Remove "count" from the Queue interface

[rybakit]

Options:

1. Remove count() method from queues

2. Leave count() and add Countable interface:

class InMemoryQueue implements Queue, \Countable
{
    ...

    public function count()
    {
        ...
    }
}

3. Put count() into separate interface:

interface AdvancedQueue extends Queue, \Countable
{
    public function slice($offset, $limit);
}

[auro1]

... why?

[rybakit]

There are several reasons that come to mind:

• I don't have a use case where I need count() to be in the Queue interface;
• Removing it will simplify decorating a queue;
• Some backends don't support count either.

Do you use Queue::count()? If so, could you please describe your use case?

[auro1]

Yes - scaling workers.

If the queue size > (current workers * 10) = scale up If the queue size < (current workers) = scale down

[rybakit]

Will the option 2) work for you? Roughly speaking, to scale workers all you need to know is the queue size, so \Countable should be enough:

// WorkerManager

public function maybeScale(\Countable $pool)
{
    $count = count($pool);
    if ($count > $numberOfWorkers * 10) {
        // create more workers
    } else if ($count < $numberOfWorkers) {
       // destroy workers
    }
}

And your workers will process the Queue instances:

// Worker

public function process(Queue $queue)
{
    $item = $queue->pop();
    // process the item
}

[auro1]

Yes that would work. :-)