php: beacon algorithm

beacon.php

<?php
$error_break = 2;
$error_array = array();

$beacon_set_list = getBeacons(true);
// reset errors
foreach($beacon_set_list as $beacon)
	$error_array[$beacon] = 0;

echo "Initial Beacon list:\n";
print_r($beacon_set_list);
echo "-------------------\n";
do
{
	$beacon_get_list = getBeacons();
	echo "Loop Beacon list:\n";
	print_r($beacon_get_list);

	if(count($beacon_set_list)!==count($beacon_get_list))
	{
		$error_list = array();
		foreach($beacon_set_list as $beacon)
		{
			if(!in_array($beacon, $beacon_get_list))
			{
				$error_array[$beacon]++;
				if($error_array[$beacon]===$error_break)
					$error_list[] = $beacon;
			}
			else
				$error_array[$beacon] = 0;
		}
		if(count($error_list)>0)
		{
			echo "ERROR!\n";
			print_r($error_list);
			exit();
		}
	}
	else
	{
		foreach($beacon_set_list as $beacon)
			$error_array[$beacon] = 0;
	}
	sleep(1);
}
while(true);

function getBeacons($flag = false)
{
	$array = array
	(
		'e0:97:ff:6a:4a:a9',
		'd1:09:ee:7f:5b:b0'
	);
	$r = rand(0,2);
	if($flag || $r===0)
		return $array;
	else
		return array($array[$r-1]);
}

output

Initial Beacon list:
Array
(
    [0] => e0:97:ff:6a:4a:a9
    [1] => d1:09:ee:7f:5b:b0
)
-------------------
Loop Beacon list:
Array
(
    [0] => e0:97:ff:6a:4a:a9
    [1] => d1:09:ee:7f:5b:b0
)
Loop Beacon list:
Array
(
    [0] => d1:09:ee:7f:5b:b0
)
Loop Beacon list:
Array
(
    [0] => e0:97:ff:6a:4a:a9
    [1] => d1:09:ee:7f:5b:b0
)
Loop Beacon list:
Array
(
    [0] => e0:97:ff:6a:4a:a9
    [1] => d1:09:ee:7f:5b:b0
)
Loop Beacon list:
Array
(
    [0] => e0:97:ff:6a:4a:a9
    [1] => d1:09:ee:7f:5b:b0
)
Loop Beacon list:
Array
(
    [0] => e0:97:ff:6a:4a:a9
    [1] => d1:09:ee:7f:5b:b0
)
Loop Beacon list:
Array
(
    [0] => d1:09:ee:7f:5b:b0
)
Loop Beacon list:
Array
(
    [0] => e0:97:ff:6a:4a:a9
    [1] => d1:09:ee:7f:5b:b0
)
Loop Beacon list:
Array
(
    [0] => e0:97:ff:6a:4a:a9
    [1] => d1:09:ee:7f:5b:b0
)
Loop Beacon list:
Array
(
    [0] => e0:97:ff:6a:4a:a9
)
Loop Beacon list:
Array
(
    [0] => e0:97:ff:6a:4a:a9
    [1] => d1:09:ee:7f:5b:b0
)
Loop Beacon list:
Array
(
    [0] => e0:97:ff:6a:4a:a9
)
Loop Beacon list:
Array
(
    [0] => e0:97:ff:6a:4a:a9
)
ERROR!
Array
(
    [0] => d1:09:ee:7f:5b:b0
)