Question

I am basically getting data from various APIs and using PHP to put them together – like a web mashup. I am currently using 4 foreeach statements to insert the gathered data into their individual arrays. I believe that the current code is inefficient because it takes probably around 3 seconds to load the page which is displaying the PHP data. In the past I had just one big foreach loop to go through all the data at once and also print them. But that too felt inefficient to me.

So how can I make my code more efficient in term of it processing faster? I have seen a few mashup websites such as Soundeer which load around a second. Is that becuase of their code efficiency?

The code which I am using is:

$echonest_uri = simplexml_load_file("http://developer.echonest.com/api/v4/artist/search?api_key=$APIkey&style=rap&results=10&start=$element_num&bucket=id:deezer&bucket=images&sort=familiarity-desc&format=xml");

//Swap the comments for when in UWE or not
//$echonest_xml =  new SimpleXMLElement($echonest_uri);
$echonest_xml = $echonest_uri;

$artist_name = array();
$artist_image = array();
$echonest_id = array();
$full_deezer_id = array();
$deezer_id = array();
$num_of_albums = array();

//Loop through each entries in the id_arr and make each image of the artist a link to the album page passing all the relevant information. 
foreach($echonest_xml->artists->artist as $artist){
    $artist_name[] = $artist->name;
    $artist_image[] = $artist->images->image[0]->url;
    $echonest_id[] = $artist->id;
    $full_deezer_id[] = $artist->foreign_ids->foreign_id->foreign_id;
}

foreach($full_deezer_id as $key => $value){
    preg_match('#deezer:artist:([A-Z,a-z,0-9]+)#', $value, $id);
    $deezer_id[] = (string)$id[1];
}

foreach($deezer_id as $id_index => $id){
    $deezer_xml = simplexml_load_file("http://api.deezer.com/2.0/artist/$id/albums&output=xml");
    $num_of_albums[] = $deezer_xml->total;
}

//The variable which will contain the HTML code to display the artists.
$output = null;


foreach($deezer_id as $key => $value){

    $fav_count_query = "SELECT COUNT(user_index) FROM fav_artist WHERE artist_deezer_id = '$value'";
    $fav_count_resource = $mysqli->query($fav_count_query);
    $fav_count = $fav_count_resource->fetch_assoc(); 

    $output .=  <<<HERE
                <div class="artist-container">
                    <a href="albums.php?echonest_id={$echonest_id[$key]}&deezer_id={$deezer_id[$key]}&artist_name={$artist_name[$key]}&artist_image={$artist_image[$key]}&num_of_albums={$num_of_albums[$key]}" class="artist-image">
                        <img src="{$artist_image[$key]}" alt="{$artist_name[$key]}" title="{$artist_name[$key]}"/>
                    </a>

                    <a href="albums.php?echonest_id={$echonest_id[$key]}&deezer_id={$deezer_id[$key]}&artist_name={$artist_name[$key]}&artist_image={$artist_image[$key]}&num_of_albums={$num_of_albums[$key]}" class="artist-name">
                        {$artist_name[$key]}
                    </a>
                    <a href="albums.php?echonest_id={$echonest_id[$key]}&deezer_id={$deezer_id[$key]}&artist_name={$artist_name[$key]}&artist_image={$artist_image[$key]}" class="album-number">Albums: 
                        {$num_of_albums[$key]}
                    </a>
                </div>
HERE;

}

Answer 1

Your code most likely isn’t slow because of multiple foreach loops (honestly, you wouldn’t feel the difference in a realistic scenario). What’s hurting you here is downloading something from an external site.

My solution would be to download this automatically every 5th minute (either via a cronjob, or just when the user accesses the page), and if it’s less than 5 minutes ago, then show a cached version placed on the server.

That said, this seems to be a search, so the results most likely wouldn’t change a lot. Maybe have a 1 day cache instead? (It would still take 3 seconds per new search query, but if you expect many users to make the same query, then this will make your site seem a lot quicker).

An easy way of testing where in your code it is that something goes wrong timewise is using the microtime function. What I usually do is something like this:

$beforeCall = microtime(true);
$echonest_uri = simplexml_load_file("http://developer.echonest.com/api/v4/artist/search?api_key=$APIkey&style=rap&results=10&start=$element_num&bucket=id:deezer&bucket=images&sort=familiarity-desc&format=xml");
echo "The call took " . number_format(microtime(true) - $beforeCall, 4) . " seconds";

If you’re using XML (which is seems like) you can use SimplePie with cache enabled. A good article for this is SimplePie’s own article on their cache system where you can adjust the cache duration with set_cache_duration.