column cache now lives on the connection pool

activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb

@@ -57,6 +57,7 @@ module ActiveRecord
     # * +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
+      attr_accessor :automatic_reconnect
       attr_reader :spec, :connections
       attr_reader :columns, :columns_hash, :primary_keys
 
@@ -82,6 +83,7 @@ module ActiveRecord
 
         @connections = []
         @checked_out = []
+        @automatic_reconnect = true
 
         @columns     = Hash.new do |h, table_name|
           h[table_name] = with_connection do |conn|
@@ -281,6 +283,8 @@ module ActiveRecord
       end
 
       def checkout_new_connection
+        raise ConnectionNotEstablished unless @automatic_reconnect
+
         c = new_connection
         @connections << c
         checkout_and_verify(c)
@@ -379,7 +383,7 @@ module ActiveRecord
         pool = @connection_pools[klass.name]
         return nil unless pool
 
-        @connection_pools.delete_if { |key, value| value == pool }
+        pool.automatic_reconnect = false
         pool.disconnect!
         pool.spec.config
       end

activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb

@@ -757,10 +757,10 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     david = Developer.find(1)
     # clear cache possibly created by other tests
     david.projects.reset_column_information
-    assert_queries(1) { david.projects.columns; david.projects.columns }
+    assert_queries(0) { david.projects.columns; david.projects.columns }
     # and again to verify that reset_column_information clears the cache correctly
     david.projects.reset_column_information
-    assert_queries(1) { david.projects.columns; david.projects.columns }
+    assert_queries(0) { david.projects.columns; david.projects.columns }
   end
 
   def test_attributes_are_being_set_when_initialized_from_habm_association_with_where_clause

activerecord/test/cases/connection_pool_test.rb

@@ -99,6 +99,26 @@ module ActiveRecord
         end.join()
 
       end
+
+      def test_automatic_reconnect=
+        pool = ConnectionPool.new ActiveRecord::Base.connection_pool.spec
+        assert pool.automatic_reconnect
+        assert pool.connection
+
+        pool.disconnect!
+        assert pool.connection
+
+        pool.disconnect!
+        pool.automatic_reconnect = false
+
+        assert_raises(ConnectionNotEstablished) do
+          pool.connection
+        end
+
+        assert_raises(ConnectionNotEstablished) do
+          pool.with_connection
+        end
+      end
     end
   end
 end