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Date: Tue, 12 Feb 2019 16:00:06 +0100
Message-ID: <CAF+90c-q631w16DahA9bZPWyZPtYMaA0yB+vvKLxKi3AApUQDg@mail.gmail.com>
To: PHP internals <internals@lists.php.net>
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Subject: Convert ext/xml to use an object instead of resource
From: nikita.ppv@gmail.com (Nikita Popov)

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Hi internals,

The ext/xml extension currently has GC issues, see
https://bugs.php.net/bug.php?id=76874. The tl;dr is that uses of xml_parser
will usually result in a cyclic structure, but resources do not support
cycle GC. This means that the user is required to take care of breaking GC
cycles manually, which is very unusual for PHP.

I would like to port the xml extension from using a resources towards using
an object, which is fully GC integrated. This is implemented in
https://github.com/php/php-src/pull/3526.

An XmlParser class is used instead of a resource. The class is final and
cannot be manually constructed. It is still used with the normal
xml_parser_* APIs. This is intended as an internal representation change,
not a conversion to OO APIs. The xml_parser_free() method becomes
effectively a no-op and may be deprecated in some future version.

This change is intended for PHP 7.4. While it is technically BC breaking
(in that code that goes out of the way to use is_resource or similar may
break), but we've done a couple of these resource->object migration in
minor versions in the past (ref
https://wiki.php.net/rfc/operator_overloading_gmp and
https://wiki.php.net/rfc/hash-context.as-resource).

Any thoughts?

Regards,
Nikita

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