Add the cancel event for local/remote stream cancellation

5 files changed, 66 insertions, 21 deletions

diff --git a/src/gun.erl b/src/gun.erl
index b55d3a1..9add685 100644
--- a/src/gun.erl
+++ b/src/gun.erl
@@ -973,10 +973,12 @@ connected(info, {connect_protocol, Protocol}, #state{protocol=Protocol}) ->
 	keep_state_and_data;
 connected(info, {connect_protocol, Protocol}, State=#state{protocol_state=ProtoState}) ->
 	commands([{switch_protocol, Protocol, ProtoState}], State);
-connected(cast, {cancel, ReplyTo, StreamRef},
-		State=#state{protocol=Protocol, protocol_state=ProtoState}) ->
-	ProtoState2 = Protocol:cancel(ProtoState, StreamRef, ReplyTo),
-	{keep_state, State#state{protocol_state=ProtoState2}};
+connected(cast, {cancel, ReplyTo, StreamRef}, State=#state{
+		protocol=Protocol, protocol_state=ProtoState,
+		event_handler=EvHandler, event_handler_state=EvHandlerState0}) ->
+	{ProtoState2, EvHandlerState} = Protocol:cancel(ProtoState,
+		StreamRef, ReplyTo, EvHandler, EvHandlerState0),
+	{keep_state, State#state{protocol_state=ProtoState2, event_handler_state=EvHandlerState}};
 %% Public Websocket interface.
 %% @todo Maybe make an interface in the protocol module instead of checking on protocol name.
 %% An interface would also make sure that HTTP/1.0 can't upgrade.
diff --git a/src/gun_default_event_h.erl b/src/gun_default_event_h.erl
index 25076ac..213db06 100644
--- a/src/gun_default_event_h.erl
+++ b/src/gun_default_event_h.erl
@@ -39,6 +39,7 @@
 -export([ws_recv_frame_end/2]).
 -export([ws_send_frame_start/2]).
 -export([ws_send_frame_end/2]).
+-export([cancel/2]).
 -export([disconnect/2]).
 -export([terminate/2]).
 
@@ -114,6 +115,9 @@ ws_send_frame_start(_EventData, State) ->
 ws_send_frame_end(_EventData, State) ->
 	State.
 
+cancel(_EventData, State) ->
+	State.
+
 disconnect(_EventData, State) ->
 	State.
 
diff --git a/src/gun_event.erl b/src/gun_event.erl
index f27d336..c87af58 100644
--- a/src/gun_event.erl
+++ b/src/gun_event.erl
@@ -236,6 +236,25 @@
 -callback ws_send_frame_start(ws_send_frame_event(), State) -> State.
 -callback ws_send_frame_end(ws_send_frame_event(), State) -> State.
 
+%% cancel.
+%%
+%% In the case of HTTP/1.1 we cannot actually cancel the stream,
+%% we only silence the stream to the user. Further response events
+%% may therefore be received and they provide a useful metric as
+%% these canceled requests monopolize the connection.
+%%
+%% For HTTP/2 both the client and the server may cancel streams.
+%% Events may still occur for a short time after the cancel.
+
+-type cancel_event() :: #{
+	stream_ref := reference(),
+	reply_to := pid(),
+	endpoint := local | remote,
+	reason := atom()
+}.
+
+-callback cancel(cancel_event(), State) -> State.
+
 %% disconnect.
 
 -type disconnect_event() :: #{
@@ -255,5 +274,3 @@
 
 %% @todo origin_changed
 %% @todo transport_changed
-%% @todo cancel_start
-%% @todo cancel_end
diff --git a/src/gun_http.erl b/src/gun_http.erl
index da72527..738b6e9 100644
--- a/src/gun_http.erl
+++ b/src/gun_http.erl
@@ -24,7 +24,7 @@
 -export([request/11]).
 -export([data/7]).
 -export([connect/5]).
--export([cancel/3]).
+-export([cancel/5]).
 -export([stream_info/2]).
 -export([down/1]).
 -export([ws_upgrade/9]).
@@ -605,12 +605,19 @@ connect(State=#http_state{socket=Socket, transport=Transport, version=Version},
 	new_stream(State, {connect, StreamRef, Destination}, ReplyTo, <<"CONNECT">>).
 
 %% We can't cancel anything, we can just stop forwarding messages to the owner.
-cancel(State, StreamRef, ReplyTo) ->
-	case is_stream(State, StreamRef) of
+cancel(State0, StreamRef, ReplyTo, EvHandler, EvHandlerState0) ->
+	case is_stream(State0, StreamRef) of
 		true ->
-			cancel_stream(State, StreamRef);
+			State = cancel_stream(State0, StreamRef),
+			EvHandlerState = EvHandler:cancel(#{
+				stream_ref => StreamRef,
+				reply_to => ReplyTo,
+				endpoint => local,
+				reason => cancel
+			}, EvHandlerState0),
+			{State, EvHandlerState};
 		false ->
-			error_stream_not_found(State, StreamRef, ReplyTo)
+			{error_stream_not_found(State0, StreamRef, ReplyTo), EvHandlerState0}
 	end.
 
 stream_info(#http_state{streams=Streams}, StreamRef) ->
diff --git a/src/gun_http2.erl b/src/gun_http2.erl
index d039ecb..78b137b 100644
--- a/src/gun_http2.erl
+++ b/src/gun_http2.erl
@@ -23,7 +23,7 @@
 -export([headers/10]).
 -export([request/11]).
 -export([data/7]).
--export([cancel/3]).
+-export([cancel/5]).
 -export([stream_info/2]).
 -export([down/1]).
 
@@ -150,8 +150,8 @@ frame(State=#http2_state{http2_machine=HTTP2Machine0}, Frame, EvHandler, EvHandl
 			trailers_frame(State#http2_state{http2_machine=HTTP2Machine},
 				StreamID, Trailers, EvHandler, EvHandlerState);
 		{ok, {rst_stream, StreamID, Reason}, HTTP2Machine} ->
-			{rst_stream_frame(State#http2_state{http2_machine=HTTP2Machine}, StreamID, Reason),
-				EvHandlerState};
+			rst_stream_frame(State#http2_state{http2_machine=HTTP2Machine},
+				StreamID, Reason, EvHandler, EvHandlerState);
 		{ok, {push_promise, StreamID, PromisedStreamID, Headers, PseudoHeaders}, HTTP2Machine} ->
 			push_promise_frame(State#http2_state{http2_machine=HTTP2Machine},
 				StreamID, PromisedStreamID, Headers, PseudoHeaders,
@@ -268,14 +268,21 @@ trailers_frame(State, StreamID, Trailers, EvHandler, EvHandlerState0) ->
 	EvHandlerState = EvHandler:response_end(ResponseEvent, EvHandlerState1),
 	{maybe_delete_stream(State, StreamID, remote, fin), EvHandlerState}.
 
-rst_stream_frame(State=#http2_state{streams=Streams0}, StreamID, Reason) ->
+rst_stream_frame(State=#http2_state{streams=Streams0},
+		StreamID, Reason, EvHandler, EvHandlerState0) ->
 	case lists:keytake(StreamID, #stream.id, Streams0) of
 		{value, #stream{ref=StreamRef, reply_to=ReplyTo}, Streams} ->
 			ReplyTo ! {gun_error, self(), StreamRef,
 				{stream_error, Reason, 'Stream reset by server.'}},
-			State#http2_state{streams=Streams};
+			EvHandlerState = EvHandler:cancel(#{
+				stream_ref => StreamRef,
+				reply_to => ReplyTo,
+				endpoint => remote,
+				reason => Reason
+			}, EvHandlerState0),
+			{State#http2_state{streams=Streams}, EvHandlerState};
 		false ->
-			State
+			{State, EvHandlerState0}
 	end.
 
 push_promise_frame(State=#http2_state{streams=Streams},
@@ -482,15 +489,23 @@ reset_stream(State=#http2_state{socket=Socket, transport=Transport,
 			State
 	end.
 
-cancel(State=#http2_state{socket=Socket, transport=Transport,
-		http2_machine=HTTP2Machine0}, StreamRef, ReplyTo) ->
+cancel(State=#http2_state{socket=Socket, transport=Transport, http2_machine=HTTP2Machine0},
+		StreamRef, ReplyTo, EvHandler, EvHandlerState0) ->
 	case get_stream_by_ref(State, StreamRef) of
 		#stream{id=StreamID} ->
 			{ok, HTTP2Machine} = cow_http2_machine:reset_stream(StreamID, HTTP2Machine0),
 			Transport:send(Socket, cow_http2:rst_stream(StreamID, cancel)),
-			delete_stream(State#http2_state{http2_machine=HTTP2Machine}, StreamID);
+			EvHandlerState = EvHandler:cancel(#{
+				stream_ref => StreamRef,
+				reply_to => ReplyTo,
+				endpoint => local,
+				reason => cancel
+			}, EvHandlerState0),
+			{delete_stream(State#http2_state{http2_machine=HTTP2Machine}, StreamID),
+				EvHandlerState};
 		false ->
-			error_stream_not_found(State, StreamRef, ReplyTo)
+			{error_stream_not_found(State, StreamRef, ReplyTo),
+				EvHandlerState0}
 	end.
 
 stream_info(State, StreamRef) ->