Arvind Gupta

If you have a website that gets millions of page requests per day each starting a session and you wish to get the last ounce of performance from your server and you’re still using file-based sessions then by all means give this a try. The more volume of dynamic content you’re serving, the more you’ll benefit in terms of load average and site-speed.

One of my website gets about 8 million page views per day almost all needing a session to be started. Using memcached-based sessions helped reduce the load at least 6-folds and sped-up the site considerably.

Since I came to know about it rather late in my career I say it’s one of least known but much simple and effective way to solve performance problems when you have lots of traffic. Remember high-traffic is a must to see any considerable effect.

Use the following code in the bootstrap script of your website:

ini_set('session.save_handler', 'memcache');
ini_set('session.save_path', "MEMCACHE_SOCKET_PATH");

You can also set the above variables in the php.ini file for activating it globally. You must have memcache and memcache PHP extension installed for this to work.

You’ll have to estimate the amount of memory sessions will require and set memcache with a higher value than that. You can check the /tmp directory for the session files and see how much memory is being taken by sess_ files. If you give less memory session data might clear automatically (FIFO by memcached) and users may get logged out etc. depending on what you’re using sessions for.

You can also use redis in place of memcached if you absolutely don’t want the session data to get cleared in any way (other than by the GC).

How does this work? Memory is SO MUCH faster than HDD.

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Created this data validation class a couple of days back for validating some forms. Thought it might be useful for others. This one’s very basic and light-weight but still fully working with many pre-defined rules.

Before listing the class, let me first show how it’s used:

require 'Validator.class.php';

$validator = new Validator();

// Add rules
$validator->addRule('name', array('minlength' => 5, 'maxlength' => 20));
$validator->addRule('age', array('min' => 13, 'max' => 35));
$validator->addRule('url', array('url'));
$validator->addRule('about', array('require'));

// Data to be validated, would normally come from a form
$data = array(
        'name' => 'Arvind Gupta',
        'age' => '80',
        'url' => 'http:www.arvindgupta',
);

// Set data to be validated
$validator->setData($data);

// Check
if ($validator->isValid())
{
    echo '<h1>Data is valid!</h1>';
}
else
{
    echo '<h1>Data is not valid!</h1>';
    echo '<ol>';

    // Get and print errors in a nice manner
    foreach ($validator->getErrors() as $field => $messages)
    {
        if (count($messages) == 1)
        {
            echo "<li><strong>$field</strong>: $messages[0]</li>";
        }
        else
        {
            // If a field has more than one error
            echo "<li><strong>$field</strong>:</li>";
            echo '<ol>';
            foreach ($messages as $message)
            {
                echo "<li>$message</li>";
            }
            echo '</ol>';
        }
    }
    echo '</ol>';
}

Very straightforward!

Validating a form is equally straightforward. The best way would be to have the form elements named like arrays, for example:

<form ...>
	<input type="text" name="form1[text1]" value="" />
	<input type="text" name="form1[text2]" value="" />
</form>

And, use something the following line to provide the form data to the validator at one go:

$validator->setData($_REQUEST['form1']);

That’s it! Here is the class code:

/**
 * Validator
 *
 * Data validation class
 *
 * @author      Arvind Gupta <contact [ AT ] arvindgupta [ DOT ] co [ DOT ] in>
 * @copyright   Arvind Gupta (c) 2011
 * @link        http://www.arvindgupta.co.in
 * @license     You're free to do whatever with this as long as this notice
 *              remains intact.
 */
class Validator
{

    protected $_rules = array();
    protected $_data = array();
    protected $_messages = array();
    protected $_errors = array();

    public function __construct()
    {
        $this->setDefaultMessages();
    }

    /**
     * Add a rule
     *
     * @param string $field	Field name (index of data to be validated)
     * @param array  $rules	Array of rule(s)
     */
    public function addRule($field, array $rules)
    {
        $this->_rules[$field] = $rules;
    }

    /**
     * Set data to be validated
     *
     * @param array $data   Data to be validated
     */
    public function setData(array $data)
    {
        $this->_data = $data;
    }

    /**
     * Set error message for rule
     *
     * @param string $rule	Rule name
     * @param string $message	New message
     */
    public function setMessage($rule, $message)
    {
        $this->_messages[$rule] = $message;
    }

    /**
     * Validates current data with current rules
     *
     * @return boolean
     */
    public function isValid()
    {
        $valid = true;
        foreach ($this->_rules as $field => $rules)
        {
            $value = isset($this->_data[$field]) ? $this->_data[$field] : '';

            foreach ($rules as $rule => $parameter)
            {
                // If rule does not require parameter
                if (is_int($rule))
                {
                    $rule = $parameter;
                    $parameter = null;
                }

                if (!$this->check($value, $rule, $parameter))
                {
                    $valid = false;

                    if (stripos($this->_messages[$rule], '%s') !== false)
                    {
                        $this->_errors[$field][] = sprintf($this->_messages[$rule], $parameter);
                    }
                    else
                    {
                        $this->_errors[$field][] = $this->_messages[$rule];
                    }
                }
            }
        }

        return $valid;
    }

    /**
     * Get error messages if validation fails
     *
     * @return array	Error messages
     */
    public function getErrors()
    {
        return $this->_errors;
    }

    protected function check($value, $rule, $parameter)
    {
        switch ($rule)
        {
            case 'require' :
                return!(trim($value) == '');

            case 'maxlength' :
                return (strlen($value) <= $parameter);

            case 'minlength' :
                return (strlen($value) >= $parameter);

            case 'numeric' :
                return is_numeric($value);

            case 'int' :
                return is_int($value);

            case 'min' :
                return $value > $parameter ? true : false;

            case 'max' :
                return $value < $parameter ? true : false;

            case 'url':
                // Regex taken from symfony
                return preg_match('~^
			      (https?)://                               # protocol
			      (
				([a-z0-9-]+\.)+[a-z]{2,6}               # a domain name
				  |                                     #  or
				\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}      # a IP address
			      )
			      (:[0-9]+)?                                # a port (optional)
			      (/?|/\S+)                                 # a /, nothing or a / with something
			    $~ix', $value);

            case 'email':
                return preg_match('/^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i', $value);

            case 'regex':
                return preg_match($parameter, $value);

            case 'pass':
                return true;

            default :
                return false;
        }
    }

    protected function setDefaultMessages()
    {
        $this->_messages = array(
                'require' => 'Field is required.',
                'maxlength' => 'Too long (%s characters max).',
                'minlength' => 'Too short (%s characters min).',
                'numeric' => 'Value must be numeric.',
                'int' => 'Value must be an integer.',
                'max' => 'Value must be at most %s',
                'min' => 'Value must be at least %s',
                'url' => 'Value must be a valid URL.',
                'email' => 'Value must be a valid email.',
                'regex' => 'Invalid value.',
        );
    }
}

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