aboutsummaryrefslogtreecommitdiffstats
path: root/src/ranch_conns_sup.erl
blob: 245a5e0de766263b8e0bfa5c8c0d0ab82325b37e (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
%% Copyright (c) 2011-2012, Loïc Hoguin <[email protected]>
%%
%% Permission to use, copy, modify, and/or distribute this software for any
%% purpose with or without fee is hereby granted, provided that the above
%% copyright notice and this permission notice appear in all copies.
%%
%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

%% @private
%%
%% Make sure to never reload this module outside a release upgrade,
%% as calling l(ranch_conns_sup) twice will kill the process and all
%% the currently open connections.
-module(ranch_conns_sup).

%% API.
-export([start_link/4]).
-export([start_protocol/2]).
-export([active_connections/1]).

%% Supervisor internals.
-export([init/5]).
-export([system_continue/3]).
-export([system_terminate/4]).
-export([system_code_change/4]).

-type conn_type() :: worker | supervisor.

-record(state, {
	parent = undefined :: pid(),
	ref :: ranch:ref(),
	conn_type :: conn_type(),
	transport = undefined :: module(),
	protocol = undefined :: module(),
	opts :: any(),
	max_conns = undefined :: non_neg_integer() | infinity
}).

%% API.

-spec start_link(ranch:ref(), conn_type(), module(), module()) -> {ok, pid()}.
start_link(Ref, ConnType, Transport, Protocol) ->
	proc_lib:start_link(?MODULE, init,
		[self(), Ref, ConnType, Transport, Protocol]).

%% We can safely assume we are on the same node as the supervisor.
%%
%% We can also safely avoid having a monitor and a timeout here
%% because only three things can happen:
%%  *  The supervisor died; rest_for_one strategy killed all acceptors
%%     so this very calling process is going to di--
%%  *  There's too many connections, the supervisor will resume the
%%     acceptor only when we get below the limit again.
%%  *  The supervisor is overloaded, there's either too many acceptors
%%     or the max_connections limit is too large. It's better if we
%%     don't keep accepting connections because this leaves
%%     more room for the situation to be resolved.
%%
%% We do not need the reply, we only need the ok from the supervisor
%% to continue. The supervisor sends its own pid when the acceptor can
%% continue.
-spec start_protocol(pid(), inet:socket()) -> ok.
start_protocol(SupPid, Socket) ->
	SupPid ! {?MODULE, start_protocol, self(), Socket},
	receive SupPid -> ok end.

%% We can't make the above assumptions here. This function might be
%% called from anywhere.
-spec active_connections(pid()) -> non_neg_integer().
active_connections(SupPid) ->
	Tag = erlang:monitor(process, SupPid),
	catch erlang:send(SupPid, {?MODULE, active_connections, self(), Tag},
		[noconnect]),
	receive
		{Tag, Ret} ->
			erlang:demonitor(Tag, [flush]),
			Ret;
		{'DOWN', Tag, _, _, noconnection} ->
			exit({nodedown, node(SupPid)});
		{'DOWN', Tag, _, _, Reason} ->
			exit(Reason)
	after 5000 ->
		erlang:demonitor(Tag, [flush]),
		exit(timeout)
	end.

%% Supervisor internals.

-spec init(pid(), ranch:ref(), conn_type(), module(), module()) -> no_return().
init(Parent, Ref, ConnType, Transport, Protocol) ->
	process_flag(trap_exit, true),
	ok = ranch_server:set_connections_sup(Ref, self()),
	MaxConns = ranch_server:get_max_connections(Ref),
	Opts = ranch_server:get_protocol_options(Ref),
	ok = proc_lib:init_ack(Parent, {ok, self()}),
	loop(#state{parent=Parent, ref=Ref, conn_type=ConnType,
		transport=Transport, protocol=Protocol, opts=Opts,
		max_conns=MaxConns}, 0, 0, []).

loop(State=#state{parent=Parent, ref=Ref, conn_type=ConnType,
		transport=Transport, protocol=Protocol, opts=Opts,
		max_conns=MaxConns}, CurConns, NbChildren, Sleepers) ->
	receive
		{?MODULE, start_protocol, To, Socket} ->
			case Protocol:start_link(Ref, Socket, Transport, Opts) of
				{ok, Pid} ->
					Transport:controlling_process(Socket, Pid),
					Pid ! {shoot, Ref},
					put(Pid, true),
					CurConns2 = CurConns + 1,
					if CurConns2 < MaxConns ->
							To ! self(),
							loop(State, CurConns2, NbChildren + 1,
								Sleepers);
						true ->
							loop(State, CurConns2, NbChildren + 1,
								[To|Sleepers])
					end;
				_ ->
					To ! self(),
					Transport:close(Socket),
					loop(State, CurConns, NbChildren, Sleepers)
			end;
		{?MODULE, active_connections, To, Tag} ->
			To ! {Tag, CurConns},
			loop(State, CurConns, NbChildren, Sleepers);
		%% Remove a connection from the count of connections.
		{remove_connection, Ref} ->
			loop(State, CurConns - 1, NbChildren, Sleepers);
		%% Upgrade the max number of connections allowed concurrently.
		%% We resume all sleeping acceptors if this number increases.
		{set_max_conns, MaxConns2} when MaxConns2 > MaxConns ->
			_ = [To ! self() || To <- Sleepers],
			loop(State#state{max_conns=MaxConns2},
				CurConns, NbChildren, []);
		{set_max_conns, MaxConns2} ->
			loop(State#state{max_conns=MaxConns2},
				CurConns, NbChildren, Sleepers);
		%% Upgrade the protocol options.
		{set_opts, Opts2} ->
			loop(State#state{opts=Opts2},
				CurConns, NbChildren, Sleepers);
		{'EXIT', Parent, Reason} ->
			exit(Reason);
		{'EXIT', Pid, Reason} when Sleepers =:= [] ->
			report_error(Ref, Protocol, Pid, Reason),
			erase(Pid),
			loop(State, CurConns - 1, NbChildren - 1, Sleepers);
		%% Resume a sleeping acceptor if needed.
		{'EXIT', Pid, Reason} ->
			report_error(Ref, Protocol, Pid, Reason),
			erase(Pid),
			[To|Sleepers2] = Sleepers,
			To ! self(),
			loop(State, CurConns - 1, NbChildren - 1, Sleepers2);
		{system, From, Request} ->
			sys:handle_system_msg(Request, From, Parent, ?MODULE, [],
				{State, CurConns, NbChildren, Sleepers});
		%% Calls from the supervisor module.
		{'$gen_call', {To, Tag}, which_children} ->
			Pids = get_keys(true),
			Children = [{Protocol, Pid, ConnType, [Protocol]}
				|| Pid <- Pids, is_pid(Pid)],
			To ! {Tag, Children},
			loop(State, CurConns, NbChildren, Sleepers);
		{'$gen_call', {To, Tag}, count_children} ->
			Counts = case ConnType of
				worker -> [{supervisors, 0}, {workers, NbChildren}];
				supervisor -> [{supervisors, NbChildren}, {workers, 0}]
			end,
			Counts2 = [{specs, 1}, {active, NbChildren}|Counts],
			To ! {Tag, Counts2},
			loop(State, CurConns, NbChildren, Sleepers);
		{'$gen_call', {To, Tag}, _} ->
			To ! {Tag, {error, ?MODULE}},
			loop(State, CurConns, NbChildren, Sleepers);
		Msg ->
			error_logger:error_msg(
				"Ranch listener ~p received unexpected message ~p~n",
				[Ref, Msg])
	end.

system_continue(_, _, {State, CurConns, NbChildren, Sleepers}) ->
	loop(State, CurConns, NbChildren, Sleepers).

-spec system_terminate(any(), _, _, _) -> no_return().
system_terminate(Reason, _, _, _) ->
	exit(Reason).

system_code_change(Misc, _, _, _) ->
	{ok, Misc}.

%% We use ~999999p here instead of ~w because the latter doesn't
%% support printable strings.
report_error(_, _, _, normal) ->
	ok;
report_error(_, _, _, shutdown) ->
	ok;
report_error(_, _, _, {shutdown, _}) ->
	ok;
report_error(Ref, Protocol, Pid, Reason) ->
	error_logger:error_msg(
		"Ranch listener ~p had connection process started with "
		"~p:start_link/4 at ~p exit with reason: ~999999p~n",
		[Ref, Protocol, Pid, Reason]).