mirror of
https://github.com/swc-project/swc.git
synced 2024-12-21 04:32:01 +03:00
50 lines
1.6 KiB
TypeScript
50 lines
1.6 KiB
TypeScript
// Loaded from https://deno.land/std@0.81.0/async/pool.ts
|
|
|
|
|
|
// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
|
|
|
|
/**
|
|
* pooledMap transforms values from an (async) iterable into another async
|
|
* iterable. The transforms are done concurrently, with a max concurrency
|
|
* defined by the poolLimit.
|
|
*
|
|
* @param poolLimit The maximum count of items being processed concurrently.
|
|
* @param array The input array for mapping.
|
|
* @param iteratorFn The function to call for every item of the array.
|
|
*/
|
|
export function pooledMap<T, R>(
|
|
poolLimit: number,
|
|
array: Iterable<T> | AsyncIterable<T>,
|
|
iteratorFn: (data: T) => Promise<R>,
|
|
): AsyncIterableIterator<R> {
|
|
// Create the async iterable that is returned from this function.
|
|
const res = new TransformStream<Promise<R>, R>({
|
|
async transform(
|
|
p: Promise<R>,
|
|
controller: TransformStreamDefaultController<R>,
|
|
): Promise<void> {
|
|
controller.enqueue(await p);
|
|
},
|
|
});
|
|
// Start processing items from the iterator
|
|
(async (): Promise<void> => {
|
|
const writer = res.writable.getWriter();
|
|
const executing: Array<Promise<unknown>> = [];
|
|
for await (const item of array) {
|
|
const p = Promise.resolve().then(() => iteratorFn(item));
|
|
writer.write(p);
|
|
const e: Promise<unknown> = p.then(() =>
|
|
executing.splice(executing.indexOf(e), 1)
|
|
);
|
|
executing.push(e);
|
|
if (executing.length >= poolLimit) {
|
|
await Promise.race(executing);
|
|
}
|
|
}
|
|
// Wait until all ongoing events have processed, then close the writer.
|
|
await Promise.all(executing);
|
|
writer.close();
|
|
})();
|
|
return res.readable.getIterator();
|
|
}
|