Merge commit 'mainstream/master'

Conflicts:

	actionpack/lib/action_controller/resources.rb

29 files changed, 816 insertions, 430 deletions

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index 12295ac799..58d0669770 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,9 @@
 *Edge*
 
+* Connection pooling.  #936 [Nick Sieger]
+
+* Merge scoped :joins together instead of overwriting them. May expose scoping bugs in your code!  #501 [Andrew White]
+
 * before_save, before_validation and before_destroy callbacks that return false will now ROLLBACK the transaction.  Previously this would have been committed before the processing was aborted. #891 [Xavier Noria]
 
 * Transactional migrations for databases which support them.  #834 [divoxx, Adam Wiggins, Tarmo Tänav]
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 1af8ddcaf8..6405071354 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -878,10 +878,10 @@ module ActiveRecord
 
           method_name = "has_one_after_save_for_#{reflection.name}".to_sym
           define_method(method_name) do
-            association = instance_variable_get("#{ivar}") if instance_variable_defined?("#{ivar}")
+            association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
 
-            if !association.nil? && (new_record? || association.new_record? || association["#{reflection.primary_key_name}"] != id)
-              association["#{reflection.primary_key_name}"] = id
+            if !association.nil? && (new_record? || association.new_record? || association[reflection.primary_key_name] != id)
+              association[reflection.primary_key_name] = id
               association.save(true)
             end
           end
@@ -994,7 +994,7 @@ module ActiveRecord
 
           method_name = "polymorphic_belongs_to_before_save_for_#{reflection.name}".to_sym
           define_method(method_name) do
-            association = instance_variable_get("#{ivar}") if instance_variable_defined?("#{ivar}")
+            association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
 
             if association && association.target
               if association.new_record?
@@ -1002,8 +1002,8 @@ module ActiveRecord
               end
 
               if association.updated?
-                self["#{reflection.primary_key_name}"] = association.id
-                self["#{reflection.options[:foreign_type]}"] = association.class.base_class.name.to_s
+                self[reflection.primary_key_name] = association.id
+                self[reflection.options[:foreign_type]] = association.class.base_class.name.to_s
               end
             end
           end
@@ -1015,7 +1015,7 @@ module ActiveRecord
 
           method_name = "belongs_to_before_save_for_#{reflection.name}".to_sym
           define_method(method_name) do
-            association = instance_variable_get("#{ivar}") if instance_variable_defined?("#{ivar}")
+            association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
 
             if !association.nil?
               if association.new_record?
@@ -1023,7 +1023,7 @@ module ActiveRecord
               end
 
               if association.updated?
-                self["#{reflection.primary_key_name}"] = association.id
+                self[reflection.primary_key_name] = association.id
               end
             end
           end
@@ -1038,15 +1038,15 @@ module ActiveRecord
 
           method_name = "belongs_to_counter_cache_after_create_for_#{reflection.name}".to_sym
           define_method(method_name) do
-            association = send("#{reflection.name}")
-            association.class.increment_counter("#{cache_column}", send("#{reflection.primary_key_name}")) unless association.nil?
+            association = send(reflection.name)
+            association.class.increment_counter(cache_column, send(reflection.primary_key_name)) unless association.nil?
           end
           after_create method_name
 
           method_name = "belongs_to_counter_cache_before_destroy_for_#{reflection.name}".to_sym
           define_method(method_name) do
-            association = send("#{reflection.name}")
-            association.class.decrement_counter("#{cache_column}", send("#{reflection.primary_key_name}")) unless association.nil?
+            association = send(reflection.name)
+            association.class.decrement_counter(cache_column, send(reflection.primary_key_name)) unless association.nil?
           end
           before_destroy method_name
 
@@ -1164,6 +1164,9 @@ module ActiveRecord
       #   If true, duplicate associated objects will be ignored by accessors and query methods.
       # [:finder_sql]
       #   Overwrite the default generated SQL statement used to fetch the association with a manual statement
+      # [:counter_sql]
+      #   Specify a complete SQL statement to fetch the size of the association. If <tt>:finder_sql</tt> is
+      #   specified but not <tt>:counter_sql</tt>, <tt>:counter_sql</tt> will be generated by replacing <tt>SELECT ... FROM</tt> with <tt>SELECT COUNT(*) FROM</tt>.
       # [:delete_sql]
       #   Overwrite the default generated SQL statement used to remove links between the associated
       #   classes with a manual statement.
@@ -1300,7 +1303,11 @@ module ActiveRecord
           end
 
           define_method("#{reflection.name.to_s.singularize}_ids") do
-            send(reflection.name).map { |record| record.id }
+            if send(reflection.name).loaded?
+              send(reflection.name).map(&:id)
+            else
+              send(reflection.name).all(:select => "#{reflection.quoted_table_name}.#{reflection.klass.primary_key}").map(&:id)
+            end
           end
         end
 
@@ -1321,19 +1328,19 @@ module ActiveRecord
             end
           end
         end
-        
+
         def add_single_associated_validation_callbacks(association_name)
           method_name = "validate_associated_records_for_#{association_name}".to_sym
           define_method(method_name) do
             association = instance_variable_get("@#{association_name}")
             if !association.nil?
-              errors.add "#{association_name}" unless association.target.nil? || association.valid?
+              errors.add association_name unless association.target.nil? || association.valid?
             end
           end
-        
+
           validate method_name
         end
-        
+
         def add_multiple_associated_validation_callbacks(association_name)
           method_name = "validate_associated_records_for_#{association_name}".to_sym
           ivar = "@#{association_name}"
@@ -1349,7 +1356,7 @@ module ActiveRecord
               else
                 association.target.select { |record| record.new_record? }
               end.each do |record|
-                errors.add "#{association_name}" unless record.valid?
+                errors.add association_name unless record.valid?
               end
             end
           end
@@ -1369,7 +1376,7 @@ module ActiveRecord
 
           method_name = "after_create_or_update_associated_records_for_#{association_name}".to_sym
           define_method(method_name) do
-            association = instance_variable_get("#{ivar}") if instance_variable_defined?("#{ivar}")
+            association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
 
             records_to_save = if @new_record_before_save
               association
@@ -1436,7 +1443,7 @@ module ActiveRecord
               when :destroy
                 method_name = "has_many_dependent_destroy_for_#{reflection.name}".to_sym
                 define_method(method_name) do
-                  send("#{reflection.name}").each { |o| o.destroy }
+                  send(reflection.name).each { |o| o.destroy }
                 end
                 before_destroy method_name
               when :delete_all
@@ -1455,22 +1462,22 @@ module ActiveRecord
               when :destroy
                 method_name = "has_one_dependent_destroy_for_#{reflection.name}".to_sym
                 define_method(method_name) do
-                  association = send("#{reflection.name}")
+                  association = send(reflection.name)
                   association.destroy unless association.nil?
                 end
                 before_destroy method_name
               when :delete
                 method_name = "has_one_dependent_delete_for_#{reflection.name}".to_sym
                 define_method(method_name) do
-                  association = send("#{reflection.name}")
+                  association = send(reflection.name)
                   association.class.delete(association.id) unless association.nil?
                 end
                 before_destroy method_name
               when :nullify
                 method_name = "has_one_dependent_nullify_for_#{reflection.name}".to_sym
                 define_method(method_name) do
-                  association = send("#{reflection.name}")
-                  association.update_attribute("#{reflection.primary_key_name}", nil) unless association.nil?
+                  association = send(reflection.name)
+                  association.update_attribute(reflection.primary_key_name, nil) unless association.nil?
                 end
                 before_destroy method_name
               else
@@ -1485,14 +1492,14 @@ module ActiveRecord
               when :destroy
                 method_name = "belongs_to_dependent_destroy_for_#{reflection.name}".to_sym
                 define_method(method_name) do
-                  association = send("#{reflection.name}")
+                  association = send(reflection.name)
                   association.destroy unless association.nil?
                 end
                 before_destroy method_name
               when :delete
                 method_name = "belongs_to_dependent_delete_for_#{reflection.name}".to_sym
                 define_method(method_name) do
-                  association = send("#{reflection.name}")
+                  association = send(reflection.name)
                   association.class.delete(association.id) unless association.nil?
                 end
                 before_destroy method_name
@@ -1527,7 +1534,7 @@ module ActiveRecord
 
           create_reflection(:has_one, association_id, options, self)
         end
-        
+
         def create_has_one_through_reflection(association_id, options)
           options.assert_valid_keys(
             :class_name, :foreign_key, :remote, :select, :conditions, :order, :include, :dependent, :counter_cache, :extend, :as, :through, :source, :source_type, :validate
@@ -1595,7 +1602,7 @@ module ActiveRecord
           sql = "SELECT #{column_aliases(join_dependency)} FROM #{(scope && scope[:from]) || options[:from] || quoted_table_name} "
           sql << join_dependency.join_associations.collect{|join| join.association_join }.join
 
-          add_joins!(sql, options, scope)
+          add_joins!(sql, options[:joins], scope)
           add_conditions!(sql, options[:conditions], scope)
           add_limited_ids_condition!(sql, options, join_dependency) if !using_limitable_reflections?(join_dependency.reflections) && ((scope && scope[:limit]) || options[:limit])
 
@@ -1651,7 +1658,7 @@ module ActiveRecord
 
           if is_distinct
             sql << distinct_join_associations.collect { |assoc| assoc.association_join }.join
-            add_joins!(sql, options, scope)
+            add_joins!(sql, options[:joins], scope)
           end
 
           add_conditions!(sql, options[:conditions], scope)
@@ -1919,7 +1926,7 @@ module ActiveRecord
             end
 
             def aliased_primary_key
-              "#{ aliased_prefix }_r0"
+              "#{aliased_prefix}_r0"
             end
 
             def aliased_table_name
@@ -1931,7 +1938,7 @@ module ActiveRecord
                 @column_names_with_alias = []
 
                 ([primary_key] + (column_names - [primary_key])).each_with_index do |column_name, i|
-                  @column_names_with_alias << [column_name, "#{ aliased_prefix }_r#{ i }"]
+                  @column_names_with_alias << [column_name, "#{aliased_prefix}_r#{i}"]
                 end
               end
 
@@ -1968,11 +1975,11 @@ module ActiveRecord
               @aliased_prefix     = "t#{ join_dependency.joins.size }"
               @parent_table_name  = parent.active_record.table_name
               @aliased_table_name = aliased_table_name_for(table_name)
-              
+
               if reflection.macro == :has_and_belongs_to_many
                 @aliased_join_table_name = aliased_table_name_for(reflection.options[:join_table], "_join")
               end
-        
+
               if [:has_many, :has_one].include?(reflection.macro) && reflection.options[:through]
                 @aliased_join_table_name = aliased_table_name_for(reflection.through_reflection.klass.table_name, "_join")
               end
@@ -2109,7 +2116,7 @@ module ActiveRecord
             end
 
             protected
-            
+
               def aliased_table_name_for(name, suffix = nil)
                 if !parent.table_joins.blank? && parent.table_joins.to_s.downcase =~ %r{join(\s+\w+)?\s+#{name.downcase}\son}
                   @join_dependency.table_aliases[name] += 1
@@ -2127,7 +2134,7 @@ module ActiveRecord
 
                 name
               end
-              
+
               def pluralize(table_name)
                 ActiveRecord::Base.pluralize_table_names ? table_name.to_s.pluralize : table_name
               end
diff --git a/activerecord/lib/active_record/associations/association_collection.rb b/activerecord/lib/active_record/associations/association_collection.rb
index a12d4face4..168443e092 100644
--- a/activerecord/lib/active_record/associations/association_collection.rb
+++ b/activerecord/lib/active_record/associations/association_collection.rb
@@ -141,6 +141,35 @@ module ActiveRecord
         end
       end
 
+      # Count all records using SQL. If the +:counter_sql+ option is set for the association, it will
+      # be used for the query. If no +:counter_sql+ was supplied, but +:finder_sql+ was set, the
+      # descendant's +construct_sql+ method will have set :counter_sql automatically.
+      # Otherwise, construct options and pass them with scope to the target class's +count+.
+      def count(*args)
+        if @reflection.options[:counter_sql]
+          @reflection.klass.count_by_sql(@counter_sql)
+        else
+          column_name, options = @reflection.klass.send(:construct_count_options_from_args, *args)
+          if @reflection.options[:uniq]
+            # This is needed because 'SELECT count(DISTINCT *)..' is not valid SQL.
+            column_name = "#{@reflection.quoted_table_name}.#{@reflection.klass.primary_key}" if column_name == :all
+            options.merge!(:distinct => true)
+          end
+
+          value = @reflection.klass.send(:with_scope, construct_scope) { @reflection.klass.count(column_name, options) }
+
+          limit  = @reflection.options[:limit]
+          offset = @reflection.options[:offset]
+
+          if limit || offset
+            [ [value - offset.to_i, 0].max, limit.to_i ].min
+          else
+            value
+          end
+        end
+      end
+
+
       # Remove +records+ from this association.  Does not destroy +records+.
       def delete(*records)
         records = flatten_deeper(records)
diff --git a/activerecord/lib/active_record/associations/has_and_belongs_to_many_association.rb b/activerecord/lib/active_record/associations/has_and_belongs_to_many_association.rb
index e7e433b6b6..3d689098b5 100644
--- a/activerecord/lib/active_record/associations/has_and_belongs_to_many_association.rb
+++ b/activerecord/lib/active_record/associations/has_and_belongs_to_many_association.rb
@@ -78,6 +78,16 @@ module ActiveRecord
           end
 
           @join_sql = "INNER JOIN #{@owner.connection.quote_table_name @reflection.options[:join_table]} ON #{@reflection.quoted_table_name}.#{@reflection.klass.primary_key} = #{@owner.connection.quote_table_name @reflection.options[:join_table]}.#{@reflection.association_foreign_key}"
+
+          if @reflection.options[:counter_sql]
+            @counter_sql = interpolate_sql(@reflection.options[:counter_sql])
+          elsif @reflection.options[:finder_sql]
+            # replace the SELECT clause with COUNT(*), preserving any hints within /* ... */
+            @reflection.options[:counter_sql] = @reflection.options[:finder_sql].sub(/SELECT (\/\*.*?\*\/ )?(.*)\bFROM\b/im) { "SELECT #{$1}COUNT(*) FROM" }
+            @counter_sql = interpolate_sql(@reflection.options[:counter_sql])
+          else
+            @counter_sql = @finder_sql
+          end
         end
 
         def construct_scope
diff --git a/activerecord/lib/active_record/associations/has_many_association.rb b/activerecord/lib/active_record/associations/has_many_association.rb
index 451bf8faa9..dda22668c6 100644
--- a/activerecord/lib/active_record/associations/has_many_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_association.rb
@@ -5,32 +5,6 @@ module ActiveRecord
     # If the association has a <tt>:through</tt> option further specialization
     # is provided by its child HasManyThroughAssociation.
     class HasManyAssociation < AssociationCollection #:nodoc:
-      # Count the number of associated records. All arguments are optional.
-      def count(*args)
-        if @reflection.options[:counter_sql]
-          @reflection.klass.count_by_sql(@counter_sql)
-        elsif @reflection.options[:finder_sql]
-          @reflection.klass.count_by_sql(@finder_sql)
-        else
-          column_name, options = @reflection.klass.send(:construct_count_options_from_args, *args)          
-          options[:conditions] = options[:conditions].blank? ?
-            @finder_sql :
-            @finder_sql + " AND (#{sanitize_sql(options[:conditions])})"
-          options[:include] ||= @reflection.options[:include]
-
-          value = @reflection.klass.count(column_name, options)
-
-          limit  = @reflection.options[:limit]
-          offset = @reflection.options[:offset]
-
-          if limit || offset
-            [ [value - offset.to_i, 0].max, limit.to_i ].min
-          else
-            value
-          end
-        end
-      end
-
       protected
         def owner_quoted_id
           if @reflection.options[:primary_key]
diff --git a/activerecord/lib/active_record/associations/has_many_through_association.rb b/activerecord/lib/active_record/associations/has_many_through_association.rb
index 24b02efc35..84fa900f46 100644
--- a/activerecord/lib/active_record/associations/has_many_through_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_through_association.rb
@@ -31,16 +31,6 @@ module ActiveRecord
         return count
       end
       
-      def count(*args)
-        column_name, options = @reflection.klass.send(:construct_count_options_from_args, *args)
-        if @reflection.options[:uniq]
-          # This is needed because 'SELECT count(DISTINCT *)..' is not valid SQL statement.
-          column_name = "#{@reflection.quoted_table_name}.#{@reflection.klass.primary_key}" if column_name == :all
-          options.merge!(:distinct => true) 
-        end
-        @reflection.klass.send(:with_scope, construct_scope) { @reflection.klass.count(column_name, options) } 
-      end
-
       protected
         def construct_find_options!(options)
           options[:select]  = construct_select(options[:select])
diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb
index fab16a4446..0a1baff87d 100644
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -214,7 +214,7 @@ module ActiveRecord
             if logger
               logger.warn "Exception occurred during reader method compilation."
               logger.warn "Maybe #{attr_name} is not a valid Ruby identifier?"
-              logger.warn "#{err.message}"
+              logger.warn err.message
             end
           end
         end
@@ -330,8 +330,8 @@ module ActiveRecord
       end
     end
     
-    # A Person object with a name attribute can ask <tt>person.respond_to?("name")</tt>,
-    # <tt>person.respond_to?("name=")</tt>, and <tt>person.respond_to?("name?")</tt>
+    # A Person object with a name attribute can ask <tt>person.respond_to?(:name)</tt>,
+    # <tt>person.respond_to?(:name=)</tt>, and <tt>person.respond_to?(:name?)</tt>
     # which will all return +true+.
     alias :respond_to_without_attributes? :respond_to?
     def respond_to?(method, include_priv = false)
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 4a23c8c690..3419aad580 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -452,13 +452,6 @@ module ActiveRecord #:nodoc:
     cattr_accessor :default_timezone, :instance_writer => false
     @@default_timezone = :local
 
-    # Determines whether to use a connection for each thread, or a single shared connection for all threads.
-    # Defaults to false. If you're writing a threaded application, set to true
-    # and periodically call verify_active_connections! to clear out connections
-    # assigned to stale threads.
-    cattr_accessor :allow_concurrency, :instance_writer => false
-    @@allow_concurrency = false
-
     # Specifies the format to use when dumping the database schema with Rails'
     # Rakefile.  If :sql, the schema is dumped as (potentially database-
     # specific) SQL statements.  If :ruby, the schema is dumped as an
@@ -930,12 +923,12 @@ module ActiveRecord #:nodoc:
       # To start from an all-closed default and enable attributes as needed,
       # have a look at +attr_accessible+.
       def attr_protected(*attributes)
-        write_inheritable_attribute("attr_protected", Set.new(attributes.map(&:to_s)) + (protected_attributes || []))
+        write_inheritable_attribute(:attr_protected, Set.new(attributes.map(&:to_s)) + (protected_attributes || []))
       end
 
       # Returns an array of all the attributes that have been protected from mass-assignment.
       def protected_attributes # :nodoc:
-        read_inheritable_attribute("attr_protected")
+        read_inheritable_attribute(:attr_protected)
       end
 
       # Specifies a white list of model attributes that can be set via
@@ -963,22 +956,22 @@ module ActiveRecord #:nodoc:
       #   customer.credit_rating = "Average"
       #   customer.credit_rating # => "Average"
       def attr_accessible(*attributes)
-        write_inheritable_attribute("attr_accessible", Set.new(attributes.map(&:to_s)) + (accessible_attributes || []))
+        write_inheritable_attribute(:attr_accessible, Set.new(attributes.map(&:to_s)) + (accessible_attributes || []))
       end
 
       # Returns an array of all the attributes that have been made accessible to mass-assignment.
       def accessible_attributes # :nodoc:
-        read_inheritable_attribute("attr_accessible")
+        read_inheritable_attribute(:attr_accessible)
       end
 
        # Attributes listed as readonly can be set for a new record, but will be ignored in database updates afterwards.
        def attr_readonly(*attributes)
-         write_inheritable_attribute("attr_readonly", Set.new(attributes.map(&:to_s)) + (readonly_attributes || []))
+         write_inheritable_attribute(:attr_readonly, Set.new(attributes.map(&:to_s)) + (readonly_attributes || []))
        end
 
        # Returns an array of all the attributes that have been specified as readonly.
        def readonly_attributes
-         read_inheritable_attribute("attr_readonly")
+         read_inheritable_attribute(:attr_readonly)
        end
 
       # If you have an attribute that needs to be saved to the database as an object, and retrieved as the same object,
@@ -1002,7 +995,7 @@ module ActiveRecord #:nodoc:
 
       # Returns a hash of all the attributes that have been specified for serialization as keys and their class restriction as values.
       def serialized_attributes
-        read_inheritable_attribute("attr_serialized") or write_inheritable_attribute("attr_serialized", {})
+        read_inheritable_attribute(:attr_serialized) or write_inheritable_attribute(:attr_serialized, {})
       end
 
 
@@ -1552,7 +1545,7 @@ module ActiveRecord #:nodoc:
           sql  = "SELECT #{options[:select] || (scope && scope[:select]) || ((options[:joins] || (scope && scope[:joins])) && quoted_table_name + '.*') || '*'} "
           sql << "FROM #{(scope && scope[:from]) || options[:from] || quoted_table_name} "
 
-          add_joins!(sql, options, scope)
+          add_joins!(sql, options[:joins], scope)
           add_conditions!(sql, options[:conditions], scope)
 
           add_group!(sql, options[:group], scope)
@@ -1568,6 +1561,22 @@ module ActiveRecord #:nodoc:
          (safe_to_array(first) + safe_to_array(second)).uniq
         end
 
+        def merge_joins(first, second)
+          if first.is_a?(String) && second.is_a?(String)
+            "#{first} #{second}"
+          elsif first.is_a?(String) || second.is_a?(String)
+            if first.is_a?(String)
+              join_dependency = ActiveRecord::Associations::ClassMethods::InnerJoinDependency.new(self, second, nil)
+              "#{first} #{join_dependency.join_associations.collect { |assoc| assoc.association_join }.join}"
+            else
+              join_dependency = ActiveRecord::Associations::ClassMethods::InnerJoinDependency.new(self, first, nil)
+              "#{join_dependency.join_associations.collect { |assoc| assoc.association_join }.join} #{second}"
+            end
+          else
+            (safe_to_array(first) + safe_to_array(second)).uniq
+          end
+        end
+
         # Object#to_a is deprecated, though it does have the desired behavior
         def safe_to_array(o)
           case o
@@ -1623,16 +1632,15 @@ module ActiveRecord #:nodoc:
         end
 
         # The optional scope argument is for the current <tt>:find</tt> scope.
-        def add_joins!(sql, options, scope = :auto)
+        def add_joins!(sql, joins, scope = :auto)
           scope = scope(:find) if :auto == scope
-          [(scope && scope[:joins]), options[:joins]].each do |join|
-            case join
-            when Symbol, Hash, Array
-              join_dependency = ActiveRecord::Associations::ClassMethods::InnerJoinDependency.new(self, join, nil)
-              sql << " #{join_dependency.join_associations.collect { |assoc| assoc.association_join }.join} "
-            else
-              sql << " #{join} "
-            end
+          merged_joins = scope && scope[:joins] && joins ? merge_joins(scope[:joins], joins) : (joins || scope && scope[:joins])
+          case merged_joins
+          when Symbol, Hash, Array
+            join_dependency = ActiveRecord::Associations::ClassMethods::InnerJoinDependency.new(self, merged_joins, nil)
+            sql << " #{join_dependency.join_associations.collect { |assoc| assoc.association_join }.join} "
+          when String
+            sql << " #{merged_joins} "
           end
         end
 
@@ -1882,6 +1890,8 @@ module ActiveRecord #:nodoc:
                         hash[method][key] = merge_conditions(params[key], hash[method][key])
                       elsif key == :include && merge
                         hash[method][key] = merge_includes(hash[method][key], params[key]).uniq
+                      elsif key == :joins && merge
+                        hash[method][key] = merge_joins(params[key], hash[method][key])
                       else
                         hash[method][key] = hash[method][key] || params[key]
                       end
@@ -1929,22 +1939,11 @@ module ActiveRecord #:nodoc:
           end
         end
 
-        def thread_safe_scoped_methods #:nodoc:
+        def scoped_methods #:nodoc:
           scoped_methods = (Thread.current[:scoped_methods] ||= {})
           scoped_methods[self] ||= []
         end
 
-        def single_threaded_scoped_methods #:nodoc:
-          @scoped_methods ||= []
-        end
-
-        # pick up the correct scoped_methods version from @@allow_concurrency
-        if @@allow_concurrency
-          alias_method :scoped_methods, :thread_safe_scoped_methods
-        else
-          alias_method :scoped_methods, :single_threaded_scoped_methods
-        end
-
         def current_scoped_methods #:nodoc:
           scoped_methods.last
         end
diff --git a/activerecord/lib/active_record/calculations.rb b/activerecord/lib/active_record/calculations.rb
index 26acbf53b5..a675af4787 100644
--- a/activerecord/lib/active_record/calculations.rb
+++ b/activerecord/lib/active_record/calculations.rb
@@ -188,7 +188,7 @@ module ActiveRecord
           end
 
           joins = ""
-          add_joins!(joins, options, scope)
+          add_joins!(joins, options[:joins], scope)
 
           if merged_includes.any?
             join_dependency = ActiveRecord::Associations::ClassMethods::JoinDependency.new(self, merged_includes, joins)
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
new file mode 100644
index 0000000000..838b0434b0
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb
@@ -0,0 +1,281 @@
+require 'monitor'
+require 'set'
+
+module ActiveRecord
+  # Raised when a connection could not be obtained within the connection
+  # acquisition timeout period.
+  class ConnectionTimeoutError < ConnectionNotEstablished
+  end
+
+  module ConnectionAdapters
+    # Connection pool base class for managing ActiveRecord database
+    # connections.
+    #
+    # Connections can be obtained and used from a connection pool in several
+    # ways:
+    #
+    # 1. Simply use ActiveRecord::Base.connection as with ActiveRecord 2.1 and
+    #    earlier (pre-connection-pooling). Eventually, when you're done with
+    #    the connection(s) and wish it to be returned to the pool, you call
+    #    ActiveRecord::Base.clear_active_connections!. This will be the
+    #    default behavior for ActiveRecord when used in conjunction with
+    #    ActionPack's request handling cycle.
+    # 2. Manually check out a connection from the pool with
+    #    ActiveRecord::Base.connection_pool.checkout. You are responsible for
+    #    returning this connection to the pool when finished by calling
+    #    ActiveRecord::Base.connection_pool.checkin(connection).
+    # 3. Use ActiveRecord::Base.connection_pool.with_connection(&block), which
+    #    obtains a connection, yields it as the sole argument to the block,
+    #    and returns it to the pool after the block completes.
+    #
+    # There are two connection-pooling-related options that you can add to
+    # your database connection configuration:
+    #
+    # * +pool+: number indicating size of connection pool (default 5)
+    # * +wait_timeout+: number of seconds to block and wait for a connection
+    #   before giving up and raising a timeout error (default 5 seconds).
+    class ConnectionPool
+      delegate :verification_timeout, :to => "::ActiveRecord::Base"
+      attr_reader :spec
+
+      def initialize(spec)
+        @spec = spec
+        # The cache of reserved connections mapped to threads
+        @reserved_connections = {}
+        # The mutex used to synchronize pool access
+        @connection_mutex = Monitor.new
+        @queue = @connection_mutex.new_cond
+        # default 5 second timeout
+        @timeout = spec.config[:wait_timeout] || 5
+        # default max pool size to 5
+        @size = (spec.config[:pool] && spec.config[:pool].to_i) || 5
+        @connections = []
+        @checked_out = []
+      end
+
+      # Retrieve the connection associated with the current thread, or call
+      # #checkout to obtain one if necessary.
+      #
+      # #connection can be called any number of times; the connection is
+      # held in a hash keyed by the thread id.
+      def connection
+        if conn = @reserved_connections[current_connection_id]
+          conn.verify!(verification_timeout)
+          conn
+        else
+          @reserved_connections[current_connection_id] = checkout
+        end
+      end
+
+      # Signal that the thread is finished with the current connection.
+      # #release_connection releases the connection-thread association
+      # and returns the connection to the pool.
+      def release_connection
+        conn = @reserved_connections.delete(current_connection_id)
+        checkin conn if conn
+      end
+
+      # Reserve a connection, and yield it to a block. Ensure the connection is
+      # checked back in when finished.
+      def with_connection
+        conn = checkout
+        yield conn
+      ensure
+        checkin conn
+      end
+
+      # Returns true if a connection has already been opened.
+      def connected?
+        !@connections.empty?
+      end
+
+      # Disconnect all connections in the pool.
+      def disconnect!
+        @reserved_connections.each do |name,conn|
+          checkin conn
+        end
+        @reserved_connections = {}
+        @connections.each do |conn|
+          conn.disconnect!
+        end
+        @connections = []
+      end
+
+      # Clears the cache which maps classes
+      def clear_reloadable_connections!
+        @reserved_connections.each do |name, conn|
+          checkin conn
+        end
+        @reserved_connections = {}
+        @connections.each do |conn|
+          conn.disconnect! if conn.requires_reloading?
+        end
+        @connections = []
+      end
+
+      # Verify active connections and remove and disconnect connections
+      # associated with stale threads.
+      def verify_active_connections! #:nodoc:
+        clear_stale_cached_connections!
+        @connections.each do |connection|
+          connection.verify!(verification_timeout)
+        end
+      end
+
+      # Return any checked-out connections back to the pool by threads that
+      # are no longer alive.
+      def clear_stale_cached_connections!
+        remove_stale_cached_threads!(@reserved_connections) do |name, conn|
+          checkin conn
+        end
+      end
+
+      # Check-out a database connection from the pool.
+      def checkout
+        # Checkout an available connection
+        conn = @connection_mutex.synchronize do
+          if @checked_out.size < @connections.size
+            checkout_existing_connection
+          elsif @connections.size < @size
+            checkout_new_connection
+          end
+        end
+        return conn if conn
+
+        # No connections available; wait for one
+        @connection_mutex.synchronize do
+          if @queue.wait(@timeout)
+            checkout_existing_connection
+          else
+            raise ConnectionTimeoutError, "could not obtain a database connection in a timely fashion"
+          end
+        end
+      end
+
+      # Check-in a database connection back into the pool.
+      def checkin(conn)
+        @connection_mutex.synchronize do
+          conn.run_callbacks :checkin
+          @checked_out.delete conn
+          @queue.signal
+        end
+      end
+
+      synchronize :clear_reloadable_connections!, :verify_active_connections!,
+        :connected?, :disconnect!, :with => :@connection_mutex
+
+      private
+      def new_connection
+        config = spec.config.reverse_merge(:allow_concurrency => true)
+        ActiveRecord::Base.send(spec.adapter_method, config)
+      end
+
+      def current_connection_id #:nodoc:
+        Thread.current.object_id
+      end
+
+      # Remove stale threads from the cache.
+      def remove_stale_cached_threads!(cache, &block)
+        keys = Set.new(cache.keys)
+
+        Thread.list.each do |thread|
+          keys.delete(thread.object_id) if thread.alive?
+        end
+        keys.each do |key|
+          next unless cache.has_key?(key)
+          block.call(key, cache[key])
+          cache.delete(key)
+        end
+      end
+
+      def checkout_new_connection
+        c = new_connection
+        @connections << c
+        checkout_and_verify(c)
+      end
+
+      def checkout_existing_connection
+        c = (@connections - @checked_out).first
+        checkout_and_verify(c)
+      end
+
+      def checkout_and_verify(c)
+        c.run_callbacks :checkout
+        c.verify!(verification_timeout)
+        @checked_out << c
+        c
+      end
+    end
+
+    class ConnectionHandler
+      def initialize(pools = {})
+        @connection_pools = pools
+      end
+
+      def connection_pools
+        @connection_pools ||= {}
+      end
+
+      def establish_connection(name, spec)
+        @connection_pools[name] = ConnectionAdapters::ConnectionPool.new(spec)
+      end
+
+      # Returns any connections in use by the current thread back to the pool,
+      # and also returns connections to the pool cached by threads that are no
+      # longer alive.
+      def clear_active_connections!
+        @connection_pools.each_value do |pool|
+          pool.release_connection
+          pool.clear_stale_cached_connections!
+        end
+      end
+
+      # Clears the cache which maps classes
+      def clear_reloadable_connections!
+        @connection_pools.each_value {|pool| pool.clear_reloadable_connections! }
+      end
+
+      def clear_all_connections!
+        @connection_pools.each_value {|pool| pool.disconnect! }
+      end
+
+      # Verify active connections.
+      def verify_active_connections! #:nodoc:
+        @connection_pools.each_value {|pool| pool.verify_active_connections! }
+      end
+
+      # Locate the connection of the nearest super class. This can be an
+      # active or defined connection: if it is the latter, it will be
+      # opened and set as the active connection for the class it was defined
+      # for (not necessarily the current class).
+      def retrieve_connection(klass) #:nodoc:
+        pool = retrieve_connection_pool(klass)
+        (pool && pool.connection) or raise ConnectionNotEstablished
+      end
+
+      # Returns true if a connection that's accessible to this class has
+      # already been opened.
+      def connected?(klass)
+        retrieve_connection_pool(klass).connected?
+      end
+
+      # Remove the connection for this class. This will close the active
+      # connection and the defined connection (if they exist). The result
+      # can be used as an argument for establish_connection, for easily
+      # re-establishing the connection.
+      def remove_connection(klass)
+        pool = @connection_pools[klass.name]
+        @connection_pools.delete_if { |key, value| value == pool }
+        pool.disconnect! if pool
+        pool.spec.config if pool
+      end
+
+      def retrieve_connection_pool(klass)
+        pool = @connection_pools[klass.name]
+        return pool if pool
+        return nil if ActiveRecord::Base == klass
+        retrieve_connection_pool klass.superclass
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb b/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
index 2a8807fb78..417a333aab 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/connection_specification.rb
@@ -1,5 +1,3 @@
-require 'set'
-
 module ActiveRecord
   class Base
     class ConnectionSpecification #:nodoc:
@@ -14,158 +12,9 @@ module ActiveRecord
     cattr_accessor :verification_timeout, :instance_writer => false
     @@verification_timeout = 0
 
-    # The class -> [adapter_method, config] map
-    @@defined_connections = {}
-
-    # The class -> thread id -> adapter cache. (class -> adapter if not allow_concurrency)
-    @@active_connections = {}
-
-    class << self
-      # Retrieve the connection cache.
-      def thread_safe_active_connections #:nodoc:
-        @@active_connections[Thread.current.object_id] ||= {}
-      end
-     
-      def single_threaded_active_connections #:nodoc:
-        @@active_connections
-      end
-     
-      # pick up the right active_connection method from @@allow_concurrency
-      if @@allow_concurrency
-        alias_method :active_connections, :thread_safe_active_connections
-      else
-        alias_method :active_connections, :single_threaded_active_connections
-      end
-     
-      # set concurrency support flag (not thread safe, like most of the methods in this file)
-      def allow_concurrency=(threaded) #:nodoc:
-        logger.debug "allow_concurrency=#{threaded}" if logger
-        return if @@allow_concurrency == threaded
-        clear_all_cached_connections!
-        @@allow_concurrency = threaded
-        method_prefix = threaded ? "thread_safe" : "single_threaded"
-        sing = (class << self; self; end)
-        [:active_connections, :scoped_methods].each do |method|
-          sing.send(:alias_method, method, "#{method_prefix}_#{method}")
-        end
-        log_connections if logger
-      end
-      
-      def active_connection_name #:nodoc:
-        @active_connection_name ||=
-           if active_connections[name] || @@defined_connections[name]
-             name
-           elsif self == ActiveRecord::Base
-             nil
-           else
-             superclass.active_connection_name
-           end
-      end
-
-      def clear_active_connection_name #:nodoc:
-        @active_connection_name = nil
-        subclasses.each { |klass| klass.clear_active_connection_name }
-      end
-
-      # Returns the connection currently associated with the class. This can
-      # also be used to "borrow" the connection to do database work unrelated
-      # to any of the specific Active Records.
-      def connection
-        if defined?(@active_connection_name) && (conn = active_connections[@active_connection_name])
-          conn
-        else
-          # retrieve_connection sets the cache key.
-          conn = retrieve_connection
-          active_connections[@active_connection_name] = conn
-        end
-      end
-
-      # Clears the cache which maps classes to connections.
-      def clear_active_connections!
-        clear_cache!(@@active_connections) do |name, conn|
-          conn.disconnect!
-        end
-      end
-      
-      # Clears the cache which maps classes 
-      def clear_reloadable_connections!
-        if @@allow_concurrency
-          # With concurrent connections @@active_connections is
-          # a hash keyed by thread id.
-          @@active_connections.each do |thread_id, conns|
-            conns.each do |name, conn|
-              if conn.requires_reloading?
-                conn.disconnect!
-                @@active_connections[thread_id].delete(name)
-              end
-            end
-          end
-        else
-          @@active_connections.each do |name, conn|
-            if conn.requires_reloading?
-              conn.disconnect!
-              @@active_connections.delete(name)
-            end
-          end
-        end
-      end
-
-      # Verify active connections.
-      def verify_active_connections! #:nodoc:
-        if @@allow_concurrency
-          remove_stale_cached_threads!(@@active_connections) do |name, conn|
-            conn.disconnect!
-          end
-        end
-        
-        active_connections.each_value do |connection|
-          connection.verify!(@@verification_timeout)
-        end
-      end
-
-      private
-        def clear_cache!(cache, thread_id = nil, &block)
-          if cache
-            if @@allow_concurrency
-              thread_id ||= Thread.current.object_id
-              thread_cache, cache = cache, cache[thread_id]
-              return unless cache
-            end
-
-            cache.each(&block) if block_given?
-            cache.clear
-          end
-        ensure
-          if thread_cache && @@allow_concurrency
-            thread_cache.delete(thread_id)
-          end
-        end
-
-        # Remove stale threads from the cache.
-        def remove_stale_cached_threads!(cache, &block)
-          stale = Set.new(cache.keys)
-
-          Thread.list.each do |thread|
-            stale.delete(thread.object_id) if thread.alive?
-          end
-
-          stale.each do |thread_id|
-            clear_cache!(cache, thread_id, &block)
-          end
-        end
-        
-        def clear_all_cached_connections!
-          if @@allow_concurrency
-            @@active_connections.each_value do |connection_hash_for_thread|
-              connection_hash_for_thread.each_value {|conn| conn.disconnect! }
-              connection_hash_for_thread.clear
-            end
-          else
-            @@active_connections.each_value {|conn| conn.disconnect! }
-          end
-          @@active_connections.clear          
-        end
-    end
+    # The connection handler
+    cattr_accessor :connection_handler, :instance_writer => false
+    @@connection_handler = ConnectionAdapters::ConnectionHandler.new
 
     # Returns the connection currently associated with the class. This can
     # also be used to "borrow" the connection to do database work that isn't
@@ -208,9 +57,7 @@ module ActiveRecord
           raise AdapterNotSpecified unless defined? RAILS_ENV
           establish_connection(RAILS_ENV)
         when ConnectionSpecification
-          clear_active_connection_name
-          @active_connection_name = name
-          @@defined_connections[name] = spec
+          @@connection_handler.establish_connection(name, spec)
         when Symbol, String
           if configuration = configurations[spec.to_s]
             establish_connection(configuration)
@@ -243,67 +90,42 @@ module ActiveRecord
       end
     end
 
-    # Locate the connection of the nearest super class. This can be an
-    # active or defined connection: if it is the latter, it will be
-    # opened and set as the active connection for the class it was defined
-    # for (not necessarily the current class).
-    def self.retrieve_connection #:nodoc:
-      # Name is nil if establish_connection hasn't been called for
-      # some class along the inheritance chain up to AR::Base yet.
-      if name = active_connection_name
-        if conn = active_connections[name]
-          # Verify the connection.
-          conn.verify!(@@verification_timeout)
-        elsif spec = @@defined_connections[name]
-          # Activate this connection specification.
-          klass = name.constantize
-          klass.connection = spec
-          conn = active_connections[name]
-        end
+    class << self
+      # Deprecated and no longer has any effect.
+      def allow_concurrency
+        ActiveSupport::Deprecation.warn("ActiveRecord::Base.allow_concurrency has been deprecated and no longer has any effect. Please remove all references to allow_concurrency.")
       end
 
-      conn or raise ConnectionNotEstablished
-    end
+      # Deprecated and no longer has any effect.
+      def allow_concurrency=(flag)
+        ActiveSupport::Deprecation.warn("ActiveRecord::Base.allow_concurrency= has been deprecated and no longer has any effect. Please remove all references to allow_concurrency=.")
+      end
 
-    # Returns true if a connection that's accessible to this class has already been opened.
-    def self.connected?
-      active_connections[active_connection_name] ? true : false
-    end
+      # Returns the connection currently associated with the class. This can
+      # also be used to "borrow" the connection to do database work unrelated
+      # to any of the specific Active Records.
+      def connection
+        retrieve_connection
+      end
 
-    # Remove the connection for this class. This will close the active
-    # connection and the defined connection (if they exist). The result
-    # can be used as an argument for establish_connection, for easily
-    # re-establishing the connection.
-    def self.remove_connection(klass=self)
-      spec = @@defined_connections[klass.name]
-      konn = active_connections[klass.name]
-      @@defined_connections.delete_if { |key, value| value == spec }
-      active_connections.delete_if { |key, value| value == konn }
-      konn.disconnect! if konn
-      spec.config if spec
-    end
+      def connection_pool
+        connection_handler.retrieve_connection_pool(self)
+      end
 
-    # Set the connection for the class.
-    def self.connection=(spec) #:nodoc:
-      if spec.kind_of?(ActiveRecord::ConnectionAdapters::AbstractAdapter)
-        active_connections[name] = spec
-      elsif spec.kind_of?(ConnectionSpecification)
-        config = spec.config.reverse_merge(:allow_concurrency => @@allow_concurrency)
-        self.connection = self.send(spec.adapter_method, config)
-      elsif spec.nil?
-        raise ConnectionNotEstablished
-      else
-        establish_connection spec
+      def retrieve_connection
+        connection_handler.retrieve_connection(self)
       end
-    end
 
-    # connection state logging
-    def self.log_connections #:nodoc:
-      if logger
-        logger.info "Defined connections: #{@@defined_connections.inspect}"
-        logger.info "Active connections: #{active_connections.inspect}"
-        logger.info "Active connection name: #{@active_connection_name}"
+      def connected?
+        connection_handler.connected?(self)
       end
+
+      def remove_connection(klass = self)
+        connection_handler.remove_connection(klass)
+      end
+
+      delegate :clear_active_connections!, :clear_reloadable_connections!,
+        :clear_all_connections!,:verify_active_connections!, :to => :connection_handler
     end
   end
 end
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb b/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb
index 2afd6064ad..2fc50b9bfa 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb
@@ -4,7 +4,6 @@ module ActiveRecord
       class << self
         def included(base)
           base.class_eval do
-            attr_accessor :query_cache_enabled
             alias_method_chain :columns, :query_cache
             alias_method_chain :select_all, :query_cache
           end
@@ -16,7 +15,7 @@ module ActiveRecord
           method_names.each do |method_name|
             base.class_eval <<-end_code, __FILE__, __LINE__
               def #{method_name}_with_query_dirty(*args)
-                clear_query_cache if @query_cache_enabled
+                clear_query_cache if query_cache_enabled
                 #{method_name}_without_query_dirty(*args)
               end
 
@@ -26,22 +25,38 @@ module ActiveRecord
         end
       end
 
+      def query_cache_enabled
+        Thread.current['query_cache_enabled']
+      end
+
+      def query_cache_enabled=(flag)
+        Thread.current['query_cache_enabled'] = flag
+      end
+
+      def query_cache
+        Thread.current['query_cache']
+      end
+
+      def query_cache=(cache)
+        Thread.current['query_cache'] = cache
+      end
+
       # Enable the query cache within the block.
       def cache
-        old, @query_cache_enabled = @query_cache_enabled, true
-        @query_cache ||= {}
+        old, self.query_cache_enabled = query_cache_enabled, true
+        self.query_cache ||= {}
         yield
       ensure
         clear_query_cache
-        @query_cache_enabled = old
+        self.query_cache_enabled = old
       end
 
       # Disable the query cache within the block.
       def uncached
-        old, @query_cache_enabled = @query_cache_enabled, false
+        old, self.query_cache_enabled = query_cache_enabled, false
         yield
       ensure
-        @query_cache_enabled = old
+        self.query_cache_enabled = old
       end
 
       # Clears the query cache.
@@ -51,11 +66,11 @@ module ActiveRecord
       # the same SQL query and repeatedly return the same result each time, silently
       # undermining the randomness you were expecting.
       def clear_query_cache
-        @query_cache.clear if @query_cache
+        query_cache.clear if query_cache
       end
 
       def select_all_with_query_cache(*args)
-        if @query_cache_enabled
+        if query_cache_enabled
           cache_sql(args.first) { select_all_without_query_cache(*args) }
         else
           select_all_without_query_cache(*args)
@@ -63,8 +78,8 @@ module ActiveRecord
       end
 
       def columns_with_query_cache(*args)
-        if @query_cache_enabled
-          @query_cache["SHOW FIELDS FROM #{args.first}"] ||= columns_without_query_cache(*args)
+        if query_cache_enabled
+          query_cache["SHOW FIELDS FROM #{args.first}"] ||= columns_without_query_cache(*args)
         else
           columns_without_query_cache(*args)
         end
@@ -73,11 +88,11 @@ module ActiveRecord
       private
         def cache_sql(sql)
           result =
-            if @query_cache.has_key?(sql)
+            if query_cache.has_key?(sql)
               log_info(sql, "CACHE", 0.0)
-              @query_cache[sql]
+              query_cache[sql]
             else
-              @query_cache[sql] = yield
+              query_cache[sql] = yield
             end
 
           if Array === result
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index 6924bb7e6f..005be9d72f 100644..100755
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -7,6 +7,7 @@ require 'active_record/connection_adapters/abstract/schema_definitions'
 require 'active_record/connection_adapters/abstract/schema_statements'
 require 'active_record/connection_adapters/abstract/database_statements'
 require 'active_record/connection_adapters/abstract/quoting'
+require 'active_record/connection_adapters/abstract/connection_pool'
 require 'active_record/connection_adapters/abstract/connection_specification'
 require 'active_record/connection_adapters/abstract/query_cache'
 
@@ -24,6 +25,9 @@ module ActiveRecord
     class AbstractAdapter
       include Quoting, DatabaseStatements, SchemaStatements
       include QueryCache
+      include ActiveSupport::Callbacks
+      define_callbacks :checkout, :checkin
+      checkout :reset!
       @@row_even = true
 
       def initialize(connection, logger = nil) #:nodoc:
@@ -102,14 +106,25 @@ module ActiveRecord
         @active = false
       end
 
+      # Reset the state of this connection, directing the DBMS to clear
+      # transactions and other connection-related server-side state. Usually a
+      # database-dependent operation; the default method simply executes a
+      # ROLLBACK and swallows any exceptions which is probably not enough to
+      # ensure the connection is clean.
+      def reset!
+        silence_stderr do # postgres prints on stderr when you do this w/o a txn
+          execute "ROLLBACK" rescue nil
+        end
+      end
+
       # Returns true if its safe to reload the connection between requests for development mode.
       # This is not the case for Ruby/MySQL and it's not necessary for any adapters except SQLite.
       def requires_reloading?
         false
       end
 
-      # Lazily verify this connection, calling <tt>active?</tt> only if it hasn't
-      # been called for +timeout+ seconds.
+      # Lazily verify this connection, calling <tt>active?</tt> only if it
+      # hasn't been called for +timeout+ seconds.
       def verify!(timeout)
         now = Time.now.to_i
         if (now - @last_verification) > timeout
diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index 204ebaa2e2..14c76ac455 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -280,6 +280,16 @@ module ActiveRecord
         @connection.close rescue nil
       end
 
+      def reset!
+        if @connection.respond_to?(:change_user)
+          # See http://bugs.mysql.com/bug.php?id=33540 -- the workaround way to
+          # reset the connection is to change the user to the same user.
+          @connection.change_user(@config[:username], @config[:password], @config[:database])
+          configure_connection
+        else
+          super
+        end
+      end
 
       # DATABASE STATEMENTS ======================================
 
@@ -529,7 +539,11 @@ module ActiveRecord
           end
 
           @connection.real_connect(*@connection_options)
+          configure_connection
+        end
 
+        def configure_connection
+          encoding = @config[:encoding]
           execute("SET NAMES '#{encoding}'") if encoding
 
           # By default, MySQL 'where id is null' selects the last inserted id.
diff --git a/activerecord/lib/active_record/fixtures.rb b/activerecord/lib/active_record/fixtures.rb
index 622cfc3c3f..114141a646 100644
--- a/activerecord/lib/active_record/fixtures.rb
+++ b/activerecord/lib/active_record/fixtures.rb
@@ -955,7 +955,7 @@ module Test #:nodoc:
           ActiveRecord::Base.connection.rollback_db_transaction
           ActiveRecord::Base.connection.decrement_open_transactions
         end
-        ActiveRecord::Base.verify_active_connections!
+        ActiveRecord::Base.clear_active_connections!
       end
 
       private
diff --git a/activerecord/lib/active_record/named_scope.rb b/activerecord/lib/active_record/named_scope.rb
index 46eaa42a55..83043c2c22 100644
--- a/activerecord/lib/active_record/named_scope.rb
+++ b/activerecord/lib/active_record/named_scope.rb
@@ -101,9 +101,9 @@ module ActiveRecord
     
     class Scope
       attr_reader :proxy_scope, :proxy_options
-
+      NON_DELEGATE_METHODS = %w(nil? send object_id class extend find size count sum average maximum minimum paginate first last empty? any? respond_to?).to_set
       [].methods.each do |m|
-        unless m =~ /(^__|^nil\?|^send|^object_id$|class|extend|^find$|count|sum|average|maximum|minimum|paginate|first|last|empty?|any?|respond_to?)/
+        unless m =~ /^__/ || NON_DELEGATE_METHODS.include?(m.to_s)
           delegate m, :to => :proxy_found
         end
       end
@@ -136,6 +136,10 @@ module ActiveRecord
         end
       end
 
+      def size
+        @found ? @found.length : count
+      end
+
       def empty?
         @found ? @found.empty? : count.zero?
       end
diff --git a/activerecord/lib/active_record/validations.rb b/activerecord/lib/active_record/validations.rb
index 687f1261cd..577e30ec86 100644
--- a/activerecord/lib/active_record/validations.rb
+++ b/activerecord/lib/active_record/validations.rb
@@ -54,7 +54,7 @@ module ActiveRecord
     def add_on_empty(attributes, custom_message = nil)
       for attr in [attributes].flatten
         value = @base.respond_to?(attr.to_s) ? @base.send(attr.to_s) : @base[attr.to_s]
-        is_empty = value.respond_to?("empty?") ? value.empty? : false        
+        is_empty = value.respond_to?(:empty?) ? value.empty? : false
         add(attr, :empty, :default => custom_message) unless !value.nil? && !is_empty
       end
     end
@@ -87,6 +87,8 @@ module ActiveRecord
     # </ol>
     def generate_message(attribute, message = :invalid, options = {})
 
+      message, options[:default] = options[:default], message if options[:default].is_a?(Symbol)
+
       defaults = @base.class.self_and_descendents_from_active_record.map do |klass| 
         [ :"models.#{klass.name.underscore}.attributes.#{attribute}.#{message}", 
           :"models.#{klass.name.underscore}.#{message}" ]
@@ -95,7 +97,6 @@ module ActiveRecord
       defaults << options.delete(:default)
       defaults = defaults.compact.flatten << :"messages.#{message}"
 
-      model_name = @base.class.name
       key = defaults.shift
       value = @base.respond_to?(attribute) ? @base.send(attribute) : nil
 
@@ -664,7 +665,7 @@ module ActiveRecord
             condition_params = [value]
           else
             condition_sql = "LOWER(#{sql_attribute}) #{comparison_operator}"
-            condition_params = [value.downcase]
+            condition_params = [value.chars.downcase]
           end
 
           if scope = configuration[:scope]
@@ -750,7 +751,7 @@ module ActiveRecord
 
         enum = configuration[:in] || configuration[:within]
 
-        raise(ArgumentError, "An object with the method include? is required must be supplied as the :in option of the configuration hash") unless enum.respond_to?("include?")
+        raise(ArgumentError, "An object with the method include? is required must be supplied as the :in option of the configuration hash") unless enum.respond_to?(:include?)
 
         validates_each(attr_names, configuration) do |record, attr_name, value|
           unless enum.include?(value)
@@ -784,7 +785,7 @@ module ActiveRecord
 
         enum = configuration[:in] || configuration[:within]
 
-        raise(ArgumentError, "An object with the method include? is required must be supplied as the :in option of the configuration hash") unless enum.respond_to?("include?")
+        raise(ArgumentError, "An object with the method include? is required must be supplied as the :in option of the configuration hash") unless enum.respond_to?(:include?)
 
         validates_each(attr_names, configuration) do |record, attr_name, value|
           if enum.include?(value)
diff --git a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
index 0572418e3b..edca3c622b 100644
--- a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
@@ -223,10 +223,10 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     devel = Developer.find(1)
     proj = assert_no_queries { devel.projects.build("name" => "Projekt") }
     assert !devel.projects.loaded?
-    
+
     assert_equal devel.projects.last, proj
     assert devel.projects.loaded?
-    
+
     assert proj.new_record?
     devel.save
     assert !proj.new_record?
@@ -251,10 +251,10 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     devel = Developer.find(1)
     proj = devel.projects.create("name" => "Projekt")
     assert !devel.projects.loaded?
-    
+
     assert_equal devel.projects.last, proj
     assert devel.projects.loaded?
-    
+
     assert !proj.new_record?
     assert_equal Developer.find(1).projects.sort_by(&:id).last, proj  # prove join table is updated
   end
@@ -274,10 +274,10 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
 
   def test_creation_respects_hash_condition
     post = categories(:general).post_with_conditions.build(:body => '')
-    
+
     assert        post.save
     assert_equal  'Yet Another Testing Title', post.title
-    
+
     another_post = categories(:general).post_with_conditions.create(:body => '')
 
     assert        !another_post.new_record?
@@ -288,7 +288,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     dev = developers(:jamis)
     dev.projects << projects(:active_record)
     dev.projects << projects(:active_record)
-    
+
     assert_equal 3, dev.projects.size
     assert_equal 1, dev.projects.uniq.size
   end
@@ -415,13 +415,13 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     project.developers.class # force load target
 
     developer = project.developers.first
-    
+
     assert_no_queries do
       assert project.developers.loaded?
       assert project.developers.include?(developer)
     end
   end
-  
+
   def test_include_checks_if_record_exists_if_target_not_loaded
     project = projects(:active_record)
     developer = project.developers.first
@@ -641,6 +641,22 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     assert_equal [projects(:active_record).id], developers(:jamis).project_ids
   end
 
+  def test_get_ids_for_loaded_associations
+    developer = developers(:david)
+    developer.projects(true)
+    assert_queries(0) do
+      developer.project_ids
+      developer.project_ids
+    end
+  end
+
+  def test_get_ids_for_unloaded_associations_does_not_load_them
+    developer = developers(:david)
+    assert !developer.projects.loaded?
+    assert_equal projects(:active_record, :action_controller).map(&:id).sort, developer.project_ids.sort
+    assert !developer.projects.loaded?
+  end
+
   def test_assign_ids
     developer = Developer.new("name" => "Joe")
     developer.project_ids = projects(:active_record, :action_controller).map(&:id)
@@ -703,4 +719,11 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     # due to Unknown column 'authors.id'
     assert Category.find(1).posts_with_authors_sorted_by_author_id.find_by_title('Welcome to the weblog')
   end
+
+  def test_counting_on_habtm_association_and_not_array
+    david = Developer.find(1)
+    # Extra parameter just to make sure we aren't falling back to
+    # Array#count in Ruby >=1.8.7, which would raise an ArgumentError
+    assert_nothing_raised { david.projects.count(:all, :conditions => '1=1') }
+  end
 end
diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index 17fd88ce65..feac4b002b 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -384,7 +384,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     company = companies(:first_firm)
     new_client = assert_no_queries { company.clients_of_firm.build("name" => "Another Client") }
     assert !company.clients_of_firm.loaded?
-    
+
     assert_equal "Another Client", new_client.name
     assert new_client.new_record?
     assert_equal new_client, company.clients_of_firm.last
@@ -416,7 +416,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
   def test_build_many
     company = companies(:first_firm)
     new_clients = assert_no_queries { company.clients_of_firm.build([{"name" => "Another Client"}, {"name" => "Another Client II"}]) }
-    
+
     assert_equal 2, new_clients.size
     company.name += '-changed'
     assert_queries(3) { assert company.save }
@@ -655,10 +655,10 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
 
   def test_creation_respects_hash_condition
     ms_client = companies(:first_firm).clients_like_ms_with_hash_conditions.build
-    
+
     assert        ms_client.save
     assert_equal  'Microsoft', ms_client.name
-    
+
     another_ms_client = companies(:first_firm).clients_like_ms_with_hash_conditions.create
 
     assert        !another_ms_client.new_record?
@@ -830,6 +830,22 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal [companies(:first_client).id, companies(:second_client).id], companies(:first_firm).client_ids
   end
 
+  def test_get_ids_for_loaded_associations
+    company = companies(:first_firm)
+    company.clients(true)
+    assert_queries(0) do
+      company.client_ids
+      company.client_ids
+    end
+  end
+
+  def test_get_ids_for_unloaded_associations_does_not_load_them
+    company = companies(:first_firm)
+    assert !company.clients.loaded?
+    assert_equal [companies(:first_client).id, companies(:second_client).id], company.client_ids
+    assert !company.clients.loaded?
+  end
+
   def test_assign_ids
     firm = Firm.new("name" => "Apple")
     firm.client_ids = [companies(:first_client).id, companies(:second_client).id]
@@ -900,7 +916,7 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal 4, authors(:david).limited_comments.find(:all, :conditions => "comments.type = 'SpecialComment'", :limit => 9_000).length
     assert_equal 4, authors(:david).limited_comments.find_all_by_type('SpecialComment', :limit => 9_000).length
   end
-  
+
   def test_find_all_include_over_the_same_table_for_through
     assert_equal 2, people(:michael).posts.find(:all, :include => :people).length
   end
@@ -937,13 +953,13 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
   def test_include_loads_collection_if_target_uses_finder_sql
     firm = companies(:first_firm)
     client = firm.clients_using_sql.first
-    
+
     firm.reload
     assert ! firm.clients_using_sql.loaded?
     assert firm.clients_using_sql.include?(client)
     assert firm.clients_using_sql.loaded?
   end
-  
+
 
   def test_include_returns_false_for_non_matching_record_to_verify_scoping
     firm = companies(:first_firm)
diff --git a/activerecord/test/cases/associations/has_many_through_associations_test.rb b/activerecord/test/cases/associations/has_many_through_associations_test.rb
index 353262c81b..0be050ec81 100644
--- a/activerecord/test/cases/associations/has_many_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_through_associations_test.rb
@@ -200,4 +200,24 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
   def test_count_with_include_should_alias_join_table
     assert_equal 2, people(:michael).posts.count(:include => :readers)
   end
+
+  def test_get_ids
+    assert_equal [posts(:welcome).id, posts(:authorless).id].sort, people(:michael).post_ids.sort
+  end
+
+  def test_get_ids_for_loaded_associations
+    person = people(:michael)
+    person.posts(true)
+    assert_queries(0) do
+      person.post_ids
+      person.post_ids
+    end
+  end
+
+  def test_get_ids_for_unloaded_associations_does_not_load_them
+    person = people(:michael)
+    assert !person.posts.loaded?
+    assert_equal [posts(:welcome).id, posts(:authorless).id].sort, person.post_ids.sort
+    assert !person.posts.loaded?
+  end
 end
diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index c8111358e3..ac9081e003 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -880,7 +880,7 @@ class BasicsTest < ActiveRecord::TestCase
 
   def test_mass_assignment_protection_against_class_attribute_writers
     [:logger, :configurations, :primary_key_prefix_type, :table_name_prefix, :table_name_suffix, :pluralize_table_names, :colorize_logging,
-      :default_timezone, :allow_concurrency, :schema_format, :verification_timeout, :lock_optimistically, :record_timestamps].each do |method|
+      :default_timezone, :schema_format, :verification_timeout, :lock_optimistically, :record_timestamps].each do |method|
       assert  Task.respond_to?(method)
       assert  Task.respond_to?("#{method}=")
       assert  Task.new.respond_to?(method)
diff --git a/activerecord/test/cases/locking_test.rb b/activerecord/test/cases/locking_test.rb
index 701187223f..bbe8582466 100644
--- a/activerecord/test/cases/locking_test.rb
+++ b/activerecord/test/cases/locking_test.rb
@@ -210,13 +210,6 @@ unless current_adapter?(:SQLServerAdapter, :SybaseAdapter, :OpenBaseAdapter)
     def setup
       # Avoid introspection queries during tests.
       Person.columns; Reader.columns
-
-      @allow_concurrency = ActiveRecord::Base.allow_concurrency
-      ActiveRecord::Base.allow_concurrency = true
-    end
-
-    def teardown
-      ActiveRecord::Base.allow_concurrency = @allow_concurrency
     end
 
     # Test typical find.
diff --git a/activerecord/test/cases/method_scoping_test.rb b/activerecord/test/cases/method_scoping_test.rb
index ee66ac948d..af6fcd32ad 100644
--- a/activerecord/test/cases/method_scoping_test.rb
+++ b/activerecord/test/cases/method_scoping_test.rb
@@ -1,4 +1,5 @@
 require "cases/helper"
+require 'models/author'
 require 'models/developer'
 require 'models/project'
 require 'models/comment'
@@ -6,7 +7,7 @@ require 'models/post'
 require 'models/category'
 
 class MethodScopingTest < ActiveRecord::TestCase
-  fixtures :developers, :projects, :comments, :posts, :developers_projects
+  fixtures :authors, :developers, :projects, :comments, :posts, :developers_projects
 
   def test_set_conditions
     Developer.with_scope(:find => { :conditions => 'just a test...' }) do
@@ -97,6 +98,46 @@ class MethodScopingTest < ActiveRecord::TestCase
     assert_equal developers(:david).attributes, scoped_developers.first.attributes
   end
 
+  def test_scoped_find_using_new_style_joins
+    scoped_developers = Developer.with_scope(:find => { :joins => :projects }) do
+      Developer.find(:all, :conditions => 'projects.id = 2')
+    end
+    assert scoped_developers.include?(developers(:david))
+    assert !scoped_developers.include?(developers(:jamis))
+    assert_equal 1, scoped_developers.size
+    assert_equal developers(:david).attributes, scoped_developers.first.attributes
+  end
+
+  def test_scoped_find_merges_old_style_joins
+    scoped_authors = Author.with_scope(:find => { :joins => 'INNER JOIN posts ON authors.id = posts.author_id ' }) do
+      Author.find(:all, :select => 'DISTINCT authors.*', :joins => 'INNER JOIN comments ON posts.id = comments.post_id', :conditions => 'comments.id = 1')
+    end
+    assert scoped_authors.include?(authors(:david))
+    assert !scoped_authors.include?(authors(:mary))
+    assert_equal 1, scoped_authors.size
+    assert_equal authors(:david).attributes, scoped_authors.first.attributes
+  end
+
+  def test_scoped_find_merges_new_style_joins
+    scoped_authors = Author.with_scope(:find => { :joins => :posts }) do
+      Author.find(:all, :select => 'DISTINCT authors.*', :joins => :comments, :conditions => 'comments.id = 1')
+    end
+    assert scoped_authors.include?(authors(:david))
+    assert !scoped_authors.include?(authors(:mary))
+    assert_equal 1, scoped_authors.size
+    assert_equal authors(:david).attributes, scoped_authors.first.attributes
+  end
+
+  def test_scoped_find_merges_new_and_old_style_joins
+    scoped_authors = Author.with_scope(:find => { :joins => :posts }) do
+      Author.find(:all, :select => 'DISTINCT authors.*', :joins => 'JOIN comments ON posts.id = comments.post_id', :conditions => 'comments.id = 1')
+    end
+    assert scoped_authors.include?(authors(:david))
+    assert !scoped_authors.include?(authors(:mary))
+    assert_equal 1, scoped_authors.size
+    assert_equal authors(:david).attributes, scoped_authors.first.attributes
+  end
+
   def test_scoped_count_include
     # with the include, will retrieve only developers for the given project
     Developer.with_scope(:find => { :include => :projects }) do
@@ -152,7 +193,7 @@ class MethodScopingTest < ActiveRecord::TestCase
 end
 
 class NestedScopingTest < ActiveRecord::TestCase
-  fixtures :developers, :projects, :comments, :posts
+  fixtures :authors, :developers, :projects, :comments, :posts
 
   def test_merge_options
     Developer.with_scope(:find => { :conditions => 'salary = 80000' }) do
@@ -357,6 +398,42 @@ class NestedScopingTest < ActiveRecord::TestCase
       assert_equal scoped_methods, Developer.instance_eval('current_scoped_methods')
     end
   end
+
+  def test_nested_scoped_find_merges_old_style_joins
+    scoped_authors = Author.with_scope(:find => { :joins => 'INNER JOIN posts ON authors.id = posts.author_id' }) do
+      Author.with_scope(:find => { :joins => 'INNER JOIN comments ON posts.id = comments.post_id' }) do
+        Author.find(:all, :select => 'DISTINCT authors.*', :conditions => 'comments.id = 1')
+      end
+    end
+    assert scoped_authors.include?(authors(:david))
+    assert !scoped_authors.include?(authors(:mary))
+    assert_equal 1, scoped_authors.size
+    assert_equal authors(:david).attributes, scoped_authors.first.attributes
+  end
+
+  def test_nested_scoped_find_merges_new_style_joins
+    scoped_authors = Author.with_scope(:find => { :joins => :posts }) do
+      Author.with_scope(:find => { :joins => :comments }) do
+        Author.find(:all, :select => 'DISTINCT authors.*', :conditions => 'comments.id = 1')
+      end
+    end
+    assert scoped_authors.include?(authors(:david))
+    assert !scoped_authors.include?(authors(:mary))
+    assert_equal 1, scoped_authors.size
+    assert_equal authors(:david).attributes, scoped_authors.first.attributes
+  end
+
+  def test_nested_scoped_find_merges_new_and_old_style_joins
+    scoped_authors = Author.with_scope(:find => { :joins => :posts }) do
+      Author.with_scope(:find => { :joins => 'INNER JOIN comments ON posts.id = comments.post_id' }) do
+        Author.find(:all, :select => 'DISTINCT authors.*', :joins => '', :conditions => 'comments.id = 1')
+      end
+    end
+    assert scoped_authors.include?(authors(:david))
+    assert !scoped_authors.include?(authors(:mary))
+    assert_equal 1, scoped_authors.size
+    assert_equal authors(:david).attributes, scoped_authors.first.attributes
+  end
 end
 
 class HasManyScopingTest< ActiveRecord::TestCase
diff --git a/activerecord/test/cases/named_scope_test.rb b/activerecord/test/cases/named_scope_test.rb
index 6f6ea1cbe9..444debd255 100644
--- a/activerecord/test/cases/named_scope_test.rb
+++ b/activerecord/test/cases/named_scope_test.rb
@@ -249,7 +249,26 @@ class NamedScopeTest < ActiveRecord::TestCase
     assert_equal Topic.base.select(&:approved), Topic.base.find_all(&:approved)
   end
 
+  def test_rand_should_select_a_random_object_from_proxy
+    assert Topic.approved.rand.is_a?(Topic)
+  end
+
   def test_should_use_where_in_query_for_named_scope
     assert_equal Developer.find_all_by_name('Jamis'), Developer.find_all_by_id(Developer.jamises)
   end
+
+  def test_size_should_use_count_when_results_are_not_loaded
+    topics = Topic.base
+    assert_queries(1) do
+      assert_sql(/COUNT/i) { topics.size }
+    end
+  end
+
+  def test_size_should_use_length_when_results_are_loaded
+    topics = Topic.base
+    topics.reload # force load
+    assert_no_queries do
+      topics.size # use loaded (no query)
+    end
+  end
 end
diff --git a/activerecord/test/cases/pooled_connections_test.rb b/activerecord/test/cases/pooled_connections_test.rb
new file mode 100644
index 0000000000..078ca1d679
--- /dev/null
+++ b/activerecord/test/cases/pooled_connections_test.rb
@@ -0,0 +1,87 @@
+require "cases/helper"
+
+class PooledConnectionsTest < ActiveRecord::TestCase
+  def setup
+    super
+    @connection = ActiveRecord::Base.remove_connection
+  end
+
+  def teardown
+    ActiveRecord::Base.clear_all_connections!
+    ActiveRecord::Base.establish_connection(@connection)
+    super
+  end
+
+  def checkout_connections
+    ActiveRecord::Base.establish_connection(@connection.merge({:pool => 2, :wait_timeout => 0.3}))
+    @connections = []
+    @timed_out = 0
+
+    4.times do
+      Thread.new do
+        begin
+          @connections << ActiveRecord::Base.connection_pool.checkout
+        rescue ActiveRecord::ConnectionTimeoutError
+          @timed_out += 1
+        end
+      end.join
+    end
+  end
+
+  def test_pooled_connection_checkout
+    checkout_connections
+    assert_equal @connections.length, 2
+    assert_equal @timed_out, 2
+  end
+
+  def checkout_checkin_connections(pool_size, threads)
+    ActiveRecord::Base.establish_connection(@connection.merge({:pool => pool_size, :wait_timeout => 0.5}))
+    @connection_count = 0
+    @timed_out = 0
+    threads.times do
+      Thread.new do
+        begin
+          conn = ActiveRecord::Base.connection_pool.checkout
+          sleep 0.1
+          ActiveRecord::Base.connection_pool.checkin conn
+          @connection_count += 1
+        rescue ActiveRecord::ConnectionTimeoutError
+          @timed_out += 1
+        end
+      end.join
+    end
+  end
+
+  def test_pooled_connection_checkin_one
+    checkout_checkin_connections 1, 2
+    assert_equal 2, @connection_count
+    assert_equal 0, @timed_out
+  end
+
+  def test_pooled_connection_checkin_two
+    checkout_checkin_connections 2, 3
+    assert_equal 3, @connection_count
+    assert_equal 0, @timed_out
+  end
+
+  def test_pooled_connection_checkout_existing_first
+    ActiveRecord::Base.establish_connection(@connection.merge({:pool => 1}))
+    conn_pool = ActiveRecord::Base.connection_pool
+    conn = conn_pool.checkout
+    conn_pool.checkin(conn)
+    conn = conn_pool.checkout
+    assert ActiveRecord::ConnectionAdapters::AbstractAdapter === conn
+    conn_pool.checkin(conn)
+  end
+end unless %w(FrontBase).include? ActiveRecord::Base.connection.adapter_name
+
+class AllowConcurrencyDeprecatedTest < ActiveRecord::TestCase
+  def test_allow_concurrency_is_deprecated
+    assert_deprecated('ActiveRecord::Base.allow_concurrency') do
+      ActiveRecord::Base.allow_concurrency
+    end
+    assert_deprecated('ActiveRecord::Base.allow_concurrency=') do
+      ActiveRecord::Base.allow_concurrency = true
+    end
+  end
+end
diff --git a/activerecord/test/cases/threaded_connections_test.rb b/activerecord/test/cases/threaded_connections_test.rb
deleted file mode 100644
index 28f8302367..0000000000
--- a/activerecord/test/cases/threaded_connections_test.rb
+++ /dev/null
@@ -1,48 +0,0 @@
-require "cases/helper"
-require 'models/topic'
-require 'models/reply'
-
-unless %w(FrontBase).include? ActiveRecord::Base.connection.adapter_name
-  class ThreadedConnectionsTest < ActiveRecord::TestCase
-    self.use_transactional_fixtures = false
-
-    fixtures :topics
-
-  def setup
-    @connection = ActiveRecord::Base.remove_connection
-    @connections = []
-    @allow_concurrency = ActiveRecord::Base.allow_concurrency
-  end
-
-  def teardown
-    # clear the connection cache
-    ActiveRecord::Base.send(:clear_all_cached_connections!)
-    # set allow_concurrency to saved value
-    ActiveRecord::Base.allow_concurrency = @allow_concurrency
-    # reestablish old connection
-    ActiveRecord::Base.establish_connection(@connection)
-  end
-
-  def gather_connections(use_threaded_connections)
-    ActiveRecord::Base.allow_concurrency = use_threaded_connections
-    ActiveRecord::Base.establish_connection(@connection)
-
-      5.times do
-        Thread.new do
-          Topic.find :first
-          @connections << ActiveRecord::Base.active_connections.values.first
-        end.join
-      end
-    end
-
-    def test_threaded_connections
-      gather_connections(true)
-      assert_equal @connections.uniq.length, 5
-    end
-
-    def test_unthreaded_connections
-      gather_connections(false)
-      assert_equal @connections.uniq.length, 1
-    end
-  end
-end
diff --git a/activerecord/test/cases/transactions_test.rb b/activerecord/test/cases/transactions_test.rb
index af3ee6ddba..8383ba58e9 100644
--- a/activerecord/test/cases/transactions_test.rb
+++ b/activerecord/test/cases/transactions_test.rb
@@ -283,17 +283,6 @@ end
 
 if current_adapter?(:PostgreSQLAdapter)
   class ConcurrentTransactionTest < TransactionTest
-    def setup
-      @allow_concurrency = ActiveRecord::Base.allow_concurrency
-      ActiveRecord::Base.allow_concurrency = true
-      super
-    end
-
-    def teardown
-      super
-      ActiveRecord::Base.allow_concurrency = @allow_concurrency
-    end
-
     # This will cause transactions to overlap and fail unless they are performed on
     # separate database connections.
     def test_transaction_per_thread
diff --git a/activerecord/test/cases/validations_i18n_test.rb b/activerecord/test/cases/validations_i18n_test.rb
index 43592bcee3..090f347a20 100644
--- a/activerecord/test/cases/validations_i18n_test.rb
+++ b/activerecord/test/cases/validations_i18n_test.rb
@@ -675,6 +675,38 @@ class ActiveRecordValidationsI18nTests < Test::Unit::TestCase
     replied_topic.valid?
     assert_equal 'global message', replied_topic.errors.on(:replies)
   end
+
+  def test_validations_with_message_symbol_must_translate
+    I18n.backend.store_translations 'en-US', :activerecord => {:errors => {:messages => {:custom_error => "I am a custom error"}}}
+    Topic.validates_presence_of :title, :message => :custom_error
+    @topic.title = nil
+    @topic.valid?
+    assert_equal "I am a custom error", @topic.errors.on(:title)
+  end
+
+  def test_validates_with_message_symbol_must_translate_per_attribute
+    I18n.backend.store_translations 'en-US', :activerecord => {:errors => {:models => {:topic => {:attributes => {:title => {:custom_error => "I am a custom error"}}}}}}
+    Topic.validates_presence_of :title, :message => :custom_error
+    @topic.title = nil
+    @topic.valid?
+    assert_equal "I am a custom error", @topic.errors.on(:title)
+  end
+
+  def test_validates_with_message_symbol_must_translate_per_model
+    I18n.backend.store_translations 'en-US', :activerecord => {:errors => {:models => {:topic => {:custom_error => "I am a custom error"}}}}
+    Topic.validates_presence_of :title, :message => :custom_error
+    @topic.title = nil
+    @topic.valid?
+    assert_equal "I am a custom error", @topic.errors.on(:title)
+  end
+
+  def test_validates_with_message_string
+    Topic.validates_presence_of :title, :message => "I am a custom error"
+    @topic.title = nil
+    @topic.valid?
+    assert_equal "I am a custom error", @topic.errors.on(:title)
+  end
+
 end
 
 class ActiveRecordValidationsGenerateMessageI18nTests < Test::Unit::TestCase
@@ -855,4 +887,5 @@ class ActiveRecordValidationsGenerateMessageI18nTests < Test::Unit::TestCase
   def test_generate_message_even_with_default_message
     assert_equal "must be even", @topic.errors.generate_message(:title, :even, :default => nil, :value => 'title', :count => 10)
   end
+
 end
diff --git a/activerecord/test/cases/validations_test.rb b/activerecord/test/cases/validations_test.rb
index a40bda2533..4999d93a86 100644
--- a/activerecord/test/cases/validations_test.rb
+++ b/activerecord/test/cases/validations_test.rb
@@ -451,6 +451,18 @@ class ValidationsTest < ActiveRecord::TestCase
     t2.title = nil
     assert t2.valid?, "should validate with nil"
     assert t2.save, "should save with nil"
+
+    with_kcode('UTF8') do
+      t_utf8 = Topic.new("title" => "Я тоже уникальный!")
+      assert t_utf8.save, "Should save t_utf8 as unique"
+
+      # If database hasn't UTF-8 character set, this test fails
+      if Topic.find(t_utf8, :select => 'LOWER(title) AS title').title == "я тоже уникальный!"
+        t2_utf8 = Topic.new("title" => "я тоже УНИКАЛЬНЫЙ!")
+        assert !t2_utf8.valid?, "Shouldn't be valid"
+        assert !t2_utf8.save, "Shouldn't save t2_utf8 as unique"
+      end
+    end
   end
 
   def test_validate_case_sensitive_uniqueness