Only reload connections in development mode that supports (and requires that) -- in other words, only do it for SQLite (closes #6687, #6700) [DHH]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5637 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

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

@@ -86,6 +86,14 @@ module ActiveRecord
           conn.disconnect!
         end
       end
+      
+      # Clears the cache which maps classes 
+      def clear_reloadable_connections!
+        @@active_connections.each do |name, conn|
+          conn.disconnect! if conn.supports_reloading?
+          @@active_connections.delete(name)
+        end
+      end
 
       # Verify active connections.
       def verify_active_connections! #:nodoc:

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -79,6 +79,12 @@ module ActiveRecord
         @active = false
       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 supports_reloading?
+        false
+      end
+
       # Lazily verify this connection, calling +active?+ only if it hasn't
       # been called for +timeout+ seconds.       
       def verify!(timeout)

activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb

@@ -102,6 +102,10 @@ module ActiveRecord
         true
       end
 
+      def supports_reloading?
+        true
+      end
+
       def supports_count_distinct? #:nodoc:
         sqlite_version >= '3.2.6'
       end

railties/lib/dispatcher.rb

@@ -62,7 +62,7 @@ class Dispatcher
         Class.remove_class(*Reloadable.reloadable_classes)
       end
         
-      ActiveRecord::Base.clear_active_connections! if defined?(ActiveRecord)
+      ActiveRecord::Base.clear_reloadable_connections! if defined?(ActiveRecord)
     end
     
     # Add a preparation callback. Preparation callbacks are run before every
@@ -76,13 +76,16 @@ class Dispatcher
     def to_prepare(identifier = nil, &block)
       unless identifier.nil?
         callback = preparation_callbacks.detect { |ident, _| ident == identifier }
+
         if callback # Already registered: update the existing callback
           callback[-1] = block
           return
         end
       end
+
       preparation_callbacks << [identifier, block]
-      nil
+
+      return
     end
 
     private