Re: irsend synchronous or asynchronous?

[Alec L. <lea...@gm...>]

> Lircd is running on a Raspberry Pi with 10 pushbuttons.
> 
> When the user presses a button, channelnumbers consisting of one or more 
> digits are sent to the TV. When shortly after this event (less than a 
> second) a new call is executed, (maybe because of bouncing buttons maybe 
> because of unhappy user) the TV ends up with channel numbers that can be 
> a combination of channelnumbers, or digits may be lost.
> 
> 
> When I see the TV getting channel numbers mixed up, is this happening in 
> the TV and can I rule out lircd as the culprit?
> 
> This is the code that is used:
> 
>      import subprocess
> 
>      def irsend(self,key_list):
>          arg_list = ["irsend", "SEND_ONCE", remote] + key_list
>          rtn = subprocess.call(arg_list)
>          if rtn:
>              print(' '.join(key_list), ' returned errorcode: ', rtn)
> 
> 
> 
> 
> Will control to the main python program return only after all key-codes 
> are sent completely?
> There is no risc to start a new send while the previous is not finished 
> yet?

I wouldn't say "no risc"... That said, there is code generating a delay 
so that the calling code shouldn't return until the sending is completed.

You could have a look at lib/ir_remote.c, the function send_ir_ncode(), 
called from send_once() in daemons/lircd.cpp. This should complete 
before sending a reply to the irsend client.

> Is the irsend daemon maintaining a queue with codes to transmit?

No, it's basically fire-and-forget. BTW, there is no specific irsend 
daemon, it's the same lircd which is handling input decoding.

> In fact the most important question:
> 
> Has the client program some responsibility when sending codes in rapid 
> succession?

To be honest, this has not been defined to my limited knowledge. One 
thing to do is certainly to test with some delays between each irsend 
invocation to see possible results.


Cheers!

--alec