php code like transaction in database? - php

Question

I have certain code that I want to be run by only one user at a time. I don't want to make son complex lock/session relied system, I just wish to delay the users request our to return some message to try again.
The code is actually ssh/powershell connection so I want to isolate it.
It's there any handy way to do that??
I forgot mention it's laravel/php code.

Answer 1

You need to acquire a "lock" of some sort. If there is no lock, no one is accessing anything. If there is a lock, someone is accessing something and the rest should wait. The easiest way is to implement this using files and acquiring an exclusive lock. I'll post an example class (untested) and example usage. You can derive a working example using the sample code that follows:
class MyLockClass
{
protected $fh = null;
protected $file_path = '';
public function __construct($file_path)
{
$this->file_path = $file_path;
}
public function acquire()
{
$handler = $this->getFileHandler();
return flock($handler, LOCK_EX);
}
public function release($close = false)
{
$handler = $this->getFileHandler();
return flock($handler, LOCK_UN);
if($close)
{
fclose($handler);
$this->fh = null;
}
}
protected function acquireLock($handler)
{
return flock($handler, LOCK_EX);
}
protected function getFileHandler()
{
if(is_null($this->fh))
{
$this->fh = fopen($this->file_path, 'c');
if($this->fh === false)
{
throw new \Exception(sprintf("Unable to open the specified file: %s", $this->file_path));
}
}
return $this->fh;
}
}
Usage:
$lock = new MyLockClass('/my/file/path');
try
{
if($lock->acquire())
{
// Do stuff
$lock->release(true);
}
else
{
// Someone is working, either wait or disconnect the user
}
}
catch(\Exception $e)
{
echo "An error occurred!<br />";
echo $e->getMessage();
}