Re: [Playerstage-users] load a new driver w/o restarting player?

[Brian G. <br...@ge...>]

On Nov 17, 2008, at 10:29 AM, Edwin Simons wrote:

> I'm fairly new to player, but I have been tasked with achieving the
> following goal. I need player to be able to load a new device driver
> some time after it has started, without restarting. Is this at all
> possible in Player right now? If so, how do I do it? If not, would  
> it be
> possible for me to modify existing code to achieve this goal? If so,
> what would I need to modify? Any help or advice would be greatly
> appreciated. Thank you for your time.

That's not something we designed for, but in principle, it's quite  
possible.

Have a look at libplayercore/plugins.cc and libplayercore/ 
configfile.cc.  In the latter, ConfigFile::ParseDriver() calls  
LoadPlugin() when a driver block specifies a plugin to be loaded.  It  
then calls InitDriverPlugin(), which reaches into the plugin and calls  
player_driver_init(), which presumably adds the driver to the  
driverTable.

You could call LoadPlugin() and InitDriverPlugin() during execution.   
Two things to be done:

- add a mutex to driverTable and ensure that it's locked when the  
table is accessed.  Right now, there's no locking, because the table  
is only mutated on startup, in a non-concurrent fashion.

- provide a mechanism to tell the server to actually do the load.   
Without knowing anything about your use case, I can't say what would  
be the best way to do this, among several possibilities (e.g., send a  
signal, write to a fifo, add a new server request message).

This sounds like neat functionality that we'd happily incorporate once  
you have it working.

	brian.