Re: Merge HashTable and zend_array into a single data structure.

On Wed, Dec 31, 2014 at 11:19 AM, Dmitry Stogov <dmitry@zend.com> wrote: > 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. > In your patch zend_hash_init (and zend_hash_destroy as well) ignores the refcounted header. So currently you wouldn't be able to use just any HashTable* in a refcounted way (e.g. do an object->array cast by adding a ref to the properties HT and sticking it in a zval). You can only do the reverse, i.e. use a no longer used refcounted array somewhere else (like the way properties are assigned in pdo/... now). What's the plan about this? Is this intentional or will the hash API start managing the refcount as well (like strings already do)? > 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. > Could you elaborate on the first part? How is it possible to alloc arData/arHash together with zend_array? (Or rather, if you do that, how can you change the size later?) Nikita