From 5ce4c2bfb40ecc4b687a2941e612025a1c4ff913 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Lo=C3=AFc=20Hoguin?= Date: Fri, 26 Sep 2014 15:58:44 +0300 Subject: Unify the init and terminate callbacks This set of changes is the first step to simplify the writing of handlers, by removing some extraneous callbacks and making others optional. init/3 is now init/2, its first argument being removed. rest_init/2 and rest_terminate/2 have been removed. websocket_init/3 and websocket_terminate/3 have been removed. terminate/3 is now optional. It is called regardless of the type of handler, including rest and websocket. The return value of init/2 changed. It now returns {Mod, Req, Opts} with Mod being either one of the four handler type or a custom module. It can also return extra timeout and hibernate options. The signature for sub protocols has changed, they now receive these extra timeout and hibernate options. Loop handlers are now implemented in cowboy_long_polling, and will be renamed throughout the project in a future commit. --- src/cowboy_handler.erl | 299 ++++++++----------------------------------------- 1 file changed, 49 insertions(+), 250 deletions(-) (limited to 'src/cowboy_handler.erl') diff --git a/src/cowboy_handler.erl b/src/cowboy_handler.erl index 1e8261f..a666714 100644 --- a/src/cowboy_handler.erl +++ b/src/cowboy_handler.erl @@ -17,287 +17,86 @@ %% 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. -%% -%% 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 -%% init/3 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 loop_max_buffer -%% environment value. The request will be terminated with an -%% {error, overflow} reason if this threshold is reached. -module(cowboy_handler). -behaviour(cowboy_middleware). -export([execute/2]). --export([handler_loop/4]). - --record(state, { - env :: cowboy_middleware:env(), - hibernate = false :: boolean(), - loop_buffer_size = 0 :: non_neg_integer(), - loop_max_buffer = 5000 :: non_neg_integer() | infinity, - loop_timeout = infinity :: timeout(), - loop_timeout_ref = undefined :: undefined | reference(), - resp_sent = false :: boolean() -}). +-export([terminate/5]). --spec execute(Req, Env) - -> {ok, Req, Env} | {suspend, ?MODULE, handler_loop, [any()]} +-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), - MaxBuffer = case lists:keyfind(loop_max_buffer, 1, Env) of - false -> 5000; - {_, MaxBuffer0} -> MaxBuffer0 - end, - handler_init(Req, #state{env=Env, loop_max_buffer=MaxBuffer}, - Handler, HandlerOpts). - --spec handler_init(Req, #state{}, module(), any()) - -> {ok, Req, cowboy_middleware:env()} | {suspend, module(), atom(), [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_after_callback(Req2, State, Handler, HandlerState); - {loop, Req2, HandlerState, hibernate} -> - handler_after_callback(Req2, State#state{hibernate=true}, - Handler, HandlerState); - {loop, Req2, HandlerState, Timeout} -> - State2 = handler_loop_timeout(State#state{loop_timeout=Timeout}), - handler_after_callback(Req2, State2, Handler, HandlerState); - {loop, Req2, HandlerState, Timeout, hibernate} -> - State2 = handler_loop_timeout(State#state{ - hibernate=true, loop_timeout=Timeout}), - handler_after_callback(Req2, State2, Handler, HandlerState); - {shutdown, Req2, HandlerState} -> - terminate_request(Req2, State, Handler, HandlerState, - {normal, shutdown}); - {upgrade, protocol, Module} -> - upgrade_protocol(Req, State, Handler, HandlerOpts, Module); - {upgrade, protocol, Module, Req2, HandlerOpts2} -> - upgrade_protocol(Req2, State, Handler, HandlerOpts2, Module) + try Handler:init(Req, HandlerOpts) of + {http, Req2, State} -> + handle(Req2, Env, Handler, State); + {shutdown, Req2, State} -> + terminate(Req2, Env, Handler, State, {normal, shutdown}); + {Mod, Req2, State} -> + upgrade(Req2, Env, Handler, State, infinity, run, Mod); + {Mod, Req2, State, hibernate} -> + upgrade(Req2, Env, Handler, State, infinity, hibernate, Mod); + {Mod, Req2, State, Timeout} -> + upgrade(Req2, Env, Handler, State, Timeout, run, Mod); + {Mod, Req2, State, Timeout, hibernate} -> + upgrade(Req2, Env, Handler, State, Timeout, hibernate, Mod) catch Class:Reason -> Stacktrace = erlang:get_stacktrace(), cowboy_req:maybe_reply(Stacktrace, Req), erlang:Class([ {reason, Reason}, - {mfa, {Handler, init, 3}}, + {mfa, {Handler, init, 2}}, {stacktrace, Stacktrace}, {req, cowboy_req:to_list(Req)}, {opts, HandlerOpts} ]) end. --spec upgrade_protocol(Req, #state{}, module(), any(), module()) - -> {ok, Req, Env} - | {suspend, module(), atom(), any()} - | {halt, 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()} 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}) +handle(Req, Env, Handler, State) -> + try Handler:handle(Req, State) of + {ok, Req2, State2} -> + terminate(Req2, Env, Handler, State2, {normal, shutdown}) catch Class:Reason -> Stacktrace = erlang:get_stacktrace(), cowboy_req:maybe_reply(Stacktrace, Req), - handler_terminate(Req, Handler, HandlerState, Reason), + _ = terminate(Req, Env, Handler, State, Reason), erlang:Class([ {reason, Reason}, {mfa, {Handler, handle, 2}}, {stacktrace, Stacktrace}, {req, cowboy_req:to_list(Req)}, - {state, HandlerState} + {state, State} ]) end. -%% Update the state if the response was sent in the callback. --spec handler_after_callback(Req, #state{}, module(), any()) - -> {ok, Req, cowboy_middleware:env()} | {suspend, module(), atom(), [any()]} - when Req::cowboy_req:req(). -handler_after_callback(Req, State=#state{resp_sent=false}, Handler, - HandlerState) -> - receive - {cowboy_req, resp_sent} -> - handler_before_loop(Req, State#state{resp_sent=true}, Handler, - HandlerState) - after 0 -> - handler_before_loop(Req, State, Handler, HandlerState) - end; -handler_after_callback(Req, State, Handler, HandlerState) -> - handler_before_loop(Req, State, Handler, HandlerState). - --spec handler_before_loop(Req, #state{}, module(), any()) - -> {ok, Req, cowboy_middleware:env()} | {suspend, module(), atom(), [any()]} - when Req::cowboy_req:req(). -handler_before_loop(Req, State=#state{hibernate=true}, Handler, HandlerState) -> - [Socket, Transport] = cowboy_req:get([socket, transport], Req), - Transport:setopts(Socket, [{active, once}]), - {suspend, ?MODULE, handler_loop, - [Req, State#state{hibernate=false}, Handler, HandlerState]}; -handler_before_loop(Req, State, Handler, HandlerState) -> - [Socket, Transport] = cowboy_req:get([socket, transport], Req), - Transport:setopts(Socket, [{active, once}]), - handler_loop(Req, State, 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) +upgrade(Req, Env, Handler, State, Timeout, Hibernate, Mod) -> + Mod2 = case Mod of + long_polling -> cowboy_long_polling; + rest -> cowboy_rest; + ws -> cowboy_websocket; + _ when Mod =/= http -> Mod end, - TRef = erlang:start_timer(Timeout, self(), ?MODULE), - State#state{loop_timeout_ref=TRef}. - --spec handler_loop(Req, #state{}, module(), any()) - -> {ok, Req, cowboy_middleware:env()} | {suspend, module(), atom(), [any()]} - when Req::cowboy_req:req(). -handler_loop(Req, State=#state{loop_buffer_size=NbBytes, - loop_max_buffer=Threshold, loop_timeout_ref=TRef, - resp_sent=RespSent}, Handler, HandlerState) -> - [Socket, Transport] = cowboy_req:get([socket, transport], Req), - {OK, Closed, Error} = Transport:messages(), - receive - {OK, Socket, Data} -> - NbBytes2 = NbBytes + byte_size(Data), - if NbBytes2 > Threshold -> - _ = handler_terminate(Req, Handler, HandlerState, - {error, overflow}), - _ = if RespSent -> ok; true -> - cowboy_req:reply(500, Req) - end, - exit(normal); - true -> - Req2 = cowboy_req:append_buffer(Data, Req), - State2 = handler_loop_timeout(State#state{ - loop_buffer_size=NbBytes2}), - handler_before_loop(Req2, State2, Handler, HandlerState) + Mod2:upgrade(Req, Env, Handler, State, Timeout, Hibernate). + +-spec terminate(Req, Env, module(), any(), {normal, shutdown} | {error, atom()} | any()) + -> {ok, Req, Env} when Req::cowboy_req:req(), Env::cowboy_middleware:env(). +terminate(Req, Env, Handler, State, Reason) -> + Result = case erlang:function_exported(Handler, terminate, 3) of + true -> + try + Handler:terminate(Reason, cowboy_req:lock(Req), State) + catch Class:Reason2 -> + erlang:Class([ + {reason, Reason2}, + {mfa, {Handler, terminate, 3}}, + {stacktrace, erlang:get_stacktrace()}, + {req, cowboy_req:to_list(Req)}, + {state, State}, + {terminate_reason, Reason} + ]) end; - {Closed, Socket} -> - terminate_request(Req, State, Handler, HandlerState, - {error, closed}); - {Error, Socket, Reason} -> - terminate_request(Req, State, Handler, HandlerState, - {error, Reason}); - {timeout, TRef, ?MODULE} -> - handler_after_loop(Req, State, Handler, HandlerState, - {normal, timeout}); - {timeout, OlderTRef, ?MODULE} when is_reference(OlderTRef) -> - handler_loop(Req, State, Handler, HandlerState); - Message -> - %% We set the socket back to {active, false} mode in case - %% the handler is going to call recv. We also flush any - %% data received after that and put it into the buffer. - %% We do not check the size here, if data keeps coming - %% we'll error out on the next packet received. - Transport:setopts(Socket, [{active, false}]), - Req2 = receive {OK, Socket, Data} -> - cowboy_req:append_buffer(Data, Req) - after 0 -> - Req - end, - handler_call(Req2, State, Handler, HandlerState, Message) - end. - --spec handler_call(Req, #state{}, module(), any(), any()) - -> {ok, Req, cowboy_middleware:env()} | {suspend, module(), atom(), [any()]} - when Req::cowboy_req:req(). -handler_call(Req, State=#state{resp_sent=RespSent}, - Handler, HandlerState, Message) -> - try Handler:info(Message, Req, HandlerState) of - {ok, Req2, HandlerState2} -> - handler_after_loop(Req2, State, Handler, HandlerState2, - {normal, shutdown}); - {loop, Req2, HandlerState2} -> - handler_after_callback(Req2, State, Handler, HandlerState2); - {loop, Req2, HandlerState2, hibernate} -> - handler_after_callback(Req2, State#state{hibernate=true}, - Handler, HandlerState2) - catch Class:Reason -> - Stacktrace = erlang:get_stacktrace(), - if RespSent -> ok; true -> - cowboy_req:maybe_reply(Stacktrace, Req) - end, - handler_terminate(Req, Handler, HandlerState, Reason), - erlang:Class([ - {reason, Reason}, - {mfa, {Handler, info, 3}}, - {stacktrace, Stacktrace}, - {req, cowboy_req:to_list(Req)}, - {state, HandlerState} - ]) - end. - -%% It is sometimes important to make a socket passive as it was initially -%% and as it is expected to be by cowboy_protocol, right after we're done -%% with loop handling. The browser may freely pipeline a bunch of requests -%% if previous one was, say, a JSONP long-polling request. --spec handler_after_loop(Req, #state{}, module(), any(), - {normal, timeout | shutdown} | {error, atom()}) -> - {ok, Req, cowboy_middleware:env()} when Req::cowboy_req:req(). -handler_after_loop(Req, State, Handler, HandlerState, Reason) -> - [Socket, Transport] = cowboy_req:get([socket, transport], Req), - Transport:setopts(Socket, [{active, false}]), - {OK, _Closed, _Error} = Transport:messages(), - Req2 = receive - {OK, Socket, Data} -> - cowboy_req:append_buffer(Data, Req) - after 0 -> - Req - end, - terminate_request(Req2, State, Handler, HandlerState, Reason). - --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, loop_timeout_ref=TRef}, - Handler, HandlerState, Reason) -> - HandlerRes = handler_terminate(Req, Handler, HandlerState, Reason), - _ = case TRef of - undefined -> ignore; - TRef -> erlang:cancel_timer(TRef) + false -> + ok end, - flush_timeouts(), - {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 -> - erlang:Class([ - {reason, Reason2}, - {mfa, {Handler, terminate, 3}}, - {stacktrace, erlang:get_stacktrace()}, - {req, cowboy_req:to_list(Req)}, - {state, HandlerState}, - {terminate_reason, Reason} - ]) - end. - --spec flush_timeouts() -> ok. -flush_timeouts() -> - receive - {timeout, TRef, ?MODULE} when is_reference(TRef) -> - flush_timeouts() - after 0 -> - ok - end. + {ok, Req, [{result, Result}|Env]}. -- cgit v1.2.3