Unify the init and terminate callbacks

This set of changes is the first step to simplify the
writing of handlers, by removing some extraneous
callbacks and making others optional.

init/3 is now init/2, its first argument being removed.

rest_init/2 and rest_terminate/2 have been removed.

websocket_init/3 and websocket_terminate/3 have been removed.

terminate/3 is now optional. It is called regardless of
the type of handler, including rest and websocket.

The return value of init/2 changed. It now returns
{Mod, Req, Opts} with Mod being either one of the four
handler type or a custom module. It can also return extra
timeout and hibernate options.

The signature for sub protocols has changed, they now
receive these extra timeout and hibernate options.

Loop handlers are now implemented in cowboy_long_polling,
and will be renamed throughout the project in a future commit.

src/cowboy_websocket.erl

@@ -17,7 +17,7 @@
 -module(cowboy_websocket).
 -behaviour(cowboy_sub_protocol).
 
--export([upgrade/4]).
+-export([upgrade/6]).
 -export([handler_loop/4]).
 
 -type close_code() :: 1000..4999.
@@ -53,19 +53,18 @@
 	deflate_state :: undefined | port()
 }).
 
--spec upgrade(Req, Env, module(), any())
-	-> {ok, Req, Env}
-	| {suspend, module(), atom(), [any()]}
+-spec upgrade(Req, Env, module(), any(), timeout(), run | hibernate)
+	-> {ok, Req, Env} | {suspend, module(), atom(), [any()]}
 	when Req::cowboy_req:req(), Env::cowboy_middleware:env().
-upgrade(Req, Env, Handler, HandlerOpts) ->
+upgrade(Req, Env, Handler, HandlerState, Timeout, Hibernate) ->
 	{_, Ref} = lists:keyfind(listener, 1, Env),
 	ranch:remove_connection(Ref),
 	[Socket, Transport] = cowboy_req:get([socket, transport], Req),
-	State = #state{env=Env, socket=Socket, transport=Transport,
-		handler=Handler},
+	State = #state{env=Env, socket=Socket, transport=Transport, handler=Handler,
+		timeout=Timeout, hibernate=Hibernate =:= hibernate},
 	try websocket_upgrade(State, Req) of
 		{ok, State2, Req2} ->
-			handler_init(State2, Req2, HandlerOpts)
+			websocket_handshake(State2, Req2, HandlerState)
 	catch _:_ ->
 		receive
 			{cowboy_req, resp_sent} -> ok
@@ -121,38 +120,6 @@ websocket_extensions(State, Req) ->
 			end
 	end.
 
--spec handler_init(#state{}, Req, any())
-	-> {ok, Req, cowboy_middleware:env()} | {suspend, module(), atom(), [any()]}
-	when Req::cowboy_req:req().
-handler_init(State=#state{env=Env, transport=Transport,
-		handler=Handler}, Req, HandlerOpts) ->
-	try Handler:websocket_init(Transport:name(), Req, HandlerOpts) of
-		{ok, Req2, HandlerState} ->
-			websocket_handshake(State, Req2, HandlerState);
-		{ok, Req2, HandlerState, hibernate} ->
-			websocket_handshake(State#state{hibernate=true},
-				Req2, HandlerState);
-		{ok, Req2, HandlerState, Timeout} ->
-			websocket_handshake(State#state{timeout=Timeout},
-				Req2, HandlerState);
-		{ok, Req2, HandlerState, Timeout, hibernate} ->
-			websocket_handshake(State#state{timeout=Timeout,
-				hibernate=true}, Req2, HandlerState);
-		{shutdown, Req2} ->
-			cowboy_req:ensure_response(Req2, 400),
-			{ok, Req2, [{result, closed}|Env]}
-	catch Class:Reason ->
-		Stacktrace = erlang:get_stacktrace(),
-		cowboy_req:maybe_reply(Stacktrace, Req),
-		erlang:Class([
-			{reason, Reason},
-			{mfa, {Handler, websocket_init, 3}},
-			{stacktrace, Stacktrace},
-			{req, cowboy_req:to_list(Req)},
-			{opts, HandlerOpts}
-		])
-	end.
-
 -spec websocket_handshake(#state{}, Req, any())
 	-> {ok, Req, cowboy_middleware:env()}
 	| {suspend, module(), atom(), [any()]}
@@ -703,6 +670,15 @@ websocket_send({Type, Payload0}, State=#state{socket=Socket, transport=Transport
 	{Transport:send(Socket,
 		[<< 1:1, Rsv/bits, Opcode:4, 0:1, BinLen/bits >>, Payload]), State2}.
 
+-spec payload_length_to_binary(0..16#7fffffffffffffff)
+	-> << _:7 >> | << _:23 >> | << _:71 >>.
+payload_length_to_binary(N) ->
+	case N of
+		N when N =< 125 -> << N:7 >>;
+		N when N =< 16#ffff -> << 126:7, N:16 >>;
+		N when N =< 16#7fffffffffffffff -> << 127:7, N:64 >>
+	end.
+
 -spec websocket_send_many([frame()], #state{})
 	-> {ok, #state{}} | {shutdown, #state{}} | {{error, atom()}, #state{}}.
 websocket_send_many([], State) ->
@@ -739,26 +715,6 @@ websocket_close(State=#state{socket=Socket, transport=Transport},
 	-> {ok, Req, cowboy_middleware:env()}
 	when Req::cowboy_req:req().
 handler_terminate(#state{env=Env, handler=Handler},
-		Req, HandlerState, TerminateReason) ->
-	try
-		Handler:websocket_terminate(TerminateReason, Req, HandlerState)
-	catch Class:Reason ->
-		erlang:Class([
-			{reason, Reason},
-			{mfa, {Handler, websocket_terminate, 3}},
-			{stacktrace, erlang:get_stacktrace()},
-			{req, cowboy_req:to_list(Req)},
-			{state, HandlerState},
-			{terminate_reason, TerminateReason}
-		])
-	end,
+		Req, HandlerState, Reason) ->
+	_ = cowboy_handler:terminate(Req, Env, Handler, HandlerState, Reason),
 	{ok, Req, [{result, closed}|Env]}.
-
--spec payload_length_to_binary(0..16#7fffffffffffffff)
-	-> << _:7 >> | << _:23 >> | << _:71 >>.
-payload_length_to_binary(N) ->
-	case N of
-		N when N =< 125 -> << N:7 >>;
-		N when N =< 16#ffff -> << 126:7, N:16 >>;
-		N when N =< 16#7fffffffffffffff -> << 127:7, N:64 >>
-	end.