Make connection pool retrieval faster

* Loop rather than recurse in retrieve_connection_pool
* Key the hash by class rather than class name. This avoids creating
  unnecessary strings.

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

@@ -505,9 +505,9 @@ def connection_pools
         @connection_pools[Process.pid]
       end
 
-      def establish_connection(name, spec)
+      def establish_connection(klass, spec)
         set_pool_for_spec spec, ConnectionAdapters::ConnectionPool.new(spec)
-        set_class_to_pool name, connection_pools[spec]
+        set_class_to_pool klass, connection_pools[spec]
       end
 
       # Returns true if there are any active connections among the connection
@@ -553,7 +553,7 @@ def connected?(klass)
       # can be used as an argument for establish_connection, for easily
       # re-establishing the connection.
       def remove_connection(klass)
-        pool = class_to_pool.delete(klass.name)
+        pool = class_to_pool.delete(klass)
         return nil unless pool
 
         connection_pools.delete pool.spec
@@ -563,12 +563,15 @@ def remove_connection(klass)
       end
 
       def retrieve_connection_pool(klass)
-        if !(klass < Model::Tag)
-          get_pool_for_class('ActiveRecord::Model') # default connection
-        else
-          pool = get_pool_for_class(klass.name)
-          pool || retrieve_connection_pool(klass.superclass)
+        pool = get_pool_for_class(klass)
+
+        until pool
+          klass = klass.superclass
+          break unless klass < Model::Tag
+          pool = get_pool_for_class(klass)
         end
+
+        pool || get_pool_for_class(ActiveRecord::Model)
       end
 
       private
@@ -581,8 +584,8 @@ def set_pool_for_spec(spec, pool)
         @connection_pools[Process.pid][spec] = pool
       end
 
-      def set_class_to_pool(name, pool)
-        @class_to_pool[Process.pid][name] = pool
+      def set_class_to_pool(klass, pool)
+        @class_to_pool[Process.pid][klass] = pool
         pool
       end
 

activerecord/lib/active_record/connection_handling.rb

@@ -44,7 +44,7 @@ def establish_connection(spec = ENV["DATABASE_URL"])
       end
 
       remove_connection
-      connection_handler.establish_connection name, spec
+      connection_handler.establish_connection self, spec
     end
 
     # Returns the connection currently associated with the class. This can

activerecord/test/cases/connection_adapters/connection_handler_test.rb

@@ -4,16 +4,11 @@ module ActiveRecord
   module ConnectionAdapters
     class ConnectionHandlerTest < ActiveRecord::TestCase
       def setup
+        @klass    = Class.new { include Model::Tag }
+        @subklass = Class.new(@klass) { include Model::Tag }
+
         @handler = ConnectionHandler.new
-        @handler.establish_connection 'america', Base.connection_pool.spec
-        @klass = Class.new do
-          include Model::Tag
-          def self.name; 'america'; end
-        end
-        @subklass = Class.new(@klass) do
-          include Model::Tag
-          def self.name; 'north america'; end
-        end
+        @handler.establish_connection @klass, Base.connection_pool.spec
       end
 
       def test_retrieve_connection