%% Copyright (c) 2011-2013, 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.
%% @doc 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.
%%
%% @see cowboy_http_handler
-module(cowboy_handler).
-behaviour(cowboy_middleware).
-export([execute/2]).
-export([handler_loop/4]).
-record(state, {
env :: cowboy_middleware:env(),
hibernate = false :: boolean(),
loop_timeout = infinity :: timeout(),
loop_timeout_ref :: undefined | reference(),
resp_sent = false :: boolean()
}).
%% @private
-spec execute(Req, Env)
-> {ok, Req, Env} | {error, 500, Req}
| {suspend, ?MODULE, handler_loop, [any()]}
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),
handler_init(Req, #state{env=Env}, Handler, HandlerOpts).
-spec handler_init(Req, #state{}, module(), any())
-> {ok, Req, cowboy_middleware:env()}
| {error, 500, Req} | {suspend, module(), function(), [any()]}
when Req::cowboy_req:req().
handler_init(Req, State, Handler, HandlerOpts) ->
Transport = cowboy_req:get(transport, Req),
try Handler:init({Transport:name(), http}, Req, HandlerOpts) of
{ok, Req2, HandlerState} ->
handler_handle(Req2, State, Handler, HandlerState);
{loop, Req2, HandlerState} ->
handler_before_loop(Req2, State#state{hibernate=false},
Handler, HandlerState);
{loop, Req2, HandlerState, hibernate} ->
handler_before_loop(Req2, State#state{hibernate=true},
Handler, HandlerState);
{loop, Req2, HandlerState, Timeout} ->
handler_before_loop(Req2, State#state{loop_timeout=Timeout},
Handler, HandlerState);
{loop, Req2, HandlerState, Timeout, hibernate} ->
handler_before_loop(Req2, State#state{
hibernate=true, loop_timeout=Timeout}, Handler, HandlerState);
{shutdown, Req2, HandlerState} ->
terminate_request(Req2, State, Handler, HandlerState,
{normal, shutdown});
%% @todo {upgrade, transport, Module}
{upgrade, protocol, Module} ->
upgrade_protocol(Req, State, Handler, HandlerOpts, Module);
{upgrade, protocol, Module, Req2, HandlerOpts2} ->
upgrade_protocol(Req2, State, Handler, HandlerOpts2, Module)
catch Class:Reason ->
error_logger:error_msg(
"** Cowboy handler ~p terminating in ~p/~p~n"
" for the reason ~p:~p~n"
"** Options were ~p~n"
"** Request was ~p~n"
"** Stacktrace: ~p~n~n",
[Handler, init, 3, Class, Reason, HandlerOpts,
cowboy_req:to_list(Req), erlang:get_stacktrace()]),
error_terminate(Req, State)
end.
-spec upgrade_protocol(Req, #state{}, module(), any(), module())
-> {ok, Req, Env}
| {suspend, module(), atom(), any()}
| {halt, Req}
| {error, cowboy_http:status(), Req}
when Req::cowboy_req:req(), Env::cowboy_middleware:env().
upgrade_protocol(Req, #state{env=Env},
Handler, HandlerOpts, Module) ->
Module:upgrade(Req, Env, Handler, HandlerOpts).
-spec handler_handle(Req, #state{}, module(), any())
-> {ok, Req, cowboy_middleware:env()}
| {error, 500, Req}
when Req::cowboy_req:req().
handler_handle(Req, State, Handler, HandlerState) ->
try Handler:handle(Req, HandlerState) of
{ok, Req2, HandlerState2} ->
terminate_request(Req2, State, Handler, HandlerState2,
{normal, shutdown})
catch Class:Reason ->
error_logger:error_msg(
"** Cowboy handler ~p terminating in ~p/~p~n"
" for the reason ~p:~p~n"
"** Handler state was ~p~n"
"** Request was ~p~n"
"** Stacktrace: ~p~n~n",
[Handler, handle, 2, Class, Reason, HandlerState,
cowboy_req:to_list(Req), erlang:get_stacktrace()]),
handler_terminate(Req, Handler, HandlerState, Reason),
error_terminate(Req, State)
end.
%% We don't listen for Transport closes because that would force us
%% to receive data and buffer it indefinitely.
-spec handler_before_loop(Req, #state{}, module(), any())
-> {ok, Req, cowboy_middleware:env()}
| {error, 500, Req} | {suspend, module(), function(), [any()]}
when Req::cowboy_req:req().
handler_before_loop(Req, State=#state{hibernate=true}, Handler, HandlerState) ->
State2 = handler_loop_timeout(State),
{suspend, ?MODULE, handler_loop,
[Req, State2#state{hibernate=false}, Handler, HandlerState]};
handler_before_loop(Req, State, Handler, HandlerState) ->
State2 = handler_loop_timeout(State),
handler_loop(Req, State2, Handler, HandlerState).
%% Almost the same code can be found in cowboy_websocket.
-spec handler_loop_timeout(#state{}) -> #state{}.
handler_loop_timeout(State=#state{loop_timeout=infinity}) ->
State#state{loop_timeout_ref=undefined};
handler_loop_timeout(State=#state{loop_timeout=Timeout,
loop_timeout_ref=PrevRef}) ->
_ = case PrevRef of undefined -> ignore; PrevRef ->
erlang:cancel_timer(PrevRef) end,
TRef = erlang:start_timer(Timeout, self(), ?MODULE),
State#state{loop_timeout_ref=TRef}.
%% @private
-spec handler_loop(Req, #state{}, module(), any())
-> {ok, Req, cowboy_middleware:env()}
| {error, 500, Req} | {suspend, module(), function(), [any()]}
when Req::cowboy_req:req().
handler_loop(Req, State=#state{loop_timeout_ref=TRef}, Handler, HandlerState) ->
receive
{cowboy_req, resp_sent} ->
handler_loop(Req, State#state{resp_sent=true},
Handler, HandlerState);
{timeout, TRef, ?MODULE} ->
terminate_request(Req, State, Handler, HandlerState,
{normal, timeout});
{timeout, OlderTRef, ?MODULE} when is_reference(OlderTRef) ->
handler_loop(Req, State, Handler, HandlerState);
Message ->
handler_call(Req, State, Handler, HandlerState, Message)
end.
-spec handler_call(Req, #state{}, module(), any(), any())
-> {ok, Req, cowboy_middleware:env()}
| {error, 500, Req} | {suspend, module(), function(), [any()]}
when Req::cowboy_req:req().
handler_call(Req, State, Handler, HandlerState, Message) ->
try Handler:info(Message, Req, HandlerState) of
{ok, Req2, HandlerState2} ->
terminate_request(Req2, State, Handler, HandlerState2,
{normal, shutdown});
{loop, Req2, HandlerState2} ->
handler_before_loop(Req2, State, Handler, HandlerState2);
{loop, Req2, HandlerState2, hibernate} ->
handler_before_loop(Req2, State#state{hibernate=true},
Handler, HandlerState2)
catch Class:Reason ->
error_logger:error_msg(
"** Cowboy handler ~p terminating in ~p/~p~n"
" for the reason ~p:~p~n"
"** Handler state was ~p~n"
"** Request was ~p~n"
"** Stacktrace: ~p~n~n",
[Handler, info, 3, Class, Reason, HandlerState,
cowboy_req:to_list(Req), erlang:get_stacktrace()]),
handler_terminate(Req, Handler, HandlerState, Reason),
error_terminate(Req, State)
end.
-spec terminate_request(Req, #state{}, module(), any(),
{normal, timeout | shutdown} | {error, atom()}) ->
{ok, Req, cowboy_middleware:env()} when Req::cowboy_req:req().
terminate_request(Req, #state{env=Env}, Handler, HandlerState, Reason) ->
HandlerRes = handler_terminate(Req, Handler, HandlerState, Reason),
{ok, Req, [{result, HandlerRes}|Env]}.
-spec handler_terminate(cowboy_req:req(), module(), any(),
{normal, timeout | shutdown} | {error, atom()}) -> ok.
handler_terminate(Req, Handler, HandlerState, Reason) ->
try
Handler:terminate(Reason, cowboy_req:lock(Req), HandlerState)
catch Class:Reason2 ->
error_logger:error_msg(
"** Cowboy handler ~p terminating in ~p/~p~n"
" for the reason ~p:~p~n"
"** Handler state was ~p~n"
"** Request was ~p~n"
"** Stacktrace: ~p~n~n",
[Handler, terminate, 3, Class, Reason2, HandlerState,
cowboy_req:to_list(Req), erlang:get_stacktrace()])
end.
%% Only send an error reply if there is no resp_sent message.
-spec error_terminate(Req, #state{})
-> {error, 500, Req} | {halt, Req} when Req::cowboy_req:req().
error_terminate(Req, #state{resp_sent=true}) ->
%% Close the connection, but do not attempt sending a reply.
{halt, cowboy_req:set([{connection, close}, {resp_state, done}], Req)};
error_terminate(Req, _) ->
{error, 500, Req}.
