aboutsummaryrefslogtreecommitdiffstats
path: root/src/cowboy_handler.erl
blob: 4dbe2267d3aec4a3fb90fa3738ef71a903d04bf4 (plain) (blame)
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
%% 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.

%% Handler middleware.
%%
%% Execute the handler given by the <em>handler</em> and <em>handler_opts</em>
%% environment values. The result of this execution is added to the
%% environment under the <em>result</em> value.
-module(cowboy_handler).
-behaviour(cowboy_middleware).

-export([execute/2]).
-export([terminate/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 terminate(any(), cowboy_req:req(), any()) -> ok.
-optional_callbacks([terminate/3]).

-spec execute(Req, Env) -> {ok, Req, Env}
	when Req::cowboy_req:req(), Env::cowboy_middleware:env().
execute(Req, Env=#{handler := Handler, handler_opts := HandlerOpts}) ->
	try Handler:init(Req, HandlerOpts) of
		{ok, Req2, State} ->
			Result = terminate(normal, Req2, State, Handler),
			{ok, Req2, Env#{result => Result}};
		{Mod, Req2, State} ->
			Mod:upgrade(Req2, Env, Handler, State, infinity, run);
		{Mod, Req2, State, hibernate} ->
			Mod:upgrade(Req2, Env, Handler, State, infinity, hibernate);
		{Mod, Req2, State, Timeout} ->
			Mod:upgrade(Req2, Env, Handler, State, Timeout, run);
		{Mod, Req2, State, Timeout, hibernate} ->
			Mod:upgrade(Req2, Env, Handler, State, Timeout, hibernate)
	catch Class:Reason ->
		terminate({crash, Class, Reason}, Req, HandlerOpts, Handler),
		erlang:raise(Class, Reason, erlang:get_stacktrace())
	end.

-spec terminate(any(), Req | undefined, any(), module()) -> ok when Req::cowboy_req:req().
terminate(Reason, Req, State, Handler) ->
	case erlang:function_exported(Handler, terminate, 3) of
		true ->
			Handler:terminate(Reason, Req, State);
		false ->
			ok
	end.