Sunday, July 25, 2010

EOL for USE=concurrentmodphp

As previously mentioned, concurrentmodphp is currently available as a USE flag for dev-lang/php. It enables you to run two versions of PHP in parallel, loaded into your apache's mod_php.

With the advent of FastCGI/fpm in PHP-5.3.3 (very soon on a mirror near you), the preferred way to run multiple versions of PHP in parallel is CGI. Not only can you run several PHP versions independently, you also get proper script isolation (running each script as a different user, if you wish so) and thus enhanced security.

This is why I've decided to end support for USE=concurrentmodphp after php-5.3.3 and php-5.2.14. Versions after those will simply stop shipping the patches required to support this USE flag. Please use the time with PHP-5.3.3 to switch to fpm, if you need the functionality currently provided by concurrentmodphp.

Friday, July 16, 2010

Using multiple PHP versions

This is another "state of php in gentoo" article. Specifically, I want to talk about using SLOTs with PHP.

The current situation was created during the switch from PHP-4 to PHP-5, one of the biggest and more drastic in terms of features. PHP-5 added a full blown object oriented system, ending PHP's dubious fame as a highly advanced template engine and easing work on large code base projects. Clearly, porting your code from using PHP-4 to 5 was a tremendous effort if you wanted to take advantage of all the new and powerful features PHP-5 offered. So the then gentoo php team decided to make it possible to install PHP-4 and 5 alongside, easing migration testing and extension usage.
What they did was to slot PHP to it's major version. This is why today you're left with dev-lang/php in one slot: "5".

In a meeting on 11th April, the gentoo php team decided to halt decisions on slotting less (i.e. removing slotting) or more (i.e. on minor versions), due to manpower restrictions. This was chiefly due to our desire to get php-5.3.2 into the tree as fast as possible and we needed every minute we could contribute to gentoo at that time to this task.

Now that php-5.3.2 is in the tree and I'm slowly killing the remaining bugs left (helped, and mostly driven, by many friendly contributors, thank you!), we can focus on other areas to improve the overall quality of gentoo's PHP offers.

So slotting became an issue once again.

In an informal meeting, we agreed that removing slotting was the easiest solution, but not the best. While slotting to minor versions increases ebuild complexity and comes with it's own problems (you need a way to select the "active" PHP installation to run for the apache module, for example), the advantages in migration testing and also for shared hosting providers, who want to offer more than one PHP version, trumped the relatively low cost of slotting.

Here's a short pro-contra overview of minor version slotting I came up with:

  • test your code against the most current PHP version on the same machine

  • provide your customers the PHP they want


  • need to remove slots you don't need (or they'll take up hard disk space)

  • increased complexity in configuration

That's pretty short and I'm sure you can come up with more benefits and disadvantages. Do let me know in the comments!

I'm still somewhat disappointed with the lack of "end-user" benefits in this move. If you just want to run that cool webservice your friend has been telling you about, you'll emerge php and will receive slot updates instead of the normal ones thereafter. You regularly want to run emerge --depclean, so you don't keep around PHP slots you no longer need (thanks to darkside for helping me with this one).

Another hurdle will be that we require you to "enable" the PHP version you want via eselect to benefit from the slotting. This affects for what PHP version your PHP extensions like apc or suhosin will get compiled (each minor version has a different ABI, so for each SLOT you need a special build). We're trying to make it so that not "enabling" anything will guess the correct PHP version (probably your highest slot), but that's not sure right now. You will also use eselect to switch from one php apache module to another.

Speaking of apache modules, I've another proposal: currently, Gentoo supports a highly experimental feature called concurrentmodphp. It's a USE flag for dev-lang/php and enables you to run multiple versions of php in the same apache. Usually, this results in a symbol name clash of the php modules you try to load, but with this USE flag enabled, it should work. That said, I never used it, did not test it and upstream will tell you to rebuild without it if you do and run into problems. It's in no way supported neither by Apache or PHP. What is supported is running multiple versions of whatever you like via cgi (fpm, for that matter). So if you want that functionality, you can get it anyway, without causing maintenance problems for the team.

So here's the proposal: I will drop the concurrentmodphp functionality starting in August, if nobody objects with a technical argument on why to keep it. I'd like to hear cases where concurrentmodphp solves a problem fpm can't handle.

Anyway, if you want to help with the slotting efforts, please visit #gentoo-php on freenode, tell us to pull your ideas from your git repository (you can clone your local copy off of our slotting branch) or open bugs explaining why such and such change in said branch won't work, kills kittens or is otherwise undesirable. As always: comments welcome!

Thursday, July 8, 2010

Why you want PHP-5.3.2

In this post, I'm going to spend some bytes telling you why PHP-5.3(.2) is awesome. The goal is to get you wanting to type echo "=dev-lang/php-5.3.2" >> /etc/portage/package.keywords followed by emerge php after reading this.

In my current little survey, 6 out of 7 who have voted so far, said that their code is ready for PHP-5.3. So they probably know about the goodies already and hopefully have already tried Gentoo's all new and shiny php-5.3.2 ebuild or even the php-5.3.3 RCs Ole maintains in our overlay.

For the rest of you, I'll highlight some points of the PHP-5.3 migration list:

Late Static Binding

Here's what the PHP website says: [...] can be used to reference the called class in a context of static inheritance [...] So far, so unclear. But it continues:
[...] static:: will no longer be resolved using the class where the method is defined but it will rather be computed using runtime information.

This is most useful in a class hierarchy, where your (abstract) base class does most of the work, but needs bits of information from the child class. Using static::, you can call back to methods of your child class from the base class without your base class having to know about the particular child class at all! This saves you numerous instanceof tests.

I use this in a MVC-Framework, where a BaseController holds a generic way to generate pagination data and forward it to the view. It also collects cookie and database information to save and restore user's preferences. This forced the cookie and database query methods into the ChildControllers, as the particular cookie or database column name was specified there. With PHP-5.3 I can now access those bits via static:: calls in the base class! No need for code duplication anymore.


If PHP-5.3 had contained no new features but this one, I'd still be happy. Closures are a powerful concept, but as the Late Static Binding above, can take a little bit of time to get into. In short, you can do everything you could do with create_function but instead of hiding all your code in a big string (loosing all the syntax highlighting and error checking of your editor), you now have perfectly valid PHP code inside a function you can declare about anywhere you could use a statement. You can assign your function like so:

$f = function($v) { return $v*$v; }
$f(2); // 4

Or you can use it directly, like so:

$squares = array_map(function($v){ return $v*$v; }, range(1,10));

This even saved me some precious horizontal space compared to array_map(create_function('$v', 'return $v*$v;'), range(1,10));

For additional coolness, you can let the closure use data from the parent scope (the context it is defined in, not the one it is run in), something you could achieve using create_function and embedding the extern variable in the string - it's so ugly I won't repeat it here. But look at the cleanliness of the closure approach (taken from the PHP manual):

$callback =
function ($quantity, $product) use ($tax, &$total)
$pricePerItem = constant(__CLASS__ . "::PRICE_" .
$total += ($pricePerItem * $quantity) * ($tax + 1.0);

array_walk($this->products, $callback);

You definitely want to give closures a try!

Ternary default operator

Folks have lobbied long and hard for this. In short, it's your well-known ternary operator (bool ? if-true : if-false) shortened to return the evaluated ("bool" in my case) statement if you supply nothing for the "if-true" part but "bool" actually evaluated to true. Here's an example:

return 'gentoo is cool' ?: 'who wants to read this, anyway?';

This will return "gentoo is cool", as a non-zero-length string evaluates to true and nothing was given to be return in this case.

New date/time functions

Not much to see here: you can now use date_add(), date_diff() and date_sub() for which I've been waiting for ever since I needed to display dates and calculate expiry times. strtotime() is good for a lot of things, but sometimes you need more.


Some new stuff I still need to test out:

  • The new mysqlnd library now returns correctly typed data instead of strings only for a query result

  • SPL gained a host of basic data structures like Heap, PriorityQueue or Stack
  • Phar archive support is now shipped with PHP

As expected, some things stopped to work in PHP-5.3 - they are documented in the list of Backward Incompatible Changes. The most notable changes for my code were various array functions (like usort) not accepting anything besides arrays anymore and call_user_method() now issuing E_DEPRECATED notices. Also note that the POSIX regular expressions are now deprecated in favor of Perl regexes.

That's it for now, I hope you're on your way to emerge php (if you haven't done so already)!

Saturday, July 3, 2010

PHP-5.3.2 availability in ~arch imminent

So, another status update on PHP... If you're following PHP in Gentoo closely, you might already fear this will turn into a never-ending story. It's been over a year bug #274512, requesting 5.3 to be added, has been filed and we're now three days after the release of PHP-5.3.0. Well, sorry! Real-life has taken a heavy toll with all of the php team members.

Okay, on the bright side, the PHP team has had tremendous support in the last months. Thanks again to Vladimir Tsisaruk and Ole Markus With, who I already mentioned in the last post. They were joined by more awesome tinderbox testing by Diego (flameeyes) - many thanks for the dozen bugs you found and filed! Thanks to Christian Hoffmann for background discussion and insights, too! As well as an uncounted number of users who helped on bugs, you were most helpful.

And now the news: we currently have 60 bugs assigned to the php team, and no more critical bugs left on the PHP-5.3 Tracker. And as promised, I'll push php-5.3.2 out of package.mask accordingly. This is your one-time heads-up that php-5.3.2 will hit your testing system tomorrow, 04.07.2010, around 10.00GMT.

In other news: I touched a few packages today, updating them for PHP-5.3. If I stepped on someone's toes while doing this: I'm sorry if I broke something! If you find a message in your package's Changelog mentioning bug #298205 that means I updated your package to EAPI2 or just updated your {R,}DEPENDs to directly depend on "dev-lang/php" and whatever USE-flags you needed. To get the gory details, just have a look at the linked bug.

So, to sum it up: php-5.3.2 will be available without more work on your part if you're running a testing amd64 or x86 system tomorrow (4.7.2010)! Sorry to the other arches, please help your respective arch-team test the PHP-5.3 awesomeness on bug #321743. It will still have raw edges and some packages still fail to compile with it (have a look at the bugs assigned to to get the full picture), but for the overwhelming part of our tree it works just fine now! Enjoy!

P.S.: I'll start on a post detailing the changes coming your way with PHP-5.3.2 right away...