In this post I want to make a short list of different ways to detect errors and bottle necks in our PHP projects. It’s an informal list of recommendations and best practises useful at least for me

Python has a great characteristic. Code blocks are defined with indentation. Not with any especial character like other program languages. That’s means if you don’t want syntax errors and you want to execute your program, your script must be properly indented. That’s is a great practise., even in program languages not as restrictive as python with code indention. For example when I need to check a piece of code with a any kind of error, if it isn’t correctly indented I start to indent it. I know it isn’t necessary but for me at least it helps me to understand the code (if I’m not the original developer of the code) and quickly find errors like wrong if clauses and another things like that.

Analyze code and check syntax

You must use a modern text editor or IDE with at least check syntax and also code analyze tools. That’s mandatory. Chose what you want but use one. Zend Studio is a great tool but you also can do it with another editors, even with vi. You can programing PHP with notepad but it’s definitely a waste of time. You will use significant less time programming with modern IDE. I like Zend Studio code Analyzer. It helps you with errors easy to implement and difficult to find like :

// error 1
if ($a=1) {

// error 2
$variable= 2;
if ($Variable == 2) {
...
}

I like to fix every warning even if those warnings are recommendations and not in fact a problem.

Check indentation level.

Even with a perfect indentation big indentation level is a clear signal of “code smell”. Take care of it. If you see a big indentation level you must ask yourself: Is it really the way to do it?

Loops.

If you want to check performance issues and you don’t have too many time,focus yourself finding loops and analyze them. If there is a performance problem is very probably to discover your problem inside a loop. One slow operation executed one time is a problem. But if this operation is executed 1000 times inside a loop is definitely a big problem. OK it’s the same problem but the impact is 1000 times bigger.

Copy-paste code

Avoid them like a plague. It can be helpfully and attractive but the use of the same piece of code distributed among a set of source code files will give you definitely a headache in the future, Be sure about it. We have a lot techniques in to avoid copy and paste code.

I faced this problem when I was developing a comet server but it can happen with any script that needs too many time. I have done a comet process. This process is very simple. Basically is a PHP script who looks the modification date of a file. When it changes, the script ends but if nothing happens the script ends after 30 seconds and start again (with a JavaScript loop). The script worked perfectly on sandbox. In production also worked (brilliant isn’t it?). But the problem appears when I open other tabs in the browser. The application became slow. Very slow. Every click, even really simple operations turned into unusable operations. I realized this behavior appear only when comet was enabled.

A small skeleton of comet server (the code ):

for ($i=0; $i<10; $i++) {
    if (checkSomething()) {
        echo getData();
        flush();
    }
    sleep(1);
}

The problem was in the authentication. The comet server uses session for authentication. The session are stored as files. The system worked perfectly but I realized I didn’t use session_write_close. That’s means server open session file and frees it when the script ends. Normally script takes one second or less but the comet server may take 20-30 seconds.

auth();
for ($i=0; $i<10; $i++) {
    if (checkSomething()) {
        echo getData();
        flush();
    }
    sleep(1);
}

In this case the solution was easy. The auth process was only in the beginning of the script so I only need to use session_write_close after authentication process. With this simple command the server doesn’t lock user sessions and I can ope as many tabs as I need.

auth();
session_write_close(); // this command is on auth function but I put it here for legibility purposes

for ($i=0; $i<10; $i++) {
    if (checkSomething()) {
        echo getData();
        flush();
    }
    sleep(1);
}

There are other storage to session files instead of filesystem (it’s the default one). In relational database, non-relational database and even in memory with mm

Yes that’s another template engine in PHP. I’ve been using Smarty for years. It’s easy to install and easy to use. But there is something I don’t like in Smarty. I need to learn another language (smarty markup) to create my templates. Normally my templates are not very complex. I only use them to move HTML code outside PHP. Basically my templates are: HTML and some variables that pass from PHP to tpl. Sometimes I need to do a loop. I know Smarty has a lot of helpers but I never use them.

Now I’m in a project and I must to choose a template engine. This project don’t have any dependencies to any other libraries, so I don’t want to include full Smarty library to my simple templates. A quick search in Google gives us a list of template engines in PHP. Mostly all engines use PHP as template language. That’s a good decision. In fact PHP is a template language so, why we need to use another one?. I think the main problem of using PHP as template language is the temptation of put logic in the template and have a nice spaghetti code.

So I am going to build a simple template engine. Let’s start:
As always I like to start from the interface. When I start a library I like to think the library is finished (before start coding. cool isn’t it?) and write the code to use it. Finally when the I like the interface I start coding the library.

I want this template:

<h1>Example of tpl</h1>
var1 = _('var1') ?>
var2 = _('var2') ?>
foreach ($this->_('var3') as $item) {
    echo $this->clean($item);
}
?>

And I want to call it with something like this:

echo Tpl::singleton()->init('demo1.phtml')->render(array(
    'var1' => 1,
    'var2' => 2,
    'var3' => array(1, 2, 3, 4, 5, 6, 7)
    ));

Basically Tpl class will be a container to collect the configuration and init function will be a factory of another class (Tpl_Instance) that will do the templating itself.

render function is the main function. Basically call to php’s include function with the selected tpl.

if (!is_file($_tplFile)) {
    throw new Exception('Template file not found');
}

ini_set('implicit_flush',false);
ob_start();
include ($_tplFile);

$out = ob_get_contents();
ob_end_clean();
ini_set('implicit_flush',true);

return $out;

As we see the tpl file is a simple PHP file included in our script with Tpl_Instance::render. So $this in our tpl’s PHP code is the instance of Tpl_Instance. That means whe can use protected and even private functions of Tpl_Instance.

Now I going to show different usages of the library:

// Sets the path of templates. If nuls asumes file is absolute
Tpl::singleton()->setConf(Tpl::TPL_DIR, realpath(dirname(__FILE__)));
echo Tpl::singleton()->init('demo1.phtml')->render(array(
    'var1' => 1,
    'var2' => 2,
    'var3' => array(1, 2, 3, 4, 5, 6, 7)
    ));

// The same instance a different template and params added in a different way
$tpl = Tpl::singleton()->init('demo2.phtml');
$tpl->addParam('header', 'header');
$tpl->addParam('footer', 'footer');
echo $tpl->render();

// Disable exceptions if we don't assign a variable
Tpl::singleton()->setConf(Tpl::THROW_EXCEPTION_WITH_PARAMS, false);
$tpl = Tpl::singleton()->init('demo1.phtml');
$tpl->addParam('var1', 'aaaa');
$tpl->addParam('var3', array(1, 2, 3, 4, 5, 6, 7));
echo $tpl->render();

// Using factory
$objTpl = Tpl::factory();
$objTpl->setConf(Tpl::THROW_EXCEPTION_WITH_PARAMS, true);
try {
    $tpl = $objTpl->init('demo1.phtml');
    $tpl->addParam('var1', 'aaaa');
    $tpl->addParam('var3', array(1, 2, 3, 4, 5, 6, 7));
    echo $tpl->render();
} catch (Exception $e) {
    echo "" . $e->getMessage() . "

";
}

And like always full source code is available on google code.

One month ago I posted an article called Building a simple HTTP client with PHP. A REST client. In this post I tried to create a simple fluid interface to call REST webservices in PHP. Some days ago I read an article and one light switch on on my mind. I can use curl’s “multi” functions to improve my library and perform simultaneous calls very easily.

I’ve got a project that needs to call to different webservices. Those webservices sometimes are slow (2-3 seconds). If I need to call to, for example, three webservices my script will use the add of every single call’s time. With this improve to the library I will use only the time of the slowest webservice. 2 seconds instead of 2+2+2 seconds. Great.

For the example I’ve created a really complex php script that sleeps x seconds depend on an input param:

sleep((integer) $_REQUEST['sleep']);
echo $_REQUEST['sleep'];

With synchronous calls:

echo Http::connect('localhost', 8082)
    ->doGet('/tests/gam_http/sleep.php', array('sleep' => 3));
echo Http::connect('localhost', 8082)
    ->doPost('/tests/gam_http/sleep.php', array('sleep' => 2));
echo Http::connect('localhost', 8082)
    ->doGet('/tests/gam_http/sleep.php', array('sleep' => 1));

This script takes more or less 6 seconds (3+2+1)

But If I switch it to:

$out = Http::connect('localhost', 8082)
    ->get('/tests/gam_http/sleep.php', array('sleep' => 3))
    ->post('/tests/gam_http/sleep.php', array('sleep' => 2))
    ->get('/tests/gam_http/sleep.php', array('sleep' => 1))
    ->run();
print_r($out);

The script only uses 3 seconds (the slowest process)

I’ve got a project that uses it. But I have a problem. I have webservices in different hosts so I’ve done a bit change to the library:

$out = Http::multiConnect()
    ->add(Http::connect('localhost', 8082)->get('/tests/gam_http/sleep.php', array('sleep' => 3)))
    ->add(Http::connect('localhost', 8082)->post('/tests/gam_http/sleep.php', array('sleep' => 2)))
    ->add(Http::connect('localhost', 8082)->get('/tests/gam_http/sleep.php', array('sleep' => 1)))
    ->run();

With a single connection, the exceptions are easy to implement. If curl_getinfo() returns an error message I throw an exception, but now with a multiple interface how I can do it? I throw an exception if one call fail, or not? I have decided not to use exceptions in multiple interface. I always return an array with all the output of every webservice’s call and if something wrong happens instead of the output I will return an instance of Http_Multiple_Error class. Why I use a class instead of a error message? The answer is easy. If I want to check all the answers I can check if any of them is an instanceof Http_Multiple_Error. Also I don’t want to check anything I put a silentMode() function to switch off all error messages.

$out = Http::multiConnect()
    ->silentMode()
    ->add(Http::connect('localhost', 8082)->get('/tests/gam_http/sleep.php', array('sleep' => 3)))
    ->add(Http::connect('localhost', 8082)->post('/tests/gam_http/sleep.php', array('sleep' => 2)))
    ->add(Http::connect('localhost', 8082)->get('/tests/gam_http/sleep.php', array('sleep' => 1)))
    ->run();

The full code is available on google code but the main function is the following one:

    ...
    private function _run()
    {
        $headers = $this->_headers;
        $curly = $result = array();

        $mh = curl_multi_init();
        foreach ($this->_requests as $id => $reg) {
            $curly[$id] = curl_init();

            $type     = $reg[0];
            $url       = $reg[1];
            $params = $reg[2];

            if(!is_null($this->_user)){
               curl_setopt($curly[$id], CURLOPT_USERPWD, $this->_user.':'.$this->_pass);
            }

            switch ($type) {
                case self::DELETE:
                    curl_setopt($curly[$id], CURLOPT_URL, $url . '?' . http_build_query($params));
                    curl_setopt($curly[$id], CURLOPT_CUSTOMREQUEST, self::DELETE);
                    break;
                case self::POST:
                    curl_setopt($curly[$id], CURLOPT_URL, $url);
                    curl_setopt($curly[$id], CURLOPT_POST, true);
                    curl_setopt($curly[$id], CURLOPT_POSTFIELDS, $params);
                    break;
                case self::GET:
                    curl_setopt($curly[$id], CURLOPT_URL, $url . '?' . http_build_query($params));
                    break;
            }
            curl_setopt($curly[$id], CURLOPT_RETURNTRANSFER, true);
            curl_setopt($curly[$id], CURLOPT_HTTPHEADER, $headers);

            curl_multi_add_handle($mh, $curly[$id]);
        }

        $running = null;
        do {
            curl_multi_exec($mh, $running);
            sleep(0.2);
        } while($running > 0);

        foreach($curly as $id => $c) {
            $status = curl_getinfo($c, CURLINFO_HTTP_CODE);
            switch ($status) {
                case self::HTTP_OK:
                case self::HTTP_CREATED:
                case self::HTTP_ACEPTED:
                    $result[$id] = curl_multi_getcontent($c);
                    break;
                default:
                    if (!$this->_silentMode) {
                        $result[$id] = new Http_Multiple_Error($status, $type, $url, $params);
                    }
            }
            curl_multi_remove_handle($mh, $c);
        }

        curl_multi_close($mh);
        return $result;