Allow passing options to sub protocols

Before this commit we had an issue where configuring a
Websocket connection was simply not possible without
doing magic, adding callbacks or extra return values.
The init/2 function only allowed setting hibernate
and timeout options.

After this commit, when switching to a different
type of handler you can either return

  {module, Req, State}

or

  {module, Req, State, Opts}

where Opts is any value (as far as the sub protocol
interface is concerned) and is ultimately checked
by the custom handlers.

A large protocol like Websocket would accept only
a map there, with many different options, while a
small interface like loop handlers would allow
passing hibernate and nothing else.

For Websocket, hibernate must be set from the
websocket_init/1 callback, because init/2 executes
in a separate process.

Sub protocols now have two callbacks: one with the
Opts value, one without.

The loop handler code was largely reworked and
simplified. It does not need to manage a timeout
or read from the socket anymore, it's the job of
the protocol code. A lot of unnecessary stuff was
therefore removed.

Websocket compression must now be enabled from
the handler options instead of per listener. This
means that a project can have two separate Websocket
handlers with different options. Compression is
still disabled by default, and the idle_timeout
value was changed from inifnity to 60000 (60 seconds),
as that's safer and is also a good value for mobile
devices.

doc/src/guide/loop_handlers.asciidoc

@@ -34,7 +34,7 @@ loop handler behavior. This tuple may optionally contain
 a timeout value and/or the atom `hibernate` to make the
 process enter hibernation until a message is received.
 
-This snippet enables the loop handler.
+This snippet enables the loop handler:
 
 [source,erlang]
 ----
@@ -42,14 +42,12 @@ init(Req, State) ->
     {cowboy_loop, Req, State}.
 ----
 
-However it is largely recommended that you set a timeout
-value. The next example sets a timeout value of 30s and
-also makes the process hibernate.
+This also makes the process hibernate:
 
 [source,erlang]
 ----
 init(Req, State) ->
-    {cowboy_loop, Req, State, 30000, hibernate}.
+    {cowboy_loop, Req, State, hibernate}.
 ----
 
 === Receive loop
@@ -123,25 +121,6 @@ a subsequent request.
 Please refer to the xref:handlers[Handlers chapter]
 for general instructions about cleaning up.
 
-=== Timeout
-
-Note that this feature currently does not work. It will be
-brought back in a future 2.0 pre-release.
-
-By default Cowboy will not attempt to close the connection
-if there is no activity from the client. This is not always
-desirable, which is why you can set a timeout. Cowboy will
-close the connection if no data was received from the client
-after the configured time. The timeout only needs to be set
-once and can't be modified afterwards.
-
-Because the request may have had a body, or may be followed
-by another request, Cowboy is forced to buffer all data it
-receives. This data may grow to become too large though,
-so there is a configurable limit for it. The default buffer
-size is of 5000 bytes, but it may be changed by setting the
-`loop_max_buffer` middleware environment value.
-
 === Hibernate
 
 To save memory, you may hibernate the process in between

doc/src/guide/sub_protocols.asciidoc

@@ -20,31 +20,31 @@ init(Req, State) ->
     {cowboy_websocket, Req, State}.
 ----
 
-The return value may also have a `Timeout` value and/or the
-atom `hibernate`. These options are useful for long living
-connections. When they are not provided, the timeout value
-defaults to `infinity` and the hibernate value to `run`.
+The returned tuple may also have a fourth element containing
+options for the sub protocol. No option is universal. While
+it will usually be a map of options, it doesn't have to be.
+For example loop handlers accept the atom `hibernate`.
 
 The following snippet switches to the `my_protocol` sub
 protocol, sets the timeout value to 5 seconds and enables
 hibernation:
 
-// @todo Yeah maybe what we really need is an Opts map.
-
 [source,erlang]
 ----
 init(Req, State) ->
-    {my_protocol, Req, State, 5000, hibernate}.
+    {my_protocol, Req, State, #{
+        timeout => 5000,
+        compress => true}}.
 ----
 
-If a sub protocol does not make use of these options, it should
-crash if it receives anything other than the default values.
+Sub protocols should ignore unknown options so as to not waste
+resources doing unnecessary validation.
 
 === Upgrade
 
-After the `init/2` function returns, Cowboy will then call the
-`upgrade/6` function. This is the only callback defined by the
-`cowboy_sub_protocol` behavior.
+After the `init/2` function returns, Cowboy will call either
+the `upgrade/4` or the `upgrade/5` function. The former is called
+when no options were given; the latter when they were given.
 
 The function is named `upgrade` because it mimics the mechanism
 of HTTP protocol upgrades. For some sub protocols, like Websocket,
@@ -53,16 +53,19 @@ only an upgrade at Cowboy's level and the client has nothing to
 do about it.
 
 The upgrade callback receives the Req object, the middleware
-environment, the handler and its options, and the aforementioned
-timeout and hibernate values.
+environment, the handler and its state, and for `upgrade/5`
+also the aformentioned options.
 
 [source,erlang]
 ----
-upgrade(Req, Env, Handler, HandlerOpts, Timeout, Hibernate) ->
+upgrade(Req, Env, Handler, State) ->
+    %% Sub protocol code here.
+
+upgrade(Req, Env, Handler, State, Opts) ->
     %% Sub protocol code here.
 ----
 
-This callback is expected to behave like a middleware and to
+These callbacks are expected to behave like middlewares and to
 return an updated environment and Req object.
 
 Sub protocols are expected to call the `cowboy_handler:terminate/4`

doc/src/guide/ws_handlers.asciidoc

@@ -60,13 +60,13 @@ be:
 init(Req, State) ->
     case cowboy_req:parse_header(<<"sec-websocket-protocol">>, Req) of
         undefined ->
-            {ok, Req, State};
+            {cowboy_websocket, Req, State};
         Subprotocols ->
             case lists:keymember(<<"mqtt">>, 1, Subprotocols) of
                 true ->
                     Req2 = cowboy_req:set_resp_header(<<"sec-websocket-protocol">>,
                         <<"mqtt">>, Req),
-                    {ok, Req2, State};
+                    {cowboy_websocket, Req2, State};
                 false ->
                     {stop, Req, State}
             end
@@ -210,12 +210,13 @@ than needed.
 
 The `init/2` callback can set the timeout to be used
 for the connection. For example, this would make Cowboy
-close connections idle for more than 60 seconds:
+close connections idle for more than 30 seconds:
 
 [source,erlang]
 ----
 init(Req, State) ->
-    {cowboy_websocket, Req, State, 60000}.
+    {cowboy_websocket, Req, State, #{
+        idle_timeout => 30000}}.
 ----
 
 This value cannot be changed once it is set. It defaults to

doc/src/guide/ws_protocol.asciidoc

@@ -65,6 +65,5 @@ Cowboy's Websocket implementation also includes the
 permessage-deflate and x-webkit-deflate-frame compression
 extensions.
 
-Cowboy will automatically use compression as long as the
-`websocket_compress` protocol option is set when starting
-the listener.
+Cowboy will automatically use compression when the
+`compress` option is returned from the `init/2` function.

doc/src/manual/cowboy_app.asciidoc

@@ -59,8 +59,6 @@ Middlewares:
 * ssl - Secure communication over sockets
 * crypto - Crypto functions
 
-// @todo Explicitly depend on ssl.
-
 All these applications must be started before the `cowboy`
 application. To start Cowboy and all dependencies at once:
 

doc/src/manual/cowboy_loop.asciidoc

@@ -29,8 +29,6 @@ Loop handlers implement the following interface:
 init(Req, State)
     -> {cowboy_loop, Req, State}
      | {cowboy_loop, Req, State, hibernate}
-     | {cowboy_loop, Req, State, timeout()}
-     | {cowboy_loop, Req, State, timeout(), hibernate}
 
 info(Info, Req, State)
     -> {ok, Req, State}
@@ -42,7 +40,7 @@ terminate(Reason, Req, State) -> ok  %% optional
 Req    :: cowboy_req:req()
 State  :: any()
 Info   :: any()
-Reason :: stop | timeout
+Reason :: stop
         | {crash, error | exit | throw, any()}
 ----
 
@@ -65,37 +63,15 @@ stop::
     The handler requested to close the connection by returning
     a `stop` tuple.
 
-timeout::
-    The connection has been closed due to inactivity. The timeout
-    value can be configured from `init/2`. The response sent when
-    this happens is a `204 No Content`.
-
 {crash, Class, Reason}::
     A crash occurred in the handler. `Class` and `Reason` can be
     used to obtain more information about the crash. The function
     `erlang:get_stacktrace/0` can also be called to obtain the
     stacktrace of the process when the crash occurred.
 
-//{error, overflow}::
-//    The connection is being closed and the process terminated
-//    because the buffer Cowboy uses to keep data sent by the
-//    client has reached its maximum. The buffer size can be
-//    configured through the environment value `loop_max_buffer`
-//    and defaults to 5000 bytes.
-//    +
-//    If the long running request comes with a body it is recommended
-//    to process this body before switching to the loop sub protocol.
-//
-//{error, closed}::
-//    The socket has been closed brutally without a close frame being
-//    received first.
-//
-//{error, Reason}::
-//    A socket error ocurred.
-
 == Changelog
 
-* *2.0*: Cowboy temporarily no longer checks the socket for data with HTTP/1.1.
+* *2.0*: Loop handlers no longer need to handle overflow/timeouts.
 * *1.0*: Behavior introduced.
 
 == See also

doc/src/manual/cowboy_rest.asciidoc

@@ -21,9 +21,6 @@ REST handlers implement the following interface:
 ----
 init(Req, State)
     -> {cowboy_rest, Req, State}
-     | {cowboy_rest, Req, State, hibernate}
-     | {cowboy_rest, Req, State, timeout()}
-     | {cowboy_rest, Req, State, timeout(), hibernate}
 
 Callback(Req, State)
     -> {Result, Req, State}

doc/src/manual/cowboy_websocket.asciidoc

@@ -10,31 +10,6 @@ The module `cowboy_websocket` implements Websocket
 as a Ranch protocol. It also defines a callback interface
 for handling Websocket connections.
 
-== Options
-
-[source,erlang]
-----
-opts() :: #{
-    websocket_compress := boolean()
-}
-----
-
-Configuration for the Websocket protocol.
-
-This configuration is passed to Cowboy when starting listeners
-using `cowboy:start_clear/4` or `cowboy:start_tls/4` functions.
-
-It can be updated without restarting listeners using the
-Ranch functions `ranch:get_protocol_options/1` and
-`ranch:set_protocol_options/2`.
-
-The default value is given next to the option name:
-
-websocket_compress (false)::
-    Whether to enable the Websocket frame compression
-    extension. Frames will only be compressed for the
-    clients that support this extension.
-
 == Callbacks
 
 Websocket handlers must implement the following callback
@@ -44,9 +19,7 @@ interface:
 ----
 init(Req, State)
     -> {cowboy_websocket, Req, State}
-     | {cowboy_websocket, Req, State, hibernate}
-     | {cowboy_websocket, Req, State, timeout()}
-     | {cowboy_websocket, Req, State, timeout(), hibernate}
+     | {cowboy_websocket, Req, State, Opts}
 
 websocket_init(State)            -> CallResult  %% optional
 websocket_handle(InFrame, State) -> CallResult
@@ -56,6 +29,7 @@ terminate(Reason, undefined, State) -> ok       %% optional
 
 Req        :: cowboy_req:req()
 State      :: any()
+Opts       :: cowboy_websocket:opts()
 InFrame    :: {text | binary | ping | pong, binary()}
 OutFrame   :: cow_ws:frame()
 Info       :: any()
@@ -152,6 +126,42 @@ timeout::
 {error, Reason}::
     A socket error ocurred.
 
+== Types
+
+=== opts()
+
+[source,erlang]
+----
+opts() :: #{
+    compress => boolean(),
+    idle_timeout => timeout()
+}
+----
+
+Websocket handler options.
+
+This configuration is passed to Cowboy from the `init/2`
+function:
+
+[source,erlang]
+----
+init(Req, State) ->
+    Opts = #{compress => true},
+    {cowboy_websocket, Req, State, Opts}.
+----
+
+The default value is given next to the option name:
+
+compress (false)::
+    Whether to enable the Websocket frame compression
+    extension. Frames will only be compressed for the
+    clients that support this extension.
+
+idle_timeout (60000)::
+    Time in milliseconds that Cowboy will keep the
+    connection open without receiving anything from
+    the client.
+
 == Changelog
 
 * *2.0*: The Req object is no longer passed to Websocket callbacks.