Re: [PATCH pve-guest-common v5 3/7] add module to track previously used guest IDs

[Fiona Ebner <f.ebner@proxmox.com>]

Am 22.09.26 um 5:55 PM schrieb Michael Köppl:
> On Tue Sep 22, 2026 at 4:22 PM CEST, Fiona Ebner wrote:
>>> +    my ($filename, $raw) = @_;
>>> +
>>> +    my $used_ids = {};
>>> +
>>> +    return $used_ids if !defined($raw);
>>> +
>>> +    for my $line (split(/\n/, $raw)) {
>>> +        next if $line =~ m/^\s*$/;
>>> +
>>> +        if ($line =~ m/^(\d+)$/) {
>>> +            $used_ids->{$1} = 1;
>>> +        } elsif ($line =~ m/^(\d+)-(\d+)$/) {
>>> +            my ($start, $end) = ($1, $2);
>>> +            if ($start > $end) {
>>> +                warn "skipping reversed range in $filename: $line\n";
>>> +                next;
>>> +            }
>>> +            $used_ids->{$_} = 1 for $start .. $end;
>>
>> Nit: we could be smarter and avoid adding every single ID to the hash
>> (with a lot of (past) guests that can become a non-trivial cost), and
>> instead track ranges. Instead of having a public read_list() function
>> then, there could be a check_id_unused() function. When writing out the
>> file we can still merge adjacent ranges.
> 
> Thanks for pointing this out! I think the range approach is a good idea!
> Should we have a public function that returns the end of a range for a
> given guest ID instead of the boolean check_id_unused()? We could then
> use it to skip ranges when searching for a free guest ID at
> /cluster/nextid instead of invoking cfs_read_file() for each check if a
> candidate ID is available. Something like this:
> 
> my $i = $lower;
> while ($i < $upper) {
>     if (defined($idlist->{$i})) { $i++; next; }
>     if ($check_unique) {
>         if (defined(my $end =
> 		  PVE::UsedGuestIDs::get_used_range_end($i))) {
>             $i = $end + 1;
>             next;
>         }
>     }
>     return $i;
> }

Yes. Or have the function return the next free ID equal to or bigger
than the input directly?