%% %% %CopyrightBegin% %% %% Copyright Ericsson AB 1996-2014. 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). -behaviour(gen_server). %% External exports -export([start_link/2, start_link/3, start_child/2, restart_child/2, delete_child/2, terminate_child/2, which_children/1, count_children/1, check_childspecs/1]). %% Internal exports -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]). -export([try_again_restart/2]). %%-------------------------------------------------------------------------- -export_type([sup_flags/0, child_spec/0, startchild_ret/0, strategy/0]). %%-------------------------------------------------------------------------- -type child() :: 'undefined' | pid(). -type child_id() :: term(). -type mfargs() :: {M :: module(), F :: atom(), A :: [term()] | undefined}. -type modules() :: [module()] | 'dynamic'. -type restart() :: 'permanent' | 'transient' | 'temporary'. -type shutdown() :: 'brutal_kill' | timeout(). -type worker() :: 'worker' | 'supervisor'. -type sup_name() :: {'local', Name :: atom()} | {'global', Name :: atom()} | {'via', Module :: module(), Name :: any()}. -type sup_ref() :: (Name :: atom()) | {Name :: atom(), Node :: node()} | {'global', Name :: atom()} | {'via', Module :: module(), Name :: any()} | pid(). -type child_spec() :: #{id => child_id(), % mandatory start => mfargs(), % mandatory restart => restart(), % optional shutdown => shutdown(), % optional type => worker(), % optional modules => modules()} % optional | {Id :: child_id(), StartFunc :: mfargs(), Restart :: restart(), Shutdown :: shutdown(), Type :: worker(), Modules :: modules()}. -type strategy() :: 'one_for_all' | 'one_for_one' | 'rest_for_one' | 'simple_one_for_one'. -type sup_flags() :: #{strategy => strategy(), % optional intensity => non_neg_integer(), % optional period => pos_integer()} % optional | {RestartStrategy :: strategy(), Intensity :: non_neg_integer(), Period :: pos_integer()}. %%-------------------------------------------------------------------------- %% Defaults -define(default_flags, #{strategy => one_for_one, intensity => 1, period => 5}). -define(default_child_spec, #{restart => permanent, type => worker}). %% Default 'shutdown' is 5000 for workers and infinity for supervisors. %% Default 'modules' is [M], where M comes from the child's start {M,F,A}. %%-------------------------------------------------------------------------- -record(child, {% pid is undefined when child is not running pid = undefined :: child() | {restarting, pid() | undefined} | [pid()], name :: child_id(), mfargs :: mfargs(), restart_type :: restart(), shutdown :: shutdown(), child_type :: worker(), modules = [] :: modules()}). -type child_rec() :: #child{}. -define(DICTS, dict). -define(DICT, dict:dict). -define(SETS, sets). -define(SET, sets:set). -record(state, {name, strategy :: strategy(), children = [] :: [child_rec()], dynamics :: ?DICT(pid(), list()) | ?SET(pid()), intensity :: non_neg_integer(), period :: pos_integer(), restarts = [], module, args}). -type state() :: #state{}. -define(is_simple(State), State#state.strategy =:= simple_one_for_one). -callback init(Args :: term()) -> {ok, {SupFlags :: sup_flags(), [ChildSpec :: child_spec()]}} | ignore. -define(restarting(_Pid_), {restarting,_Pid_}). %%% --------------------------------------------------- %%% This is a general process supervisor built upon gen_server.erl. %%% Servers/processes should/could also be built using gen_server.erl. %%% SupName = {local, atom()} | {global, atom()}. %%% --------------------------------------------------- -type startlink_err() :: {'already_started', pid()} | {'shutdown', term()} | term(). -type startlink_ret() :: {'ok', pid()} | 'ignore' | {'error', startlink_err()}. -spec start_link(Module, Args) -> startlink_ret() when Module :: module(), Args :: term(). start_link(Mod, Args) -> gen_server:start_link(supervisor, {self, Mod, Args}, []). -spec start_link(SupName, Module, Args) -> startlink_ret() when SupName :: sup_name(), Module :: module(), Args :: term(). start_link(SupName, Mod, Args) -> gen_server:start_link(SupName, supervisor, {SupName, Mod, Args}, []). %%% --------------------------------------------------- %%% Interface functions. %%% --------------------------------------------------- -type startchild_err() :: 'already_present' | {'already_started', Child :: child()} | term(). -type startchild_ret() :: {'ok', Child :: child()} | {'ok', Child :: child(), Info :: term()} | {'error', startchild_err()}. -spec start_child(SupRef, ChildSpec) -> startchild_ret() when SupRef :: sup_ref(), ChildSpec :: child_spec() | (List :: [term()]). start_child(Supervisor, ChildSpec) -> call(Supervisor, {start_child, ChildSpec}). -spec restart_child(SupRef, Id) -> Result when SupRef :: sup_ref(), Id :: child_id(), Result :: {'ok', Child :: child()} | {'ok', Child :: child(), Info :: term()} | {'error', Error}, Error :: 'running' | 'restarting' | 'not_found' | 'simple_one_for_one' | term(). restart_child(Supervisor, Name) -> call(Supervisor, {restart_child, Name}). -spec delete_child(SupRef, Id) -> Result when SupRef :: sup_ref(), Id :: child_id(), Result :: 'ok' | {'error', Error}, Error :: 'running' | 'restarting' | 'not_found' | 'simple_one_for_one'. delete_child(Supervisor, Name) -> call(Supervisor, {delete_child, Name}). %%----------------------------------------------------------------- %% Func: terminate_child/2 %% Returns: ok | {error, Reason} %% Note that the child is *always* terminated in some %% way (maybe killed). %%----------------------------------------------------------------- -spec terminate_child(SupRef, Id) -> Result when SupRef :: sup_ref(), Id :: pid() | child_id(), Result :: 'ok' | {'error', Error}, Error :: 'not_found' | 'simple_one_for_one'. terminate_child(Supervisor, Name) -> call(Supervisor, {terminate_child, Name}). -spec which_children(SupRef) -> [{Id,Child,Type,Modules}] when SupRef :: sup_ref(), Id :: child_id() | undefined, Child :: child() | 'restarting', Type :: worker(), Modules :: modules(). which_children(Supervisor) -> call(Supervisor, which_children). -spec count_children(SupRef) -> PropListOfCounts when SupRef :: sup_ref(), PropListOfCounts :: [Count], Count :: {specs, ChildSpecCount :: non_neg_integer()} | {active, ActiveProcessCount :: non_neg_integer()} | {supervisors, ChildSupervisorCount :: non_neg_integer()} |{workers, ChildWorkerCount :: non_neg_integer()}. count_children(Supervisor) -> call(Supervisor, count_children). call(Supervisor, Req) -> gen_server:call(Supervisor, Req, infinity). -spec check_childspecs(ChildSpecs) -> Result when ChildSpecs :: [child_spec()], Result :: 'ok' | {'error', Error :: term()}. check_childspecs(ChildSpecs) when is_list(ChildSpecs) -> case check_startspec(ChildSpecs) of {ok, _} -> ok; Error -> {error, Error} end; check_childspecs(X) -> {error, {badarg, X}}. %%%----------------------------------------------------------------- %%% Called by timer:apply_after from restart/2 -spec try_again_restart(SupRef, Child) -> ok when SupRef :: sup_ref(), Child :: child_id() | pid(). try_again_restart(Supervisor, Child) -> cast(Supervisor, {try_again_restart, Child}). cast(Supervisor, Req) -> gen_server:cast(Supervisor, Req). %%% --------------------------------------------------- %%% %%% Initialize the supervisor. %%% %%% --------------------------------------------------- -type init_sup_name() :: sup_name() | 'self'. -type stop_rsn() :: {'shutdown', term()} | {'bad_return', {module(),'init', term()}} | {'bad_start_spec', term()} | {'start_spec', term()} | {'supervisor_data', term()}. -spec init({init_sup_name(), module(), [term()]}) -> {'ok', state()} | 'ignore' | {'stop', stop_rsn()}. init({SupName, Mod, Args}) -> process_flag(trap_exit, true), case Mod:init(Args) of {ok, {SupFlags, StartSpec}} -> case init_state(SupName, SupFlags, Mod, Args) of {ok, State} when ?is_simple(State) -> init_dynamic(State, StartSpec); {ok, State} -> init_children(State, StartSpec); Error -> {stop, {supervisor_data, Error}} end; ignore -> ignore; Error -> {stop, {bad_return, {Mod, init, Error}}} end. init_children(State, StartSpec) -> SupName = State#state.name, case check_startspec(StartSpec) of {ok, Children} -> case start_children(Children, SupName) of {ok, NChildren} -> {ok, State#state{children = NChildren}}; {error, NChildren, Reason} -> _ = terminate_children(NChildren, SupName), {stop, {shutdown, Reason}} end; Error -> {stop, {start_spec, Error}} end. init_dynamic(State, [StartSpec]) -> case check_startspec([StartSpec]) of {ok, Children} -> {ok, State#state{children = Children}}; Error -> {stop, {start_spec, Error}} end; init_dynamic(_State, StartSpec) -> {stop, {bad_start_spec, StartSpec}}. %%----------------------------------------------------------------- %% Func: start_children/2 %% Args: Children = [child_rec()] in start order %% SupName = {local, atom()} | {global, atom()} | {pid(), Mod} %% Purpose: Start all children. The new list contains #child's %% with pids. %% Returns: {ok, NChildren} | {error, NChildren, Reason} %% NChildren = [child_rec()] in termination order (reversed %% start order) %%----------------------------------------------------------------- start_children(Children, SupName) -> start_children(Children, [], SupName). start_children([Child|Chs], NChildren, SupName) -> case do_start_child(SupName, Child) of {ok, undefined} when Child#child.restart_type =:= temporary -> start_children(Chs, NChildren, SupName); {ok, Pid} -> start_children(Chs, [Child#child{pid = Pid}|NChildren], SupName); {ok, Pid, _Extra} -> start_children(Chs, [Child#child{pid = Pid}|NChildren], SupName); {error, Reason} -> report_error(start_error, Reason, Child, SupName), {error, lists:reverse(Chs) ++ [Child | NChildren], {failed_to_start_child,Child#child.name,Reason}} end; start_children([], NChildren, _SupName) -> {ok, NChildren}. do_start_child(SupName, Child) -> #child{mfargs = {M, F, Args}} = Child, case catch apply(M, F, Args) of {ok, Pid} when is_pid(Pid) -> NChild = Child#child{pid = Pid}, report_progress(NChild, SupName), {ok, Pid}; {ok, Pid, Extra} when is_pid(Pid) -> NChild = Child#child{pid = Pid}, report_progress(NChild, SupName), {ok, Pid, Extra}; ignore -> {ok, undefined}; {error, What} -> {error, What}; What -> {error, What} end. do_start_child_i(M, F, A) -> case catch apply(M, F, A) of {ok, Pid} when is_pid(Pid) -> {ok, Pid}; {ok, Pid, Extra} when is_pid(Pid) -> {ok, Pid, Extra}; ignore -> {ok, undefined}; {error, Error} -> {error, Error}; What -> {error, What} end. %%% --------------------------------------------------- %%% %%% Callback functions. %%% %%% --------------------------------------------------- -type call() :: 'which_children' | 'count_children' | {_, _}. % XXX: refine -spec handle_call(call(), term(), state()) -> {'reply', term(), state()}. handle_call({start_child, EArgs}, _From, State) when ?is_simple(State) -> Child = hd(State#state.children), #child{mfargs = {M, F, A}} = Child, Args = A ++ EArgs, case do_start_child_i(M, F, Args) of {ok, undefined} when Child#child.restart_type =:= temporary -> {reply, {ok, undefined}, State}; {ok, Pid} -> NState = save_dynamic_child(Child#child.restart_type, Pid, Args, State), {reply, {ok, Pid}, NState}; {ok, Pid, Extra} -> NState = save_dynamic_child(Child#child.restart_type, Pid, Args, State), {reply, {ok, Pid, Extra}, NState}; What -> {reply, What, State} end; %% terminate_child for simple_one_for_one can only be done with pid handle_call({terminate_child, Name}, _From, State) when not is_pid(Name), ?is_simple(State) -> {reply, {error, simple_one_for_one}, State}; handle_call({terminate_child, Name}, _From, State) -> case get_child(Name, State, ?is_simple(State)) of {value, Child} -> case do_terminate(Child, State#state.name) of #child{restart_type=RT} when RT=:=temporary; ?is_simple(State) -> {reply, ok, state_del_child(Child, State)}; NChild -> {reply, ok, replace_child(NChild, State)} end; false -> {reply, {error, not_found}, State} end; %%% The requests delete_child and restart_child are invalid for %%% simple_one_for_one supervisors. handle_call({_Req, _Data}, _From, State) when ?is_simple(State) -> {reply, {error, simple_one_for_one}, State}; handle_call({start_child, ChildSpec}, _From, State) -> case check_childspec(ChildSpec) of {ok, Child} -> {Resp, NState} = handle_start_child(Child, State), {reply, Resp, NState}; What -> {reply, {error, What}, State} end; handle_call({restart_child, Name}, _From, State) -> case get_child(Name, State) of {value, Child} when Child#child.pid =:= undefined -> case do_start_child(State#state.name, Child) of {ok, Pid} -> NState = replace_child(Child#child{pid = Pid}, State), {reply, {ok, Pid}, NState}; {ok, Pid, Extra} -> NState = replace_child(Child#child{pid = Pid}, State), {reply, {ok, Pid, Extra}, NState}; Error -> {reply, Error, State} end; {value, #child{pid=?restarting(_)}} -> {reply, {error, restarting}, State}; {value, _} -> {reply, {error, running}, State}; _ -> {reply, {error, not_found}, State} end; handle_call({delete_child, Name}, _From, State) -> case get_child(Name, State) of {value, Child} when Child#child.pid =:= undefined -> NState = remove_child(Child, State), {reply, ok, NState}; {value, #child{pid=?restarting(_)}} -> {reply, {error, restarting}, State}; {value, _} -> {reply, {error, running}, State}; _ -> {reply, {error, not_found}, State} end; handle_call(which_children, _From, #state{children = [#child{restart_type = temporary, child_type = CT, modules = Mods}]} = State) when ?is_simple(State) -> Reply = lists:map(fun(Pid) -> {undefined, Pid, CT, Mods} end, ?SETS:to_list(dynamics_db(temporary, State#state.dynamics))), {reply, Reply, State}; handle_call(which_children, _From, #state{children = [#child{restart_type = RType, child_type = CT, modules = Mods}]} = State) when ?is_simple(State) -> Reply = lists:map(fun({?restarting(_),_}) -> {undefined,restarting,CT,Mods}; ({Pid, _}) -> {undefined, Pid, CT, Mods} end, ?DICTS:to_list(dynamics_db(RType, State#state.dynamics))), {reply, Reply, State}; handle_call(which_children, _From, State) -> Resp = lists:map(fun(#child{pid = ?restarting(_), name = Name, child_type = ChildType, modules = Mods}) -> {Name, restarting, ChildType, Mods}; (#child{pid = Pid, name = Name, child_type = ChildType, modules = Mods}) -> {Name, Pid, ChildType, Mods} end, State#state.children), {reply, Resp, State}; handle_call(count_children, _From, #state{children = [#child{restart_type = temporary, child_type = CT}]} = State) when ?is_simple(State) -> {Active, Count} = ?SETS:fold(fun(Pid, {Alive, Tot}) -> case is_pid(Pid) andalso is_process_alive(Pid) of true ->{Alive+1, Tot +1}; false -> {Alive, Tot + 1} end end, {0, 0}, dynamics_db(temporary, State#state.dynamics)), Reply = case CT of supervisor -> [{specs, 1}, {active, Active}, {supervisors, Count}, {workers, 0}]; worker -> [{specs, 1}, {active, Active}, {supervisors, 0}, {workers, Count}] end, {reply, Reply, State}; handle_call(count_children, _From, #state{children = [#child{restart_type = RType, child_type = CT}]} = State) when ?is_simple(State) -> {Active, Count} = ?DICTS:fold(fun(Pid, _Val, {Alive, Tot}) -> case is_pid(Pid) andalso is_process_alive(Pid) of true -> {Alive+1, Tot +1}; false -> {Alive, Tot + 1} end end, {0, 0}, dynamics_db(RType, State#state.dynamics)), Reply = case CT of supervisor -> [{specs, 1}, {active, Active}, {supervisors, Count}, {workers, 0}]; worker -> [{specs, 1}, {active, Active}, {supervisors, 0}, {workers, Count}] end, {reply, Reply, State}; handle_call(count_children, _From, State) -> %% Specs and children are together on the children list... {Specs, Active, Supers, Workers} = lists:foldl(fun(Child, Counts) -> count_child(Child, Counts) end, {0,0,0,0}, State#state.children), %% Reformat counts to a property list. Reply = [{specs, Specs}, {active, Active}, {supervisors, Supers}, {workers, Workers}], {reply, Reply, State}. count_child(#child{pid = Pid, child_type = worker}, {Specs, Active, Supers, Workers}) -> case is_pid(Pid) andalso is_process_alive(Pid) of true -> {Specs+1, Active+1, Supers, Workers+1}; false -> {Specs+1, Active, Supers, Workers+1} end; count_child(#child{pid = Pid, child_type = supervisor}, {Specs, Active, Supers, Workers}) -> case is_pid(Pid) andalso is_process_alive(Pid) of true -> {Specs+1, Active+1, Supers+1, Workers}; false -> {Specs+1, Active, Supers+1, Workers} end. %%% If a restart attempt failed, this message is sent via %%% timer:apply_after(0,...) in order to give gen_server the chance to %%% check it's inbox before trying again. -spec handle_cast({try_again_restart, child_id() | pid()}, state()) -> {'noreply', state()} | {stop, shutdown, state()}. handle_cast({try_again_restart,Pid}, #state{children=[Child]}=State) when ?is_simple(State) -> RT = Child#child.restart_type, RPid = restarting(Pid), case dynamic_child_args(RPid, dynamics_db(RT, State#state.dynamics)) of {ok, Args} -> {M, F, _} = Child#child.mfargs, NChild = Child#child{pid = RPid, mfargs = {M, F, Args}}, case restart(NChild,State) of {ok, State1} -> {noreply, State1}; {shutdown, State1} -> {stop, shutdown, State1} end; error -> {noreply, State} end; handle_cast({try_again_restart,Name}, State) -> case lists:keyfind(Name,#child.name,State#state.children) of Child = #child{pid=?restarting(_)} -> case restart(Child,State) of {ok, State1} -> {noreply, State1}; {shutdown, State1} -> {stop, shutdown, State1} end; _ -> {noreply,State} end. %% %% Take care of terminated children. %% -spec handle_info(term(), state()) -> {'noreply', state()} | {'stop', 'shutdown', state()}. handle_info({'EXIT', Pid, Reason}, State) -> case restart_child(Pid, Reason, State) of {ok, State1} -> {noreply, State1}; {shutdown, State1} -> {stop, shutdown, State1} end; handle_info(Msg, State) -> error_logger:error_msg("Supervisor received unexpected message: ~p~n", [Msg]), {noreply, State}. %% %% Terminate this server. %% -spec terminate(term(), state()) -> 'ok'. terminate(_Reason, #state{children=[Child]} = State) when ?is_simple(State) -> terminate_dynamic_children(Child, dynamics_db(Child#child.restart_type, State#state.dynamics), State#state.name); terminate(_Reason, State) -> terminate_children(State#state.children, State#state.name). %% %% Change code for the supervisor. %% Call the new call-back module and fetch the new start specification. %% Combine the new spec. with the old. If the new start spec. is %% not valid the code change will not succeed. %% Use the old Args as argument to Module:init/1. %% NOTE: This requires that the init function of the call-back module %% does not have any side effects. %% -spec code_change(term(), state(), term()) -> {'ok', state()} | {'error', term()}. code_change(_, State, _) -> case (State#state.module):init(State#state.args) of {ok, {SupFlags, StartSpec}} -> case set_flags(SupFlags, State) of {ok, State1} -> update_childspec(State1, StartSpec); {invalid_type, SupFlags} -> {error, {bad_flags, SupFlags}}; % backwards compatibility Error -> {error, Error} end; ignore -> {ok, State}; Error -> Error end. update_childspec(State, StartSpec) when ?is_simple(State) -> case check_startspec(StartSpec) of {ok, [Child]} -> {ok, State#state{children = [Child]}}; Error -> {error, Error} end; update_childspec(State, StartSpec) -> case check_startspec(StartSpec) of {ok, Children} -> OldC = State#state.children, % In reverse start order ! NewC = update_childspec1(OldC, Children, []), {ok, State#state{children = NewC}}; Error -> {error, Error} end. update_childspec1([Child|OldC], Children, KeepOld) -> case update_chsp(Child, Children) of {ok,NewChildren} -> update_childspec1(OldC, NewChildren, KeepOld); false -> update_childspec1(OldC, Children, [Child|KeepOld]) end; update_childspec1([], Children, KeepOld) -> %% Return them in (kept) reverse start order. lists:reverse(Children ++ KeepOld). update_chsp(OldCh, Children) -> case lists:map(fun(Ch) when OldCh#child.name =:= Ch#child.name -> Ch#child{pid = OldCh#child.pid}; (Ch) -> Ch end, Children) of Children -> false; % OldCh not found in new spec. NewC -> {ok, NewC} end. %%% --------------------------------------------------- %%% Start a new child. %%% --------------------------------------------------- handle_start_child(Child, State) -> case get_child(Child#child.name, State) of false -> case do_start_child(State#state.name, Child) of {ok, undefined} when Child#child.restart_type =:= temporary -> {{ok, undefined}, State}; {ok, Pid} -> {{ok, Pid}, save_child(Child#child{pid = Pid}, State)}; {ok, Pid, Extra} -> {{ok, Pid, Extra}, save_child(Child#child{pid = Pid}, State)}; {error, What} -> {{error, {What, Child}}, State} end; {value, OldChild} when is_pid(OldChild#child.pid) -> {{error, {already_started, OldChild#child.pid}}, State}; {value, _OldChild} -> {{error, already_present}, State} end. %%% --------------------------------------------------- %%% Restart. A process has terminated. %%% Returns: {ok, state()} | {shutdown, state()} %%% --------------------------------------------------- restart_child(Pid, Reason, #state{children = [Child]} = State) when ?is_simple(State) -> RestartType = Child#child.restart_type, case dynamic_child_args(Pid, dynamics_db(RestartType, State#state.dynamics)) of {ok, Args} -> {M, F, _} = Child#child.mfargs, NChild = Child#child{pid = Pid, mfargs = {M, F, Args}}, do_restart(RestartType, Reason, NChild, State); error -> {ok, State} end; restart_child(Pid, Reason, State) -> Children = State#state.children, case lists:keyfind(Pid, #child.pid, Children) of #child{restart_type = RestartType} = Child -> do_restart(RestartType, Reason, Child, State); false -> {ok, State} end. do_restart(permanent, Reason, Child, State) -> report_error(child_terminated, Reason, Child, State#state.name), restart(Child, State); do_restart(_, normal, Child, State) -> NState = state_del_child(Child, State), {ok, NState}; do_restart(_, shutdown, Child, State) -> NState = state_del_child(Child, State), {ok, NState}; do_restart(_, {shutdown, _Term}, Child, State) -> NState = state_del_child(Child, State), {ok, NState}; do_restart(transient, Reason, Child, State) -> report_error(child_terminated, Reason, Child, State#state.name), restart(Child, State); do_restart(temporary, Reason, Child, State) -> report_error(child_terminated, Reason, Child, State#state.name), NState = state_del_child(Child, State), {ok, NState}. restart(Child, State) -> case add_restart(State) of {ok, NState} -> case restart(NState#state.strategy, Child, NState) of {try_again,NState2} -> %% Leaving control back to gen_server before %% trying again. This way other incoming requsts %% for the supervisor can be handled - e.g. a %% shutdown request for the supervisor or the %% child. Id = if ?is_simple(State) -> Child#child.pid; true -> Child#child.name end, {ok, _TRef} = timer:apply_after(0, ?MODULE, try_again_restart, [self(),Id]), {ok,NState2}; {try_again, NState2, #child{name=ChName}} -> {ok, _TRef} = timer:apply_after(0, ?MODULE, try_again_restart, [self(),ChName]), {ok,NState2}; Other -> Other end; {terminate, NState} -> report_error(shutdown, reached_max_restart_intensity, Child, State#state.name), {shutdown, remove_child(Child, NState)} end. restart(simple_one_for_one, Child, State) -> #child{pid = OldPid, mfargs = {M, F, A}} = Child, Dynamics = ?DICTS:erase(OldPid, dynamics_db(Child#child.restart_type, State#state.dynamics)), case do_start_child_i(M, F, A) of {ok, Pid} -> NState = State#state{dynamics = ?DICTS:store(Pid, A, Dynamics)}, {ok, NState}; {ok, Pid, _Extra} -> NState = State#state{dynamics = ?DICTS:store(Pid, A, Dynamics)}, {ok, NState}; {error, Error} -> NState = State#state{dynamics = ?DICTS:store(restarting(OldPid), A, Dynamics)}, report_error(start_error, Error, Child, State#state.name), {try_again, NState} end; restart(one_for_one, Child, State) -> OldPid = Child#child.pid, case do_start_child(State#state.name, Child) of {ok, Pid} -> NState = replace_child(Child#child{pid = Pid}, State), {ok, NState}; {ok, Pid, _Extra} -> NState = replace_child(Child#child{pid = Pid}, State), {ok, NState}; {error, Reason} -> NState = replace_child(Child#child{pid = restarting(OldPid)}, State), report_error(start_error, Reason, Child, State#state.name), {try_again, NState} end; restart(rest_for_one, Child, State) -> {ChAfter, ChBefore} = split_child(Child#child.pid, State#state.children), ChAfter2 = terminate_children(ChAfter, State#state.name), case start_children(ChAfter2, State#state.name) of {ok, ChAfter3} -> {ok, State#state{children = ChAfter3 ++ ChBefore}}; {error, ChAfter3, {failed_to_start_child, ChName, _Reason}} when ChName =:= Child#child.name -> NChild = Child#child{pid=restarting(Child#child.pid)}, NState = State#state{children = ChAfter3 ++ ChBefore}, {try_again, replace_child(NChild,NState)}; {error, ChAfter3, {failed_to_start_child, ChName, _Reason}} -> NChild = lists:keyfind(ChName, #child.name, ChAfter3), NChild2 = NChild#child{pid=?restarting(undefined)}, NState = State#state{children = ChAfter3 ++ ChBefore}, {try_again, replace_child(NChild2,NState), NChild2} end; restart(one_for_all, Child, State) -> Children1 = del_child(Child#child.pid, State#state.children), Children2 = terminate_children(Children1, State#state.name), case start_children(Children2, State#state.name) of {ok, NChs} -> {ok, State#state{children = NChs}}; {error, NChs, {failed_to_start_child, ChName, _Reason}} when ChName =:= Child#child.name -> NChild = Child#child{pid=restarting(Child#child.pid)}, NState = State#state{children = NChs}, {try_again, replace_child(NChild,NState)}; {error, NChs, {failed_to_start_child, ChName, _Reason}} -> NChild = lists:keyfind(ChName, #child.name, NChs), NChild2 = NChild#child{pid=?restarting(undefined)}, NState = State#state{children = NChs}, {try_again, replace_child(NChild2,NState), NChild2} end. restarting(Pid) when is_pid(Pid) -> ?restarting(Pid); restarting(RPid) -> RPid. %%----------------------------------------------------------------- %% Func: terminate_children/2 %% Args: Children = [child_rec()] in termination order %% SupName = {local, atom()} | {global, atom()} | {pid(),Mod} %% Returns: NChildren = [child_rec()] in %% startup order (reversed termination order) %%----------------------------------------------------------------- terminate_children(Children, SupName) -> terminate_children(Children, SupName, []). %% Temporary children should not be restarted and thus should %% be skipped when building the list of terminated children, although %% we do want them to be shut down as many functions from this module %% use this function to just clear everything. terminate_children([Child = #child{restart_type=temporary} | Children], SupName, Res) -> _ = do_terminate(Child, SupName), terminate_children(Children, SupName, Res); terminate_children([Child | Children], SupName, Res) -> NChild = do_terminate(Child, SupName), terminate_children(Children, SupName, [NChild | Res]); terminate_children([], _SupName, Res) -> Res. do_terminate(Child, SupName) when is_pid(Child#child.pid) -> case shutdown(Child#child.pid, Child#child.shutdown) of ok -> ok; {error, normal} when Child#child.restart_type =/= permanent -> ok; {error, OtherReason} -> report_error(shutdown_error, OtherReason, Child, SupName) end, Child#child{pid = undefined}; do_terminate(Child, _SupName) -> Child#child{pid = undefined}. %%----------------------------------------------------------------- %% Shutdowns a child. We must check the EXIT value %% of the child, because it might have died with another reason than %% the wanted. In that case we want to report the error. We put a %% monitor on the child an check for the 'DOWN' message instead of %% checking for the 'EXIT' message, because if we check the 'EXIT' %% message a "naughty" child, who does unlink(Sup), could hang the %% supervisor. %% Returns: ok | {error, OtherReason} (this should be reported) %%----------------------------------------------------------------- shutdown(Pid, brutal_kill) -> case monitor_child(Pid) of ok -> exit(Pid, kill), receive {'DOWN', _MRef, process, Pid, killed} -> ok; {'DOWN', _MRef, process, Pid, OtherReason} -> {error, OtherReason} end; {error, Reason} -> {error, Reason} end; shutdown(Pid, Time) -> case monitor_child(Pid) of ok -> exit(Pid, shutdown), %% Try to shutdown gracefully receive {'DOWN', _MRef, process, Pid, shutdown} -> ok; {'DOWN', _MRef, process, Pid, OtherReason} -> {error, OtherReason} after Time -> exit(Pid, kill), %% Force termination. receive {'DOWN', _MRef, process, Pid, OtherReason} -> {error, OtherReason} end end; {error, Reason} -> {error, Reason} end. %% Help function to shutdown/2 switches from link to monitor approach monitor_child(Pid) -> %% Do the monitor operation first so that if the child dies %% before the monitoring is done causing a 'DOWN'-message with %% reason noproc, we will get the real reason in the 'EXIT'-message %% unless a naughty child has already done unlink... erlang:monitor(process, Pid), unlink(Pid), receive %% If the child dies before the unlik we must empty %% the mail-box of the 'EXIT'-message and the 'DOWN'-message. {'EXIT', Pid, Reason} -> receive {'DOWN', _, process, Pid, _} -> {error, Reason} end after 0 -> %% If a naughty child did unlink and the child dies before %% monitor the result will be that shutdown/2 receives a %% 'DOWN'-message with reason noproc. %% If the child should die after the unlink there %% will be a 'DOWN'-message with a correct reason %% that will be handled in shutdown/2. ok end. %%----------------------------------------------------------------- %% Func: terminate_dynamic_children/3 %% Args: Child = child_rec() %% Dynamics = ?DICT() | ?SET() %% SupName = {local, atom()} | {global, atom()} | {pid(),Mod} %% Returns: ok %% %% %% Shutdown all dynamic children. This happens when the supervisor is %% stopped. Because the supervisor can have millions of dynamic children, we %% can have an significative overhead here. %%----------------------------------------------------------------- terminate_dynamic_children(Child, Dynamics, SupName) -> {Pids, EStack0} = monitor_dynamic_children(Child, Dynamics), Sz = ?SETS:size(Pids), EStack = case Child#child.shutdown of brutal_kill -> ?SETS:fold(fun(P, _) -> exit(P, kill) end, ok, Pids), wait_dynamic_children(Child, Pids, Sz, undefined, EStack0); infinity -> ?SETS:fold(fun(P, _) -> exit(P, shutdown) end, ok, Pids), wait_dynamic_children(Child, Pids, Sz, undefined, EStack0); Time -> ?SETS:fold(fun(P, _) -> exit(P, shutdown) end, ok, Pids), TRef = erlang:start_timer(Time, self(), kill), wait_dynamic_children(Child, Pids, Sz, TRef, EStack0) end, %% Unroll stacked errors and report them ?DICTS:fold(fun(Reason, Ls, _) -> report_error(shutdown_error, Reason, Child#child{pid=Ls}, SupName) end, ok, EStack). monitor_dynamic_children(#child{restart_type=temporary}, Dynamics) -> ?SETS:fold(fun(P, {Pids, EStack}) -> case monitor_child(P) of ok -> {?SETS:add_element(P, Pids), EStack}; {error, normal} -> {Pids, EStack}; {error, Reason} -> {Pids, ?DICTS:append(Reason, P, EStack)} end end, {?SETS:new(), ?DICTS:new()}, Dynamics); monitor_dynamic_children(#child{restart_type=RType}, Dynamics) -> ?DICTS:fold(fun(P, _, {Pids, EStack}) when is_pid(P) -> case monitor_child(P) of ok -> {?SETS:add_element(P, Pids), EStack}; {error, normal} when RType =/= permanent -> {Pids, EStack}; {error, Reason} -> {Pids, ?DICTS:append(Reason, P, EStack)} end; (?restarting(_), _, {Pids, EStack}) -> {Pids, EStack} end, {?SETS:new(), ?DICTS:new()}, Dynamics). wait_dynamic_children(_Child, _Pids, 0, undefined, EStack) -> EStack; wait_dynamic_children(_Child, _Pids, 0, TRef, EStack) -> %% If the timer has expired before its cancellation, we must empty the %% mail-box of the 'timeout'-message. _ = erlang:cancel_timer(TRef), receive {timeout, TRef, kill} -> EStack after 0 -> EStack end; wait_dynamic_children(#child{shutdown=brutal_kill} = Child, Pids, Sz, TRef, EStack) -> receive {'DOWN', _MRef, process, Pid, killed} -> wait_dynamic_children(Child, ?SETS:del_element(Pid, Pids), Sz-1, TRef, EStack); {'DOWN', _MRef, process, Pid, Reason} -> wait_dynamic_children(Child, ?SETS:del_element(Pid, Pids), Sz-1, TRef, ?DICTS:append(Reason, Pid, EStack)) end; wait_dynamic_children(#child{restart_type=RType} = Child, Pids, Sz, TRef, EStack) -> receive {'DOWN', _MRef, process, Pid, shutdown} -> wait_dynamic_children(Child, ?SETS:del_element(Pid, Pids), Sz-1, TRef, EStack); {'DOWN', _MRef, process, Pid, normal} when RType =/= permanent -> wait_dynamic_children(Child, ?SETS:del_element(Pid, Pids), Sz-1, TRef, EStack); {'DOWN', _MRef, process, Pid, Reason} -> wait_dynamic_children(Child, ?SETS:del_element(Pid, Pids), Sz-1, TRef, ?DICTS:append(Reason, Pid, EStack)); {timeout, TRef, kill} -> ?SETS:fold(fun(P, _) -> exit(P, kill) end, ok, Pids), wait_dynamic_children(Child, Pids, Sz-1, undefined, EStack) end. %%----------------------------------------------------------------- %% Child/State manipulating functions. %%----------------------------------------------------------------- %% Note we do not want to save the parameter list for temporary processes as %% they will not be restarted, and hence we do not need this information. %% Especially for dynamic children to simple_one_for_one supervisors %% it could become very costly as it is not uncommon to spawn %% very many such processes. save_child(#child{restart_type = temporary, mfargs = {M, F, _}} = Child, #state{children = Children} = State) -> State#state{children = [Child#child{mfargs = {M, F, undefined}} |Children]}; save_child(Child, #state{children = Children} = State) -> State#state{children = [Child |Children]}. save_dynamic_child(temporary, Pid, _, #state{dynamics = Dynamics} = State) -> State#state{dynamics = ?SETS:add_element(Pid, dynamics_db(temporary, Dynamics))}; save_dynamic_child(RestartType, Pid, Args, #state{dynamics = Dynamics} = State) -> State#state{dynamics = ?DICTS:store(Pid, Args, dynamics_db(RestartType, Dynamics))}. dynamics_db(temporary, undefined) -> ?SETS:new(); dynamics_db(_, undefined) -> ?DICTS:new(); dynamics_db(_,Dynamics) -> Dynamics. dynamic_child_args(Pid, Dynamics) -> case ?SETS:is_set(Dynamics) of true -> {ok, undefined}; false -> ?DICTS:find(Pid, Dynamics) end. state_del_child(#child{pid = Pid, restart_type = temporary}, State) when ?is_simple(State) -> NDynamics = ?SETS:del_element(Pid, dynamics_db(temporary, State#state.dynamics)), State#state{dynamics = NDynamics}; state_del_child(#child{pid = Pid, restart_type = RType}, State) when ?is_simple(State) -> NDynamics = ?DICTS:erase(Pid, dynamics_db(RType, State#state.dynamics)), State#state{dynamics = NDynamics}; state_del_child(Child, State) -> NChildren = del_child(Child#child.name, State#state.children), State#state{children = NChildren}. del_child(Name, [Ch|Chs]) when Ch#child.name =:= Name, Ch#child.restart_type =:= temporary -> Chs; del_child(Name, [Ch|Chs]) when Ch#child.name =:= Name -> [Ch#child{pid = undefined} | Chs]; del_child(Pid, [Ch|Chs]) when Ch#child.pid =:= Pid, Ch#child.restart_type =:= temporary -> Chs; del_child(Pid, [Ch|Chs]) when Ch#child.pid =:= Pid -> [Ch#child{pid = undefined} | Chs]; del_child(Name, [Ch|Chs]) -> [Ch|del_child(Name, Chs)]; del_child(_, []) -> []. %% Chs = [S4, S3, Ch, S1, S0] %% Ret: {[S4, S3, Ch], [S1, S0]} split_child(Name, Chs) -> split_child(Name, Chs, []). split_child(Name, [Ch|Chs], After) when Ch#child.name =:= Name -> {lists:reverse([Ch#child{pid = undefined} | After]), Chs}; split_child(Pid, [Ch|Chs], After) when Ch#child.pid =:= Pid -> {lists:reverse([Ch#child{pid = undefined} | After]), Chs}; split_child(Name, [Ch|Chs], After) -> split_child(Name, Chs, [Ch | After]); split_child(_, [], After) -> {lists:reverse(After), []}. get_child(Name, State) -> get_child(Name, State, false). get_child(Pid, State, AllowPid) when AllowPid, is_pid(Pid) -> get_dynamic_child(Pid, State); get_child(Name, State, _) -> lists:keysearch(Name, #child.name, State#state.children). get_dynamic_child(Pid, #state{children=[Child], dynamics=Dynamics}) -> DynamicsDb = dynamics_db(Child#child.restart_type, Dynamics), case is_dynamic_pid(Pid, DynamicsDb) of true -> {value, Child#child{pid=Pid}}; false -> RPid = restarting(Pid), case is_dynamic_pid(RPid, DynamicsDb) of true -> {value, Child#child{pid=RPid}}; false -> case erlang:is_process_alive(Pid) of true -> false; false -> {value, Child} end end end. is_dynamic_pid(Pid, Dynamics) -> case ?SETS:is_set(Dynamics) of true -> ?SETS:is_element(Pid, Dynamics); false -> ?DICTS:is_key(Pid, Dynamics) end. replace_child(Child, State) -> Chs = do_replace_child(Child, State#state.children), State#state{children = Chs}. do_replace_child(Child, [Ch|Chs]) when Ch#child.name =:= Child#child.name -> [Child | Chs]; do_replace_child(Child, [Ch|Chs]) -> [Ch|do_replace_child(Child, Chs)]. remove_child(Child, State) -> Chs = lists:keydelete(Child#child.name, #child.name, State#state.children), State#state{children = Chs}. %%----------------------------------------------------------------- %% Func: init_state/4 %% Args: SupName = {local, atom()} | {global, atom()} | self %% Type = {Strategy, MaxIntensity, Period} %% Strategy = one_for_one | one_for_all | simple_one_for_one | %% rest_for_one %% MaxIntensity = integer() >= 0 %% Period = integer() > 0 %% Mod :== atom() %% Args :== term() %% Purpose: Check that Type is of correct type (!) %% Returns: {ok, state()} | Error %%----------------------------------------------------------------- init_state(SupName, Type, Mod, Args) -> set_flags(Type, #state{name = supname(SupName,Mod), module = Mod, args = Args}). set_flags(Flags, State) -> try check_flags(Flags) of #{strategy := Strategy, intensity := MaxIntensity, period := Period} -> {ok, State#state{strategy = Strategy, intensity = MaxIntensity, period = Period}} catch Thrown -> Thrown end. check_flags(SupFlags) when is_map(SupFlags) -> do_check_flags(maps:merge(?default_flags,SupFlags)); check_flags({Strategy, MaxIntensity, Period}) -> check_flags(#{strategy => Strategy, intensity => MaxIntensity, period => Period}); check_flags(What) -> throw({invalid_type, What}). do_check_flags(#{strategy := Strategy, intensity := MaxIntensity, period := Period} = Flags) -> validStrategy(Strategy), validIntensity(MaxIntensity), validPeriod(Period), Flags. validStrategy(simple_one_for_one) -> true; validStrategy(one_for_one) -> true; validStrategy(one_for_all) -> true; validStrategy(rest_for_one) -> true; validStrategy(What) -> throw({invalid_strategy, What}). validIntensity(Max) when is_integer(Max), Max >= 0 -> true; validIntensity(What) -> throw({invalid_intensity, What}). validPeriod(Period) when is_integer(Period), Period > 0 -> true; validPeriod(What) -> throw({invalid_period, What}). supname(self, Mod) -> {self(), Mod}; supname(N, _) -> N. %%% ------------------------------------------------------ %%% Check that the children start specification is valid. %%% Input: [child_spec()] %%% Returns: {ok, [child_rec()]} | Error %%% ------------------------------------------------------ check_startspec(Children) -> check_startspec(Children, []). check_startspec([ChildSpec|T], Res) -> case check_childspec(ChildSpec) of {ok, Child} -> case lists:keymember(Child#child.name, #child.name, Res) of %% The error message duplicate_child_name is kept for %% backwards compatibility, although %% duplicate_child_id would be more correct. true -> {duplicate_child_name, Child#child.name}; false -> check_startspec(T, [Child | Res]) end; Error -> Error end; check_startspec([], Res) -> {ok, lists:reverse(Res)}. check_childspec(ChildSpec) when is_map(ChildSpec) -> catch do_check_childspec(maps:merge(?default_child_spec,ChildSpec)); check_childspec({Name, Func, RestartType, Shutdown, ChildType, Mods}) -> check_childspec(#{id => Name, start => Func, restart => RestartType, shutdown => Shutdown, type => ChildType, modules => Mods}); check_childspec(X) -> {invalid_child_spec, X}. do_check_childspec(#{restart := RestartType, type := ChildType} = ChildSpec)-> Name = case ChildSpec of #{id := N} -> N; _ -> throw(missing_id) end, Func = case ChildSpec of #{start := F} -> F; _ -> throw(missing_start) end, validName(Name), validFunc(Func), validRestartType(RestartType), validChildType(ChildType), Shutdown = case ChildSpec of #{shutdown := S} -> S; #{type := worker} -> 5000; #{type := supervisor} -> infinity end, validShutdown(Shutdown), Mods = case ChildSpec of #{modules := Ms} -> Ms; _ -> {M,_,_} = Func, [M] end, validMods(Mods), {ok, #child{name = Name, mfargs = Func, restart_type = RestartType, shutdown = Shutdown, child_type = ChildType, modules = Mods}}. validChildType(supervisor) -> true; validChildType(worker) -> true; validChildType(What) -> throw({invalid_child_type, What}). validName(_Name) -> true. validFunc({M, F, A}) when is_atom(M), is_atom(F), is_list(A) -> true; validFunc(Func) -> throw({invalid_mfa, Func}). validRestartType(permanent) -> true; validRestartType(temporary) -> true; validRestartType(transient) -> true; validRestartType(RestartType) -> throw({invalid_restart_type, RestartType}). validShutdown(Shutdown) when is_integer(Shutdown), Shutdown > 0 -> true; validShutdown(infinity) -> true; validShutdown(brutal_kill) -> true; validShutdown(Shutdown) -> throw({invalid_shutdown, Shutdown}). validMods(dynamic) -> true; validMods(Mods) when is_list(Mods) -> lists:foreach(fun(Mod) -> if is_atom(Mod) -> ok; true -> throw({invalid_module, Mod}) end end, Mods); validMods(Mods) -> throw({invalid_modules, Mods}). %%% ------------------------------------------------------ %%% Add a new restart and calculate if the max restart %%% intensity has been reached (in that case the supervisor %%% shall terminate). %%% All restarts accured inside the period amount of seconds %%% are kept in the #state.restarts list. %%% Returns: {ok, State'} | {terminate, State'} %%% ------------------------------------------------------ add_restart(State) -> I = State#state.intensity, P = State#state.period, R = State#state.restarts, Now = erlang:now(), R1 = add_restart([Now|R], Now, P), State1 = State#state{restarts = R1}, case length(R1) of CurI when CurI =< I -> {ok, State1}; _ -> {terminate, State1} end. add_restart([R|Restarts], Now, Period) -> case inPeriod(R, Now, Period) of true -> [R|add_restart(Restarts, Now, Period)]; _ -> [] end; add_restart([], _, _) -> []. inPeriod(Time, Now, Period) -> case difference(Time, Now) of T when T > Period -> false; _ -> true end. %% %% Time = {MegaSecs, Secs, MicroSecs} (NOTE: MicroSecs is ignored) %% Calculate the time elapsed in seconds between two timestamps. %% If MegaSecs is equal just subtract Secs. %% Else calculate the Mega difference and add the Secs difference, %% note that Secs difference can be negative, e.g. %% {827, 999999, 676} diff {828, 1, 653753} == > 2 secs. %% difference({TimeM, TimeS, _}, {CurM, CurS, _}) when CurM > TimeM -> ((CurM - TimeM) * 1000000) + (CurS - TimeS); difference({_, TimeS, _}, {_, CurS, _}) -> CurS - TimeS. %%% ------------------------------------------------------ %%% Error and progress reporting. %%% ------------------------------------------------------ report_error(Error, Reason, Child, SupName) -> ErrorMsg = [{supervisor, SupName}, {errorContext, Error}, {reason, Reason}, {offender, extract_child(Child)}], error_logger:error_report(supervisor_report, ErrorMsg). extract_child(Child) when is_list(Child#child.pid) -> [{nb_children, length(Child#child.pid)}, {id, Child#child.name}, {mfargs, Child#child.mfargs}, {restart_type, Child#child.restart_type}, {shutdown, Child#child.shutdown}, {child_type, Child#child.child_type}]; extract_child(Child) -> [{pid, Child#child.pid}, {id, Child#child.name}, {mfargs, Child#child.mfargs}, {restart_type, Child#child.restart_type}, {shutdown, Child#child.shutdown}, {child_type, Child#child.child_type}]. report_progress(Child, SupName) -> Progress = [{supervisor, SupName}, {started, extract_child(Child)}], error_logger:info_report(progress, Progress).