Re: errbacktrace

On 2019-Jul-08, Dmitry Dolgov wrote:

> > On Sat, Jun 29, 2019 at 7:41 AM Jaime Casanova <jaime(dot)casanova(at)2ndquadrant(dot)com> wrote:
> >
> > This is certainly a very useful thing. Sadly, it doesn't seem to compile when
> > trying to use libunwind.
>
> Yeah, the same for me. To make it works I've restricted libunwind to local
> unwinding only:
>
> #ifdef USE_LIBUNWIND
> #define UNW_LOCAL_ONLY
> #include <libunwind.h>
> #endif

Ah, yes. unwind's manpage says:

Normally, libunwind supports both local and remote unwinding (the latter will
be explained in the next section). However, if you tell libunwind that your
program only needs local unwinding, then a special implementation can be
selected which may run much faster than the generic implementation which
supports both kinds of unwinding. To select this optimized version, simply
define the macro UNW_LOCAL_ONLY before including the headerfile <libunwind.h>.

so I agree with unconditionally defining that symbol.

Nitpicking dept: I think in these tests:

+ if (!edata->backtrace &&
+ edata->funcname &&
+ backtrace_function[0] &&
+ strcmp(backtrace_function, edata->funcname) == 0)
+ set_backtrace(edata, 2);

we should test for backtrace_function[0] before edata->funcname, since
it seems more likely to be unset.

--
Álvaro Herrera https://www.2ndQuadrant.com/
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