[Xen-devel] [PATCH OSSTEST 3/4] Add support for selecting resources based on their properties.

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

In particular for allocating hosts based on host properties.

To do this we extend the hostflags syntax with "condition:arg1:arg2".
This specifies that the candidate host must pass the condition given
the arguments.

Each "condition" is a new module in the Osstest::ResourceCondition
namespace. For each condition an object is constructed using the given
arguments (split on ':') and stored in $hid.

When allocating for each candidate host the object's ->check method is
called giving $restype and $resname and will return true or false
depending on whether the given host meets the condition.

Only a single condition is implemented here "PropMinVer" which
requires that a given property on the resource has at least the given
value when compared as a version string. The actual database name of
the property must be in the new CamelCase style (as output by
propname_massage) since it is looked up by precisely that name and
possible legacy aliases are not considered. Lack of the property being
compared is taken a "no restriction" and hence is allowed.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 Osstest/ResourceCondition/PropMinVer.pm | 74 +++++++++++++++++++++++++++++++++
 ts-hosts-allocate-Executive             | 25 +++++++++--
 2 files changed, 96 insertions(+), 3 deletions(-)
 create mode 100644 Osstest/ResourceCondition/PropMinVer.pm

diff --git a/Osstest/ResourceCondition/PropMinVer.pm 
b/Osstest/ResourceCondition/PropMinVer.pm
new file mode 100644
index 0000000..d842fe7
--- /dev/null
+++ b/Osstest/ResourceCondition/PropMinVer.pm
@@ -0,0 +1,74 @@
+# This is part of "osstest", an automated testing framework for Xen.
+# Copyright (C) 2015 Citrix Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Osstest::ResourceCondition::PropMinVer;
+
+use strict;
+use warnings;
+
+use Osstest;
+use Osstest::TestSupport;
+
+use Sort::Versions;
+
+use overload '""' => 'stringify';
+
+BEGIN {
+    use Exporter ();
+    our ($VERSION, @ISA, @EXPORT, @EXPORT_OK, %EXPORT_TAGS);
+    $VERSION     = 1.00;
+    @ISA         = qw(Exporter);
+    @EXPORT      = qw();
+    %EXPORT_TAGS = ( );
+
+    @EXPORT_OK   = qw();
+}
+
+sub new {
+    my ($class, $name, $prop, $val) = @_;
+    return bless {
+       Prop => propname_massage($prop),
+       MinVal => $val
+    }, $class;
+}
+
+sub stringify {
+    my ($pmv) = @_;
+    return "$pmv->{MinVal} >= property $pmv->{Prop}";
+}
+
+sub check {
+    my ($pmv, $restype, $resname) = @_;
+
+    # Using _cached avoids needing to worry about $dbh_tests being
+    # closed/reopened between invocations
+    my $hpropq = $dbh_tests->prepare_cached(<<END);
+       SELECT val FROM resource_properties
+       WHERE restype = ? AND resname = ? AND name = ?
+END
+    $hpropq->execute($restype, $resname, $pmv->{Prop});
+
+    my $row= $hpropq->fetchrow_arrayref();
+    $hpropq->finish();
+
+    return 1 unless $row; # No prop == no restriction.
+
+    # If the required minimum is >= to the resource's minimum then the
+    # resource meets the requirement.
+    return versioncmp($pmv->{MinVal}, $row->[0]) >= 0;
+}
+
+1;
diff --git a/ts-hosts-allocate-Executive b/ts-hosts-allocate-Executive
index 294395d..345ffeb 100755
--- a/ts-hosts-allocate-Executive
+++ b/ts-hosts-allocate-Executive
@@ -213,7 +213,7 @@ sub compute_hids () {
     our %equivs;
 
     foreach my $ident (@ARGV) {
-        my $hid= { };
+        my $hid= { Conds => { host => [] } };
         my $override_use;
         if ($ident =~ m/\=/) {
             $hid->{OverrideUse}= $'; #'
@@ -251,11 +251,23 @@ sub compute_hids () {
                 my $equiv= $hid->{Equiv}= $equivs{$formalclass};
                 print DEBUG "HID $ident FLAG $flag EQUIV $equiv->{Wanted}\n";
                 next;
-            }
+            } elsif ($flag =~ m/:/) {
+               my (@c) = split /:/, $flag;
+               my $o;
+               eval ("use Osstest::ResourceCondition::$c[0];".
+                     "\$o = Osstest::ResourceCondition::$c[0]->new(\@c);")
+                   or die "get ResourceCondition $@";
+
+               push @{$hid->{Conds}{host}}, $o;
+
+               print DEBUG "HID $ident FLAG $flag HCOND $o\n";
+               next;
+           }
             $flags{$flag}= 1;
         }
         $hid->{Flags}= \%flags;
-        print DEBUG "HID $ident FLAGS ".(join ',', sort keys %flags)."\n";
+        print DEBUG "HID $ident FLAGS ".(join ',', sort keys %flags).
+           " + ".scalar @{$hid->{Conds}{host}}." host conditions(s)\n";
         push @hids, $hid;
     }
 }
@@ -363,6 +375,13 @@ END
             push @{ $candrow->{Warnings} },
                 "specified host lacks flags @missingflags";
         }
+
+       foreach my $c (@{$hid->{Conds}{$candrow->{restype}}}) {
+           if (!$c->check($candrow->{restype}, $candrow->{resname})) {
+               print DEBUG "$dbg failed $c condition\n";
+               next CANDIDATE unless defined $use;
+           }
+       }
         $any++;
 
         print DEBUG "$dbg GOOD\n";
-- 
2.5.1


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