Memory leak in xcache extension of PHP

I recently encountered memory leak while using the xcache extension (version 1.2) with PHP 5.2.6.

The following code confirms the memory leak:

$data = "data";
xcache_set("key",$data);
while(1) {
$a = xcache_get("key");
echo "Memory Usage :".memory_get_usage()."\n";
}

This seems like a known issue and a worksround is suggested by oli at http://xcache.lighttpd.net/ticket/95 . Simply type-cast the data to a string while using xcache_set. The following works without any memory leak:

$data = "data";
xcache_set("key",(string)$data);
while(1) {
$a = xcache_get("key");
echo "Memory Usage :".memory_get_usage()."\n";
}

Don't know the root cause of this issue but the workaround helped.

Tagging pattern in an element of XML using PHP

Recently I had a requirement to tag a pattern within an element of the provided XML.

Following code worked:
<?php

function replaceElementWithTaggedElement($doc, $element, $pattern, $tagNameForPattern)
{
$newElement = $doc->appendChild(new domelement($element->nodeName));

$content = $element->nodeValue;
while(preg_match($pattern, $content, $matches, PREG_OFFSET_CAPTURE))
{
$match = $matches[0][0];
$offset = $matches[0][1];
$firstPart = substr($content,0,$offset);
$secondPart = substr($content,$offset+strlen($match));
$newElement->appendChild($doc->createTextNode($firstPart));

$taggedElement = $doc->createElement($tagNameForPattern);
$taggedElement->appendChild($doc->createTextNode($match));
$newElement->appendChild($taggedElement);

$content = $secondPart;
}
$newElement->appendChild($doc->createTextNode($content));

$element->parentNode->replaceChild($newElement, $element);
}

$doc = new DOMDocument();
$doc->loadXML("<root><one>This is the first text node</one><two>This is the second text node and the word to be highlighted is second</two></root>");
$oldElement = $doc->getElementsByTagName("two")->item(0);

replaceElementWithTaggedElement($doc, $oldElement, "/second/", "tagged");

echo $doc->saveXML();
?>

OUTPUT

<?xml version="1.0"?>
<root><one>This is the first text node</one><two>This is the <tagged>second</tagged> text node and the word to be highlighted is <tagged>second</tagged></two></root>

Gearman Client and Worker with PHP

To write the Gearman client or worker in PHP there are 2 options available:

1) Net_Gearman pear package: http://pear.php.net/package/Net_Gearman/download/0.1.1
2) Gearman PHP Extension: http://www.gearman.org/doku.php?id=download

As per my experiments, Net_Gearman does not processes all requests when multiple (more than 5) simultaneous clients are sending requests.

The PHP extension available on gearman.org is better and initial tests are encouraging.

I encourage using the Gearman server and library available on gearman.org as well.

Keyword Suggestor in PHP 5

To add a feature like Google's Did You Mean in your PHP application a reasonable solution is to use PHP's pspell library.

This comes bundled with PHP (http://php.net/pspell). Compile PHP with the '--with-pspell' option but before this ensure that you have aspell (version 0.6 or above) already installed.

Custom dictionary can also be created for aspell but this will require the aspell-lang package. You can download the same from here.

Details on how to create your custom dictionary are available here under the 'Creating a Custom Language Dictionary' section.

Profiling PHP code with xdebug

Using xdebug to profile php code is very simple.

Following are the steps to get started:

1) Install the xdebug extension (http://xdebug.org/docs/install) for PHP.
2) Enable profiling for any PHP which gets executed by setting xdebug.profiler_enable=1 in php.ini
3) Restart the Apache Server

From now on, whenever you execute a PHP, files with name starting from cachegrind.out will be created under the /tmp directory.

4) Install kcachegrind (http://kcachegrind.sourceforge.net/)
5) start kcachegrind with the cachegrind.out file as the parameter (eg. kcachegrind cachegrind.out.12345)
6) Set xdebug.profiler_enable=0 in php.ini to disable profiling.

Compiling PHP with PDO-mysql

To install pdo-mysql with PHP, following are the steps:

1) configure PHP with '--enable-pdo=shared --with-pdo-mysql=shared' options.
2) compile and install PHP (make, make install)
3) Add 'extension = pdo.so' and 'extension = pdo_mysql.so' in the php.ini after pointing the extension_dir variable to the appropriate location where these 'so' reside. (eg. extension_dir = /usr/local/php/lib/php/extensions/no-debug-non-zts-20060613)

Removing all non-ASCII characters from a string using php

ASCII characters have hex code from 00 to 7F (http://www.asciitable.com/).

Following php function removes all non-ASCII characters from a string:

function removeNonAscii($string) {
return preg_replace('/[^\x00-\x7f]/','',$string);
}