[Tarantool-patches] [tarantool-patches] Re: [PATCH 1/1] app: exit gracefully when a main script throws an error
Vladislav Shpilevoy
v.shpilevoy at tarantool.org
Thu Oct 24 22:53:17 MSK 2019
Hi!
On 24/10/2019 02:21, Alexander Turenko wrote:
> I know, the patch was already pushed, but I looked on it briefly anyway.
>
If something is wrong, it may be fixed as a follow up.
> It is LGTM, however I have one question: see below.
>
> WBR, Alexander Turenko.
>
>> @@ -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?
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.
>
> So, things seems to work good, but I didn't got how exactly.
>
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