From 7006c50c3ed6c3cbcb24e9e88a76ebd1aaf3a5f8 Mon Sep 17 00:00:00 2001
From: "j.uhlig" <j.uhlig@mailingwork.de>
Date: Mon, 9 Apr 2018 12:53:02 +0200
Subject: Add suspend/resume of listeners and update of transport options

This allows graceful draining of connections, updating transport
options on a running listener without having to drop connections
and other similar scenarios.

Note that when updating transport options the listener must be
suspended which means that new connections will be rejected until
the listener is resumed.
---
 src/ranch.erl | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 77 insertions(+), 4 deletions(-)

(limited to 'src/ranch.erl')

diff --git a/src/ranch.erl b/src/ranch.erl
index 70fb64c..5af4b74 100644
--- a/src/ranch.erl
+++ b/src/ranch.erl
@@ -17,17 +17,23 @@
 -export([start_listener/5]).
 -export([start_listener/6]).
 -export([stop_listener/1]).
+-export([suspend_listener/1]).
+-export([resume_listener/1]).
 -export([child_spec/5]).
 -export([child_spec/6]).
 -export([accept_ack/1]).
 -export([remove_connection/1]).
+-export([get_status/1]).
 -export([get_addr/1]).
 -export([get_port/1]).
 -export([get_max_connections/1]).
 -export([set_max_connections/2]).
+-export([get_transport_options/1]).
+-export([set_transport_options/2]).
 -export([get_protocol_options/1]).
 -export([set_protocol_options/2]).
 -export([info/0]).
+-export([info/1]).
 -export([procs/2]).
 -export([filter_options/3]).
 -export([set_option_default/3]).
@@ -110,6 +116,37 @@ stop_listener(Ref) ->
 			{error, Reason}
 	end.
 
+-spec suspend_listener(ref()) -> ok | {error, term()}.
+suspend_listener(Ref) ->
+	case get_status(Ref) of
+		running ->
+			ListenerSup = ranch_server:get_listener_sup(Ref),
+			ok = ranch_server:set_addr(Ref, {undefined, undefined}),
+			supervisor:terminate_child(ListenerSup, ranch_acceptors_sup);
+		suspended ->
+			ok
+	end.
+
+-spec resume_listener(ref()) -> ok | {error, term()}.
+resume_listener(Ref) ->
+	case get_status(Ref) of
+		running ->
+			ok;
+		suspended ->
+			ListenerSup = ranch_server:get_listener_sup(Ref),
+			Res = supervisor:restart_child(ListenerSup, ranch_acceptors_sup),
+			maybe_resumed(Res)
+	end.
+
+maybe_resumed(Error={error, {listen_error, _, Reason}}) ->
+	start_error(Reason, Error);
+maybe_resumed({ok, _}) ->
+	ok;
+maybe_resumed({ok, _, _}) ->
+	ok;
+maybe_resumed(Res) ->
+	Res.
+
 -spec child_spec(ref(), module(), any(), module(), any())
 	-> supervisor:child_spec().
 child_spec(Ref, Transport, TransOpts, Protocol, ProtoOpts) ->
@@ -137,11 +174,22 @@ remove_connection(Ref) ->
 	ConnsSup ! {remove_connection, Ref, self()},
 	ok.
 
--spec get_addr(ref()) -> {inet:ip_address(), inet:port_number()}.
+-spec get_status(ref()) -> running | suspended | restarting.
+get_status(Ref) ->
+	ListenerSup = ranch_server:get_listener_sup(Ref),
+	Children = supervisor:which_children(ListenerSup),
+	case lists:keyfind(ranch_acceptors_sup, 1, Children) of
+		{_, undefined, _, _} ->
+			suspended;
+		{_, AcceptorsSup, _, _} when is_pid(AcceptorsSup) ->
+			running
+	end.
+
+-spec get_addr(ref()) -> {inet:ip_address(), inet:port_number()} | {undefined, undefined}.
 get_addr(Ref) ->
 	ranch_server:get_addr(Ref).
 
--spec get_port(ref()) -> inet:port_number().
+-spec get_port(ref()) -> inet:port_number() | undefined.
 get_port(Ref) ->
 	{_, Port} = get_addr(Ref),
 	Port.
@@ -154,6 +202,19 @@ get_max_connections(Ref) ->
 set_max_connections(Ref, MaxConnections) ->
 	ranch_server:set_max_connections(Ref, MaxConnections).
 
+-spec get_transport_options(ref()) -> any().
+get_transport_options(Ref) ->
+	ranch_server:get_transport_options(Ref).
+
+-spec set_transport_options(ref(), any()) -> ok | {error, running}.
+set_transport_options(Ref, TransOpts) ->
+	case get_status(Ref) of
+		suspended ->
+			ok = ranch_server:set_transport_options(Ref, TransOpts);
+		running ->
+			{error, running}
+	end.
+
 -spec get_protocol_options(ref()) -> any().
 get_protocol_options(Ref) ->
 	ranch_server:get_protocol_options(Ref).
@@ -167,14 +228,22 @@ info() ->
 	[{Ref, listener_info(Ref, Pid)}
 		|| {Ref, Pid} <- ranch_server:get_listener_sups()].
 
+-spec info(ref()) -> [{atom(), any()}].
+info(Ref) ->
+	Pid = ranch_server:get_listener_sup(Ref),
+	listener_info(Ref, Pid).
+
 listener_info(Ref, Pid) ->
-	[_, NumAcceptors, Transport, TransOpts, Protocol, _] = ranch_server:get_listener_start_args(Ref),
+	[_, NumAcceptors, Transport, _, Protocol, _] = ranch_server:get_listener_start_args(Ref),
 	ConnsSup = ranch_server:get_connections_sup(Ref),
+	Status = get_status(Ref),
 	{IP, Port} = get_addr(Ref),
 	MaxConns = get_max_connections(Ref),
+	TransOpts = ranch_server:get_transport_options(Ref),
 	ProtoOpts = get_protocol_options(Ref),
 	[
 		{pid, Pid},
+		{status, Status},
 		{ip, IP},
 		{port, Port},
 		{num_acceptors, NumAcceptors},
@@ -197,7 +266,11 @@ procs1(Ref, Sup) ->
 	ListenerSup = ranch_server:get_listener_sup(Ref),
 	{_, SupPid, _, _} = lists:keyfind(Sup, 1,
 		supervisor:which_children(ListenerSup)),
-	[Pid || {_, Pid, _, _} <- supervisor:which_children(SupPid)].
+	try
+		[Pid || {_, Pid, _, _} <- supervisor:which_children(SupPid)]
+	catch exit:{noproc, _} when Sup =:= ranch_acceptors_sup ->
+		[]
+	end.
 
 -spec filter_options([inet | inet6 | {atom(), any()} | {raw, any(), any(), any()}],
 	[atom()], Acc) -> Acc when Acc :: [any()].
-- 
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