Re: [Firebird-devel] Service errors returned by API (was: [FirebirdSQL/firebird] [FR] Database restore must make every effort on activating deferred indexes (Issue #7269))

[Alex P. <pes...@ma...>]

On 8/24/22 20:59, Dimitry Sibiryakov wrote:
> Alexander Peshkov wrote 24.08.2022 19:06:
>> On 8/24/22 14:31, Dimitry Sibiryakov wrote:
>>  > Without it services seem to be pretty useless.
>>
>> I think this to be suggested in devel and if nobody sees problems - feel
>> free to add a ticket, I will implement it.
>
>   Ok. But I don't think that a simple hack returning only thread exit 
> code is a right way to go.

If I was thinking that way that feature could be present since 2. 5 :-)

>
>> Notice - in status vector it will be a notice that service thread failed
>> with exit code NNN, original message with a reason for is unknown at the
>> final point.
>
>   It is not quite try.
>   In the old dark days when the service thread just run an external 
> utility and mindlessly redirect whole output to the client it was so. 
> But nowadays the thread is doing whole work itself 

Just small notice - an ability to return errors in SV does not directly 
depend upon does service run as a process or as a thread. It's possible 
to pass SV cross-process but nobody cared about. With service threads 
pre-2.5 it was a mix - some errors were returned as SV, some - as text 
lines.

> so it can return a proper errors, warnings and verbose messages 
> through isc_svc_query() as soon as they happen.

But here are some problems:
- An error when querying service is treated by 99% of callers (starting 
with fbsvcmgr) as fatal one. Other errors will not be displayed.
- What about warnings - yes, they probably may be used at the first 
glance. But once again big problems with old clients. What should return 
isc_service_query - success or failure? On failure one prints status and 
detachs from service, on success - ignores SV.
- Verbose messages are already passed through isc_svc_query().

Certainly we may require analyzing warnings from clients who want to 
receive verbose messages in machine-readable form. Is it what you want?