[ruby-core:17812] Tracing versus coverage (was Re: Re: Features to be included in Ruby 1.9.1)

Sorry for not noticing sooner. It occurs to me that the built-in
coverage feature that is currently being implemented for the next
release is not all that different from a line tracing feature. I
wonder if it could be extended so that a method is called instead of
updating a hash. In fact one can think of the coverage mechanism as a
special kind of trace mechanism that only updates a hash.

And it's also true that the instruction replacement for setting a
(temporary) breakpoint in 1.9 can also be used in implementing
something like rcov.

Here you set temporary breakpoints at every known statement boundary.
If all you care about is coverage like rcov after the temporary
breakpoint is serviced by updating a mark indicating the line was hit,
the original opcode can go back and in terms of performance the only
penalty is the initial time to put in the temporary breakpoints and
the time to update however many counts are actually covered.

And one can reliably know what has not been run by scanning the code
for trace instructions. Finally, I suppose all of this could be sped
up by building initial trace replacement into the compiler.

On Tue, Jul 8, 2008 at 8:22 AM, Yusuke ENDOH <[e-mail]> wrote:
> Hi,
>
> 2008/7/8 Yugui (Yuki Sonoda) <[e-mail]>:
>> Committers and anyone who intend to write patches, let me know your
>> plan. What features will be implemented by 25 Sep? What will not?
>
> I hope to include built-in coverage measurement feature.
>
> I have already committed some primitive features that measure
> coverage into the core interpreter.  But I haven't implemented
> a practical front-end tool which controls measurement and outputs
> the measured result.
>
> As a matter of fact, my goal is to measure coverage of the
> standard libraries for maintenance and enhancement of their tests,
> not to provide useful coverage measurement tool.  So I'm not in a
> hurry to implement a front-end tool.  If it's permitted, let's
> just say that it will be implemented by 1.9.5 :-)
>
> --
> Yusuke ENDOH <[e-mail]>
>
>