1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
|
%% Copyright (c) 2011-2014, Loïc Hoguin <[email protected]>
%%
%% Permission to use, copy, modify, and/or distribute this software for any
%% purpose with or without fee is hereby granted, provided that the above
%% copyright notice and this permission notice appear in all copies.
%%
%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
%% When using loop handlers, we are receiving data from the socket because we
%% want to know when the socket gets closed. This is generally not an issue
%% because these kinds of requests are generally not pipelined, and don't have
%% a body. If they do have a body, this body is often read in the
%% <em>init/2</em> callback and this is no problem. Otherwise, this data
%% accumulates in a buffer until we reach a certain threshold of 5000 bytes
%% by default. This can be configured through the <em>loop_max_buffer</em>
%% environment value. The request will be terminated with an
%% <em>{error, overflow}</em> reason if this threshold is reached.
-module(cowboy_loop).
-behaviour(cowboy_sub_protocol).
-export([upgrade/6]).
-export([loop/4]).
-callback init(Req, any())
-> {ok | module(), Req, any()}
| {module(), Req, any(), hibernate}
| {module(), Req, any(), timeout()}
| {module(), Req, any(), timeout(), hibernate}
when Req::cowboy_req:req().
-callback info(any(), Req, State)
-> {ok, Req, State}
| {ok, Req, State, hibernate}
| {stop, Req, State}
when Req::cowboy_req:req(), State::any().
-callback terminate(any(), cowboy_req:req(), any()) -> ok.
-optional_callbacks([terminate/3]).
-record(state, {
env :: cowboy_middleware:env(),
hibernate = false :: boolean(),
buffer_size = 0 :: non_neg_integer(),
max_buffer = 5000 :: non_neg_integer() | infinity,
timeout = infinity :: timeout(),
timeout_ref = undefined :: undefined | reference()
}).
-spec upgrade(Req, Env, module(), any(), timeout(), run | hibernate)
-> {ok, Req, Env} | {suspend, module(), atom(), [any()]}
when Req::cowboy_req:req(), Env::cowboy_middleware:env().
upgrade(Req, Env, Handler, HandlerState, Timeout, Hibernate) ->
State = #state{env=Env, max_buffer=get_max_buffer(Env), timeout=Timeout,
hibernate=Hibernate =:= hibernate},
State2 = timeout(State),
before_loop(Req, State2, Handler, HandlerState).
get_max_buffer(#{loop_max_buffer := MaxBuffer}) -> MaxBuffer;
get_max_buffer(_) -> 5000.
before_loop(Req, State=#state{hibernate=true}, Handler, HandlerState) ->
%% @todo Yeah we can't get the socket anymore.
%% Everything changes since we are a separate process now.
%% Proper flow control at the connection level should be implemented
%% instead of what we have here.
% [Socket, Transport] = cowboy_req:get([socket, transport], Req),
% Transport:setopts(Socket, [{active, once}]),
{suspend, ?MODULE, loop, [Req, State#state{hibernate=false}, Handler, HandlerState]};
before_loop(Req, State, Handler, HandlerState) ->
%% Same here.
% [Socket, Transport] = cowboy_req:get([socket, transport], Req),
% Transport:setopts(Socket, [{active, once}]),
loop(Req, State, Handler, HandlerState).
%% Almost the same code can be found in cowboy_websocket.
timeout(State=#state{timeout=infinity}) ->
State#state{timeout_ref=undefined};
timeout(State=#state{timeout=Timeout,
timeout_ref=PrevRef}) ->
_ = case PrevRef of
undefined -> ignore%;
% @todo PrevRef -> erlang:cancel_timer(PrevRef)
end,
TRef = erlang:start_timer(Timeout, self(), ?MODULE),
State#state{timeout_ref=TRef}.
-spec loop(Req, #state{}, module(), any())
-> {ok, Req, cowboy_middleware:env()} | {suspend, module(), atom(), [any()]}
when Req::cowboy_req:req().
loop(Req, State=#state{timeout_ref=TRef}, Handler, HandlerState) ->
receive
{timeout, TRef, ?MODULE} ->
terminate(Req, State, Handler, HandlerState, timeout);
{timeout, OlderTRef, ?MODULE} when is_reference(OlderTRef) ->
loop(Req, State, Handler, HandlerState);
Message ->
call(Req, State, Handler, HandlerState, Message)
end.
call(Req, State, Handler, HandlerState, Message) ->
try Handler:info(Message, Req, HandlerState) of
{ok, Req2, HandlerState2} ->
before_loop(Req2, State, Handler, HandlerState2);
{ok, Req2, HandlerState2, hibernate} ->
before_loop(Req2, State#state{hibernate=true}, Handler, HandlerState2);
{stop, Req2, HandlerState2} ->
terminate(Req2, State, Handler, HandlerState2, stop)
catch Class:Reason ->
cowboy_handler:terminate({crash, Class, Reason}, Req, HandlerState, Handler),
erlang:raise(Class, Reason, erlang:get_stacktrace())
end.
terminate(Req, #state{env=Env, timeout_ref=TRef},
Handler, HandlerState, Reason) ->
_ = case TRef of
undefined -> ignore;
TRef -> erlang:cancel_timer(TRef)
end,
flush_timeouts(),
Result = cowboy_handler:terminate(Reason, Req, HandlerState, Handler),
{ok, Req, Env#{result => Result}}.
flush_timeouts() ->
receive
{timeout, TRef, ?MODULE} when is_reference(TRef) ->
flush_timeouts()
after 0 ->
ok
end.
|
