Re: [Tarantool-patches] [tarantool-patches] Re: [PATCH 1/1] app: exit gracefully when a main script throws an error

[Alexander Turenko <alexander.turenko@tarantool.org>]

> >> @@ -678,6 +686,12 @@ tarantool_lua_run_script(char *path, bool interactive,
> >>  		ev_run(loop(), 0);
> >>  	/* The fiber running the startup script has ended. */
> >>  	script_fiber = NULL;
> >> +	/*
> >> +	 * Result can't be obtained via fiber_join - script fiber
> >> +	 * never dies if os.exit() was called. This is why diag
> >> +	 * is checked explicitly.
> >> +	 */
> >> +	return diag_is_empty(diag_get()) ? 0 : -1;
> > 
> > This is the only part I'm a bit tentative: can the diagnostic area be
> > populated by a user somehow? I tried to do--
> > 
> >  | fio.open('non_existent', {'O_RDONLY'})
> >  | os.exit()
> > 
> > --in the main script and it seems that it uses some other diagnostic
> > area, because the fio error was not reported as the main script fail.
> 
> Should it have been reported?

No, current behaviour looks right for me.

> Talking of why it is not now - well, yes, it uses another diagnostics
> area. tarantool_lua_run_script() starts a special fiber to run a
> script or a console. And the error is forwarded to the main fiber
> only when the script fiber does it voluntary, in the end of
> run_script_f().
> 
> In case of os.exit() the script fiber never finishes, and therefore
> never moves its diag to the main fiber. Os.exit() breaks event loop
> and freezes the current fiber. It makes ev_run() return in
> tarantool_lua_run_script(). After that we see that the diag is empty,
> because the script fiber never got to the point of filling it.

Now I understood the logic, thanks!