Question

I have a php class that connects to certain devices via ssh.
I would like to add logic to control the number of connections, per device.
This is what my class constructor looks like:

public function __construct($hostname, $password, $username = "", $timeout = 10) 
    {
        set_include_path(get_include_path() . PATH_SEPARATOR . '/var/www/phpseclib');
        include_once('Net/SSH2.php');
        $this->_hostname = $hostname;
        $this->_password = $password;
        $this->_username = $username;

    } // __construct

I’ve read some other posts like : How to save a variable at application level in php?

and I guess I just want to confirm the following:

1. I think database would be better than file because of scenarios where multiple sessions are trying to write / update the class counter.
2. the class contructor and destructors are the best / only place to add this type of logic.

The only thing is that currently, I don’t have a database associated with my app – so I hate to add this “dependency” but it does seem like the best way to go. If you have any comments / suggestions, please let me know.

Thanks.

EDIT 1:

One additional question that comes up with adding the logic in my constructor is the following…
Assuming I have the following logic (pseudocode)

  public function __construct($hostname) 
  {
     if (!  ok_to_connect($hostname)  )
     {
         exit;
     }
  }

  public function ok_to_connect($hostname)
  {
    $filelist = glob($counterslocation.$hostname.'*.tmp');

    if ( count($filelist)  < 4) {
        $handle = fopen($counterslocation.$hostname.rand(1,4).".tmp", "r");
        return true;
    }       
    else {
        return false;
    }
   }

In the case where i already have 4 active connections, wouldn’t calling exit() in my constructor still envoke the destructor? This means that the destructor will try to delete one of the temp files, even though the ok_to_connect() function didn’t actually create a file. I guess i can have the ok_to_connect() method set a public variable in the class, and have the destructor check this before deleting any files.
Is this the best way to go?

Answer 1

Instead of keeping count in a single file, you could,

• on __construct create a file in a common directory,
• and on __destruct remove that file.

This way you won’t have problems with simultaneous write operations. And the total number of files would show the number of open connections.