aboutsummaryrefslogtreecommitdiffstats
path: root/lib/stdlib/src/supervisor_bridge.erl
blob: ff4502f0b92c8dc17f591b1c54d4e26ad9ab7299 (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
%%
%% %CopyrightBegin%
%% 
%% Copyright Ericsson AB 1996-2011. All Rights Reserved.
%% 
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%% 
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%% 
%% %CopyrightEnd%
%%
-module(supervisor_bridge).

-behaviour(gen_server).

%% External exports
-export([start_link/2, start_link/3]).
%% Internal exports
-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2]).
-export([code_change/3]).

-callback init(Args :: term()) ->
    {ok, Pid :: pid(), State :: term()} | ignore | {error, Error :: term()}.
-callback terminate(Reason :: (shutdown | term()), State :: term()) ->
    Ignored :: term().

%%%-----------------------------------------------------------------
%%% This is a rewrite of supervisor_bridge from BS.3.
%%%
%%% This module is built to function as process code
%%% for a process sitting inbetween a real supervisor
%%% and a not start&recovery complient server/system
%%% The process inbetween simulates start&recovery
%%% behaviour of the server/system below.
%%%
%%% The supervisor_bridge behaviour must export the following
%%% functions:
%%%    init(Args) -> {ok, Pid, State} | {error, Reason} | ignore
%%%       where Pid is the child process
%%%    terminate(Reason, State) -> ok
%%%-----------------------------------------------------------------
-record(state, {mod, pid, child_state, name}).

-spec start_link(Module, Args) -> Result when
      Module :: module(),
      Args :: term(),
      Result :: {ok, Pid} | ignore | {error, Error},
      Error :: {already_started, Pid} | term(),
      Pid :: pid().

start_link(Mod, StartArgs) ->
    gen_server:start_link(supervisor_bridge, [Mod, StartArgs, self], []).

-spec start_link(SupBridgeName, Module, Args) -> Result when
      SupBridgeName :: {local, Name} | {global, Name},
      Name :: atom(),
      Module :: module(),
      Args :: term(),
      Result :: {ok, Pid} | ignore | {error, Error},
      Error :: {already_started, Pid} | term(),
      Pid :: pid().

start_link(Name, Mod, StartArgs) ->
    gen_server:start_link(Name, supervisor_bridge, [Mod, StartArgs, Name], []).

%%-----------------------------------------------------------------
%% Callback functions from gen_server
%%-----------------------------------------------------------------
init([Mod, StartArgs, Name0]) ->  
    process_flag(trap_exit, true),
    Name = supname(Name0, Mod),
    case Mod:init(StartArgs) of
	{ok, Pid, ChildState} when is_pid(Pid) ->
	    link(Pid),
	    report_progress(Pid, Mod, StartArgs, Name),
	    {ok, #state{mod = Mod, pid = Pid,
			child_state = ChildState, name = Name}};
	ignore ->
	    ignore;
	{error, Reason} ->
	    {stop, Reason}
    end.

supname(self, Mod) -> {self(),Mod};
supname(N, _)      -> N.

%% A supervisor *must* answer the supervisor:which_children call.
handle_call(which_children, _From, State) ->
    {reply, [], State};
handle_call(_Req, _From, State) ->
    {reply, {error, badcall}, State}.

handle_cast(_, State) ->
    {noreply, State}.

handle_info({'EXIT', Pid, Reason}, State) when State#state.pid =:= Pid ->
	case Reason of
	normal ->
	    ok;
	shutdown ->
	    ok;
	{shutdown, _Term} ->
	    ok;
	_ ->
	    report_error(child_terminated, Reason, State)
	end,
    {stop, Reason, State#state{pid = undefined}};
handle_info(_, State) ->
    {noreply, State}.

terminate(_Reason, #state{pid = undefined}) ->
    ok;
terminate(Reason, State) ->
    terminate_pid(Reason, State).

code_change(_OldVsn, State, _Extra) ->
    {ok, State}.

%% This function is supposed to terminate the 'real' server.
terminate_pid(Reason, #state{mod = Mod, child_state = ChildState}) ->
    Mod:terminate(Reason, ChildState).

report_progress(Pid, Mod, StartArgs, SupName) ->
    Progress = [{supervisor, SupName},
		{started, [{pid, Pid}, {mfa, {Mod, init, [StartArgs]}}]}],
    error_logger:info_report(progress, Progress).

report_error(Error, Reason, #state{name = Name, pid = Pid, mod = Mod}) ->
    ErrorMsg = [{supervisor, Name},
		{errorContext, Error},
		{reason, Reason},
		{offender, [{pid, Pid}, {mod, Mod}]}],
    error_logger:error_report(supervisor_report, ErrorMsg).