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authorLoïc Hoguin <[email protected]>2018-09-21 14:04:20 +0200
committerLoïc Hoguin <[email protected]>2018-09-21 15:01:57 +0200
commitf810d8dd6496da713e7c70a5e146120de3695774 (patch)
tree0572028ff1ea5fdc6d3d4b081d75ebdbb6bf557d
parent6e784f1a454c6bdeab839d99d59dac992d430c97 (diff)
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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.
-rw-r--r--doc/src/guide/migrating_from_2.4.asciidoc4
-rw-r--r--src/cowboy_websocket.erl5
-rw-r--r--test/handlers/ws_active_commands_h.erl30
-rw-r--r--test/ws_handler_SUITE.erl14
4 files changed, 52 insertions, 1 deletions
diff --git a/doc/src/guide/migrating_from_2.4.asciidoc b/doc/src/guide/migrating_from_2.4.asciidoc
index edf7d5b..0528659 100644
--- a/doc/src/guide/migrating_from_2.4.asciidoc
+++ b/doc/src/guide/migrating_from_2.4.asciidoc
@@ -31,6 +31,10 @@ also been worked on.
sent or commands yet to be introduced. New commands will
be available only through this new interface.
+* Add the `{active, boolean()}` Websocket handler command.
+ It allows disabling reading from the socket when `false`
+ is returned. `true` reenables reading from the socket.
+
* Add the protocol option `logger` that allows configuring
which logger module will be used. The logger module must
follow the interface of the new `logger` module in Erlang/OTP 21,
diff --git a/src/cowboy_websocket.erl b/src/cowboy_websocket.erl
index 2aa56b9..0e88fc4 100644
--- a/src/cowboy_websocket.erl
+++ b/src/cowboy_websocket.erl
@@ -77,6 +77,7 @@
ref :: ranch:ref(),
socket = undefined :: inet:socket() | {pid(), cowboy_stream:streamid()} | undefined,
transport = undefined :: module() | undefined,
+ active = true :: boolean(),
handler :: module(),
key = undefined :: undefined | binary(),
timeout = infinity :: timeout(),
@@ -295,6 +296,8 @@ takeover(Parent, Ref, Socket, Transport, _Opts, Buffer,
false -> before_loop(State, HandlerState, #ps_header{buffer=Buffer})
end.
+before_loop(State=#state{active=false}, HandlerState, ParseState) ->
+ loop(State, HandlerState, ParseState);
%% @todo We probably shouldn't do the setopts if we have not received a socket message.
%% @todo We need to hibernate when HTTP/2 is used too.
before_loop(State=#state{socket=Stream={Pid, _}, transport=undefined},
@@ -516,6 +519,8 @@ commands([], State, []) ->
commands([], State, Data) ->
Result = transport_send(State, nofin, lists:reverse(Data)),
{Result, State};
+commands([{active, Active}|Tail], State, Data) when is_boolean(Active) ->
+ commands(Tail, State#state{active=Active}, Data);
commands([Frame|Tail], State=#state{extensions=Extensions}, Data0) ->
Data = [cow_ws:frame(Frame, Extensions)|Data0],
case is_close_frame(Frame) of
diff --git a/test/handlers/ws_active_commands_h.erl b/test/handlers/ws_active_commands_h.erl
new file mode 100644
index 0000000..4cdb3b1
--- /dev/null
+++ b/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}.
diff --git a/test/ws_handler_SUITE.erl b/test/ws_handler_SUITE.erl
index 4848847..2caacca 100644
--- a/test/ws_handler_SUITE.erl
+++ b/test/ws_handler_SUITE.erl
@@ -26,6 +26,7 @@
all() ->
[{group, ws}, {group, ws_hibernate}].
+%% @todo Test against HTTP/2 too.
groups() ->
AllTests = ct_helper:all(?MODULE),
[{ws, [parallel], AllTests}, {ws_hibernate, [parallel], AllTests}].
@@ -48,7 +49,8 @@ init_dispatch(Name) ->
cowboy_router:compile([{'_', [
{"/init", ws_init_commands_h, RunOrHibernate},
{"/handle", ws_handle_commands_h, RunOrHibernate},
- {"/info", ws_info_commands_h, RunOrHibernate}
+ {"/info", ws_info_commands_h, RunOrHibernate},
+ {"/active", ws_active_commands_h, RunOrHibernate}
]}]).
%% Support functions for testing using Gun.
@@ -205,3 +207,13 @@ do_many_frames_then_close_frame(Config, Path) ->
{ok, {binary, <<"Two frames!">>}} = receive_ws(ConnPid, StreamRef),
{ok, close} = receive_ws(ConnPid, StreamRef),
gun_down(ConnPid).
+
+websocket_active_false(Config) ->
+ doc("The {active, false} command stops receiving data from the socket. "
+ "The {active, true} command reenables it."),
+ {ok, ConnPid, StreamRef} = gun_open_ws(Config, "/active", []),
+ gun:ws_send(ConnPid, {text, <<"Not received until the handler enables active again.">>}),
+ {error, timeout} = receive_ws(ConnPid, StreamRef),
+ {ok, {text, <<"Not received until the handler enables active again.">>}}
+ = receive_ws(ConnPid, StreamRef),
+ ok.