%% 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().
%% @todo optional -callback terminate(terminate_reason(), cowboy_req:req(), state()) -> ok.
-spec execute(Req, Env) -> {ok, Req, Env}
when Req::cowboy_req:req(), Env::cowboy_middleware:env().
execute(Req, Env) ->
{_, Handler} = lists:keyfind(handler, 1, Env),
{_, HandlerOpts} = lists:keyfind(handler_opts, 1, Env),
try Handler:init(Req, HandlerOpts) of
{ok, Req2, State} ->
Result = terminate(normal, Req2, State, Handler),
{ok, Req2, [{result, Result}|Env]};
{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 ->
Stacktrace = erlang:get_stacktrace(),
cowboy_req:maybe_reply(Stacktrace, Req),
terminate({crash, Class, Reason}, Req, HandlerOpts, Handler),
exit({cowboy_handler, [
{class, Class},
{reason, Reason},
{mfa, {Handler, init, 2}},
{stacktrace, Stacktrace},
{req, cowboy_req:to_list(Req)},
{opts, HandlerOpts}
]})
end.
-spec terminate(any(), Req, any(), module()) -> ok when Req::cowboy_req:req().
terminate(Reason, Req, State, Handler) ->
case erlang:function_exported(Handler, terminate, 3) of
true ->
try
Handler:terminate(Reason, cowboy_req:lock(Req), State)
catch Class:Reason2 ->
exit({cowboy_handler, [
{class, Class},
{reason, Reason2},
{mfa, {Handler, terminate, 3}},
{stacktrace, erlang:get_stacktrace()},
{req, cowboy_req:to_list(Req)},
{state, State},
{terminate_reason, Reason}
]})
end;
false ->
ok
end.
