[Rock-dev] Discussion: Timestamped Commands in base/types

[Sylvain Joyeux]

While you make an interesting case for the separation of command vs.
sample, I have an issue with that. Namely, "to me", an interesting
byproduct of timestamping commands is the ability to measure latency in
the control loop pipeline. To achieve this, we would need to have
timestamps in the control dataflow, instead of "mirroring it".

If there is *also* a need to timestamp when the command got actually
sent by the component that processed it, then we either need two
timestamps (yuk), or a way to associate the two timestamps (maybe a
timestamp pair sent by the monitored component, which associates the
command timestamp with the reception timestamp ?)

On 11/01/2013 03:45 PM, Steffen Planthaber wrote:
> What do you think?
Implementation-wise, you could have used a simple header class and
multiple inheritance, which is IMO a lot simpler than templating. No
need for any copy/pasting.

What I am strongly against is the initialization of the timestamp with
Time::now(). Timestamps need to be carefully thought before they get
set, and Time::now() is usually *not* the right answer. This is
promoting bad habits.

Moreover, since the time field is public, having a setter which just
sets the field is ... not really needed.

-- 
Sylvain Joyeux (Dr.Ing.)
Senior Researcher

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