DB lock method feature request

[williamhector]

Just as the Illuminate\Database\Connection class has a trait for managing transactions, I think it would be handy to have a trait for managing database locks.
I'm not referring to deadlocks or row/table locks, but the locks available in MySQL using SELECT GET_LOCK('lockName'); and SELECT RELEASE_LOCK('lockName');

We're currently using something like (translated to Laravel DB method names as much as possible) this in our custom connection class:

public function lock($lockName, $primaryCallback, $alreadyLockedCallback = null)
{
	$alreadyLocked = false;
	while(!DB::selectOne('SELECT GET_LOCK( ? , 1) `lock`', [$lockName])->lock){
		$alreadyLocked = true;
		sleep(1);
	}
	try{
		if(!$alreadyLocked){
			$r = $primaryCallback();
		}else if($alreadyLockedCallback){
			$r = $alreadyLockedCallback();
		}
		DB::select('SELECT RELEASE_LOCK( ? )', [$lockName]);
		return $r;
	}catch(\Exception $e){
		DB::select('SELECT RELEASE_LOCK( ? )', [$lockName]);
		throw new \Exception("Error during lock callback. Releasing lock", 0, $e);
	}
}

An example of it being used:

DB::lock("appNameCustomLock", function(){
	DB::update("UPDATE some_table SET some_col = some_val WHERE some_condition;");
});
$newValue = DB::selectOne("SELECT some_col FROM some_table WHERE some_condition;");

It could probably be implemented better than that though, for example with separate methods for getting and releasing locks so that they could be run manually.

I'm guessing the biggest argument against it would be that it wouldn't be used often enough to justify it being in the Laravel framework.

[williamhector]

I just happened across the lock management features in the Cache library.
While some cases may not need to use a cache with their locks and it wasn't the most intuitive place to find locking behaviour, it does make this idea mostly redundant.
Please remove this discussion.