eLog/src/eRum_sup.erl

-module(eRum_sup).

-behaviour(supervisor).

-include("eRum.hrl").

-export([
   start_link/0
]).

-export([
   init/1
]).

start_link() ->
   supervisor:start_link({local, ?MODULE}, ?MODULE, []).

% 主管的孩子被定义为孩子规格列表 。当主管启动时，将根据此列表从左到右依次启动子进程。主管终止时，它首先以相反的启动顺序从右到左终止其子进程。
% sup_flags() =
%     #{
%        strategy => strategy(),          % optional one_for_one | one_for_all | rest_for_one | simple_one_for_one
%        intensity => non_neg_integer(),  % optional MaxR 周期时间内最大重启次数
%        period => pos_integer()          % optional MaxT 重启时间周期  MaxT里重启次数大于MaxR
%     }
% child_spec() =
%     #{
%        id => child_id(),                % mandatory Id用来内部标识子规范
%        start => mfargs(),               % mandatory {M，F，A}
%        restart => restart(),            % optional  permanent(总是重启) | transient(异常关闭会重启即关闭原因非 normal,shutdown,{shutdown,Term}) | temporary(不会重启)
%        shutdown => shutdown(),          % optional  brutal_kill | infinity | integer
%        type => worker(),                % optional  supervisor | worker
%        modules => modules()             % optional  [Module] 假如子进程是supervisor、gen_server 或 gen_fsm，那么Module 是回调模块的名称；假如子进程是gen_event，那么Modules 应该是dynamic
%     }

init(_Args) ->
   %% set up the config, is safe even during relups
   rumConfig:init(),
   %%始终将lager_event作为默认值启动，并确保可以根据需要启动其他gen_event东西也许是一个用于处理接收器及其策略的新API？
   SupFlags =
      #{
         strategy => one_for_one,
         intensity => 10,
         period => 60
      },

   RumEventSpec = #{
      id => rumEvent,
      start => {gen_emm, start_link, [{local, rumEvent}]},
      restart => permanent,
      shutdown => 5000,
      type => worker,
      modules => [dynamic]
   },

   RumHWatcherSupSpec = #{
      id => rumHWatcherSup,
      start => {rumHWatcherSup, start_link, []},
      restart => permanent,
      shutdown => 5000,
      type => supervisor,
      modules => [rumHWatcherSup]
   },

   CrashLogSpec = crashLogSpec(rumUtil:get_env(crashLogFile, false)),

   ChildSpecs =
      case CrashLogSpec of
         undefined ->
            [RumEventSpec, RumHWatcherSupSpec];
         _ ->
            [RumEventSpec, RumHWatcherSupSpec, CrashLogSpec]
      end,
   {ok, {SupFlags, ChildSpecs}}.

crashLogSpec(false) ->
   undefined;
crashLogSpec(File) ->
   MaxBytes = rumUtil:get_env(crash_log_msg_size, 65536),
   RotationSize = rumUtil:get_env(crash_log_size, 0),
   RotationCount = rumUtil:get_env(crash_log_count, 0),
   RotationDate = rumUtil:get_env(crash_log_date, "$D0"),
   RotationMod = rumUtil:get_env(crash_log_rotator, lager_rotator_default),
   #{
      id => rumCrashLog,
      start => {rumCrashLog, start_link, [File, MaxBytes, RotationSize, RotationDate, RotationCount, RotationMod]},
      restart => permanent,
      shutdown => 5000,
      type => worker,
      modules => [rumCrashLog]
   }.