[Freeswitch-users] Which Lua script am I?

David Knell dave at 3c.co.uk
Fri Mar 5 11:40:14 PST 2010

Hi Mike,

You can spawn a new script with something like

api = freeswitch.API();
reply = api:executeString("luarun /tmp/msg.lua");

- and you can pass parameters, accessed in the normal way.

So there's no reason why you couldn't have a background script running which spawns one worker per task that needs doing; each worker can do its task and then exit.

Cheers --

  ----- Original Message ----- 
  From: Mike van Lammeren 
  To: FreeSWITCH Users 
  Sent: Friday, March 05, 2010 12:04 PM
  Subject: [Freeswitch-users] Which Lua script am I?


  I am working on a high-availability system and need a Lua script that can run in the background and loop forever, periodically waking up to accomplish some tasks. I would like to be able to handle at least 10 concurrent tasks.

  My first idea was to have a simple background script that would call another script, let's call it the 'task' script, every 5 seconds or so. This would spread the work around, and if any task script quit with an error, the background script would remain running, and would continue to launch new task scripts.

  However, I can see no way for the background script to launch other Lua scripts. Am I missing something? I need something like session:execute(), but unfortunately this background script has no session, and I'm not sure if session:execute() can even make a call like the "luarun" console command.

  So, my next ideas was to have 10 copies of the background script. Each script would loop forever. Upon launch, each script would perform a single task, then sleep for 60 seconds. This allows handling of 10 concurrent tasks.

  However, there are some problems with running 10 copies of the same script, which I believe can be solved if each script could be given a unique identifier. One problem is that I would like the scripts to actually sleep for a variable amount of time, say between 55 and 65 seconds, so that the workload would spread around. Another, similar problem, is that each script needs to 'claim' a number of database records from a table that is queuing up work for the scripts. Once again, if each script had a unique identifier, then I could use an update query to effectively 'set and test' a record that would be tied to that script instance.

  I could use a random number to identify each script, but since math.random is seeded with a timestamp that only resolves to seconds, then all 10 scripts will be given the same sequence of random numbers, and all 10 will run in lock-step with each other. So, random numbers are out. (If I had a unique ID to seed the random number generator, then I could just use that unique ID and wouldn't need random numbers.)

  Is there a way of uniquely identifying 10 Lua scripts that FreeSWITCH launches at startup?

  Or is there a better way of handling this situation altogether? I'm open to any suggestions that people would care to make!

  (I would entertain the idea of a single script that would start with FreeSWITCH, then launch 10 other scripts, giving each a unique identifier, but that brings me back to the original problem of not knowing how to launch other Lua scripts under FreeSWITCH.)

  Mike van Lammeren


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