[Tinyos-devel] ctp vs other radio clients

[Branislav Kusy]

guys,

is it allowed to use the radio (ie ActiveMessageC) while using Ctp? if 
not, should it be allowed? most of my applications require it...

i couldn't find anything about this in tep123, but i found this comment 
in CtpForwardingEngineP.nc,v1.17:

line 487:
       subsendResult = call SubSend.send(dest, qe->msg, payloadLen);
....
lines 509-519:
       else if (subsendResult == EBUSY) {
	// This shouldn't happen, as we sit on top of a client and
         // control our own output; it means we're trying to
         // double-send (bug). This means we expect a sendDone, so just
         // wait for that: when the sendDone comes in,  we'll try
         // sending this packet again.	
	dbg("Forwarder", "%s: subsend failed from EBUSY.\n", __FUNCTION__);
         // send a debug message to the uart
         call CollectionDebug.logEvent(NET_C_FE_SUBSEND_BUSY);
       }

if there are other radio clients, subsendResult may be EBUSY even if we 
don't double send. therefore, we should just call
	startRetxmitTimer();

if we don't do this, ctp basically hangs forever.

i've had this problem for a long time - ctp hanging on me for no good 
reason. my test application can reproduce it in a few seconds. i tested 
calling startRetxmitTimer() from the EBUSY case and it fixed the 
problem. i'm not sure if it didn't introduce any other problems, though.

brano