Map of email threads - Test

<?php


/**
 * Generate Array of threads 7000
 */
function makeThreads()
{
    for($i=1000; $i<=8000; $i++)
    {
        yield array(
            $i*10+1,
            $i*10+2,
            $i*10+3,
            $i*10+4,
            $i*10+5,
        );
    }
};
$threads = iterator_to_array(makeThreads());

/**
 * Generate list of 35000 Emails
 */
function makeEmails()
{
    for($i=1000; $i<=8000; $i++)
    {
        for($e=1; $e<=5; $e++)
        {
            $email = new stdClass;
            $email->subject = 'Cloud Storage Dump';
            $email->to = 'jondoe@domain.com';
            $email->msgno = $i*10+$e;
            yield $email;
        }
    }
};
$emails = iterator_to_array(makeEmails());

$then  = microtime();
$thenM = memory_get_peak_usage();



/**
 * TEST: 3 x foreach()
 *
 * Takes: 2,8 s
 * Memory: 5,2 MB
 */

/*
// root is the array index position of the threads message, such as 5 or 10
foreach($threads as $root => $message){

    // id is the id being given to us from `imap_thread`
    foreach($message as $key => $id){

      foreach($emails as $index => $email){

         if($id === $email->msgno){
             $threads[$root][$key] = $email;
             break;
          }
      }
    }
}
*/


/**
 * TEST: PHP 5.3/5.4 way
 *
 * Takes: 0.061 s
 * Memory: 2.7 MB
 */

/*
// Create map of key-threads
$keys = array();
foreach($emails as $k => $email)
{
    $keys[$email->msgno] = $k;
}

// Iterate threads
$threads = array_map(function($thread) use($emails, $keys)
{
    // Iterate emails in these threads
    return array_map(function($msgno) use($emails, $keys)
    {
        // Swap the msgno with the email details
        return $emails[$keys[$msgno]];

    }, $thread);

}, $threads);
*/


/**
 * TEST: PHP 5.5 way
 *
 * Takes: 0.036 s
 * Memory: 2.7 MB
 */


// Create map of key-threads
function genetateKeyMap($emails)
{
    foreach($emails as $k => $email)
    {
        yield $email->msgno => $k;
    }
};
$keys = iterator_to_array(genetateKeyMap($emails));


// Assign email details to thread map
function updateThreads($emails, $threads, $keys)
{
    foreach($threads as $thread)
    {
        $array = array();
        foreach($thread as $msgno)
        {
            $array[] = $emails[$keys[$msgno]];
        }
        yield $array;
    }
};
$threads = iterator_to_array(updateThreads($emails, $threads, $keys));




/**
 * Profile
 */

$memoryTaken = memory_get_peak_usage() - $thenM;

echo 'Took: '. (microtime() - $then) .' miliseconds';
echo '<br>';
echo 'Memory used: '. number_format($memoryTaken/1024/1024, 1) .' MB';

echo '<br>';
echo '<br><hr><br /><pre>'. print_r($threads[0], true). '</pre>';
echo '<br><hr><br /><pre>'. print_r($threads[8000], true). '</pre>';