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Date: Tue, 6 Jan 2015 05:21:26 +0100
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Subject: RE: [PHP-DEV] [RFC] Extension Prepend Files
From: francois@tekwire.net (=?UTF-8?Q?Fran=C3=A7ois_Laupretre?=)

> -----Message d'origine-----
> De : php@golemon.com [mailto:php@golemon.com] De la part de Sara =
Golemon
>
> So, I've been meaning to propose something *like* this, but with a few
> key implementation detail differences:
>=20
> 1) Create the notion of "Persistent User =
Functions/Classes/Constants/etc
>=20
> 2) Embedded text sections

First, persistent PHP code or data (NOT reloading code for each request) =
is a huge can of worms. If Sara decides to re-launch the idea, that will =
be great but the subject is probably out of scope here.

IMHO, what we need here is a generic mechanism to embed PHP code in C =
extensions and, then, execute it. It should define a way to embed PHP =
scripts as C strings at compile time, how to make these scripts known =
and accessible from the PHP core, and how to execute them when needed.

Instead of including the runtime code in every extensions, as it is done =
in ext-embed, I would prefer an extension which would provide this =
service to other 'client' extensions. It would define a stream wrapper =
to access the registered PHP scripts. Script registration would be =
registered in persistent memory during MINIT. The registration would =
return an ID for each registered script. These IDs would be stored by =
the client extension and would be used to derive a stream-wrapped path =
when the client decides to execute a registered script. These paths =
would uniquely reference the scripts, which would allow to opcode-cache =
them.

As a specific case, if an extension wants to execute some PHP code at =
the beginning of each request, it can execute its script(s) during =
RINIT, but it is just a use case of a more general mechanism. RINIT =
execution order can be resolved using module dependencies.

Extending the mechanism to userspace 'plain file' scripts could be =
provided by a 'bridge'. The user could register a plain file script, =
whose content would be stored in persistent memory, with a flag that =
would cause the script to be loaded during every RINIT.

One more word about executing scripts during every RINIT : even with =
opcode caches, as Sara notes, the performance hit is not negligible. The =
question is always the same : What is the percentage of requests that =
will really use the classes/functions we define there ? Remember that =
the list of scripts is hardcoded in an extension. If the extension wants =
to allow conditional loading for different features, it needs to define =
appropriate ini settings. Choosing the list of scripts at compile time =
is another option but would make the distribution of precompiled =
binaries complex.

I personally favor another approach. I still use the PHK extension as an =
example of this 'intermediate' approach. This extension defines C-levels =
front-end classes. These classes contain the 'fast' code. When this code =
needs to access 'slow' PHP code, it executes the PHP scripts it needs, =
then calls the just-defined PHP classes.  This way, we preserve the =
possibility to code a big part of the extension in PHP, without the =
overhead of loading the PHP code at the beginning of each request.

Thanks for your attention :)

Fran=C3=A7ois