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/**

 * Run `mapper` over `items` with at most `limit` concurrent in-flight

 * calls, preserving input order in the result. The git subprocess calls

 * this feeds are I/O-bound (fork+exec, not CPU), so running them

 * concurrently instead of one-at-a-time cuts wall-clock time roughly

 * proportional to `limit` on a multi-core machine.

 */

export const mapPool = async (items, limit, mapper) => {

  const results = new Array(items.length);

  let next = 0;

  const workers = Array.from({ length: Math.min(limit, items.length) }, async () => {

    while (next < items.length) {

      const i = next++;

      results[i] = await mapper(items[i], i);

    }

  });

  await Promise.all(workers);

  return results;

};