Bind listener ports early and start accepting connections later
It may happen that auth or rdbms client tcp connections bind a local socket to a port number required by a configered listener. The ejabberd applications fails to start up and needs to be restarted. In plain C you would bind(2) the listener port and listen(2) later on. gen_tcp:listen/2 does not allow to separate these two steps though, so another way is not to accept connections while start up. OTOH, the kernel will syn/ack incoming connections and receive data, leaving them in a buffer for the ejabberd to read from. If this is unwanted, a load balancer would need to receive data from the ejabberd server before adding the node to its pool. This patch binds tcp ports while initializing the ejabberd_listener process, storing ListenSockets in an ets table. start_listeners/0 will reuse these ports later on.
This commit is contained in:
Andreas Köhler
Badlop
parent
0c484369c9
commit
1f1d2bd5f5
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@ -48,8 +48,31 @@ start_link() ->
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init(_) ->
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ets:new(listen_sockets, [named_table, public]),
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bind_tcp_ports(),
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{ok, {{one_for_one, 10, 1}, []}}.
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bind_tcp_ports() ->
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case ejabberd_config:get_local_option(listen) of
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undefined ->
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ignore;
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Ls ->
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lists:foreach(
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fun({Port, Module, Opts}) ->
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bind_tcp_port(Port, Module, Opts)
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end, Ls)
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end.
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bind_tcp_port(PortIP, Module, RawOpts) ->
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{Port, IPT, IPS, IPV, Proto, OptsClean} = parse_listener_portip(PortIP, RawOpts),
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{_Opts, SockOpts} = prepare_opts(IPT, IPV, OptsClean),
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case Proto of
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udp -> ok;
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_ ->
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ListenSocket = listen_tcp(PortIP, Module, SockOpts, Port, IPS),
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ets:insert(listen_sockets, {PortIP, ListenSocket})
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end.
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start_listeners() ->
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case ejabberd_config:get_local_option(listen) of
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undefined ->
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@ -99,15 +122,7 @@ start_dependent(Port, Module, Opts) ->
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init(PortIP, Module, RawOpts) ->
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{Port, IPT, IPS, IPV, Proto, OptsClean} = parse_listener_portip(PortIP, RawOpts),
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%% The first inet|inet6 and the last {ip, _} work,
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%% so overriding those in Opts
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Opts = [IPV | OptsClean] ++ [{ip, IPT}],
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SockOpts = lists:filter(fun({ip, _}) -> true;
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(inet6) -> true;
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(inet) -> true;
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({backlog, _}) -> true;
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(_) -> false
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end, Opts),
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{Opts, SockOpts} = prepare_opts(IPT, IPV, OptsClean),
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if Proto == udp ->
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init_udp(PortIP, Module, Opts, SockOpts, Port, IPS);
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true ->
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@ -128,28 +143,39 @@ init_udp(PortIP, Module, Opts, SockOpts, Port, IPS) ->
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end.
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init_tcp(PortIP, Module, Opts, SockOpts, Port, IPS) ->
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SockOpts2 = try erlang:system_info(otp_release) >= "R13B" of
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true -> [{send_timeout_close, true} | SockOpts];
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false -> SockOpts
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catch
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_:_ -> []
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end,
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Res = gen_tcp:listen(Port, [binary,
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{packet, 0},
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{active, false},
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{reuseaddr, true},
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{nodelay, true},
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{send_timeout, ?TCP_SEND_TIMEOUT},
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{keepalive, true} |
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SockOpts2]),
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case Res of
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{ok, ListenSocket} ->
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%% Inform my parent that this port was opened succesfully
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proc_lib:init_ack({ok, self()}),
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%% And now start accepting connection attempts
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accept(ListenSocket, Module, Opts);
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{error, Reason} ->
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socket_error(Reason, PortIP, Module, SockOpts, Port, IPS)
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ListenSocket = listen_tcp(PortIP, Module, SockOpts, Port, IPS),
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%% Inform my parent that this port was opened succesfully
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proc_lib:init_ack({ok, self()}),
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%% And now start accepting connection attempts
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accept(ListenSocket, Module, Opts).
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listen_tcp(PortIP, Module, SockOpts, Port, IPS) ->
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case ets:lookup(listen_sockets, PortIP) of
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[{PortIP, ListenSocket}] ->
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?INFO_MSG("Reusing listening port for ~p", [Port]),
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ets:delete(listen_sockets, Port),
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ListenSocket;
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_ ->
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SockOpts2 = try erlang:system_info(otp_release) >= "R13B" of
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true -> [{send_timeout_close, true} | SockOpts];
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false -> SockOpts
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catch
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_:_ -> []
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end,
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Res = gen_tcp:listen(Port, [binary,
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{packet, 0},
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{active, false},
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{reuseaddr, true},
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{nodelay, true},
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{send_timeout, ?TCP_SEND_TIMEOUT},
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{keepalive, true} |
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SockOpts2]),
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case Res of
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{ok, ListenSocket} ->
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ListenSocket;
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{error, Reason} ->
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socket_error(Reason, PortIP, Module, SockOpts, Port, IPS)
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end
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end.
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%% @spec (PortIP, Opts) -> {Port, IPT, IPS, IPV, OptsClean}
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@ -194,6 +220,18 @@ parse_listener_portip(PortIP, Opts) ->
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end,
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{Port, IPT, IPS, IPV, Proto, OptsClean}.
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prepare_opts(IPT, IPV, OptsClean) ->
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%% The first inet|inet6 and the last {ip, _} work,
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%% so overriding those in Opts
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Opts = [IPV | OptsClean] ++ [{ip, IPT}],
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SockOpts = lists:filter(fun({ip, _}) -> true;
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(inet6) -> true;
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(inet) -> true;
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({backlog, _}) -> true;
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(_) -> false
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end, Opts),
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{Opts, SockOpts}.
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add_proto(Port, Opts) when is_integer(Port) ->
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{Port, get_proto(Opts)};
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add_proto({Port, Proto}, _Opts) when is_atom(Proto) ->
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