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In-Reply-To: <0DDFDACA-6322-461C-9D57-215E8C7D9CD0@trowski.com>
Date: Thu, 8 Feb 2018 23:54:49 +0800
Cc: PHP Internals <internals@lists.php.net>
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 <0DDFDACA-6322-461C-9D57-215E8C7D9CD0@trowski.com>
To: Aaron Piotrowski <aaron@trowski.com>
Feedback-ID: bizesmtp:lvht.net:qybgforeign:qybgforeign1
Subject: Re: [PHP-DEV] [RFC] Fiber support (again)
From: i@lvht.net (Haitao Lv)



> On Feb 8, 2018, at 12:18, Aaron Piotrowski <aaron@trowski.com> wrote:
>=20
>>=20
>> On Feb 7, 2018, at 7:05 PM, Haitao Lv <i@lvht.net> wrote:
>>=20
>> Hi internals,
>>=20
>> I propose to introduce the Fiber feature AGAIN.
>>=20
>> The main purpose of the RFC is to introducing a lightweight stackful =
coroutine support for PHP and make it possible to write non-blocking =
code in the blocking style.
>>=20
>> In this RFC, no new keyword is needed. So it will not break the PHP =
7.3 release.
>>=20
>> Please see the RFC https://wiki.php.net/rfc/fiber
>>=20
>> Dmitry and I are working on the implementation at =
https://github.com/fiberphp/fiber-ext
>> And a series of usage demo can be found at =
https://github.com/fiberphp/fiber-demo
>>=20
>> Please offer you comments.
>>=20
>> Thank you.
>>=20
>> ---
>> Haitao Lv
>>=20
>=20
>=20
> Hi Haitao,
>=20
> I'm very excited to see this sort of feature coming to PHP.
>=20
> A couple of questions and thoughts:
>=20
> - How do you determine when a fiber has returned? Looking at the =
source, it appears Fiber::status() must be used, comparing against =
constants. Separate methods similar to Generator would be better IMO. =
e.g.: Fiber::alive(), Fiber::suspended(), Fiber::running()

Offering methods like Fiber::alive, Fiber::running makes no difference =
to check the Fiber::status() return value. This is just a style issue. =
And as a language feature,
Fiber only offer the essential API and let other works to the user land.

> - What about throwing exceptions into a fiber?

Currently does not support throw exception into the fiber. User land =
code could check
the value of Fiber::yield and throw exception themselves. The Ruby's =
Fiber and Lua's
coroutine also does not support such api as well.

>=20
> - Using Fiber::resume() to initialize the fiber and resume feels =
awkward. Separate methods again would be better here, perhaps =
Fiber::init(...$args) and Fiber::resume($send).

All Fiber created with a suspended status. So make resume to do both the =
init and resume
do make sense.

Please see Ruby Fiber API https://ruby-doc.org/core-2.2.0/Fiber.html.

>=20
> - What happens if the sub1() function in the RFC is invoked outside of =
a fiber?

You will get a Fatal Error like
Fatal error: Uncaught Error: Cannot call Fiber::yield out of Fiber

> - I think a keyword here would be beneficial, even if it has a minor =
BC impact. Fibers could then be written like generators. `await` or =
`emit` as a keyword perhaps? This would be a less verbose API, feel less =
magical (a static method call that actually pauses execution feels out =
of place), and would allow Fibers to be returned from methods, named =
functions, etc with less boilerplate.

Wishing this to be accepted by the community in the PHP 7.3, so no =
keyword is accepted.
And if the community cannot accept, the Fiber can be still distributed =
as a standalone
extension. So we cannot depend on a new keyword.

> Thanks to you and Dmitry for working on this!
>=20
> Aaron Piotrowski
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