Настройка репликации. Финал #14

src/infra/infra_mnesia.erl

@@ -1,5 +1,5 @@
 %% ===================================================================
-%% EventHub – infra_mnesia (финальная рабочая версия, задача #14)
+%% EventHub – infra_mnesia (финальная версия с автоочисткой кластера)
 %% ===================================================================
 -module(infra_mnesia).
 -behaviour(gen_server).
@@ -7,6 +7,7 @@
 -include("records.hrl").
 
 -export([start_link/0, init_tables/0, wait_for_tables/0]).
+-export([add_cluster_nodes/1]).
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
   terminate/2, code_change/3]).
 
@@ -20,10 +21,9 @@
   admin_audit, notification
 ]).
 
-%% Таблицы, которые должны иметь дисковые копии на каждом узле
 -define(DISC_TABLES, ?TABLES -- [session, admin_session]).
-
 -define(TABLE_WAIT_TIMEOUT, 5000).
+-define(CLEANUP_INTERVAL, 30000). % 30 секунд
 
 %% ===================================================================
 %% API
@@ -38,6 +38,9 @@ init_tables() ->
 wait_for_tables() ->
   gen_server:call(?MODULE, wait_for_tables).
 
+add_cluster_nodes(Nodes) ->
+  gen_server:call(?MODULE, {add_nodes, Nodes}).
+
 %% ===================================================================
 %% gen_server callbacks
 %% ===================================================================
@@ -55,6 +58,11 @@ handle_call(init_tables, _From, State) ->
   end,
   lists:foreach(fun create_table/1, ?TABLES),
   ok = create_indices(),
+  ok = start_cleanup_timer(),
+  {reply, ok, State};
+
+handle_call({add_nodes, Nodes}, _From, State) ->
+  ok = do_add_nodes(Nodes),
   {reply, ok, State};
 
 handle_call(wait_for_tables, _From, State) ->
@@ -62,12 +70,17 @@ handle_call(wait_for_tables, _From, State) ->
   {reply, ok, State}.
 
 handle_cast(_Msg, State) -> {noreply, State}.
+handle_info({cleanup}, State) ->
+  prune_dead_nodes(),
+  erlang:send_after(?CLEANUP_INTERVAL, self(), {cleanup}),
+  {noreply, State};
 handle_info(_Info, State) -> {noreply, State}.
+
 terminate(_Reason, _State) -> ok.
 code_change(_OldVsn, State, _Extra) -> {ok, State}.
 
 %% ===================================================================
-%% Локальное создание схемы (только если нет extra_db_nodes)
+%% Управление схемой
 %% ===================================================================
 
 maybe_recreate_schema() ->
@@ -88,10 +101,6 @@ maybe_recreate_schema() ->
       end
   end.
 
-%% ===================================================================
-%% Присоединение к кластеру – добавляет локальные дисковые копии таблиц
-%% ===================================================================
-
 join_cluster(Nodes) ->
   case mnesia:system_info(is_running) of
     yes -> mnesia:stop();
@@ -100,22 +109,16 @@ join_cluster(Nodes) ->
   application:set_env(mnesia, extra_db_nodes, Nodes),
   mnesia:start(),
   ensure_schema_disc(),
-  % Дожидаемся появления всех таблиц в локальной схеме
   wait_for_tables_available(),
   lists:foreach(fun add_local_disc_copy/1, ?DISC_TABLES).
 
-wait_for_tables_available() ->
-  lists:foreach(fun(Tab) ->
-    wait_for_table(Tab)
-                end, ?DISC_TABLES).
-
-wait_for_table(Tab) ->
-  case lists:member(Tab, mnesia:system_info(tables)) of
-    true -> ok;
-    false ->
-      timer:sleep(100),
-      wait_for_table(Tab)
-  end.
+do_add_nodes(Nodes) ->
+  ExtraNodes = application:get_env(eventhub, extra_db_nodes, []),
+  application:set_env(eventhub, extra_db_nodes, Nodes ++ ExtraNodes),
+  {ok, _} = mnesia:change_config(extra_db_nodes, Nodes),
+  ensure_schema_disc(),
+  wait_for_tables_available(),
+  lists:foreach(fun add_local_disc_copy/1, ?DISC_TABLES).
 
 ensure_schema_disc() ->
   case lists:member(node(), mnesia:table_info(schema, disc_copies)) of
@@ -142,6 +145,41 @@ add_local_disc_copy(Tab) ->
     true -> ok
   end.
 
+wait_for_tables_available() ->
+  lists:foreach(fun(Tab) -> wait_for_table(Tab) end, ?DISC_TABLES).
+
+wait_for_table(Tab) ->
+  case lists:member(Tab, mnesia:system_info(tables)) of
+    true -> ok;
+    false ->
+      timer:sleep(100),
+      wait_for_table(Tab)
+  end.
+
+%% ===================================================================
+%% Автоматическая очистка мёртвых узлов
+%% ===================================================================
+
+start_cleanup_timer() ->
+  erlang:send_after(?CLEANUP_INTERVAL, self(), {cleanup}),
+  ok.
+
+prune_dead_nodes() ->
+  AliveNodes = lists:filter(fun(Node) ->
+    Node =/= node() andalso net_adm:ping(Node) =:= pong
+                            end, mnesia:system_info(db_nodes)),
+  DeadNodes = mnesia:system_info(db_nodes) -- [node() | AliveNodes],
+  lists:foreach(fun(Node) ->
+    io:format("Removing dead node ~p from Mnesia schema...~n", [Node]),
+    lists:foreach(fun(Tab) ->
+      case lists:member(Node, mnesia:table_info(Tab, disc_copies)) of
+        true -> catch mnesia:del_table_copy(Tab, Node);
+        false -> ok
+      end
+                  end, ?DISC_TABLES),
+    catch mnesia:del_table_copy(schema, Node)
+                end, DeadNodes).
+
 %% ===================================================================
 %% Создание / открытие таблиц
 %% ===================================================================