[PATCH] testbot: Avoid reference cycles between Collections.

[Francois Gouget]

Specifically when the Collection is used for a Detailref property (e.g.
Jobs->Steps), it should not keep a reference to the parent's ScopeItems.
Reference cycles cause Perl's primitive reference-count based garbage
collector to leak memory.

Signed-off-by: Francois Gouget <fgouget at codeweavers.com>
---
 testbot/lib/ObjectModel/Collection.pm | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/testbot/lib/ObjectModel/Collection.pm b/testbot/lib/ObjectModel/Collection.pm
index c3bc438c..a9ec9958 100644
--- a/testbot/lib/ObjectModel/Collection.pm
+++ b/testbot/lib/ObjectModel/Collection.pm
@@ -43,6 +43,7 @@ require Exporter;
 @ISA = qw(Exporter);
 @EXPORT_OK = qw(&new &ComputeMasterKey);
 
+use Scalar::Util qw(weaken);
 use ObjectModel::BackEnd;
 use ObjectModel::Item;
 use ObjectModel::PropertyDescriptor;
@@ -96,6 +97,14 @@ sub new($$$$$;$$@)
               Filters             => {},
               AllScopeItems       => $AllScopeItems || {},
               Items               => undef};
+  if ($AllScopeItems)
+  {
+    # Avoid memory cycles in case Items have Detailref properties:
+    #   ParentCollection{AllScopeItems} --> ParentItem
+    #   ParentItem --DetailrefProperty--> DetailCollection
+    #   DetailCollection{AllScopeItems} == ParentCollection{AllScopeItems}
+    weaken($self->{AllScopeItems});
+  }
   $self = bless $self, $class;
   $self->_initialize(@_);
   return $self;
-- 
2.15.1