner, delay) {
if (delay % 1000 !== 0) {
console.warn(`ProcessTimeRunOnceScheduler resolution is 1s, ${delay}ms is not a multiple of 1000ms.`);
}
this.runner = runner;
this.timeout = delay;
this.counter = 0;
this.intervalToken = -1;
this.intervalHandler = this.onInterval.bind(this);
}
dispose() {
this.cancel();
this.runner = null;
}
cancel() {
if (this.isScheduled()) {
clearInterval(this.intervalToken);
this.intervalToken = -1;
}
}
/**
* Cancel previous runner (if any) & schedule a new runner.
*/
schedule(delay = this.timeout) {
if (delay % 1000 !== 0) {
console.warn(`ProcessTimeRunOnceScheduler resolution is 1s, ${delay}ms is not a multiple of 1000ms.`);
}
this.cancel();
this.counter = Math.ceil(delay / 1000);
this.intervalToken = setInterval(this.intervalHandler, 1000);
}
/**
* Returns true if scheduled.
*/
isScheduled() {
return this.intervalToken !== -1;
}
onInterval() {
this.counter--;
if (this.counter > 0) {
// still need to wait
return;
}
// time elapsed
clearInterval(this.intervalToken);
this.intervalToken = -1;
this.runner?.();
}
}
export class RunOnceWorker extends RunOnceScheduler {
units = [];
constructor(runner, timeout) {
super(runner, timeout);
}
work(unit) {
this.units.push(unit);
if (!this.isScheduled()) {
this.schedule();
}
}
doRun() {
const units = this.units;
this.units = [];
this.runner?.(units);
}
dispose() {
this.units = [];
super.dispose();
}
}
/**
* The `ThrottledWorker` will accept units of work `T`
* to handle. The contract is:
* * there is a maximum of units the worker can handle at once (via `maxWorkChunkSize`)
* * there is a maximum of units the worker will keep in memory for processing (via `maxBufferedWork`)
* * after having handled `maxWorkChunkSize` units, the worker needs to rest (via `throttleDelay`)
*/
export class ThrottledWorker extends Disposable {
options;
handler;
pendingWork = [];
throttler = this._register(new MutableDisposable());
disposed = false;
constructor(options, handler) {
super();
this.options = options;
this.handler = handler;
}
/**
* The number of work units that are pending to be processed.
*/
get pending() {
return this.pendingWork.length;
}
/**
* Add units to be worked on. Use `pending` to figure out
* how many units are not yet processed after this method
* was called.
*
* @returns whether the work was accepted or not. If the
* worker is disposed, it will not accept any more work.
* If the number of pending units would become larger
* than `maxPendingWork`, more work will also not be accepted.
*/
work(units) {
if (this.disposed) {
return false; // work not accepted: disposed
}
// Check for reaching maximum of pending work
if (typeof this.options.maxBufferedWork === 'number') {
// Throttled: simple check if pending + units exceeds max pending
if (this.throttler.value) {
if (this.pending + units.length > this.options.maxBufferedWork) {
return false; // work not accepted: too much pending work
}
}
// Unthrottled: same as throttled, but account for max chunk getting
// worked on directly without being pending
else {
if (this.pending + units.length - this.options.maxWorkChunkSize > this.options.maxBufferedWork) {
return false; // work not accepted: too much pending work
}
}
}
// Add to pending units first
for (const unit of units) {
this.pendingWork.push(unit);
}
// If not throttled, start working directly
// Otherwise, when the throttle delay has
// past, pending work will be worked again.
if (!this.throttler.value) {
this.doWork();
}
return true; // work accepted
}
doWork() {
// Extract chunk to handle and handle it
this.handler(this.pendingWork.splice(0, this.options.maxWorkChunkSize));
// If we have remaining work, schedule it after a delay
if (this.pendingWork.length > 0) {
this.throttler.value = new RunOnceScheduler(() => {
this.throttler.clear();
this.doWork();
}, this.options.throttleDelay);
this.throttler.value.schedule();
}
}
dispose() {
super.dispose();
this.disposed = true;
}
}
/**
* Execute the callback the next time the browser is idle, returning an
* {@link IDisposable} that will cancel the callback when disposed. This wraps
* [requestIdleCallback] so it will fallback to [setTimeout] if the environment
* doesn't support it.
*
* @param callback The callback to run when idle, this includes an
* [IdleDeadline] that provides the time alloted for the idle callback by the
* browser. Not respecting this deadline will result in a degraded user
* experience.
* @param timeout A timeout at which point to queue no longer wait for an idle
* callback but queue it on the regular event loop (like setTimeout). Typically
* this should not be used.
*
* [IdleDeadline]: https://developer.mozilla.org/en-US/docs/Web/API/IdleDeadline
* [requestIdleCallback]: https://developer.mozilla.org/en-US/docs/Web/API/Window/requestIdleCallback
* [setTimeout]: https://developer.mozilla.org/en-US/docs/Web/API/Window/setTimeout
*/
export let runWhenIdle;
(function () {
if (typeof requestIdleCallback !== 'function' || typeof cancelIdleCallback !== 'function') {
runWhenIdle = (runner) => {
setTimeout0(() => {
if (disposed) {
return;
}
const end = Date.now() + 15; // one frame at 64fps
runner(
Object.freeze({
didTimeout: true,
timeRemaining() {
return Math.max(0, end - Date.now());
},
}),
);
});
let disposed = false;
return {
dispose() {
if (disposed) {
return;
}
disposed = true;
},
};
};
} else {
runWhenIdle = (runner, timeout) => {
const handle = requestIdleCallback(runner, typeof timeout === 'number' ? { timeout } : undefined);
let disposed = false;
return {
dispose() {
if (disposed) {
return;
}
disposed = true;
cancelIdleCallback(handle);
},
};
};
}
})();
/**
* An implementation of the "idle-until-urgent"-strategy as introduced
* here: https://philipwalton.com/articles/idle-until-urgent/
*/
export class IdleValue {
_executor;
_handle;
_didRun = false;
_value;
_error;
constructor(executor) {
this._executor = () => {
try {
this._value = executor();
} catch (err) {
this._error = err;
} finally {
this._didRun = true;
}
};
this._handle = runWhenIdle(() => this._executor());
}
dispose() {
this._handle.dispose();
}
get value() {
if (!this._didRun) {
this._handle.dispose();
this._executor();
}
if (this._error) {
throw this._error;
}
return this._value;
}
get isInitialized() {
return this._didRun;
}
}
//#endregion
export async function retry(task, delay, retries) {
let lastError;
for (let i = 0; i < retries; i++) {
try {
return await task();
} catch (error) {
lastError = error;
await timeout(delay);
}
}
throw lastError;
}
export class TaskSequentializer {
_pending;
_next;
hasPending(taskId) {
if (!this._pending) {
return false;
}
if (typeof taskId === 'number') {
return this._pending.taskId === taskId;
}
return !!this._pending;
}
get pending() {
return this._pending?.promise;
}
cancelPending() {
this._pending?.cancel();
}
setPending(taskId, promise, onCancel) {
this._pending = { taskId, cancel: () => onCancel?.(), promise };
promise.then(
() => this.donePending(taskId),
() => this.donePending(taskId),
);
return promise;
}
donePending(taskId) {
if (this._pending && taskId === this._pending.taskId) {
// only set pending to done if the promise finished that is associated with that taskId
this._pending = undefined;
// schedule the next task now that we are free if we have any
this.triggerNext();
}
}
triggerNext() {
if (this._next) {
const next = this._next;
this._next = undefined;
// Run next task and complete on the associated promise
next.run().then(next.promiseResolve, next.promiseReject);
}
}
setNext(run) {
// this is our first next task, so we create associated promise with it
// so that we can return a promise that completes when the task has
// completed.
if (!this._next) {
let promiseResolve;
let promiseReject;
const promise = new Promise((resolve, reject) => {
promiseResolve = resolve;
promiseReject = reject;
});
this._next = {
run,
promise,
promiseResolve: promiseResolve,
promiseReject: promiseReject,
};
}
// we have a previous next task, just overwrite it
else {
this._next.run = run;
}
return this._next.promise;
}
hasNext() {
return !!this._next;
}
async join() {
return this._next?.promise ?? this._pending?.promise;
}
}
//#endregion
//#region
/**
* The `IntervalCounter` allows to count the number
* of calls to `increment()` over a duration of
* `interval`. This utility can be used to conditionally
* throttle a frequent task when a certain threshold
* is reached.
*/
export class IntervalCounter {
interval;
nowFn;
lastIncrementTime = 0;
value = 0;
constructor(interval, nowFn = () => Date.now()) {
this.interval = interval;
this.nowFn = nowFn;
}
increment() {
const now = this.nowFn();
// We are outside of the range of `interval` and as such
// start counting from 0 and remember the time
if (now - this.lastIncrementTime > this.interval) {
this.lastIncrementTime = now;
this.value = 0;
}
this.value++;
return this.value;
}
}
/**
* Creates a promise whose resolution or rejection can be controlled imperatively.
*/
export class DeferredPromise {
completeCallback;
errorCallback;
rejected = false;
resolved = false;
get isRejected() {
return this.rejected;
}
get isResolved() {
return this.resolved;
}
get isSettled() {
return this.rejected || this.resolved;
}
p;
constructor() {
this.p = new Promise((c, e) => {
this.completeCallback = c;
this.errorCallback = e;
});
}
complete(value) {
return new Promise((resolve) => {
this.completeCallback(value);
this.resolved = true;
resolve();
});
}
error(err) {
return new Promise((resolve) => {
this.errorCallback(err);
this.rejected = true;
resolve();
});
}
cancel() {
new Promise((resolve) => {
this.errorCallback(new CancellationError());
this.rejected = true;
resolve();
});
}
}
//#endregion
//#region Promises
export var Promises;
(function (Promises) {
/**
* A drop-in replacement for `Promise.all` with the only difference
* that the method awaits every promise to either fulfill or reject.
*
* Similar to `Promise.all`, only the first error will be returned
* if any.
*/
async function settled(promises) {
let firstError = undefined;
const result = await Promise.all(
promises.map((promise) =>
promise.then(
(value) => value,
(error) => {
if (!firstError) {
firstError = error;
}
return undefined; // do not rethrow so that other promises can settle
},
),
),
);
if (typeof firstError !== 'undefined') {
throw firstError;
}
return result; // cast is needed and protected by the `throw` above
}
Promises.settled = settled;
/**
* A helper to create a new `Promise<T>` with a body that is a promise
* itself. By default, an error that raises from the async body will
* end up as a unhandled rejection, so this utility properly awaits the
* body and rejects the promise as a normal promise does without async
* body.
*
* This method should only be used in rare cases where otherwise `async`
* cannot be used (e.g. when callbacks are involved that require this).
*/
function withAsyncBody(bodyFn) {
// eslint-disable-next-line no-async-promise-executor
return new Promise(async (resolve, reject) => {
try {
await bodyFn(resolve, reject);
} catch (error) {
reject(error);
}
});
}
Promises.withAsyncBody = withAsyncBody;
})(Promises || (Promises = {}));
/**
* A rich implementation for an `AsyncIterable<T>`.
*/
export class AsyncIterableObject {
static fromArray(items) {
return new AsyncIterableObject((writer) => {
writer.emitMany(items);
});
}
static fromPromise(promise) {
return new AsyncIterableObject(async (emitter) => {
emitter.emitMany(await promise);
});
}
static fromPromises(promises) {
return new AsyncIterableObject(async (emitter) => {
await Promise.all(promises.map(async (p) => emitter.emitOne(await p)));
});
}
static merge(iterables) {
return new AsyncIterableObject(async (emitter) => {
await Promise.all(
iterables.map(async (iterable) => {
for await (const item of iterable) {
emitter.emitOne(item);
}
}),
);
});
}
static EMPTY = AsyncIterableObject.fromArray([]);
_state;
_results;
_error;
_onStateChanged;
constructor(executor) {
this._state = 0 /* AsyncIterableSourceState.Initial */;
this._results = [];
this._error = null;
this._onStateChanged = new Emitter();
queueMicrotask(async () => {
const writer = {
emitOne: (item) => this.emitOne(item),
emitMany: (items) => this.emitMany(items),
reject: (error) => this.reject(error),
};
try {
await Promise.resolve(executor(writer));
this.resolve();
} catch (err) {
this.reject(err);
} finally {
writer.emitOne = undefined;
writer.emitMany = undefined;
writer.reject = undefined;
}
});
}
[Symbol.asyncIterator]() {
let i = 0;
return {
next: async () => {
do {
if (this._state === 2 /* AsyncIterableSourceState.DoneError */) {
throw this._error;
}
if (i < this._results.length) {
return { done: false, value: this._results[i++] };
}
if (this._state === 1 /* AsyncIterableSourceState.DoneOK */) {
return { done: true, value: undefined };
}
await Event.toPromise(this._onStateChanged.event);
} while (true);
},
};
}
static map(iterable, mapFn) {
return new AsyncIterableObject(async (emitter) => {
for await (const item of iterable) {
emitter.emitOne(mapFn(item));
}
});
}
map(mapFn) {
return AsyncIterableObject.map(this, mapFn);
}
static filter(iterable, filterFn) {
return new AsyncIterableObject(async (emitter) => {
for await (const item of iterable) {
if (filterFn(item)) {
emitter.emitOne(item);
}
}
});
}
filter(filterFn) {
return AsyncIterableObject.filter(this, filterFn);
}
static coalesce(iterable) {
return AsyncIterableObject.filter(iterable, (item) => !!item);
}
coalesce() {
return AsyncIterableObject.coalesce(this);
}
static async toPromise(iterable) {
const result = [];
for await (const item of iterable) {
result.push(item);
}
return result;
}
toPromise() {
return AsyncIterableObject.toPromise(this);
}
/**
* The value will be appended at the end.
*
* **NOTE** If `resolve()` or `reject()` have already been called, this method has no effect.
*/
emitOne(value) {
if (this._state !== 0 /* AsyncIterableSourceState.Initial */) {
return;
}
// it is important to add new values at the end,
// as we may have iterators already running on the array
this._results.push(value);
this._onStateChanged.fire();
}
/**
* The values will be appended at the end.
*
* **NOTE** If `resolve()` or `reject()` have already been called, this method has no effect.
*/
emitMany(values) {
if (this._state !== 0 /* AsyncIterableSourceState.Initial */) {
return;
}
// it is important to add new values at the end,
// as we may have iterators already running on the array
this._results = this._results.concat(values);
this._onStateChanged.fire();
}
/**
* Calling `resolve()` will mark the result array as complete.
*
* **NOTE** `resolve()` must be called, otherwise all consumers of this iterable will hang indefinitely, similar to a non-resolved promise.
* **NOTE** If `resolve()` or `reject()` have already been called, this method has no effect.
*/
resolve() {
if (this._state !== 0 /* AsyncIterableSourceState.Initial */) {
return;
}
this._state = 1 /* AsyncIterableSourceState.DoneOK */;
this._onStateChanged.fire();
}
/**
* Writing an error will permanently invalidate this iterable.
* The current users will receive an error thrown, as will all future users.
*
* **NOTE** If `resolve()` or `reject()` have already been called, this method has no effect.
*/
reject(error) {
if (this._state !== 0 /* AsyncIterableSourceState.Initial */) {
return;
}
this._state = 2 /* AsyncIterableSourceState.DoneError */;
this._error = error;
this._onStateChanged.fire();
}
}
export class CancelableAsyncIterableObject extends AsyncIterableObject {
_source;
constructor(_source, executor) {
super(executor);
this._source = _source;
}
cancel() {
this._source.cancel();
}
}
export function createCancelableAsyncIterable(callback) {
const source = new CancellationTokenSource();
const innerIterable = callback(source.token);
return new CancelableAsyncIterableObject(source, async (emitter) => {
const subscription = source.token.onCancellationRequested(() => {
subscription.dispose();
source.dispose();
emitter.reject(new CancellationError());
});
try {
for await (const item of innerIterable) {
if (source.token.isCancellationRequested) {
// canceled in the meantime
return;
}
emitter.emitOne(item);
}
subscription.dispose();
source.dispose();
} catch (err) {
subscription.dispose();
source.dispose();
emitter.reject(err);
}
});
}
//#endregion