Re: Clear transmit buffer (of pending queued tx-messages)

[ajneu <ajneu1@gmail.com>]

Oliver Hartkopp <socketcan <at> hartkopp.net> writes:

> 
> The question is whether blocking write (and probably write outdated 
> content) is what you want for CAN.

Oliver Hartkopp posted that on a different thread...
Subject: Re: want blocking writes, but eventually get: errno 105 (No buffer
space available)
Date: 2016-06-22 15:52:04 GMT (15 hours and 32 minutes ago)

OK ->

I've tried non-blocking.
Unfortunately non-blocking will not tell you if messages are delivered or not.

Example:
If I send out 2 messages (non-blocking) with no participant on the bus,
those messages will remain queued.
If 5 minutes later a participant joins the bus, he'll get those 2 very old
messages: outdated content.

What are my options to solve this?
(Can I find out if a message has actually been sent out onto the bus?)
(I'm currently thinking about checking the CAN-Bus status: If NOT
error-active (and high tx count), I know that tx-messages will not get
delivered.
But if I had a few messages in the queue, I still cannot tell which ones got
delivered. Hmmmm...
  ***)
)

Thanks,
ajneu


PS:
  ***)
Perhaps in some cases it does not matter to know which messages actually
still got delivered and which not.
In that case, when the program detects NO-longer-ERROR_ACTIVE, it can enter
into an error-state "waiting for online":
first it does can_do_stop followed by can_do_start, to clear the queue. Then
it just sends periodic messages, until it get's back_to_error_active.
Once it get's back_to_error_active, it it back "online".
Thoughts?