[pve-devel] [PATCH ha-manager 1/9] implement static service stats cache

[Fiona Ebner]

Am 17.10.25 um 12:02 PM schrieb Fiona Ebner:
> Am 16.10.25 um 5:15 PM schrieb Daniel Kral:
>> On Thu Oct 16, 2025 at 1:12 PM CEST, Fiona Ebner wrote:
>>> Am 30.09.25 um 4:21 PM schrieb Daniel Kral:
>>>> @@ -497,6 +499,25 @@ sub get_datacenter_settings {
>>>>      };
>>>>  }
>>>>  
>>>> +sub get_static_service_stats {
>>>> +    my ($self, $id) = @_;
>>>> +
>>>> +    # undef if update_static_service_stats(...) failed before
>>>> +    return undef if !defined($self->{static_service_stats});
>>>> +
>>>> +    return $self->{static_service_stats}->{$id} // {};
>>>
>>> Can't returning '{}' when nothing is there lead to issues down the line?
>>> If we return undef instead, it's consistent with not having anything
>>> cached and the caller will fall back to loading the config.
>>
>> This return value type definitely needs improvement and/or better
>> documentation, but an undef $self->{static_service_stats}->{$id} value
>> indicates that it should fallback to the default value as none of the
>> properties requested by get_guest_config_properties(...) was included in
>> that particular guest config, e.g. no 'cores', 'sockets', and 'memory'
>> properties defined in a VM config.
>> When $self->{static_service_stats} itself is undef, then the static
>> cache couldn't be queried for some reason.
> 
> Okay, so get_guest_config_properties() only includes guests that do have
> one of the queried properties explicitly set in its result. Thus, we
> cannot distinguish between the cache being created at a time when a
> guest did not exist yet or a guest with none of the queried properties
> explicitly set. If returning {} as a fallback, we get the wrong values
> in the former case, if returning undef as a fallback, we just have to
> explicitly load the config in the latter case. There probably are not
> many setups with many guests without any of the queried properties
> explicitly set, so that is unlikely to hurt performance in practice.

Or additionally, we could initialize the cache with {} for the guests
that exist at that moment, but do not have any of the queried properties
explicitly set.