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--- wiki:some_examples_of_admission_rules [2017/05/11 15:32] – [Example 5:] mvesin
+++ wiki:some_examples_of_admission_rules [2020/04/07 21:49] – neyron
@@ Line 248: / Line 248: @@
 (There may be some limitations in that property filtering, which could allow malicious users to overcome the usage policy)
+==== Example 5:  ====
+Verify that the <code>oarsub -l ''resource request''</code> gives a correct resource definition.
+OAR resource request hierarchies are implicit in the OAR database, but they can be enforced by an admission rule.
+Lets assume that valid resources hierarchies are:
+  * switch > cluster > host > cpu > gpu > core
+  * cluster > switch > host > cpu > gpu > core
+  * cluster > switch > host > disk
+  * switch > cluster > host > disk
+  * license
+Here both switch > cluster, or cluster > switch can be valid (some clusters spread their nodes on many switches, some clusters share a same switch). Disks are special resources to reserve disks on hosts, independently from cpu, gpu and cores. Licenses are yet a completly independente type of resources.
+Any of those resources properties can define a valid hierarchy or resources, for instance:
+  * <code>oarsub -l switch=2/core=1</code> → get 2 cores on different switches
+  * <code>oarsub -l cluster=1/host=2/disk=1</code> → get 2 disks of 2 different hosts but on a same cluster
+  * oarsub -l license=1</code> → get 1 license
+But incorrect hierachry should raise an error:
+  * oarsub -l gpu=1/host=2 → cannot get 2 hosts for a same gpu
+  * oarsub -l host=1/disk=1/core=1 → cannot mix disk and core
+==Answer==
+<code perl>
+# definition of the valid implicit hierarchies of resources.
+my %valid_children = (
+                # both cluster > switch and switch > cluster are relevant
+                "cluster"  => ["switch", "cpu", "host", "core", "gpu", "disk"],
+                "switch"   => ["cluster", "cpu", "host", "core", "gpu", "disk"],
+                "host"     => ["cpu", "core", "gpu", "disk"],
+                "cpu"      => ["core", "gpu"],
+                "gpu"      => ["core"],
+                "disk"     => [],
+                "license"  => [],
+                );
+# nodes is synonym of host
+my %aliases = (
+        "nodes" => "host",
+);
+# valid values are in one of the possible hierarchies
+my %valid_resources;
+foreach my $key (keys %valid_children) {
+        $valid_resources{$key} = undef;
+        foreach my $child (@{%valid_children{$key}}) {
+                $valid_resources{$child} = undef;
+        }
+}
+my @valid_resources = keys %valid_resources;
+# test the user's request for possible errors
+foreach my $mold (@{$ref_resource_list}) { # loop on all moldable resources requests (oarsub -l ... -l ...)
+        foreach my $r (@{$mold->[0]}) { # loop on all joint resources requests (oarsub -l ...+...)
+                my @resources_hierarchy;
+                my $parent_resource;
+                foreach my $h (@{$r->{resources}}) { # loop on every resource, look at the resource name only ($h->{resource}) not the value ($h->{value})
+                        if(!grep { $_ eq $h->{resource} } @valid_resources) {
+                                die("[ADMISSION RULE] Error: the requested resources '$h->{resource}' is not valid, please check your syntax.\n");
+                        }
+                        if (!grep { $_ eq $h->{resource} } @resources_hierarchy) {
+                                push @resources_hierarchy, $h->{resource};
+                        } else {
+                                # catching the case `oarsub -l /cluster=a/switch=b/cluster=c` or `oarsub -l /switch=a/cluster=b/switch=c`
+                                push @resources_hierarchy, $h->{resource};
+                                die("[ADMISSION RULE] Error: duplicated resource '$h->{resource}' in the requested resources hiearchy '".join(" > ", @resources_hierarchy)."'.\n");
+                        }
+                        if (defined($parent_resource)) {
+                                if (!grep { $_ eq $h->{resource} } @{$valid_children{$parent_resource}}) {
+                                        die("[ADMISSION RULE] Error: the requested resources hierarchy '".join(" > ", @resources_hierarchy)."' is not relevant.\n");
+                                }
+                        }
+                        if (exists $aliases{$h->{resource}}) {
+                                $parent_resource = $aliases{$h->{resource}};
+                        } else {
+                                $parent_resource = $h->{resource};
+                        }
+                }
+        }
+}
+</code>