Add the {active, boolean()} Websocket command

This command is currently not documented. It allows disabling
the reading of incoming data from the socket, and can be used
as a poor man's flow control.

test/handlers/ws_active_commands_h.erl

@@ -0,0 +1,30 @@
+%% This module takes commands from the x-commands header
+%% and returns them in the websocket_init/1 callback.
+
+-module(ws_active_commands_h).
+-behavior(cowboy_websocket).
+
+-export([init/2]).
+-export([websocket_init/1]).
+-export([websocket_handle/2]).
+-export([websocket_info/2]).
+
+init(Req, RunOrHibernate) ->
+	{cowboy_websocket, Req, RunOrHibernate}.
+
+websocket_init(State=run) ->
+	erlang:send_after(1500, self(), active_true),
+	{[{active, false}], State};
+websocket_init(State=hibernate) ->
+	erlang:send_after(1500, self(), active_true),
+	{[{active, false}], State, hibernate}.
+
+websocket_handle(Frame, State=run) ->
+	{[Frame], State};
+websocket_handle(Frame, State=hibernate) ->
+	{[Frame], State, hibernate}.
+
+websocket_info(active_true, State=run) ->
+	{[{active, true}], State};
+websocket_info(active_true, State=hibernate) ->
+	{[{active, true}], State, hibernate}.