From 301f582b97f82e7f7dc2d41bb575671bcc30215e Mon Sep 17 00:00:00 2001 From: "j.uhlig" Date: Thu, 3 May 2018 13:22:30 +0200 Subject: Replace gen_server with gen_statem in examples --- doc/src/guide/protocols.asciidoc | 18 +++---- examples/tcp_reverse/README.md | 4 +- examples/tcp_reverse/src/reverse_protocol.erl | 71 ++++++++++++++------------- 3 files changed, 48 insertions(+), 45 deletions(-) diff --git a/doc/src/guide/protocols.asciidoc b/doc/src/guide/protocols.asciidoc index b9a31f2..91f4b07 100644 --- a/doc/src/guide/protocols.asciidoc +++ b/doc/src/guide/protocols.asciidoc @@ -59,30 +59,30 @@ loop(Socket, Transport) -> end. ---- -=== Using gen_server +=== Using gen_statem -Special processes like the ones that use the `gen_server` or `gen_fsm` +Special processes like the ones that use the `gen_statem` or `gen_server` behaviours have the particularity of having their `start_link` call not return until the `init` function returns. This is problematic, because you won't be able to call `ranch:accept_ack/1` from the `init` callback as this would cause a deadlock to happen. -Use the `gen_server:enter_loop/3` function. It allows you to start your process +Use the `gen_statem:enter_loop/4` function. It allows you to start your process normally (although it must be started with `proc_lib` like all special processes), then perform any needed operations before falling back into -the normal `gen_server` execution loop. +the normal `gen_statem` execution loop. -.Use a gen_server for protocol handling +.Use a gen_statem for protocol handling [source,erlang] ---- -module(my_protocol). --behaviour(gen_server). +-behaviour(gen_statem). -behaviour(ranch_protocol). -export([start_link/4]). -export([init/1]). -%% Exports of other gen_server callbacks here. +%% Exports of other gen_statem callbacks here. start_link(Ref, Socket, Transport, Opts) -> {ok, proc_lib:spawn_link(?MODULE, init, [{Ref, Socket, Transport, Opts}])}. @@ -91,9 +91,9 @@ init({Ref, Socket, Transport, _Opts = []}) -> %% Perform any required state initialization here. ok = ranch:accept_ack(Ref), ok = Transport:setopts(Socket, [{active, once}]), - gen_server:enter_loop(?MODULE, [], {state, Socket, Transport}). + gen_statem:enter_loop(?MODULE, [], state_name, {state_data, Socket, Transport}). -%% Other gen_server callbacks here. +%% Other gen_statem callbacks here. ---- Check the `tcp_reverse` example for a complete example. diff --git a/examples/tcp_reverse/README.md b/examples/tcp_reverse/README.md index 745ad2c..d4ab1de 100644 --- a/examples/tcp_reverse/README.md +++ b/examples/tcp_reverse/README.md @@ -1,11 +1,11 @@ Ranch TCP reverse example ========================= -This example uses a `gen_server` to handle a protocol to revese input. +This example uses a `gen_statem` to handle a protocol to revese input. See `reverse_protocol.erl` for the implementation. Documentation about this topic can be found in the guide: - http://ninenines.eu/docs/en/ranch/HEAD/guide/protocols/#using_gen_server + http://ninenines.eu/docs/en/ranch/HEAD/guide/protocols/#using_gen_statem To try this example, you need GNU `make` and `git` in your PATH. diff --git a/examples/tcp_reverse/src/reverse_protocol.erl b/examples/tcp_reverse/src/reverse_protocol.erl index 80ed62c..a37ca46 100644 --- a/examples/tcp_reverse/src/reverse_protocol.erl +++ b/examples/tcp_reverse/src/reverse_protocol.erl @@ -1,19 +1,18 @@ %% Feel free to use, reuse and abuse the code in this file. -module(reverse_protocol). --behaviour(gen_server). +-behaviour(gen_statem). -behaviour(ranch_protocol). %% API. -export([start_link/4]). -%% gen_server. +%% gen_statem. +-export([callback_mode/0]). -export([init/1]). --export([handle_call/3]). --export([handle_cast/2]). --export([handle_info/2]). --export([terminate/2]). --export([code_change/3]). +-export([connected/3]). +-export([terminate/3]). +-export([code_change/4]). -define(TIMEOUT, 5000). @@ -24,45 +23,49 @@ start_link(Ref, Socket, Transport, Opts) -> {ok, proc_lib:spawn_link(?MODULE, init, [{Ref, Socket, Transport, Opts}])}. -%% gen_server. +%% gen_statem. -%% This function is never called. We only define it so that -%% we can use the -behaviour(gen_server) attribute. -%init([]) -> {ok, undefined}. +callback_mode() -> + state_functions. init({Ref, Socket, Transport, _Opts = []}) -> ok = ranch:accept_ack(Ref), - ok = Transport:setopts(Socket, [{active, once}]), - gen_server:enter_loop(?MODULE, [], + ok = Transport:setopts(Socket, [{active, once}, {packet, line}]), + gen_statem:enter_loop(?MODULE, [], connected, #state{socket=Socket, transport=Transport}, - ?TIMEOUT). + [?TIMEOUT]). -handle_info({tcp, Socket, Data}, State=#state{ +connected(info, {tcp, Socket, Data}, _StateData=#state{ socket=Socket, transport=Transport}) when byte_size(Data) > 1 -> Transport:setopts(Socket, [{active, once}]), Transport:send(Socket, reverse_binary(Data)), - {noreply, State, ?TIMEOUT}; -handle_info({tcp_closed, _Socket}, State) -> - {stop, normal, State}; -handle_info({tcp_error, _, Reason}, State) -> - {stop, Reason, State}; -handle_info(timeout, State) -> - {stop, normal, State}; -handle_info(_Info, State) -> - {stop, normal, State}. - -handle_call(_Request, _From, State) -> - {reply, ok, State}. - -handle_cast(_Msg, State) -> - {noreply, State}. - -terminate(_Reason, _State) -> + {keep_state_and_data, ?TIMEOUT}; +connected(info, {tcp_closed, _Socket}, _StateData) -> + {stop, normal}; +connected(info, {tcp_error, _, Reason}, _StateData) -> + {stop, Reason}; +connected({call, From}, _Request, _StateData) -> + gen_statem:reply(From, ok), + keep_state_and_data; +connected(cast, _Msg, _StateData) -> + keep_state_and_data; +connected(timeout, _Msg, _StateData) -> + {stop, normal}; +connected(_EventType, _Msg, _StateData) -> + {stop, normal}. + +terminate(Reason, StateName, StateData=#state{ + socket=Socket, transport=Transport}) + when Socket=/=undefined andalso Transport=/=undefined -> + catch Transport:close(Socket), + terminate(Reason, StateName, + StateData#state{socket=undefined, transport=undefined}); +terminate(_Reason, _StateName, _StateData) -> ok. -code_change(_OldVsn, State, _Extra) -> - {ok, State}. +code_change(_OldVsn, StateName, StateData, _Extra) -> + {ok, StateName, StateData}. %% Internal. -- cgit v1.2.3