elephpant on rails

Doctrine\Common\Cache\CacheProvider performance-aware adapter

Sun, 13 May 2012 10:16:00 +0200

In doctrine/common project, with introduction of cache auto-prefix support (called namespaces by Doctrine guys, but it has nothing to do with PHP namespaces), unfortunately there appeared quite serious performance issue. Every single cache call always resulted in 2 additional cache storage calls due to checks for prefix (cache namespace). Quite a big overhead, imagine your memcached instance is called like this. And it just shows that object-oriented programming itself cannot save you from many headaches. Common interface and clean API are just not everything, and it’s soooo easy to get carried away. Anyway, patch has been already provided, but if you’re using older version or you don’t need namespaces support at all, here’s quick workaround.

MySQL: BLOB vs TEXT

Thu, 03 May 2012 12:21:00 +0200

The only difference between the BLOB and TEXT types is that:

BLOB types store binary data with no collation or character set,
TEXT types have a character set and collation,

PHP: Call to undefined method on tr_TR locale

Thu, 19 Apr 2012 23:05:05 +0200

It’s one of weirdest errors in PHP - if not the weirdest - I’ve ever seen. If you set your locale to tr_TR, suddenly some classes or methods names are not available anymore. Really.

Following code:

<?php
setlocale(LC_ALL, 'tr_TR');
class SomeClass {}
$r = new ReflectionClass('SomeClass');
$r->newInstanceArgs(array());

results in Fatal error: Call to undefined method ReflectionClass::newInstanceArgs() error.

After quick research it turned out that it’s actually known bug, yet still not fixed since 2002! See #18556. In short, PHP simply uses internal tolower() function, which is locale-aware, but in Turkish there are some specific rules for I (undotted ı is the lowercase of I, and the dotted İ is the uppercase of i). So if you have class name of method name having upper I (newInstanceArgs, Image, etc), you’re affected.

The only workaround for now seems to be setting LC_CTYPE to some working locale, eg. setlocale(LC_ALL, 'tr_TR'); setlocale(LC_CTYPE, 'en_US');.

Sublime Text 2: sync project side bar with active file

Tue, 31 Jan 2012 23:58:09 +0100

It is simple like adding tiny plugin:

import sublime
import sublime_plugin

class SideBarListener(sublime_plugin.EventListener):
    
    def on_activated(self, view):
        view.window().run_command('reveal_in_side_bar')

Plugin: https://github.com/sobstel/SyncedSideBar.

Actual author: http://www.sublimetext.com/for….#p19213

Internet Explorer under Linux or Mac OS X

Tue, 10 Jan 2012 18:31:00 +0100

Download and install VirtualBox
Download Internet Explorer
- curl -s https://raw.github.com/xdissent/ievms/master/ievms.sh | bash
- or curl -s https://raw.github.com/xdissent/ievms/master/ievms.sh | IEVMS_VERSIONS="9" bash (IE9 only)
- or curl -s https://raw.github.com/xdissent/ievms/master/ievms.sh | IEVMS_VERSIONS="8" bash (IE8 only)
- or curl -s https://raw.github.com/xdissent/ievms/master/ievms.sh | IEVMS_VERSIONS="7" bash (IE7 only)
Adjust RAM settings as it’s only 256MB by default (I’ve used 1GB for each on box with 8GB RAM and 768MB for each on box with 4GB RAM).
Run virtual machine and log in to Windows as Administrator (password: Password1).
Execute slmgr –rearm from terminal (to run terminal just type cmd into start menu input).
Add your hosts to C:\Windows\System32\drivers\etc\hosts file, eg. 10.0.2.2 my-super-site.local (10.0.2.2 is your host’s localhost).
Install VirtualBox guest additions.
Shutdown and make a snapshot, so you can use it as a starting point if the trial period expires (it’s not illegal, even Microsoft themselves tell us to do it this way, which is understandable as it’s all about adjusting our websites to work on their faulty browsers).

Javascript lazy loading with dependencies

Fri, 23 Dec 2011 22:05:58 +0100

Here it is, yet another javascript lazy loader. Sadly, none of existing ones has been solving my problem and I was even using great $script.js for some time, but eventually written new one.

Why?

extremely lightweight (less than 0.5KB gzipped)
lazy (on-demand) loading
support for google.load out of the box
any code (not only loaders) can be executed

Link: https://github.com/sobstel/scru.js.

Sample usage:

// Adding to queue:

$scru.queue('google:jsapi', $scru.fn.async_load('http://www.google.com/jsapi'));
$scru.queue('google:visualization', $scru.fn.google_load('visualization', '1', {packages:['corechart']}), ['google:jsapi']);

// Somewhere in some script (called only when needed)

$scru.execute(drawChart, ['google:visualization']);

All jsapi, visualization js are loaded only when “execute” is called.

Call class method via instance in Ruby

Tue, 15 Nov 2011 18:10:18 +0100

CSS Image

Sun, 13 Nov 2011 20:43:00 +0100

Using Data URI scheme you can embed images directly in HTML or CSS. It can be useful for two things:

To save on requests to image files (images are loaded and cached only in one single request together with CSS file).
To embed images in HTML emails and bypass filters that normally would prevent them from displaying.

You can encode string with Base64.encode64 (Ruby) or base64_encode (PHP).

<?php $image = base64_encode(file_get_contents('image.jpg')); echo '<img src="data:image/png;base64,'.$image.'/>'; ?>

See the output by inspecting source tag for the image.

Codility sample demo test

Tue, 25 Oct 2011 21:13:00 +0200

I have taken Codility sample demo test at last. I was delaying this memorable moment for a few months, probably for fear that it could somehow turn out Im not that good as I think I am, which is surely the case for most developers. So I did the test and I’m going to take more tests there as it’s quite good fun. And here are my solutions for sample demo test below, both in PHP and Ruby.

Devise: find by username OR e-mail

Wed, 28 Sep 2011 23:32:01 +0200

PHP date conversions between timezones

Fri, 09 Sep 2011 18:59:00 +0200

In PHP 5.x line dates are handled properly (thanks to Derick Rethans). Even in PHP 5.3 we have loads of nice date/time improvements.

One of nice things is posibility to convert dates between timezones easily.

DISTINCT vs GROUP BY

Tue, 30 Aug 2011 12:00:00 +0200

Although it may seem so, they do NOT do exactly same thing.

While GROUP BY groups results only by those columns that are explicitly listed after the clause, DISTINCT groups results by ALL columns that are present in SELECT statement (and not only by the one it precedes).

So following queries

SELECT DISTINCT article_id FROM article_authors
SELECT article_id FROM article_authors GROUP BY article_id
return same results,

but

SELECT DISTINCT article_id, author_id FROM article_authors
SELECT article_id FROM article_authors GROUP BY article_id
return different results,

though

SELECT DISTINCT article_id, author_id FROM article_authors
SELECT article_id FROM article_authors GROUP BY article_id, author_id
again return same results.

As a sidenote, with GROUP BY you have HAVING clause by your hand as well.

Avoid temporary table when using MySQL's ORDER BY

Tue, 16 Aug 2011 14:33:00 +0200

If there is an ORDER BY clause and a different GROUP BY clause, or if the ORDER BY or GROUP BY contains columns from tables other than the first table in the join queue, a temporary table is created.

If all columns in ORDER BY and GROUP BY clauses come from the same table, that table is preferred first when joining.

More tips like this in manual’s WHERE Clause Optimization.

MySQL "Using index" in EXPLAIN's extra column

Tue, 09 Aug 2011 00:01:00 +0200

When you see Using Index showing up in Extra column of EXPLAIN output, it means a covering index is used, it is MySQL is able to locate every field for a given table within an index without lookups to table itself.

It’s simply another reason to re-consider using asterisks (*) in SELECT statements.

Simplest example:

mysql> EXPLAIN SELECT * FROM people;
+----+-------------+--------+------+-...-+-------+
| id | select_type | table  | type | ... | Extra |
+----+-------------+--------+------+-...-+-------|
|  1 | SIMPLE      | people | ALL  | ... |       |
+----+-------------+--------+------+-...-|-------+

mysql> EXPLAIN SELECT people_id FROM people;
+----+-------------+--------+-------+-...-+-------------+
| id | select_type | table  | type  | ... | Extra       |
+----+-------------+--------+-------+-...-+-------------|
|  1 | SIMPLE      | people | index | ... | Using index |
+----+-------------+--------+-------+-...-|-------------+

It can be also very handy when using joins, and don’t really need data from one (or more) of joined columns.

For me more stuff like this see Jay Pipes “Target Practice: A Workshop in Tuning MySQL Queries” (OSCON 2007).

Regexp: string followed by and preceded by

Thu, 23 Jun 2011 17:00:00 +0200

Regular expressions are full of features (who can learn it all? or read off and understand a few days after it was written?). One of them is possibility to check if desired match is followed or preceded by given pattern.

It works also in PHP.

JavaScript inspect/dump made easy

Wed, 08 Jun 2011 19:55:51 +0200

Was ever looking for JavaScript equivalent of PHP’s var_dump() or Ruby’s inspect (or p or pp or y or… etc)?

Forget it! You have it by your hand available in Chrome developer tools and Firefox’s firebug. Just type it into console and you get beautifuly browseable dump.

Chrome:

Firefox:

PDO: grouping results to indexed associative array

Tue, 31 May 2011 21:08:15 +0200

Ever wondered how to group database results by first column in PHP? It’s pretty simple with PDO.

PHP: accessing private members of objects of same type

Tue, 17 May 2011 11:14:30 +0200

From PHP manual: Objects of the same type will have access to each others private and protected members even though they are not the same instances.

And example from the manual:

PHP new ternary operator gotcha

Thu, 12 May 2011 20:46:08 +0200

MySQL fast data load

Sun, 08 May 2011 17:00:27 +0200