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Date: Sat, 7 Apr 2012 07:59:09 -0400
To: Luke Scott <luke@cywh.com>
Subject: Re: [PHP-DEV] Persistent zvals
From: tom@punkave.com (Tom Boutell)

Indeed phpdaemon.net appears to cover this ground, although your idea might d=
eliver higher performance.

Sent from my iPhone

On Apr 6, 2012, at 7:46 PM, Luke Scott <luke@cywh.com> wrote:

> I've spent the last few days pouring over the Zend engine source code. I
> think I have a basic understanding on the memory management. Likely what I=

> say may be incorrect, so I apologize in advance.
>=20
> What I'm trying to do is write an extension to persist PHP variables past
> the end of the request in the SAPI to be used on the next request (differe=
nt
> user, same process). I'd like to do this without serialization. The reason=

> is certain objects in PHP (in a framework, for example) are not request
> specific and it would be useful to have these objects already loaded and
> usable without having to construct them on every request. (Sample use case=
:
> Dependency injection like Guice without having to write physical container=
s
> - using reflection, written in PHP)
>=20
> =46rom what I've gathered thus far, it is impossible to do without copying=
 the
> non-persistent memory into persistent memory, and then back again. I'm
> assuming this is because all the memory associated with PHP variables use
> emalloc, which places it onto a stack that is disposed of at the end of th=
e
> request.
>=20
> So there seems to only be two ways to do this:
>=20
> 1 - Copy non-persistent memory into persistent memory (and back) using a
> deep copy. Probably not very efficient. May not be much better than
> serialization.
>=20
> 2 - Modify the Zend engine to flag objects/zvals as persistent so they
> aren=C2=B9t thrown away until the process ends.
>=20
> #2 seems to be the better way to go. #1 seems to be the only way to do it a=
s
> an extension (maintaining its own stack).
>=20
> There seems to have been some discussion (7 years ago) of this mentioned
> here under 6.9:
>=20
> http://www.php.net/~derick/meeting-notes.html
>=20
> I've been able to do it somewhat with string zvals, but objects are a
> different story (given that a zval contains a handle index referring an
> entry in a bucket). The "goal", at least with objects, is the objects
> doesn't destruct until the end of the process. With copying memory it look=
s
> like I'd probably have to copy the object into my own bucket, modify the
> original in zend's bucket so the destructor isn't called (destructor_calll=
ed
> =3D 1), and then at the start of the request copy what's in my bucket into=

> zend's bucket.
>=20
> At this point I feel light a mad scientist. I'm hoping to gain some insigh=
t
> on how this might be done properly with PHP 5.3/5.4 (or just 5.4) - even i=
f
> it involves modifying the Zend engine. Have you guys had any recent
> discussions about doing this?
>=20
> Luke
>=20
>=20
>=20