synchronization exercise

sync-exercise.mjs

// helpers
const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));
const rand = (max) => Math.floor(Math.random() * max);
const times = (n, cb) => {
    const ret = [];

    for (let i = 0; i < n; i++) {
        ret.push(cb());
    }

    return ret;
};

const fun = async ({ sync }) => {
    while (true) {
        // TODO: implement `syncImpl` such that **all** invocations of `fun`
        //       wait for each other at this call to `sync()` for all the
        //       iterations of the while loop
        await sync();
        await sleep(rand(100));
    }
};

const syncImpl = () => {
    // implement me
};

// invoke `fun` 10 times
times(10, () => fun({ sync: syncImpl() }));