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Diffstat (limited to 'doc/src/guide/protocols.asciidoc')
| -rw-r--r-- | doc/src/guide/protocols.asciidoc | 30 |
1 files changed, 22 insertions, 8 deletions
diff --git a/doc/src/guide/protocols.asciidoc b/doc/src/guide/protocols.asciidoc index 73a0bf5..8f55cea 100644 --- a/doc/src/guide/protocols.asciidoc +++ b/doc/src/guide/protocols.asciidoc @@ -59,7 +59,7 @@ loop(Socket, Transport) -> end. ---- -=== Using gen_statem +=== Using gen_statem and gen_server Special processes like the ones that use the `gen_statem` or `gen_server` behaviours have the particularity of having their `start_link` call not @@ -67,12 +67,21 @@ return until the `init` function returns. This is problematic, because you won't be able to call `ranch:handshake/1,2` from the `init` callback as this would cause a deadlock to happen. -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_statem` execution loop. +This problem can be addressed in several ways. -.Use a gen_statem for protocol handling +==== gen_statem + +* Use state enter calls and place the `ranch:handshake/1,2` call in the enter + clause of the initial state. Check the `tcp_reverse` example for a complete + example. +* Use a `next_event` action in the return from `init/1` and place the + `ranch:handshake/1,2` call in the clause handling the event in the initial + state. +* Use the `gen_statem:enter_loop/4` function and start your process with + `proc_lib:spawn_link/3` or `proc_lib:start_link/3,4,5`. See below for an + example. + +.Using gen_statem:enter_loop/4 to start a protocol [source,erlang] ---- @@ -87,7 +96,7 @@ the normal `gen_statem` execution loop. start_link(Ref, Transport, Opts) -> {ok, proc_lib:spawn_link(?MODULE, init, [{Ref, Transport, Opts}])}. -init({Ref, Transport, _Opts = []}) -> +init({Ref, Transport, _Opts}) -> %% Perform any required state initialization here. {ok, Socket} = ranch:handshake(Ref), ok = Transport:setopts(Socket, [{active, once}]), @@ -96,4 +105,9 @@ init({Ref, Transport, _Opts = []}) -> %% Other gen_statem callbacks here. ---- -Check the `tcp_reverse` example for a complete example. +==== gen_server + +* Use `{continue, Continue}` in the return from `init/1` and place the + `ranch:handshake/1,2` call in a corresponding `handle_continue/2` clause. +* Use the `gen_server:enter_loop/3` function and start your process with + `proc_lib:spawn_link/3` or `proc_lib:start_link/3,4,5`. |