%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1996-2016. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
-module(application_master).
%% External exports
-export([start_link/2, start_type/0, stop/1]).
-export([get_child/1]).
%% Internal exports
-export([init/4, start_it/4]).
-include("application_master.hrl").
-record(state, {child, appl_data, children = [], procs = 0, gleader, req=[]}).
%%-----------------------------------------------------------------
%% Func: start_link/1
%% Args: ApplData = record(appl_data)
%% Purpose: Starts an application master for the application.
%% Called from application_controller. (The application is
%% also started).
%% Returns: {ok, Pid} | {error, Reason} (Pid is unregistered)
%%-----------------------------------------------------------------
start_link(ApplData, Type) ->
Parent = whereis(application_controller),
proc_lib:start_link(application_master, init,
[Parent, self(), ApplData, Type]).
start_type() ->
group_leader() ! {start_type, self()},
receive
{start_type, Type} ->
Type
after 5000 ->
{error, timeout}
end.
%%-----------------------------------------------------------------
%% Func: stop/1
%% Purpose: Stops the application. This function makes sure
%% that all processes belonging to the applicication is
%% stopped (shutdown or killed). The application master
%% is also stopped.
%% Returns: ok
%%-----------------------------------------------------------------
stop(AppMaster) -> call(AppMaster, stop).
%%-----------------------------------------------------------------
%% Func: get_child/1
%% Purpose: Get the topmost supervisor of an application.
%% Returns: {pid(), App}
%%-----------------------------------------------------------------
get_child(AppMaster) -> call(AppMaster, get_child).
call(AppMaster, Req) ->
Tag = make_ref(),
Ref = erlang:monitor(process, AppMaster),
AppMaster ! {Req, Tag, self()},
receive
{'DOWN', Ref, process, _, _Info} ->
ok;
{Tag, Res} ->
erlang:demonitor(Ref, [flush]),
Res
end.
%%%-----------------------------------------------------------------
%%% The logical and physical process structrure is as follows:
%%%
%%% logical physical
%%%
%%% -------- --------
%%% |AM(GL)| |AM(GL)|
%%% -------- --------
%%% | |
%%% -------- --------
%%% |Appl P| | X |
%%% -------- --------
%%% |
%%% --------
%%% |Appl P|
%%% --------
%%%
%%% Where AM(GL) == Application Master (Group Leader)
%%% Appl P == The application specific root process (child to AM)
%%% X == A special 'invisible' process
%%% The reason for not using the logical structrure is that
%%% the application start function is synchronous, and
%%% that the AM is GL. This means that if AM executed the start
%%% function, and this function uses io, deadlock would occur.
%%% Therefore, this function is executed by the process X.
%%% Also, AM needs three loops;
%%% init_loop (waiting for the start function to return)
%%% main_loop
%%% terminate_loop (waiting for the process to die)
%%% In each of these loops, io and other requests are handled.
%%%-----------------------------------------------------------------
%%% Internal functions
%%%-----------------------------------------------------------------
init(Parent, Starter, ApplData, Type) ->
link(Parent),
process_flag(trap_exit, true),
OldGleader = group_leader(),
group_leader(self(), self()),
%% Insert ourselves as master for the process. This ensures that
%% the processes in the application can use get_env/1 at startup.
Name = ApplData#appl_data.name,
ets:insert(ac_tab, {{application_master, Name}, self()}),
State = #state{appl_data = ApplData, gleader = OldGleader},
case start_it(State, Type) of
{ok, Pid} -> % apply(M,F,A) returned ok
ok = set_timer(ApplData#appl_data.maxT),
unlink(Starter),
proc_lib:init_ack(Starter, {ok,self()}),
main_loop(Parent, State#state{child = Pid});
{error, Reason} -> % apply(M,F,A) returned error
exit(Reason);
Else -> % apply(M,F,A) returned erroneous
exit(Else)
end.
%%-----------------------------------------------------------------
%% We want to start the new application synchronously, but we still
%% want to handle io requests. So we spawn off a new process that
%% performs the apply, and we wait for a start ack.
%%-----------------------------------------------------------------
start_it(State, Type) ->
Tag = make_ref(),
Pid = spawn_link(application_master, start_it, [Tag, State, self(), Type]),
init_loop(Pid, Tag, State, Type).
%%-----------------------------------------------------------------
%% These are the three different loops executed by the application_
%% master
%%-----------------------------------------------------------------
init_loop(Pid, Tag, State, Type) ->
receive
IoReq when element(1, IoReq) =:= io_request ->
State#state.gleader ! IoReq,
init_loop(Pid, Tag, State, Type);
{Tag, Res} ->
Res;
{'EXIT', Pid, Reason} ->
{error, Reason};
{start_type, From} ->
From ! {start_type, Type},
init_loop(Pid, Tag, State, Type);
Other ->
NewState = handle_msg(Other, State),
init_loop(Pid, Tag, NewState, Type)
end.
main_loop(Parent, State) ->
receive
IoReq when element(1, IoReq) =:= io_request ->
State#state.gleader ! IoReq,
main_loop(Parent, State);
{'EXIT', Parent, Reason} ->
terminate(Reason, State);
{'EXIT', Child, Reason} when State#state.child =:= Child ->
terminate(Reason, State#state{child=undefined});
{'EXIT', _, timeout} ->
terminate(normal, State);
{'EXIT', Pid, _Reason} ->
Children = lists:delete(Pid, State#state.children),
Procs = State#state.procs - 1,
main_loop(Parent, State#state{children=Children, procs=Procs});
{start_type, From} ->
From ! {start_type, local},
main_loop(Parent, State);
Other ->
NewState = handle_msg(Other, State),
main_loop(Parent, NewState)
end.
terminate_loop(Child, State) ->
receive
IoReq when element(1, IoReq) =:= io_request ->
State#state.gleader ! IoReq,
terminate_loop(Child, State);
{'EXIT', Child, _} ->
ok;
Other ->
NewState = handle_msg(Other, State),
terminate_loop(Child, NewState)
end.
%%-----------------------------------------------------------------
%% The Application Master is linked to *all* processes in the group
%% (application).
%%-----------------------------------------------------------------
handle_msg({get_child, Tag, From}, State) ->
get_child_i(State, Tag, From);
handle_msg({stop, Tag, From}, State) ->
catch terminate(normal, State),
From ! {Tag, ok},
exit(normal);
handle_msg({child, Ref, GrandChild, Mod}, #state{req=Reqs0}=State) ->
{value, {_, Tag, From}, Reqs} = lists:keytake(Ref, 1, Reqs0),
From ! {Tag, {GrandChild, Mod}},
State#state{req=Reqs};
handle_msg(_, State) ->
State.
terminate(Reason, State = #state{child=Child, children=Children, req=Reqs}) ->
_ = [From ! {Tag, error} || {_, Tag, From} <- Reqs],
terminate_child(Child, State),
kill_children(Children),
exit(Reason).
%%======================================================================
%%======================================================================
%%======================================================================
%% This is the process X above...
%%======================================================================
%%======================================================================
%%======================================================================
%%======================================================================
%% Start an application.
%% If the start_phases is defined in the .app file, the application is
%% to be started in one or several start phases.
%% If the Module in the mod-key is set to application_starter then
%% the generic help module application_starter is used to control
%% the start.
%%======================================================================
start_it(Tag, State, From, Type) ->
process_flag(trap_exit, true),
ApplData = State#state.appl_data,
case {ApplData#appl_data.phases, ApplData#appl_data.mod} of
{undefined, _} ->
start_it_old(Tag, From, Type, ApplData);
{Phases, {application_starter, [M, A]}} ->
start_it_new(Tag, From, Type, M, A, Phases,
[ApplData#appl_data.name]);
{Phases, {M, A}} ->
start_it_new(Tag, From, Type, M, A, Phases,
[ApplData#appl_data.name]);
{OtherP, OtherM} ->
From ! {Tag, {error, {bad_keys, {{mod, OtherM},
{start_phases, OtherP}}}}}
end.
%%%-----------------------------------------------------
%%% No start phases are defined
%%%-----------------------------------------------------
start_it_old(Tag, From, Type, ApplData) ->
{M,A} = ApplData#appl_data.mod,
case catch M:start(Type, A) of
{ok, Pid} ->
link(Pid),
From ! {Tag, {ok, self()}},
loop_it(From, Pid, M, []);
{ok, Pid, AppState} ->
link(Pid),
From ! {Tag, {ok, self()}},
loop_it(From, Pid, M, AppState);
{'EXIT', normal} ->
From ! {Tag, {error, {{'EXIT',normal},{M,start,[Type,A]}}}};
{error, Reason} ->
From ! {Tag, {error, {Reason, {M,start,[Type,A]}}}};
Other ->
From ! {Tag, {error, {bad_return,{{M,start,[Type,A]},Other}}}}
end.
%%%-----------------------------------------------------
%%% Start phases are defined
%%%-----------------------------------------------------
start_it_new(Tag, From, Type, M, A, Phases, Apps) ->
case catch start_the_app(Type, M, A, Phases, Apps) of
{ok, Pid, AppState} ->
From ! {Tag, {ok, self()}},
loop_it(From, Pid, M, AppState);
Error ->
From ! {Tag, Error}
end.
%%%=====================================================
%%% Start the application in the defined phases,
%%% but first the supervisors are starter.
%%%=====================================================
start_the_app(Type, M, A, Phases, Apps) ->
case start_supervisor(Type, M, A) of
{ok, Pid, AppState} ->
link(Pid),
case application_starter:start(Phases, Type, Apps) of
ok ->
{ok, Pid, AppState};
Error2 ->
unlink(Pid),
Error2
end;
Error ->
Error
end.
%%%-------------------------------------------------------------
%%% Start the supervisors
%%%-------------------------------------------------------------
start_supervisor(Type, M, A) ->
case catch M:start(Type, A) of
{ok, Pid} ->
{ok, Pid, []};
{ok, Pid, AppState} ->
{ok, Pid, AppState};
{error, Reason} ->
{error, {Reason, {M, start, [Type, A]}}};
{'EXIT', normal} ->
{error, {{'EXIT', normal}, {M, start, [Type, A]}}};
Other ->
{error, {bad_return, {{M, start, [Type, A]}, Other}}}
end.
%%======================================================================
%%
%%======================================================================
loop_it(Parent, Child, Mod, AppState) ->
receive
{Parent, get_child, Ref} ->
Parent ! {child, Ref, Child, Mod},
loop_it(Parent, Child, Mod, AppState);
{Parent, terminate} ->
NewAppState = prep_stop(Mod, AppState),
exit(Child, shutdown),
receive
{'EXIT', Child, _} -> ok
end,
catch Mod:stop(NewAppState),
exit(normal);
{'EXIT', Parent, Reason} ->
NewAppState = prep_stop(Mod, AppState),
exit(Child, Reason),
receive
{'EXIT', Child, Reason2} ->
exit(Reason2)
end,
catch Mod:stop(NewAppState);
{'EXIT', Child, Reason} -> % forward *all* exit reasons (inc. normal)
NewAppState = prep_stop(Mod, AppState),
catch Mod:stop(NewAppState),
exit(Reason);
_ ->
loop_it(Parent, Child, Mod, AppState)
end.
prep_stop(Mod, AppState) ->
case catch Mod:prep_stop(AppState) of
{'EXIT', {undef, _}} ->
AppState;
{'EXIT', Reason} ->
error_logger:error_report([{?MODULE, shutdown_error},
{Mod, {prep_stop, [AppState]}},
{error_info, Reason}]),
AppState;
NewAppState ->
NewAppState
end.
get_child_i(#state{child=Child, req=Reqs}=State, Tag, From) ->
Ref = erlang:make_ref(),
case erlang:is_process_alive(Child) of
true ->
Child ! {self(), get_child, Ref},
State#state{req=[{Ref, Tag, From}|Reqs]};
false ->
From ! {Tag, error},
State
end.
terminate_child_i(Child, State) ->
Child ! {self(), terminate},
terminate_loop(Child, State).
%% Try to shutdown the child gently
terminate_child(undefined, _) -> ok;
terminate_child(Child, State) ->
terminate_child_i(Child, State).
kill_children(Children) ->
lists:foreach(fun(Pid) -> exit(Pid, kill) end, Children),
kill_all_procs().
kill_all_procs() ->
kill_all_procs_1(processes(), self(), 0).
kill_all_procs_1([Self|Ps], Self, N) ->
kill_all_procs_1(Ps, Self, N);
kill_all_procs_1([P|Ps], Self, N) ->
case process_info(P, group_leader) of
{group_leader,Self} ->
exit(P, kill),
kill_all_procs_1(Ps, Self, N+1);
_ ->
kill_all_procs_1(Ps, Self, N)
end;
kill_all_procs_1([], _, 0) -> ok;
kill_all_procs_1([], _, _) -> kill_all_procs().
set_timer(infinity) -> ok;
set_timer(Time) ->
{ok, _} = timer:exit_after(Time, timeout),
ok.
