Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:122077
Date: Sun, 31 Dec 2023 11:59:33 +0000
CC: php internals <internals@lists.php.net>
User-Agent: K-9 Mail for Android
In-Reply-To: <CADU7aotEhGSVUXYu_9Uhge-VA_AgUrLUPd7Ud+yq=9khh1bosw@mail.gmail.com>
References: <CADU7aovcatZ++PSg0Pt0-kXJH9Oe09N0jy5uXEoBYoRv6GeUwQ@mail.gmail.com> <5060b986-2e5a-46e4-9c83-763e5b155e83@gmail.com> <CADU7aoutXwr2puZnzMJk+iNfxf-xE-2DKviSTHLK+TR3xpzsQA@mail.gmail.com> <6f7815b9-80cc-4e08-819a-49dca090116f@gmail.com> <CAPzBOBMzL78Fxb+sDTyfCoR0psKzkp8o50+RwQ2Y3Sz+K+7jUQ@mail.gmail.com> <7F63D301-1A46-49AA-9140-F64543E902C5@gmail.com> <8fb6672c-06e9-4f74-b2f2-cd1a265c75a5@app.fastmail.com> <96C28696-7C58-4018-84EB-69CF4189649B@gmail.com> <CADU7aotEhGSVUXYu_9Uhge-VA_AgUrLUPd7Ud+yq=9khh1bosw@mail.gmail.com>
Message-ID: <881CFFCD-220F-4A58-B5B9-C1FFFCE5E278@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain;
 charset=utf-8
Content-Transfer-Encoding: quoted-printable
Subject: Re: [PHP-DEV] RFC proposal: worker mode primitives for SAPIs
From: rowan.collins@gmail.com (Rowan Tommins)

On 31 December 2023 08:31:16 GMT, "K=C3=A9vin Dunglas" <kevin@dunglas=2Efr>=
 wrote:
>This new function is intended for SAPIs=2E Swoole was given as an example=
 of
>worker mode, but it isn't a SAPI=2E AFAIK, it doesn't use the SAPI
>infrastructure provided by PHP=2E
>The scope of my proposal is only to provide a new feature in the SAPI
>infrastructure to build worker modes to handle HTTP requests, not to deal
>with non-SAPI engines=2E

One of the advantages you suggested of your proposal is that users would h=
ave a consistent way to write worker scripts=2E To achieve that, you want a=
 *design* that can be adopted by as many implementations as possible, regar=
dless of how they implement it=2E Providing helper infrastructure for that =
design is a secondary concern - as you admit, the actual code you're propos=
ing to add is quite short=2E


>That being said, I don't understand what would prevent Swoole from
>implementing the proposed API

Then one of us is missing something very fundamental=2E As I understand it=
, Swoole's model is similar to that popularised by node=2Ejs: a single thre=
ad processes multiple incoming requests concurrently, using asynchronous I/=
O=2E For instance, a thread might run the following:

01 Request A received
02 Request A input validated
03 Request A sends async query to DB
04 Request A hands control to event loop while it awaits result
05 Request B received
06 Request B sends async HTTP call to some API
07 Request B awaits result
08 Request A resumed with DB result
09 Request A formats and returns response
10 Request A complete
11 Request B resumed
12 Request B fornats and returns response

Each request has its own call stack, started by a different call to the re=
gistered event handler, but any global state is shared between them - there=
 is no actual threading going on, so no partitioned memory=2E

If requests are communicated by setting up superglobals, that will happen =
at step 01 and again at step 05=2E If you try to read from them at step 09,=
 you would see them populated with information about request B, but you're =
trying to handle request A=2E

It would be possible to work around that by placing large warnings to user=
s not to read superglobals after any async call - basically forcing them to=
 create scoped copies to pass around=2E But the worse problem is output: if=
 step 09 and step 12 both just use "echo", how do you track which output ne=
eds to go to which network connection? You can't just set up an output buff=
er, because that's global state shared by both call stacks=2E You have to p=
ut *something* into the scope of the call stack - a callback to write outpu=
t, an expected return value, etc=2E

Asynchronous code ends up somewhat resembling functional programming: ever=
ything you want to have side effects on needs to be passed around as parame=
ters and return values, because the only thing isolated between requests is=
 local variable scope=2E
=20
Regards,

--=20
Rowan Tommins
[IMSoP]