Hey: On Tue, Mar 24, 2015 at 1:54 PM, Pierre Joye <pierre....@gmail.com> wrote: > On Tue, Mar 24, 2015 at 12:35 PM, Xinchen Hui <xinche...@zend.com> wrote: >> Hey: >> >> On Tue, Mar 24, 2015 at 1:31 PM, Pierre Joye <pierre....@gmail.com> wrote: >>> hi! >>> >>> On Tue, Mar 24, 2015 at 5:41 AM, Dmitry Stogov <dmi...@zend.com> wrote: >>>> Hi, >>>> >>>> Recently, Xinchen and me worked on optimization that eliminates useless >>>> reallocations and copying during string concatenation (ZEND_ADD_STRING and >>>> family + ZEND_CONCAT). >>>> >>>> The idea comes from ropes, but adopted especially for our needs. >>>> Rope is popular data structure in languages with immutable strings. >>>> http://en.wikipedia.org/wiki/Rope_%28data_structure%29 >>>> >>>> We don't try to use ropes everywhere in the engine (at least it's too later >>>> for 7.0), only for concatenation. >>>> >>>> The first branch uses ropes only instead of ZEND_ADD_STRING and family. >>>> This must be safe. The only problem is possible memory leaks on exception >>>> (but we already have this problem anyway). The simplest way to understand >>>> the patch - read code for new opcodes in zend_vm_def.h. >>>> >>>> https://github.com/php/php-src/pull/1194/files >>>> >>>> The second branch in addition uses ropes for series of ZEND_CONCAT. It >>>> disables calls to do_operation(ZEND_CONCAT) handler of custom internal >>>> classes. >>>> >>>> https://github.com/php/php-src/pull/1195/files >>>> >>>> Both make slight speed improvement (first +0.3%, second +0.6% on wordpress >>>> home page). >>>> >>>> We don't currently use ability to override CONCAT behavior in internal >>>> classes, and I'm not sure if it may be useful at all. (For example Lua >>>> doesn't provide concat meta-method). May be remove it? >>>> >>>> Thoughts and comments are welcome. >>> >>> Great work! :) >>> >>> Do you expect similar gain for other ops? >>> >>> I wonder if it would not be better to target 7.1 for that, adding it >>> for other string operations, in one go. Most of the current patch is >>> self contained, it adds quite some complexity to the engine for these >>> operations only and it is not a small change at this stage (post >>> features freeze). It sounds like a possible maintenance pain. Taking >> Actually, it's not. >> >> previously we have ADD_STRING/CHAR/VAR and CONCAT >> >> the 2nd branch cleanup these, and now we only deal with one type >> concat_list. :) > > Right, it simplifies part of the existing implementation and add some > complexities to other. It only adds this OP and keep other with the > "old" implementation, that's actually the only part where I am not > totally convinced. It may make sense to do it all at once, if that's > the long term plan, easier to maintain. > > But if we do prefer to add this now, then the sooner the better, it > may have some hard to catch bugs. Now, we have one issue, we cannot > have a RFC (deadline behind us) and this is still a rather big change > :/ from user land. this won't change anything..
and regarding to the object overriden concat..... I doubt it is not used at all :) thanks > > Cheers, > -- > Pierre > > @pierrejoye | http://www.libgd.org -- Xinchen Hui @Laruence http://www.laruence.com/ -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
