%% Copyright (c) 2011-2017, Loïc Hoguin %% %% 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 handler and handler_opts %% environment values. The result of this execution is added to the %% environment under the result value. -module(cowboy_handler). -behaviour(cowboy_middleware). -export([execute/2]). -export([terminate/4]). -callback init(Req, any()) -> {ok | module(), Req, any()} | {module(), Req, any(), any()} when Req::cowboy_req:req(). -callback terminate(any(), map(), 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); {Mod, Req2, State, Opts} -> Mod:upgrade(Req2, Env, Handler, State, Opts) catch Class:Reason:Stacktrace -> terminate({crash, Class, Reason}, Req, HandlerOpts, Handler), erlang:raise(Class, Reason, 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.