generate the association hash from the top down

This prevents us from walking back up the parent tree once for each
leaf.

1 files changed, 15 insertions, 17 deletions

diff --git a/activerecord/lib/active_record/associations/join_dependency.rb b/activerecord/lib/active_record/associations/join_dependency.rb
index ce6cd1461a..7df89ba360 100644
--- a/activerecord/lib/active_record/associations/join_dependency.rb
+++ b/activerecord/lib/active_record/associations/join_dependency.rb
@@ -71,6 +71,10 @@ module ActiveRecord
           @children  = []
         end
 
+        def association_hash
+          association_hash_iter children, {}
+        end
+
         def each
           yield self
           iter = lambda { |list|
@@ -81,6 +85,15 @@ module ActiveRecord
           }
           iter.call children
         end
+
+        private
+        def association_hash_iter nodes, acc
+          nodes.each { |node|
+            h = acc[node.join_part.reflection.name] ||= {}
+            association_hash_iter node.children, h
+          }
+          acc
+        end
       end
 
       def join_parts
@@ -93,7 +106,7 @@ module ActiveRecord
         associations.reject { |association|
           join_assocs.detect { |a| association == a }
         }.each { |association|
-          join_node = find_parent_node(association.parent) || @join_part
+          join_node = find_parent_node(association.parent) || @join_parts
           type      = association.join_type
           find_or_build_scalar association.reflection, join_node, type
         }
@@ -144,9 +157,7 @@ module ActiveRecord
       private
 
       def associations
-        join_associations.each_with_object({}) do |assoc, tree|
-          cache_joined_association assoc, tree
-        end
+        @join_parts.association_hash
       end
 
       def find_parent_node(parent)
@@ -187,19 +198,6 @@ module ActiveRecord
         end
       end
 
-      def cache_joined_association(association, tree)
-        associations = []
-        parent = association.parent
-        while parent != join_base
-          associations.unshift(parent.reflection.name)
-          parent = parent.parent
-        end
-        ref = associations.inject(tree) do |cache,key|
-          cache[key]
-        end
-        ref[association.reflection.name] ||= {}
-      end
-
       def find_reflection(klass, name)
         klass.reflect_on_association(name.intern) or
           raise ConfigurationError, "Association named '#{ name }' was not found on #{ klass.name }; perhaps you misspelled it?"