Add a warning about the non-guaranteed order

[gajus]

The way that simple mutex is implemented means that there is no guarantee of the order, i.e.,

const say = async (word: string) => {
  const release = await lock(redis, 'say');
  console.log(word);
  await release();
}

Promise.all([
  say('a'),
  say('b'),
  say('c')
]);

There is no guarantee that the output of this will be a, b c

[AmrSaber]

You are absolutely correct. As is the case with mutexes in general, this package does not guarantee the order.

I understand your example, but maybe a more complete example would be...

const key = 'some-key';

async function say (word: string) {
  const release = await lock(redis, key);
  console.log(word);
  await release();
}

// Acquire the lock
const release = await lock(redis, key);

// Start several tasks that need the lock
const promises = [say('a'), say('b'), say('c')];

// Release the lock
await release();

// Wait for all tasks to finish
await Promise.all(promises);

In this case all of created promises will initially wait, and there is no guarantee that a will be printed before b. The output could be any permutation of a, b, and c.

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That said, thank you for pointing out that this can be added the readme. I will add a notice and reference this ticket.