Настройка репликации. Финал #14

2026-05-03 21:02:29 +03:00
parent 3d61830f1c
commit 83ce92afa4
5 changed files with 148 additions and 93 deletions
@@ -1,64 +1,51 @@
-%% ===================================================================
-%% EventHub – Cluster Discovery (с репликацией, задача #14)
-%% ===================================================================
 -module(cluster_discovery).
-
 -export([discover_and_replicate/0]).

-%% ------------------------------------------------------------------
-%% @doc Основная точка входа: запускает процесс обнаружения и репликации
-%% ------------------------------------------------------------------
-discover_and_replicate() ->
-  spawn(fun() ->
-    io:format("Cluster discovery started (mode: ~s)~n", [os:getenv("CLUSTER_MODE", "local")]),
-    discover_loop()
-        end).
+-define(DNS_ALIAS, get_dns_name()).
+-define(RETRY_INTERVAL, 5000).

-%% ------------------------------------------------------------------
-%% Внутренние функции
-%% ------------------------------------------------------------------
+discover_and_replicate() ->
+  io:format("Starting cluster DNS discovery via epmd (~s)...~n", [?DNS_ALIAS]),
+  discover_loop().

 discover_loop() ->
-  % Получаем список IP-адресов через DNS
-  case inet_res:getbyname("eventhub-node", in, a) of
-    {ok, {hostent, _, _, in, 4, Ips}} ->
-      Nodes = [list_to_atom("eventhub@" ++ inet:ntoa(Ip)) || Ip <- Ips],
-      io:format("Discovered nodes: ~p~n", [Nodes]),
-      lists:foreach(fun(Node) ->
-        case net_kernel:connect_node(Node) of
-          true ->
-            io:format("Connected to ~p, joining Mnesia cluster...~n", [Node]),
-            join_and_replicate(Node);
-          false ->
-            io:format("Failed to connect to ~p~n", [Node])
+  case inet:getaddrs(?DNS_ALIAS, inet) of
+    {ok, IPs} when is_list(IPs) ->
+      lists:foreach(fun(IP) ->
+        IPStr = inet:ntoa(IP),
+        io:format("Checking epmd on ~s...~n", [IPStr]),
+        case erl_epmd:names(IP) of
+          {ok, List} ->
+            lists:foreach(fun({Name, _Port}) ->
+              Node = list_to_atom(Name ++ "@" ++ Name),
+              io:format("    Trying net_kernel:connect_node(~s)...~n", [Node]),
+              case net_kernel:connect_node(Node) of
+                true  -> io:format("    *** Connected to ~s ***~n", [Node]), join_and_replicate(Node); %io:format("    *** Connected to ~s ***~n", [Node]);
+                false -> io:format("    *** Failed to connect to ~s ***~n", [Node]);
+                ignored -> ok
+              end
+            end, List);
+          {error, Reason} ->
+            io:format("  epmd error on ~s: ~p~n", [IPStr, Reason])
        end
-                    end, Nodes);
+                    end, IPs);
    {error, Reason} ->
-      io:format("DNS lookup failed: ~p, retrying in 5s...~n", [Reason]),
-      timer:sleep(5000),
-      discover_loop()
-  end.
+      io:format("DNS lookup failed (~p), retrying...~n", [Reason])
+  end,
+  timer:sleep(?RETRY_INTERVAL),
+  discover_loop().

 %% ------------------------------------------------------------------
 %% @doc Добавляет удалённый узел в Mnesia и реплицирует данные
 %% ------------------------------------------------------------------
 join_and_replicate(Node) ->
-  % Добавляем узел в список extra_db_nodes, чтобы Mnesia знала о нём
-  ExtraNodes = application:get_env(eventhub, extra_db_nodes, []),
-  application:set_env(eventhub, extra_db_nodes, [Node | ExtraNodes]),
+  case lists:member(Node, mnesia:system_info(db_nodes)) of
+    true ->
+      io:format("Node ~p already in Mnesia cluster, skipping~n", [Node]);
+    false ->
+      io:format("Adding node ~p to Mnesia cluster...~n", [Node]),
+      infra_mnesia:add_cluster_nodes([Node])
+  end.

-  % Подключаем узел к кластеру Mnesia
-  mnesia:change_config(extra_db_nodes, [Node]),
-
-  % Реплицируем все пользовательские таблицы на себя
-  Tables = mnesia:system_info(tables) -- [schema],
-  lists:foreach(fun(Tab) ->
-    case lists:member(node(), mnesia:table_info(Tab, disc_copies)) of
-      false ->
-        io:format("Adding local disc copy of table ~p...~n", [Tab]),
-        mnesia:add_table_copy(Tab, node(), disc_copies);
-      true ->
-        ok
-    end
-                end, Tables),
-  ok.
+get_dns_name() ->
+  os:getenv("DNS_NAME", "eventhub-node").  % значение по умолчанию оставим
@@ -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
 %% ===================================================================