%%
%% %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(heart).
-compile(no_native).
% 'no_native' as part of a crude fix to make init:restart/0 work by clearing
% all hipe inter-module information (hipe_mfa_info's in hipe_bif0.c).
%%%--------------------------------------------------------------------
%%% This is a rewrite of pre_heart from BS.3.
%%%
%%% The purpose of this process-module is to act as a supervisor
%%% of the entire erlang-system. This 'heart' beats with a frequence
%%% satisfying an external port program *not* reboot the entire
%%% system. If however the erlang-emulator would hang, a reboot is
%%% then needed.
%%%
%%% It recognizes the flag '-heart'
%%%--------------------------------------------------------------------
-export([start/0, init/2,
set_cmd/1, clear_cmd/0, get_cmd/0,
set_callback/2, clear_callback/0, get_callback/0,
set_options/1, get_options/0,
cycle/0]).
-define(START_ACK, 1).
-define(HEART_BEAT, 2).
-define(SHUT_DOWN, 3).
-define(SET_CMD, 4).
-define(CLEAR_CMD, 5).
-define(GET_CMD, 6).
-define(HEART_CMD, 7).
-define(PREPARING_CRASH, 8). % Used in beam vm
-define(TIMEOUT, 5000).
-define(CYCLE_TIMEOUT, 10000).
-define(HEART_PORT_NAME, heart_port).
%% valid heart options
-define(SCHEDULER_CHECK_OPT, check_schedulers).
-type heart_option() :: ?SCHEDULER_CHECK_OPT.
-record(state,{port :: port(),
cmd :: [] | binary(),
options :: [heart_option()],
callback :: 'undefined' | {atom(), atom()}}).
%%---------------------------------------------------------------------
-spec start() -> 'ignore' | {'error', term()} | {'ok', pid()}.
start() ->
case whereis(heart) of
undefined ->
%% As heart survives a init:restart/0 the Parent
%% of heart must be init.
%% The init process is responsible to create a link
%% to heart.
Pid = spawn(?MODULE, init, [self(), whereis(init)]),
wait_for_init_ack(Pid);
Pid ->
{ok, Pid}
end.
wait_for_init_ack(From) ->
receive
{ok, From} = Ok ->
Ok;
{no_heart, From} ->
ignore;
{Error, From} ->
{error, Error}
end.
-spec init(pid(), pid()) -> {'no_heart', pid()} | {'start_error', pid()}.
init(Starter, Parent) ->
process_flag(trap_exit, true),
process_flag(priority, max),
register(?MODULE, self()),
case catch start_portprogram() of
{ok, Port} ->
Starter ! {ok, self()},
loop(Parent, #state{port=Port, cmd=[], options=[]});
no_heart ->
Starter ! {no_heart, self()};
error ->
Starter ! {start_error, self()}
end.
-spec set_cmd(Cmd) -> 'ok' | {'error', {'bad_cmd', Cmd}} when
Cmd :: string().
set_cmd(Cmd) ->
?MODULE ! {self(), set_cmd, Cmd},
wait().
-spec get_cmd() -> {ok, Cmd} when
Cmd :: string().
get_cmd() ->
?MODULE ! {self(), get_cmd},
wait().
-spec clear_cmd() -> ok.
clear_cmd() ->
?MODULE ! {self(), clear_cmd},
wait().
-spec set_callback(Module,Function) -> 'ok' | {'error', {'bad_callback', {Module, Function}}} when
Module :: atom(),
Function :: atom().
set_callback(Module, Function) ->
?MODULE ! {self(), set_callback, {Module,Function}},
wait().
-spec get_callback() -> {'ok', {Module, Function}} | 'none' when
Module :: atom(),
Function :: atom().
get_callback() ->
?MODULE ! {self(), get_callback},
wait().
-spec clear_callback() -> ok.
clear_callback() ->
?MODULE ! {self(), clear_callback},
wait().
-spec set_options(Options) -> 'ok' | {'error', {'bad_options', Options}} when
Options :: [heart_option()].
set_options(Options) ->
?MODULE ! {self(), set_options, Options},
wait().
-spec get_options() -> {'ok', Options} | 'none' when
Options :: [atom()].
get_options() ->
?MODULE ! {self(), get_options},
wait().
%%% Should be used solely by the release handler!!!!!!!
-spec cycle() -> 'ok' | {'error', term()}.
cycle() ->
?MODULE ! {self(), cycle},
wait().
wait() ->
receive
{?MODULE, Res} ->
Res
end.
start_portprogram() ->
check_start_heart(),
HeartCmd = "heart -pid " ++ os:getpid() ++ " " ++ get_heart_timeouts(),
try open_port({spawn, HeartCmd}, [{packet, 2}]) of
Port when is_port(Port) ->
case wait_ack(Port) of
ok ->
%% register port so the vm can find it if need be
register(?HEART_PORT_NAME, Port),
{ok, Port};
{error, Reason} ->
report_problem({{port_problem, Reason},
{heart, start_portprogram, []}}),
error
end
catch
_:Reason ->
report_problem({{open_port, Reason},
{heart, start_portprogram, []}}),
error
end.
get_heart_timeouts() ->
case os:getenv("HEART_BEAT_TIMEOUT") of
false -> "";
H when is_list(H) ->
"-ht " ++ H
end.
check_start_heart() ->
case init:get_argument(heart) of
{ok, [[]]} ->
ok;
error ->
throw(no_heart);
{ok, [[X|_]|_]} ->
report_problem({{bad_heart_flag, list_to_atom(X)},
{heart, check_start_heart, []}}),
throw(error)
end.
wait_ack(Port) ->
receive
{Port, {data, [?START_ACK]}} ->
ok;
{'EXIT', Port, badsig} -> % Since this is not synchronous, skip it!
wait_ack(Port);
{'EXIT', Port, Reason} -> % The port really terminated.
{error, Reason}
end.
loop(Parent, #state{port=Port}=S) ->
_ = send_heart_beat(S),
receive
{From, set_cmd, NewCmd0} ->
Enc = file:native_name_encoding(),
case catch unicode:characters_to_binary(NewCmd0,Enc,Enc) of
NewCmd when is_binary(NewCmd), byte_size(NewCmd) < 2047 ->
_ = send_heart_cmd(Port, NewCmd),
_ = wait_ack(Port),
From ! {?MODULE, ok},
loop(Parent, S#state{cmd=NewCmd});
_ ->
From ! {?MODULE, {error, {bad_cmd, NewCmd0}}},
loop(Parent, S)
end;
{From, clear_cmd} ->
From ! {?MODULE, ok},
_ = send_heart_cmd(Port, []),
_ = wait_ack(Port),
loop(Parent, S#state{cmd = []});
{From, get_cmd} ->
From ! {?MODULE, get_heart_cmd(Port)},
loop(Parent, S);
{From, set_callback, Callback} ->
case Callback of
{M,F} when is_atom(M), is_atom(F) ->
From ! {?MODULE, ok},
loop(Parent, S#state{callback=Callback});
_ ->
From ! {?MODULE, {error, {bad_callback, Callback}}},
loop(Parent, S)
end;
{From, get_callback} ->
Res = case S#state.callback of
undefined -> none;
Cb -> {ok, Cb}
end,
From ! {?MODULE, Res},
loop(Parent, S);
{From, clear_callback} ->
From ! {?MODULE, ok},
loop(Parent, S#state{callback=undefined});
{From, set_options, Options} ->
case validate_options(Options) of
Validated when is_list(Validated) ->
From ! {?MODULE, ok},
loop(Parent, S#state{options=Validated});
_ ->
From ! {?MODULE, {error, {bad_options, Options}}},
loop(Parent, S)
end;
{From, get_options} ->
Res = case S#state.options of
[] -> none;
Cb -> {ok, Cb}
end,
From ! {?MODULE, Res},
loop(Parent, S);
{From, cycle} ->
%% Calls back to loop
do_cycle_port_program(From, Parent, S);
{'EXIT', Parent, shutdown} ->
no_reboot_shutdown(Port);
{'EXIT', Parent, Reason} ->
exit(Port, Reason),
exit(Reason);
{'EXIT', Port, badsig} -> % we can ignore badsig-messages!
loop(Parent, S);
{'EXIT', Port, _Reason} ->
exit({port_terminated, {?MODULE, loop, [Parent, S]}});
_ ->
loop(Parent, S)
after
?TIMEOUT ->
loop(Parent, S)
end.
-spec no_reboot_shutdown(port()) -> no_return().
no_reboot_shutdown(Port) ->
_ = send_shutdown(Port),
receive
{'EXIT', Port, Reason} when Reason =/= badsig ->
exit(normal)
end.
validate_options(Opts) -> validate_options(Opts,[]).
validate_options([],Res) -> Res;
validate_options([?SCHEDULER_CHECK_OPT=Opt|Opts],Res) -> validate_options(Opts,[Opt|Res]);
validate_options(_,_) -> error.
do_cycle_port_program(Caller, Parent, #state{port=Port} = S) ->
unregister(?HEART_PORT_NAME),
case catch start_portprogram() of
{ok, NewPort} ->
_ = send_shutdown(Port),
receive
{'EXIT', Port, _Reason} ->
_ = send_heart_cmd(NewPort, S#state.cmd),
Caller ! {?MODULE, ok},
loop(Parent, S#state{port=NewPort})
after
?CYCLE_TIMEOUT ->
%% Huh! Two heart port programs running...
%% well, the old one has to be sick not to respond
%% so we'll settle for the new one...
_ = send_heart_cmd(NewPort, S#state.cmd),
Caller ! {?MODULE, {error, stop_error}},
loop(Parent, S#state{port=NewPort})
end;
no_heart ->
Caller ! {?MODULE, {error, no_heart}},
loop(Parent, S);
error ->
Caller ! {?MODULE, {error, start_error}},
loop(Parent, S)
end.
%% "Beates" the heart once.
send_heart_beat(#state{port=Port, callback=Cb, options=Opts}) ->
ok = check_system(Opts),
ok = check_callback(Cb),
Port ! {self(), {command, [?HEART_BEAT]}}.
%% Set a new HEART_COMMAND.
-dialyzer({no_improper_lists, send_heart_cmd/2}).
send_heart_cmd(Port, []) ->
Port ! {self(), {command, [?CLEAR_CMD]}};
send_heart_cmd(Port, Cmd) ->
Port ! {self(), {command, [?SET_CMD|Cmd]}}.
get_heart_cmd(Port) ->
Port ! {self(), {command, [?GET_CMD]}},
receive
{Port, {data, [?HEART_CMD | Cmd]}} ->
{ok, Cmd}
end.
check_system([]) -> ok;
check_system([?SCHEDULER_CHECK_OPT|Opts]) ->
ok = erts_internal:system_check(schedulers),
check_system(Opts).
%% validate system by performing a check before the heartbeat
%% return 'ok' if everything is alright.
%% Terminate if with reason if something is a miss.
%% It is fine to timeout in the callback, in fact that is the intention
%% if something goes wront -> no heartbeat.
check_callback(Callback) ->
case Callback of
undefined -> ok;
{M,F} ->
erlang:apply(M,F,[])
end.
%% Sends shutdown command to the port.
send_shutdown(Port) -> Port ! {self(), {command, [?SHUT_DOWN]}}.
%% We must report using erlang:display/1 since we don't know whether
%% there is an error_logger available or not.
report_problem(Error) ->
erlang:display(Error).
