@ezdevlol/memfs/lib/thingies/concurrency.js

In-memory file-system with Node's fs API.

import { go } from './go';
class Task {
    code;
    resolve;
    reject;
    promise = new Promise((resolve, reject) => {
        this.resolve = resolve;
        this.reject = reject;
    });
    constructor(code) {
        this.code = code;
    }
}
/** Limits concurrency of async code. */
export const concurrency = (limit) => {
    let workers = 0;
    const queue = new Set();
    const work = async () => {
        const task = queue.values().next().value;
        if (task)
            queue.delete(task);
        else
            return;
        workers++;
        try {
            task.resolve(await task.code());
        }
        catch (error) {
            task.reject(error);
        }
        finally {
            workers--, queue.size && go(work);
        }
    };
    return async (code) => {
        const task = new Task(code);
        queue.add(task);
        return workers < limit && go(work), task.promise;
    };
};