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Date: Sat, 25 Jan 2020 20:44:06 +0000
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Subject: Re: [PHP-DEV] Add viable long running execution model to php 8
From: rowan.collins@gmail.com (Rowan Tommins)

On 25/01/2020 18:51, Robert Hickman wrote:

> Yes that is what I was thinking, for example there is a userspace implementation
> 'Swoole' that works in the following way, ReactPHP is similar although I won't
> include that example as well.


So trying to get concrete: the first "official" component we'd need 
would be an outer event loop, mapping requests and responses to the 
parameter and return values of userland callbacks. In principle, not too 
difficult, although I'm sure there are plenty of devils in the details.


> In my mind right now, everything should be shareable within a single process,
> as one could do in the Swoole example above, nothing stopping you defining a
> global in that script that could cache data in-process.
>
> NodeJS, Python (wsgi) and others work fine using this model and allow sharing
> of data within the same process. Trying to limit it to only some types of things
> would be more complex as each type of thing would end up having a different
> programmatic interface.


I may be wrong, but I think this is where it gets complicated. It's not 
that we'd want to deliberately have different things have different 
behaviour between requests, it's just that we've got a bunch of existing 
stuff built on the assumptions of the current architecture.

In a single-threaded event loop, you want as much as possible to be 
asynchronous, which is why both Swoole and React have a lot of modules 
for things like network requests, file I/O, databases, and general 
asynchronous programming.

Other things just wouldn't exist if PHP hadn't been modelled as shared 
nothing from the beginning. Would set_time_limit() still be global, and 
abort the server after a fixed number of seconds? Or would it configure 
the event loop somehow?

I think there'd need to be at least a roadmap for sorting out those 
questions in the official distribution before it felt like a properly 
supported part of the language.


Regards,

-- 
Rowan Tommins (né Collins)
[IMSoP]