Use shared memory instead of the filesystem

[paragonie-scott]

airship/src/bootstrap.php

Lines 45 to 70 in cf2fc68

	if (!\ISCLI) {
	$cabinFile = \implode(DIRECTORY_SEPARATOR, [
	ROOT,
	'tmp',
	'cabin.' . $active['name'] . '.offline.txt'
	]);
	if (\file_exists($cabinFile)) {
	// There might be an automatic update in progress!
	// Let's give it up to 15 seconds, but only as much time as is needed.
	$iter = 0;
	do {
	if (!\file_exists($cabinFile)) {
	break;
	}
	\usleep(100);
	++$iter;
	} while($iter < 15000);
	\clearstatcache();
	// If we're still in the middle of that process, let's not load anything else:
	if (\file_exists($cabinFile)) {
	echo \__('This Airship is currently docked for routine maintenance. Please try again later.'), "\n";
	exit(255);
	}
	}
	}

[paragonie-scott]

After a bit of poking around, I've discovered the only sane solution right now is APCu. So, we're going with that.