Close any database connections at the end of request (#661)

Close any database connections at the end of each request

There is no need to reuse database connections for the LSP server, as
the overhead of establishing new connections locally is negligible.
Therefore, we can close any active database connections as soon as
we're done with the request.

Author: janko

lib/ruby_lsp/ruby_lsp_rails/server.rb

@@ -294,6 +294,7 @@ def start
 
           request = JSON.parse(json, symbolize_names: true)
           execute(request.fetch(:method), request[:params])
+          disconnect_from_database
         end
       end
 
@@ -493,6 +494,18 @@ def clear_file_system_resolver_hooks
         end
       end
 
+      # Keeping a connection to the database prevents it from being dropped in development. We don't actually need to
+      # to reuse database connections for the LSP server, the performance benefit of doing so only matters in production
+      # where there is latency, locally we're fine with the small overhead of establishing a new connection on each request.
+      #: -> void
+      def disconnect_from_database
+        return unless defined?(::ActiveRecord::Base)
+
+        with_notification_error_handling("disconnect_from_database") do
+          ActiveRecord::Base.connection_handler.clear_all_connections!(:all)
+        end
+      end
+
       #: (singleton(ActiveRecord::Base)) -> Array[String]
       def collect_model_foreign_keys(model)
         return [] unless model.connection.respond_to?(:supports_foreign_keys?) &&