add Usage base plugin and Usage::Basic plugin

in preparation to also support static resource scheduling via another
such Usage plugin.

The interface is designed in anticipation of the Usage::Static plugin,
the Usage::Basic plugin doesn't require all parameters.

In Usage::Static, the $haenv will necessary for logging and getting
the static node stats. add_service_usage_to_node() and
score_nodes_to_start_service() take the sid, service node and the
former also the optional migration target (during a migration it's not
clear whether the config file has already been moved or not) to be
able to get the static service stats.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>

debian/pve-ha-manager.install

@@ -33,5 +33,7 @@
 /usr/share/perl5/PVE/HA/Resources/PVECT.pm
 /usr/share/perl5/PVE/HA/Resources/PVEVM.pm
 /usr/share/perl5/PVE/HA/Tools.pm
+/usr/share/perl5/PVE/HA/Usage.pm
+/usr/share/perl5/PVE/HA/Usage/Basic.pm
 /usr/share/perl5/PVE/Service/pve_ha_crm.pm
 /usr/share/perl5/PVE/Service/pve_ha_lrm.pm

src/PVE/HA/Makefile

@@ -1,5 +1,5 @@
 SIM_SOURCES=CRM.pm Env.pm Groups.pm Resources.pm LRM.pm Manager.pm \
-	NodeStatus.pm Tools.pm FenceConfig.pm Fence.pm
+	NodeStatus.pm Tools.pm FenceConfig.pm Fence.pm Usage.pm
 
 SOURCES=${SIM_SOURCES} Config.pm
 
@@ -8,6 +8,7 @@ install:
 	install -d -m 0755 ${DESTDIR}${PERLDIR}/PVE/HA
 	for i in ${SOURCES}; do install -D -m 0644 $$i ${DESTDIR}${PERLDIR}/PVE/HA/$$i; done
 	make -C Resources install
+	make -C Usage install
 	make -C Env install
 
 .PHONY: installsim

src/PVE/HA/Usage.pm

@@ -0,0 +1,49 @@
+package PVE::HA::Usage;
+
+use strict;
+use warnings;
+
+sub new {
+    my ($class, $haenv) = @_;
+
+    die "implement in subclass";
+}
+
+sub add_node {
+    my ($self, $nodename) = @_;
+
+    die "implement in subclass";
+}
+
+sub remove_node {
+    my ($self, $nodename) = @_;
+
+    die "implement in subclass";
+}
+
+sub list_nodes {
+    my ($self) = @_;
+
+    die "implement in subclass";
+}
+
+sub contains_node {
+    my ($self, $nodename) = @_;
+
+    die "implement in subclass";
+}
+
+sub add_service_usage_to_node {
+    my ($self, $nodename, $sid, $service_node, $migration_target) = @_;
+
+    die "implement in subclass";
+}
+
+# Returns a hash with $nodename => $score pairs. A lower $score is better.
+sub score_nodes_to_start_service {
+    my ($self, $sid, $service_node) = @_;
+
+    die "implement in subclass";
+}
+
+1;

src/PVE/HA/Usage/Basic.pm

@@ -0,0 +1,52 @@
+package PVE::HA::Usage::Basic;
+
+use strict;
+use warnings;
+
+use base qw(PVE::HA::Usage);
+
+sub new {
+    my ($class, $haenv) = @_;
+
+    return bless {
+	nodes => {},
+    }, $class;
+}
+
+sub add_node {
+    my ($self, $nodename) = @_;
+
+    $self->{nodes}->{$nodename} = 0;
+}
+
+sub remove_node {
+    my ($self, $nodename) = @_;
+
+    delete $self->{nodes}->{$nodename};
+}
+
+sub list_nodes {
+    my ($self) = @_;
+
+    return keys $self->{nodes}->%*;
+}
+
+sub contains_node {
+    my ($self, $nodename) = @_;
+
+    return defined($self->{nodes}->{$nodename});
+}
+
+sub add_service_usage_to_node {
+    my ($self, $nodename, $sid, $service_node, $migration_target) = @_;
+
+    $self->{nodes}->{$nodename}++;
+}
+
+sub score_nodes_to_start_service {
+    my ($self, $sid, $service_node) = @_;
+
+    return $self->{nodes};
+}
+
+1;

src/PVE/HA/Usage/Makefile

@@ -0,0 +1,6 @@
+SOURCES=Basic.pm
+
+.PHONY: install
+install:
+	install -d -m 0755 ${DESTDIR}${PERLDIR}/PVE/HA/Usage
+	for i in ${SOURCES}; do install -D -m 0644 $$i ${DESTDIR}${PERLDIR}/PVE/HA/Usage/$$i; done