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authorLoïc Hoguin <[email protected]>2016-11-15 13:47:02 +0200
committerLoïc Hoguin <[email protected]>2016-11-15 14:00:39 +0200
commit2c93d8ef43dbae0f9a9a44d1c70d28195f2a0a40 (patch)
treec125f2b3cda17464afbe3fcf32198f9024201f86 /doc/src/guide/protocols.asciidoc
parent9d20868fea27da833cad1bcd6da7e93fb2809bea (diff)
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Remove bad advice for gen_server protocols
Also improves the good example a little by using spawn_link instead of start_link.
Diffstat (limited to 'doc/src/guide/protocols.asciidoc')
-rw-r--r--doc/src/guide/protocols.asciidoc36
1 files changed, 4 insertions, 32 deletions
diff --git a/doc/src/guide/protocols.asciidoc b/doc/src/guide/protocols.asciidoc
index 8060343..393c601 100644
--- a/doc/src/guide/protocols.asciidoc
+++ b/doc/src/guide/protocols.asciidoc
@@ -67,10 +67,7 @@ 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.
-There are two ways of solving this problem.
-
-The first, and probably the most elegant one, is to make use of the
-`gen_server:enter_loop/3` function. It allows you to start your process
+Use the `gen_server:enter_loop/3` 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.
@@ -84,14 +81,13 @@ the normal `gen_server` execution loop.
-behaviour(ranch_protocol).
-export([start_link/4]).
--export([init/4]).
+-export([init/1]).
%% Exports of other gen_server callbacks here.
start_link(Ref, Socket, Transport, Opts) ->
- proc_lib:start_link(?MODULE, init, [Ref, Socket, Transport, Opts]).
+ {ok, proc_lib:spawn_link(?MODULE, init, [{Ref, Socket, Transport, Opts}])}.
-init(Ref, Socket, Transport, _Opts = []) ->
- ok = proc_lib:init_ack({ok, self()}),
+init({Ref, Socket, Transport, _Opts = []}) ->
%% Perform any required state initialization here.
ok = ranch:accept_ack(Ref),
ok = Transport:setopts(Socket, [{active, once}]),
@@ -99,27 +95,3 @@ init(Ref, Socket, Transport, _Opts = []) ->
%% Other gen_server callbacks here.
----
-
-The second method involves triggering a timeout just after `gen_server:init`
-ends. If you return a timeout value of `0` then the `gen_server` will call
-`handle_info(timeout, _, _)` right away.
-
-.Use a gen_server for protocol handling, method 2
-
-[source,erlang]
-----
--module(my_protocol).
--behaviour(gen_server).
--behaviour(ranch_protocol).
-
-%% Exports go here.
-
-init([Ref, Socket, Transport]) ->
- {ok, {state, Ref, Socket, Transport}, 0}.
-
-handle_info(timeout, State={state, Ref, Socket, Transport}) ->
- ok = ranch:accept_ack(Ref),
- ok = Transport:setopts(Socket, [{active, once}]),
- {noreply, State};
-%% ...
-----