[pve-devel] [PATCH v2 guest-common 1/1] helpers: add pool limit/usage helpers

[Fabian Grünbichler]

one for combining the per-node broadcasted values, one for checking a pool's
limit, and one specific helper for checking guest-related actions such as
starting a VM.

Signed-off-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
---

Notes:
    v2:
    - style
    - introduce new helper for mapping limit key to usage hash
    - introduce new helper for default usage hash
    - avoid hard-coding cpu/mem and run/config where sensible

 src/PVE/GuestHelpers.pm | 183 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 183 insertions(+)

diff --git a/src/PVE/GuestHelpers.pm b/src/PVE/GuestHelpers.pm
index 961a7b8..e52eaf0 100644
--- a/src/PVE/GuestHelpers.pm
+++ b/src/PVE/GuestHelpers.pm
@@ -416,4 +416,187 @@ sub check_vnet_access {
 	if !($tag || $trunks);
 }
 
+sub pool_limit_to_usage {
+    my ($limit_key) = @_;
+
+    my ($resource, $kind) = split(/-/, $limit_key, 2);
+
+    return ($resource, $kind, $kind eq 'run' ? 1 : 0);
+}
+
+sub pool_default_usage {
+    my $default = {};
+
+    for my $limit (keys $PVE::AccessControl::pool_limits_desc->%*) {
+	my ($resource, $kind) = pool_limit_to_usage($limit);
+	$default->{$resource}->{$kind} = 0;
+    }
+
+    return $default;
+}
+
+# combines the broadcasted pool usage information to get per-pool stats
+#
+# $pools parsed pool info from user.cfg
+# $usage broadcasted KV hash
+# $pool filter for specific pool
+# $skip skip a certain guest to ignore its current usage
+#
+# returns usage hash:
+# pool -> cpu/mem/.. -> run/config -> $usage
+sub get_pool_usage {
+    my ($pools, $usage, $pool, $skip) = @_;
+
+    my $res = {};
+    my $included_guests = {};
+    for my $node (keys $usage->%*) {
+	my $node_usage = JSON::decode_json($usage->{$node} // '');
+
+	# long IDs first, so we can add children to their parents right away
+	for my $poolid (sort {$b cmp $a} keys $pools->%*) {
+	    if (
+		defined($pool)
+		&& !($pool eq $poolid || $poolid =~ m!^$pool/! || $pool =~ m!^$poolid/!)
+	    ) {
+		next;
+	    }
+
+	    my $d = $res->{$poolid} //= pool_default_usage();
+
+	    my $pool_usage = $node_usage->{data}->{$poolid} // {};
+	    for my $vmid (keys $pool_usage->%*) {
+		# only include once in case of migration between broadcast
+		next if $included_guests->{$vmid};
+		next if $skip && $skip->{$vmid};
+		$included_guests->{$vmid} = 1;
+
+		my $vm_data = $pool_usage->{$vmid};
+		for my $key (keys $vm_data->%*) {
+		    next if $key eq 'running';
+		    $d->{$key}->{run} += $vm_data->{$key}->{run} if $vm_data->{running};
+		    $d->{$key}->{config} += $vm_data->{$key}->{config};
+		}
+	    }
+
+	    if (my $parent = $pools->{$poolid}->{parent}) {
+		$res->{$parent} //= pool_default_usage();
+		for my $key (keys $d->%*) {
+		    for my $kind (keys $d->{$key}->%*) {
+			$res->{$parent}->{$key}->{$kind} = $d->{$key}->{$kind};
+		    }
+		}
+	    }
+	}
+    }
+
+    return $res;
+}
+
+# checks whether a pool is (or would be) over its resource limits
+#
+# $changes is for checking limits for config/state changes like VM starts, if
+# set, only the limits with changes are checked (see check_guest_pool_limit)
+#
+# return value indicates whether any limit was overstepped or not (if $noerr is set)
+sub check_pool_limits {
+    my ($usage, $limits, $noerr, $changes) = @_;
+
+    my $over = {};
+    my $only_changed = defined($changes);
+
+    my $check_limit = sub {
+	my ($key, $running, $limit, $change) = @_;
+
+	return if $only_changed && $change == 0;
+
+	my $kind = $running ? 'run' : 'config';
+
+	my $value = $usage->{$key}->{$kind};
+	$value = int($value);
+	$value += $change;
+	$value = $value / (1024*1024) if $key eq 'mem';
+	if ($limit < $value) {
+	    $over->{$key}->{$kind}->{change} = $change if $change;
+	    $over->{$key}->{$kind}->{over} = 1;
+	}
+    };
+
+    my $get_change = sub {
+	my ($key, $running) = @_;
+
+	return 0 if !defined($changes);
+
+	my $check_running = defined($changes->{running}) && $changes->{running} ? 1 : 0;
+
+	if ($running == $check_running) {
+	    return $changes->{$key} // 0;
+	} else {
+	    return 0;
+	}
+    };
+
+    while (my ($key, $limit) = each $limits->%*) {
+	my ($resource, $kind, $running) = pool_limit_to_usage($key);
+	my $change = $get_change->($resource, $running);
+	$check_limit->($resource, $running, $limit, $change);
+    }
+
+    if (!$noerr) {
+	my $msg = '';
+	for my $key (keys $over->%*) {
+	    for my $kind (keys $over->{$key}->%*) {
+		my $value = $usage->{$key}->{$kind};
+		$value = $value / (1024*1024) if $key eq 'mem';
+		my $change = $over->{$key}->{$kind}->{change};
+		if ($change) {
+		    $change = $change / (1024*1024) if $key eq 'mem';
+		    $value = "$value + $change" if $change;
+		}
+		my $limit = $limits->{"$key-$kind"};
+		$msg .= "($kind) $key: $value over $limit, ";
+	    }
+	}
+	if ($msg) {
+	$msg =~ s/, $//;
+	die "pool limits exhausted: $msg\n";
+	}
+    }
+
+    return $over->%* ? 1 : 0;
+}
+
+# checks whether the given changes for a certain guest would overstep a pool limit
+#
+# $changes is an optional hash containing
+# - absolute: flag whether changes are relative or absolute
+# - running: flag whether the config or running limits should be checked
+# - cpu: change value for cpu limit
+# - mem: change value for mem limit
+# all elements are optional
+#
+# if no $changes is provided, the limits are checked against the current usage
+#
+# $poolid allows overriding the guest's pool membership, for example in case it
+# is not yet properly set when creating the guest
+sub check_guest_pool_limit {
+    my ($vmid, $changes, $poolid) = @_;
+
+    my $user_cfg = PVE::Cluster::cfs_read_file("user.cfg");
+
+    $poolid = $user_cfg->{vms}->{$vmid} if !defined($poolid);
+    if ($poolid) {
+	my $pool = $user_cfg->{pools}->{$poolid};
+
+	my $limits = $pool->{limits};
+	return if !$limits;
+
+	my $skip = {};
+	$skip->{$vmid} = 1 if $changes && $changes->{absolute};
+	my $usage = PVE::Cluster::get_node_kv('pool-usage');
+
+	$usage = get_pool_usage($user_cfg->{pools}, $usage, $poolid, $skip);
+	check_pool_limits($usage->{$poolid}, $limits, 0, $changes);
+    }
+}
+
 1;
-- 
2.39.2