Add a function to lock request responses instead of inlining

Just more cleanup in order to have req() opaque.

src/cowboy_protocol.erl

@@ -383,7 +383,7 @@ handler_call(HandlerState, Req, State=#state{handler={Handler, Opts}},
 -spec handler_terminate(any(), cowboy_req:req(), #state{}) -> ok.
 handler_terminate(HandlerState, Req, #state{handler={Handler, Opts}}) ->
 	try
-		Handler:terminate(Req#http_req{resp_state=locked}, HandlerState)
+		Handler:terminate(cowboy_req:lock(Req), HandlerState)
 	catch Class:Reason ->
 		PLReq = cowboy_req:to_list(Req),
 		error_logger:error_msg(

src/cowboy_req.erl

@@ -103,6 +103,7 @@
 
 %% Misc API.
 -export([compact/1]).
+-export([lock/1]).
 -export([to_list/1]).
 -export([transport/1]).
 
@@ -908,6 +909,12 @@ compact(Req) ->
 		bindings=undefined, headers=[],
 		p_headers=[], cookies=[]}.
 
+%% @doc Prevent any further responses.
+%% @private
+-spec lock(Req) -> Req when Req::req().
+lock(Req) ->
+	Req#http_req{resp_state=locked}.
+
 %% @doc Convert the Req object to a list of key/values.
 -spec to_list(req()) -> [{atom(), any()}].
 to_list(Req) ->

src/cowboy_rest.erl

@@ -897,7 +897,7 @@ respond(Req, State, StatusCode) ->
 terminate(Req, #state{handler=Handler, handler_state=HandlerState}) ->
 	case erlang:function_exported(Handler, rest_terminate, 2) of
 		true -> ok = Handler:rest_terminate(
-			Req#http_req{resp_state=locked}, HandlerState);
+			cowboy_req:lock(Req), HandlerState);
 		false -> ok
 	end,
 	{ok, Req}.