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php

unload/reload classes?

php.internals

Rasmus Schultz

7 years ago

Hello internals,

How hard would be to add an unload (or reload) feature for
classes/interfaces?

I'm wondering with regards to running PHP as a deamon (with Swoole or
ReactPHP, etc.) could it be made possible to hot-reload e.g. for
controllers and view-models?

Of course, the other option is to launch worker sub-processes under some
sort of host process, and then restart the workers after a change - this
adds communication overhead between the host/worker processes though, and a
layer of complexity.

Another option is if a reverse proxy (NGINX maybe) could restart the actual
application daemon, but that means you have a dependency on a specific
reverse proxy.

So I know there are other options, but I'm looking for the simplest and
cleanest way to do this, and I'd prefer to stay within the language.

Other dynamic languages (where daemonizing is "normal", like Ruby, JS and
Python) have this feature and it is often used to hot-reload
controllers/views in web-apps.

Any thoughts?

Robert Hickman

7 years ago

(I'm not a internals developer, but here are some ideas:)

1: I have seen an extension which allows functions/classes to be
redefined, although I can't remember what it is called.

2: It is possible to dynamically reload code if defined as anonymous
classes or functions using return include:

<file_1.php>
<?php
return class {
function some_function($a, $b) {
return $a + $b;
}
};

<file_2.php>
$class = include "file_1.php";
$class->some_function(1,2);

----------------

This would entail creating a custom namespace system, and a facility
to watch and re-include files. I don't know if the old bytecode of
'orphaned' objects would be garbage collected.

3: Another option would be to create a watcher on the files and just
kill and reload the php process on file changes. This would be easier
if the application state is all stored externally.

4: Use Ruby/JS/Python instead?





On Mon, 18 Mar 2019 at 20:16, Rasmus Schultz <rasmus@mindplay.dk> wrote:

Ben Ramsey

7 years ago

> On Mar 18, 2019, at 18:45, Robert Hickman <robehickman@gmail.com> wrote:
>
> 1: I have seen an extension which allows functions/classes to be
> redefined, although I can't remember what it is called.

Maybe you’re thinking of the runkit extension? https://secure.php.net/manual/en/book.runkit.php

Cheers,
Ben

Robert Hickman

7 years ago

On Tue, 19 Mar 2019 at 00:55, Ben Ramsey <ben@benramsey.com> wrote:

>
>
> On Mar 18, 2019, at 18:45, Robert Hickman <robehickman@gmail.com> wrote:
>
>
> 1: I have seen an extension which allows functions/classes to be
> redefined, although I can't remember what it is called.
>
>
>
> Maybe you’re thinking of the runkit extension? https://secure.php.net/manual/en/book.runkit.php
>
> Cheers,
> Ben

Yes that's what I was thinking of. Looking at it there is
'runkit_function_redefine' but no
'runkit_class_redefine', only facility to redefine individual methods
of an existing class. Thus
not matching Rasmus Schultz request. The sandboxing facility of runkit
may make dynamic
reload possible, if a new sandbox were created when reload was
desired. That's just me
reading the API docs though, I haven't tried it.

Christoph Becker

7 years ago

On 19.03.2019 at 11:30, Robert Hickman wrote:

> On Tue, 19 Mar 2019 at 00:55, Ben Ramsey <ben@benramsey.com> wrote:
>
>> On Mar 18, 2019, at 18:45, Robert Hickman <robehickman@gmail.com> wrote:
>>
>> 1: I have seen an extension which allows functions/classes to be
>> redefined, although I can't remember what it is called.
>>
>> Maybe you’re thinking of the runkit extension? https://secure.php..net/manual/en/book.runkit.php
>
> Yes that's what I was thinking of. Looking at it there is
> 'runkit_function_redefine' but no
> 'runkit_class_redefine', only facility to redefine individual methods
> of an existing class. Thus
> not matching Rasmus Schultz request. The sandboxing facility of runkit
> may make dynamic
> reload possible, if a new sandbox were created when reload was
> desired. That's just me
> reading the API docs though, I haven't tried it.

There is runkit_import(), which will overwrite existing class
definitions.  However, runkit is still not compatible with PHP 7 to my
knowledge.  Don't know whether runkit7[1] supports it.

[1] <https://github.com/TysonAndre/runkit7>

--
Christoph M. Becker