Re: [PATCH] Tracing notes and metadata

[Stan Shebs <stan_shebs@mentor.com>]

On 10/17/2011 09:29 AM, Eli Zaretskii wrote:
>> Date: Mon, 17 Oct 2011 09:00:18 -0700
>> From: Stan Shebs<stan_shebs@mentor.com>
>>
>> With this patch, any arguments to tstart and tstop are recorded with the
>> trace run as free-form text, and reported as part of its status.  Also,
>> there is a trace-user variable (which is free form text which is
>> typically constant and you can set in your .gdbinit), and set/show
>> variables for the start and stop notes as well.
>>
>> In addition, this patch adds start/stop timestamps and per-tracepoint
>> hit counts and traceframe usage.
>>
>> The patch still needs testsuite and NEWS, but considering the user
>> interface tinkering, it seemed like a good idea to solicit feedback
>> before committing to all the details.
> The documentation part is okay, but please add some overview of the
> notes, to serve as the glue to the description of the commands.  As I
> read the patch, I was wondering whether there's only one note that can
> be set by either "tstart" or "tstop" (and then what happens if you
> give arguments to "tstop" when "tstart" already provided a note?), or
> two separate and independent notes (in which case why do we have
> "trace-stop-notes", but no "trace-start-notes"?).  Instead of
> disclosing all this piecemeal and leaving the reader with a reasonable
> doubt, why not explain it once and for all?

OK, needs more explanation then. :-)  The tstart note is the summary of 
the trace run as a whole, while the stop note only applies if the trace 
was manually stopped via tstop, vs stopping due to trace buffer full, 
bytecode dividing by zero, etc.  In practice, one would only expect to 
supply a stop note if the trace had to be manually stopped by someone 
else ("tstop I needed to stop your run so I could test my workaround for 
bug 12043 -sts"), so the original person running the trace has an 
explanation of what happened  - and can interpret the 
possibly-incomplete trace results accordingly.

> Btw, didn't the socializing parties ask you for a way to _add_ to an
> existing note, rather than overwriting it?  The way you designed it,
> fixing a single typo requires retyping (or copy/pasting) the whole
> thing, which sounds inconvenient.
>

No, you're the first person to mention adding actually.  I think the 
mental model is that the notes are typically one-liners, and we do have 
line-editing capability available from readline.  I think if things 
really needed to be much more elaborate in a multi-user setting, the 
users would set up a wiki or virtual signup sheets or some such, and at 
that point it gets generally out of scope for GDB.  ("tstart 
http://signup.intranet.com/34129")

Stan