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.

examples/chunked_hello_world/src/toppage_handler.erl

@@ -3,12 +3,11 @@
 %% @doc Chunked hello world handler.
 -module(toppage_handler).
 
--export([init/3]).
+-export([init/2]).
 -export([handle/2]).
--export([terminate/3]).
 
-init(_Transport, Req, []) ->
-	{ok, Req, undefined}.
+init(Req, Opts) ->
+	{http, Req, Opts}.
 
 handle(Req, State) ->
 	Req2 = cowboy_req:chunked_reply(200, Req),
@@ -18,6 +17,3 @@ handle(Req, State) ->
 	timer:sleep(1000),
 	cowboy_req:chunk("Chunked!\r\n", Req2),
 	{ok, Req2, State}.
-
-terminate(_Reason, _Req, _State) ->
-	ok.

examples/compress_response/src/toppage_handler.erl

@@ -3,12 +3,11 @@
 %% @doc Compress response handler.
 -module(toppage_handler).
 
--export([init/3]).
+-export([init/2]).
 -export([handle/2]).
--export([terminate/3]).
 
-init(_Transport, Req, []) ->
-	{ok, Req, undefined}.
+init(Req, Opts) ->
+	{http, Req, Opts}.
 
 handle(Req, State) ->
 	BigBody =
@@ -26,6 +25,3 @@ in many other parts of the world, particularly South America and Australia,
 who perform work similar to the cowboy in their respective nations.\n">>,
 	Req2 = cowboy_req:reply(200, [], BigBody, Req),
 	{ok, Req2, State}.
-
-terminate(_Reason, _Req, _State) ->
-	ok.

examples/cookie/src/toppage_handler.erl

@@ -3,12 +3,11 @@
 %% @doc Cookie handler.
 -module(toppage_handler).
 
--export([init/3]).
+-export([init/2]).
 -export([handle/2]).
--export([terminate/3]).
 
-init(_Transport, Req, []) ->
-	{ok, Req, undefined}.
+init(Req, Opts) ->
+	{http, Req, Opts}.
 
 handle(Req, State) ->
 	NewValue = integer_to_list(random:uniform(1000000)),
@@ -24,6 +23,3 @@ handle(Req, State) ->
 		[{<<"content-type">>, <<"text/html">>}],
 		Body, Req2),
 	{ok, Req3, State}.
-
-terminate(_Reason, _Req, _State) ->
-	ok.

examples/echo_get/src/toppage_handler.erl

@@ -3,12 +3,11 @@
 %% @doc GET echo handler.
 -module(toppage_handler).
 
--export([init/3]).
+-export([init/2]).
 -export([handle/2]).
--export([terminate/3]).
 
-init(_Transport, Req, []) ->
-	{ok, Req, undefined}.
+init(Req, Opts) ->
+	{http, Req, Opts}.
 
 handle(Req, State) ->
 	Method = cowboy_req:method(Req),
@@ -25,6 +24,3 @@ echo(<<"GET">>, Echo, Req) ->
 echo(_, _, Req) ->
 	%% Method not allowed.
 	cowboy_req:reply(405, Req).
-
-terminate(_Reason, _Req, _State) ->
-	ok.

examples/echo_post/src/toppage_handler.erl

@@ -3,12 +3,11 @@
 %% @doc POST echo handler.
 -module(toppage_handler).
 
--export([init/3]).
+-export([init/2]).
 -export([handle/2]).
--export([terminate/3]).
 
-init(_Transport, Req, []) ->
-	{ok, Req, undefined}.
+init(Req, Opts) ->
+	{http, Req, Opts}.
 
 handle(Req, State) ->
 	Method = cowboy_req:method(Req),
@@ -32,6 +31,3 @@ echo(Echo, Req) ->
 	cowboy_req:reply(200, [
 		{<<"content-type">>, <<"text/plain; charset=utf-8">>}
 	], Echo, Req).
-
-terminate(_Reason, _Req, _State) ->
-	ok.

examples/eventsource/src/eventsource_handler.erl

@@ -3,24 +3,20 @@
 %% @doc EventSource emitter.
 -module(eventsource_handler).
 
--export([init/3]).
+-export([init/2]).
 -export([info/3]).
--export([terminate/3]).
 
-init(_Transport, Req, []) ->
+init(Req, Opts) ->
 	Headers = [{<<"content-type">>, <<"text/event-stream">>}],
 	Req2 = cowboy_req:chunked_reply(200, Headers, Req),
 	erlang:send_after(1000, self(), {message, "Tick"}),
-	{loop, Req2, undefined, 5000}.
+	{long_polling, Req2, Opts, 5000}.
 
 info({message, Msg}, Req, State) ->
 	cowboy_req:chunk(["id: ", id(), "\ndata: ", Msg, "\n\n"], Req),
 	erlang:send_after(1000, self(), {message, "Tick"}),
 	{loop, Req, State}.
 
-terminate(_Reason, _Req, _State) ->
-	ok.
-
 id() ->
 	{Mega, Sec, Micro} = erlang:now(),
 	Id = (Mega * 1000000 + Sec) * 1000000 + Micro,

examples/hello_world/src/toppage_handler.erl

@@ -3,18 +3,14 @@
 %% @doc Hello world handler.
 -module(toppage_handler).
 
--export([init/3]).
+-export([init/2]).
 -export([handle/2]).
--export([terminate/3]).
 
-init(_Type, Req, []) ->
-	{ok, Req, undefined}.
+init(Req, Opts) ->
+	{http, Req, Opts}.
 
 handle(Req, State) ->
 	Req2 = cowboy_req:reply(200, [
 		{<<"content-type">>, <<"text/plain">>}
 	], <<"Hello world!">>, Req),
 	{ok, Req2, State}.
-
-terminate(_Reason, _Req, _State) ->
-	ok.

examples/rest_basic_auth/src/toppage_handler.erl

@@ -3,13 +3,13 @@
 %% @doc Handler with basic HTTP authorization.
 -module(toppage_handler).
 
--export([init/3]).
+-export([init/2]).
 -export([content_types_provided/2]).
 -export([is_authorized/2]).
 -export([to_text/2]).
 
-init(_Transport, _Req, []) ->
-	{upgrade, protocol, cowboy_rest}.
+init(Req, Opts) ->
+	{rest, Req, Opts}.
 
 is_authorized(Req, State) ->
 	case cowboy_req:parse_header(<<"authorization">>, Req) of

examples/rest_hello_world/src/toppage_handler.erl

@@ -3,14 +3,14 @@
 %% @doc Hello world handler.
 -module(toppage_handler).
 
--export([init/3]).
+-export([init/2]).
 -export([content_types_provided/2]).
 -export([hello_to_html/2]).
 -export([hello_to_json/2]).
 -export([hello_to_text/2]).
 
-init(_Transport, _Req, []) ->
-	{upgrade, protocol, cowboy_rest}.
+init(Req, Opts) ->
+	{rest, Req, Opts}.
 
 content_types_provided(Req, State) ->
 	{[

examples/rest_pastebin/src/toppage_handler.erl

@@ -4,7 +4,7 @@
 -module(toppage_handler).
 
 %% Standard callbacks.
--export([init/3]).
+-export([init/2]).
 -export([allowed_methods/2]).
 -export([content_types_provided/2]).
 -export([content_types_accepted/2]).
@@ -15,11 +15,9 @@
 -export([paste_html/2]).
 -export([paste_text/2]).
 
-init(_Transport, _Req, []) ->
-	% For the random number generator:
-	{X, Y, Z} = now(),
-	random:seed(X, Y, Z),
-	{upgrade, protocol, cowboy_rest}.
+init(Req, Opts) ->
+	random:seed(now()),
+	{rest, Req, Opts}.
 
 allowed_methods(Req, State) ->
 	{[<<"GET">>, <<"POST">>], Req, State}.

examples/rest_stream_response/src/toppage_handler.erl

@@ -3,16 +3,12 @@
 %% @doc Streaming handler.
 -module(toppage_handler).
 
--export([init/3]).
--export([rest_init/2]).
+-export([init/2]).
 -export([content_types_provided/2]).
 -export([streaming_csv/2]).
 
-init(_Transport, _Req, _Table) ->
-	{upgrade, protocol, cowboy_rest}.
-
-rest_init(Req, Table) ->
-	{ok, Req, Table}.
+init(Req, Table) ->
+	{rest, Req, Table}.
 
 content_types_provided(Req, State) ->
 	{[

examples/ssl_hello_world/src/toppage_handler.erl

@@ -3,18 +3,14 @@
 %% @doc Hello world handler.
 -module(toppage_handler).
 
--export([init/3]).
+-export([init/2]).
 -export([handle/2]).
--export([terminate/3]).
 
-init(_Transport, Req, []) ->
-	{ok, Req, undefined}.
+init(Req, Opts) ->
+	{http, Req, Opts}.
 
 handle(Req, State) ->
 	Req2 = cowboy_req:reply(200, [
 		{<<"content-type">>, <<"text/plain">>}
 	], <<"Hello world!">>, Req),
 	{ok, Req2, State}.
-
-terminate(_Reason, _Req, _State) ->
-	ok.

examples/upload/src/upload_handler.erl

@@ -1,12 +1,13 @@
+%% Feel free to use, reuse and abuse the code in this file.
+
+%% @doc Upload handler.
 -module(upload_handler).
--behaviour(cowboy_http_handler).
 
--export([init/3]).
+-export([init/2]).
 -export([handle/2]).
--export([terminate/3]).
 
-init(_, Req, _Opts) ->
-	{ok, Req, undefined}.
+init(Req, Opts) ->
+	{http, Req, Opts}.
 
 handle(Req, State) ->
 	{ok, Headers, Req2} = cowboy_req:part(Req),
@@ -16,6 +17,3 @@ handle(Req, State) ->
 	io:format("Received file ~p of content-type ~p as follow:~n~p~n~n",
 		[Filename, ContentType, Data]),
 	{ok, Req3, State}.
-
-terminate(_Reason, _Req, _State) ->
-	ok.

examples/web_server/src/directory_handler.erl

@@ -4,8 +4,7 @@
 -module(directory_handler).
 
 %% REST Callbacks
--export([init/3]).
--export([rest_init/2]).
+-export([init/2]).
 -export([allowed_methods/2]).
 -export([resource_exists/2]).
 -export([content_types_provided/2]).
@@ -14,11 +13,8 @@
 -export([list_json/2]).
 -export([list_html/2]).
 
-init(_Transport, _Req, _Paths) ->
-	{upgrade, protocol, cowboy_rest}.
-
-rest_init(Req, Paths) ->
-	{ok, Req, Paths}.
+init(Req, Paths) ->
+	{rest, Req, Paths}.
 
 allowed_methods(Req, State) ->
 	{[<<"GET">>], Req, State}.

examples/websocket/src/ws_handler.erl

@@ -1,18 +1,12 @@
 -module(ws_handler).
--behaviour(cowboy_websocket_handler).
 
--export([init/3]).
--export([websocket_init/3]).
+-export([init/2]).
 -export([websocket_handle/3]).
 -export([websocket_info/3]).
--export([websocket_terminate/3]).
 
-init({tcp, http}, _Req, _Opts) ->
-	{upgrade, protocol, cowboy_websocket}.
-
-websocket_init(_TransportName, Req, _Opts) ->
+init(Req, Opts) ->
 	erlang:start_timer(1000, self(), <<"Hello!">>),
-	{ok, Req, undefined_state}.
+	{ws, Req, Opts}.
 
 websocket_handle({text, Msg}, Req, State) ->
 	{reply, {text, << "That's what she said! ", Msg/binary >>}, Req, State};
@@ -24,6 +18,3 @@ websocket_info({timeout, _Ref, Msg}, Req, State) ->
 	{reply, {text, Msg}, Req, State};
 websocket_info(_Info, Req, State) ->
 	{ok, Req, State}.
-
-websocket_terminate(_Reason, _Req, _State) ->
-	ok.