On Fri, Mar 24, 2023 at 1:28 PM <rsbecker@xxxxxxxxxxxxx> wrote:
>
> On Thursday, March 23, 2023 7:55 PM, Felipe Contreras wrote:
> >On Thu, Mar 23, 2023 at 5:43 PM <rsbecker@xxxxxxxxxxxxx> wrote:
> >>
> >> On Thursday, March 23, 2023 7:35 PM, Felipe Contreras wrote:
> >> >On Thu, Mar 23, 2023 at 5:30 PM <rsbecker@xxxxxxxxxxxxx> wrote:
> >> >>
> >> >> On Thursday, March 23, 2023 7:22 PM, Felipe Contreras wrote:
> >> >> >On Sat, Feb 18, 2023 at 5:12 AM Phillip Wood
> >> >> ><phillip.wood123@xxxxxxxxx>
> >> >wrote:
> >> >> >>
> >> >> >> On 18/02/2023 01:59, demerphq wrote:
> >> >> >> > On Sat, 18 Feb 2023 at 00:24, Junio C Hamano <gitster@xxxxxxxxx>
> >wrote:
> >> >> >> >>
> >> >> >> >> Emily Shaffer <nasamuffin@xxxxxxxxxx> writes:
> >> >> >> >>
> >> >> >> >>> Basically, if this effort turns out not to be fruitful as a
> >> >> >> >>> whole, I'd like for us to still have left a positive impact on the codebase.
> >> >> >> >>> ...
> >> >> >> >>> So what's next? Naturally, I'm looking forward to a spirited
> >> >> >> >>> discussion about this topic - I'd like to know which
> >> >> >> >>> concerns haven't been addressed and figure out whether we
> >> >> >> >>> can find a way around them, and generally build awareness of
> >> >> >> >>> this effort with the
> >> >community.
> >> >> >> >>
> >> >> >> >> On of the gravest concerns is that the devil is in the details.
> >> >> >> >>
> >> >> >> >> For example, "die() is inconvenient to callers, let's
> >> >> >> >> propagate errors up the callchain" is an easy thing to say,
> >> >> >> >> but it would take much more than "let's propagate errors up"
> >> >> >> >> to libify something like
> >> >> >> >> check_connected() to do the same thing without spawning a
> >> >> >> >> separate process that is expected to exit with failure.
> >> >> >> >
> >> >> >> >
> >> >> >> > What does "propagate errors up the callchain" mean? One
> >> >> >> > interpretation I can think of seems quite horrible, but
> >> >> >> > another seems quite doable and reasonable and likely not even
> >> >> >> > very invasive of the existing code:
> >> >> >> >
> >> >> >> > You can use setjmp/longjmp to implement a form of "try", so
> >> >> >> > that errors dont have to be *explicitly* returned *in* the call chain.
> >> >> >> > And you could probably do so without changing very much of the
> >> >> >> > existing code at all, and maintain a high level of conceptual
> >> >> >> > alignment with the current code strategy.
> >> >> >>
> >> >> >> Using setjmp/longjmp is an interesting suggestion, I think lua
> >> >> >> does something similar to what you describe for perl. However I
> >> >> >> think both of those use a allocator with garbage collection. I
> >> >> >> worry that using longjmp in git would be more invasive (or
> >> >> >> result in more memory leaks) as we'd need to to guard each
> >> >> >> allocation with some code to clean it up and then propagate the
> >> >> >> error. That means we're back to manually propagating errors up the call
> >chain in many cases.
> >> >> >
> >> >> >We could just use talloc [1].
> >> >>
> >> >> talloc is not portable.
> >> >
> >> >What makes you say that?
> >>
> >> talloc is not part of a POSIX standard I could find.
> >
> >It's a library, like: z, ssl, curl, pcre2-8, etc. Libraries can be compiled on different
> >platforms.
>
> talloc adds additional *required* dependencies to git, including python3 - required to configure and build talloc - which is not available on the NonStop ia64 platform (required support through end of 2025). I must express my resistance to what would amount to losing support for git on this NonStop platform.
That is not true. You don't need python3 for talloc, not even to build
it, it's just a single simple c file, it's easy to compile.
The only reason python is used is to run waf, which is used to build
Samba, which is much more complex, but you don't need to run it,
especially if you know the characteristics of your system.
This simple Makefile builds libtalloc.so just fine:
CC := gcc
CFLAGS := -fPIC -I./lib/replace
LDFLAGS := -Wl,--no-undefined
# For talloc.c
CFLAGS += -DTALLOC_BUILD_VERSION_MAJOR=2
-DTALLOC_BUILD_VERSION_MINOR=4 -DTALLOC_BUILD_VERSION_RELEASE=0
CFLAGS += -DHAVE_CONSTRUCTOR_ATTRIBUTE -DHAVE_VA_COPY
-DHAVE_VALGRIND_MEMCHECK_H -DHAVE_INTPTR_T
# For replace.h
CFLAGS += -DNO_CONFIG_H -D__STDC_WANT_LIB_EXT1__=1
CFLAGS += -DHAVE_STDBOOL_H -DHAVE_BOOL -DHAVE_STRING_H
-DHAVE_LIMITS_H -DHAVE_STDINT_H
CFLAGS += -DHAVE_DLFCN_H -DHAVE_UINTPTR_T -DHAVE_C99_VSNPRINTF
-DHAVE_MEMMOVE -DHAVE_STRNLEN -DHAVE_VSNPRINTF
libtalloc.so: talloc.o
$(CC) $(LDFLAGS) -shared -o $@ $^
But of course, most of those defines are not even needed with a simple
"replace.h" that is less than 10 lines of code.
--
Felipe Contreras
