/**
* Limit the number of concurrent executions of an async mapping function.
*
* @param items - The array of items to process.
* @param limit - The maximum number of concurrent executions.
* @param fn - The async function to execute for each item.
* @returns A promise that resolves to an array of results.
*/
export async function limitConcurrency<T, R>(
items: T[],
limit: number,
fn: (item: T) => Promise<R>
): Promise<R[]> {
const results: Promise<R>[] = [];
const executing = new Set<Promise<void>>();
for (const item of items) {
const p = fn(item);
results.push(p);
const e: Promise<void> = p.then(
() => { executing.delete(e); },
() => { executing.delete(e); }
);
executing.add(e);
if (executing.size >= limit) {
await Promise.race(executing);
}
}
return Promise.all(results);
}
