use OperatingSystem\Php\Memory\Memory as PhpMemory;
use Unit\Information\Unit;

$phpMemory = new PhpMemory();

$oldPhpMemoryLimit = ini_get('memory_limit');
ini_set('memory_limit', '128M');

// Get the configured PHP memory limit
$phpMemory->getConfiguredLimit()->format(Unit::MEBIBYTE); // '128MiB'
$phpMemory->getConfiguredLimit()->format(Unit::MEGABYTE); // '134.2MB'

// Get memory allocated by PHP
$phpMemory->getAllocated()->format();
$phpMemory->getAllocatedPeak()->format();

// Get memory used by PHP
$phpMemory->getUsed()->format();
$phpMemory->getUsedPeak()->format();

// Get the difference between configured limit and used memory
$phpMemory->getAvailable()->format();

// Get the difference between allocated memory and used memory
$phpMemory->getUnusedButAllocated()->format();

ini_set('memory_limit', $oldPhpMemoryLimit);