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Date: Wed, 31 Dec 2014 14:19:09 +0400
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To: Nikita Popov <nikita.ppv@gmail.com>, Xinchen Hui <xinchen.h@zend.com>, 
	PHP Internals <internals@lists.php.net>
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Subject: Merge HashTable and zend_array into a single data structure.
From: dmitry@zend.com (Dmitry Stogov)

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Hi,

Please take a look into the patch

https://github.com/php/php-src/pull/970/files

This real changes are in zend_types.h, the rest is renaming that in most
cases makes code cleaner.

zend_array didn't change its binary representation, but now it's not
possible to get a pointer to embedded HashTable. The same zend_array shoukd
be used instead.

Each HashTable got an extra 64-bit zend_refcounted header. This leads to
some increase in memory consumption.

The performance is slightly increased (may be measured with callgrind).

The patch beaks one test (tests/lang/foreachLoopObjects.006.phpt), but
actually it just disclose a problem that we have anyway.

The patch should be a base for the future optimizations. e.g. removing
HashTable->arData and/or HashTable->arHash and allocating them together
with zend_array; introducing EG(empty_array) etc.

Opinions are welcome...

Thanks. Dmitry.

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