From cd7870df151a8686c6d204f9972f9032494c44d4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lo=C3=AFc=20Hoguin?= <essen@ninenines.eu>
Date: Wed, 4 Dec 2019 11:17:34 +0100
Subject: Experiment with {active,N}

---
 Makefile            |  4 ++--
 src/cowboy_http.erl | 34 ++++++++++++++++++++++++----------
 2 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/Makefile b/Makefile
index bd4ffa0..02df0e7 100644
--- a/Makefile
+++ b/Makefile
@@ -29,10 +29,10 @@ dep_gun = git https://github.com/ninenines/gun master
 dep_ci.erlang.mk = git https://github.com/ninenines/ci.erlang.mk master
 DEP_EARLY_PLUGINS = ci.erlang.mk
 
-AUTO_CI_OTP ?= OTP-LATEST-20+
+AUTO_CI_OTP ?= OTP-LATEST-22+
 AUTO_CI_HIPE ?= OTP-LATEST
 # AUTO_CI_ERLLVM ?= OTP-LATEST
-AUTO_CI_WINDOWS ?= OTP-LATEST-20+
+AUTO_CI_WINDOWS ?= OTP-LATEST-22+
 
 # Standard targets.
 
diff --git a/src/cowboy_http.erl b/src/cowboy_http.erl
index f128a44..7cbecef 100644
--- a/src/cowboy_http.erl
+++ b/src/cowboy_http.erl
@@ -125,6 +125,9 @@
 
 	timer = undefined :: undefined | reference(),
 
+	%% Whether we are currently receiving data from the socket.
+	active = false :: boolean(),
+
 	%% Identifier for the stream currently being read (or waiting to be received).
 	in_streamid = 1 :: pos_integer(),
 
@@ -189,12 +192,21 @@ init(Parent, Ref, Socket, Transport, ProxyHeader, Opts) ->
 				'A socket error occurred when retrieving the client TLS certificate.'})
 	end.
 
+active(State=#state{socket=Socket, transport=Transport}) ->
+	Transport:setopts(Socket, [{active, 100}]),
+	State#state{active=true}.
+
+passive(State=#state{socket=Socket, transport=Transport}) ->
+	Transport:setopts(Socket, [{active, false}]),
+	State#state{active=false}.
+
+before_loop(State=#state{active=true}) ->
+	loop(State);
 %% Do not read from the socket unless flow is large enough.
 before_loop(State=#state{flow=Flow}) when Flow =< 0 ->
 	loop(State);
-before_loop(State=#state{socket=Socket, transport=Transport}) ->
-	Transport:setopts(Socket, [{active, once}]),
-	loop(State).
+before_loop(State) ->
+	loop(active(State)).
 
 loop(State=#state{parent=Parent, socket=Socket, transport=Transport, opts=Opts,
 		buffer=Buffer, timer=TimerRef, children=Children, in_streamid=InStreamID,
@@ -213,6 +225,8 @@ loop(State=#state{parent=Parent, socket=Socket, transport=Transport, opts=Opts,
 			terminate(State, {socket_error, closed, 'The socket has been closed.'});
 		{Error, Socket, Reason} when Error =:= element(3, Messages) ->
 			terminate(State, {socket_error, Reason, 'An error has occurred on the socket.'});
+		{Passive, Socket} when Passive =:= tcp_passive; Passive =:= ssl_passive ->
+			loop(active(State));
 		%% Timeouts.
 		{timeout, Ref, {shutdown, Pid}} ->
 			cowboy_children:shutdown_timeout(Children, Ref, Pid),
@@ -939,8 +953,7 @@ commands(State=#state{out_streamid=Current, streams=Streams0}, StreamID, Command
 		Stream#stream{queue=Queue ++ Commands}),
 	State#state{streams=Streams};
 %% Read the request body.
-commands(State=#state{socket=Socket, transport=Transport, flow=Flow0}, StreamID,
-		[{flow, Size}|Tail]) ->
+commands(State0=#state{flow=Flow0}, StreamID, [{flow, Size}|Tail]) ->
 	%% We must read *at least* Size of data otherwise functions
 	%% like cowboy_req:read_body/1,2 will wait indefinitely.
 	Flow = if
@@ -948,11 +961,11 @@ commands(State=#state{socket=Socket, transport=Transport, flow=Flow0}, StreamID,
 		true -> Flow0 + Size
 	end,
 	%% Reenable active mode if necessary.
-	_ = if
+	State = if
 		Flow0 =< 0, Flow > 0 ->
-			Transport:setopts(Socket, [{active, once}]);
+			active(State0);
 		true ->
-			ok
+			State0
 	end,
 	commands(State#state{flow=Flow}, StreamID, Tail);
 %% Error responses are sent only if a response wasn't sent already.
@@ -1122,14 +1135,14 @@ commands(State0=#state{ref=Ref, parent=Parent, socket=Socket, transport=Transpor
 		out_state=OutState, opts=Opts, buffer=Buffer, children=Children}, StreamID,
 		[{switch_protocol, Headers, Protocol, InitialState}|_Tail]) ->
 	%% @todo If there's streams opened after this one, fail instead of 101.
-	State = cancel_timeout(State0),
+	State1 = cancel_timeout(State0),
 	%% Before we send the 101 response we need to stop receiving data
 	%% from the socket, otherwise the data might be receive before the
 	%% call to flush/0 and we end up inadvertently dropping a packet.
 	%%
 	%% @todo Handle cases where the request came with a body. We need
 	%% to process or skip the body before the upgrade can be completed.
-	Transport:setopts(Socket, [{active, false}]),
+	State = passive(State1),
 	%% Send a 101 response if necessary, then terminate the stream.
 	#state{streams=Streams} = case OutState of
 		wait -> info(State, StreamID, {inform, 101, Headers});
@@ -1432,6 +1445,7 @@ terminate_linger_loop(State=#state{socket=Socket, transport=Transport}, TimerRef
 	Messages = Transport:messages(),
 	%% We may already have a message in the mailbox when we do this
 	%% but it's OK because we are shutting down anyway.
+	%% @todo Use active,N here as well.
 	case Transport:setopts(Socket, [{active, once}]) of
 		ok ->
 			receive
-- 
cgit v1.2.3