From bd3b28f7f181dce53e872daa23dda101498b8fb4 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Mon, 14 Apr 2014 16:26:28 -0700
Subject: cache scope building on associations

SQL statements for querying associations are now cached
---
 .../associations/association_scope.rb              | 55 +++++++++++++++++++---
 .../associations/collection_association.rb         | 16 ++++++-
 2 files changed, 64 insertions(+), 7 deletions(-)

(limited to 'activerecord/lib/active_record/associations')

diff --git a/activerecord/lib/active_record/associations/association_scope.rb b/activerecord/lib/active_record/associations/association_scope.rb
index bb889a8f3b..f1a3b23d5a 100644
--- a/activerecord/lib/active_record/associations/association_scope.rb
+++ b/activerecord/lib/active_record/associations/association_scope.rb
@@ -1,12 +1,34 @@
 module ActiveRecord
   module Associations
     class AssociationScope #:nodoc:
-      INSTANCE = new
-
       def self.scope(association, connection)
         INSTANCE.scope association, connection
       end
 
+      class BindSubstitution
+        def initialize(block)
+          @block = block
+        end
+
+        def bind_value(scope, column, value, alias_tracker)
+          substitute = alias_tracker.connection.substitute_at(
+            column, scope.bind_values.length)
+          scope.bind_values += [[column, @block.call(value)]]
+          substitute
+        end
+      end
+
+      def self.create(&block)
+        block = block ? block : lambda { |val| val }
+        new BindSubstitution.new(block)
+      end
+
+      def initialize(bind_substitution)
+        @bind_substitution = bind_substitution
+      end
+
+      INSTANCE = create
+
       def scope(association, connection)
         klass         = association.klass
         reflection    = association.reflection
@@ -22,6 +44,30 @@ module ActiveRecord
         Arel::Nodes::InnerJoin
       end
 
+      def self.get_bind_values(owner, chain)
+        bvs = []
+        chain.each_with_index do |reflection, i|
+          if reflection.source_macro == :belongs_to
+            foreign_key = reflection.foreign_key
+          else
+            foreign_key = reflection.active_record_primary_key
+          end
+
+          if reflection == chain.last
+            bvs << owner[foreign_key]
+
+            if reflection.type
+              bvs << owner.class.base_class.name
+            end
+          else
+            if reflection.type
+              bvs << chain[i + 1].klass.base_class.name
+            end
+          end
+        end
+        bvs
+      end
+
       private
 
       def construct_tables(chain, klass, refl, alias_tracker)
@@ -49,10 +95,7 @@ module ActiveRecord
       end
 
       def bind_value(scope, column, value, alias_tracker)
-        substitute = alias_tracker.connection.substitute_at(
-          column, scope.bind_values.length)
-        scope.bind_values += [[column, value]]
-        substitute
+        @bind_substitution.bind_value scope, column, value, alias_tracker
       end
 
       def bind(scope, table_name, column_name, value, tracker)
diff --git a/activerecord/lib/active_record/associations/collection_association.rb b/activerecord/lib/active_record/associations/collection_association.rb
index 803e3ab9ab..b623f1375d 100644
--- a/activerecord/lib/active_record/associations/collection_association.rb
+++ b/activerecord/lib/active_record/associations/collection_association.rb
@@ -412,9 +412,23 @@ module ActiveRecord
       end
 
       private
+      def get_records
+        return scope.to_a if reflection.scope_chain.any?(&:any?)
+
+        conn = klass.connection
+        sc = reflection.association_scope_cache(conn) do
+          StatementCache.create(conn) { |params|
+            as = AssociationScope.create { params.bind }
+            target_scope.merge as.scope(self, conn)
+          }
+        end
+
+        binds = AssociationScope.get_bind_values(owner, reflection.chain)
+        sc.execute binds, klass, klass.connection
+      end
 
         def find_target
-          records = scope.to_a
+          records = get_records
           records.each { |record| set_inverse_instance(record) }
           records
         end
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