performance: mt_rand vs openssl_random_pseudo_bytes vs random_bytes vs uniqid vs uuid

test.php

<?php

	define('LOOP_COUNT',100000);
	
	function create_uuid_v4(){
		return sprintf('%04x%04x-%04x-%04x-%04x-%04x%04x%04x',

			// 32 bits for "time_low"
			mt_rand(0, 0xffff), mt_rand(0, 0xffff),

			// 16 bits for "time_mid"
			mt_rand(0, 0xffff),

			// 16 bits for "time_hi_and_version",
			// four most significant bits holds version number 4
			mt_rand(0, 0x0fff) | 0x4000,

			// 16 bits, 8 bits for "clk_seq_hi_res",
			// 8 bits for "clk_seq_low",
			// two most significant bits holds zero and one for variant DCE1.1
			mt_rand(0, 0x3fff) | 0x8000,

			// 48 bits for "node"
			mt_rand(0, 0xffff), mt_rand(0, 0xffff), mt_rand(0, 0xffff)
		);
	}


	$startTime = microtime(true);  

	for($x=0;$x<LOOP_COUNT;$x++)
	{
	    // Your content to test
	    $var1 =mt_rand(1000000000000000,9999999999999999);
	}

	$endTime = microtime(true);  
	$elapsed = $endTime - $startTime;

	echo 'mt_rand in:                         ',$elapsed,"\n";


	$startTime = microtime(true);  

	for($x=0;$x<LOOP_COUNT;$x++)
	{
	    // Your content to test
	    $var2 = bin2hex(openssl_random_pseudo_bytes(16));
	}

	$endTime = microtime(true);  
	$elapsed = $endTime - $startTime;

	echo 'openssl_random_pseudo_bytes(16): in ',$elapsed,"\n";


	$startTime = microtime(true);  

	for($x=0;$x< LOOP_COUNT;$x++)
	{
	    // Your content to test
	    $var3 = bin2hex(random_bytes(16));
	}

	$endTime = microtime(true);  
	$elapsed = $endTime - $startTime;

	echo 'random_bytes(16) in:                ',$elapsed,"\n";


	$startTime = microtime(true);  

	for($x=0;$x< LOOP_COUNT;$x++)
	{
	    // Your content to test
	    $var4 = uniqid('',true);
	}

	$endTime = microtime(true);  
	$elapsed = $endTime - $startTime;

	echo 'uniqid(\'\',true) in:                 ',$elapsed,"\n";

	for($x=0;$x< LOOP_COUNT;$x++)
	{
	    // Your content to test
	    $var5 = create_uuid_v4();
	}

	$endTime = microtime(true);  
	$elapsed = $endTime - $startTime;

	echo 'create_uuid_v4 in:                  ',$elapsed,"\n";

	echo "\n\n";
	echo 'mt_rand: '.$var1."\n";
	echo 'openssl_random_pseudo_bytes: '.$var2."\n";
	echo 'random_bytes: '.$var3."\n";
	echo 'uniqid: '.$var4."\n";
	echo 'create_uuid_v4: '.$var5."\n";
?>