Архивирование с быстрым подключением и серверный рендеринг для веб-клиента #15

src/archive/archive_manager.erl

@@ -0,0 +1,71 @@
+-module(archive_manager).
+-behaviour(gen_server).
+
+-export([start_link/0, get_archive_node/1]).
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2]).
+
+-define(TIMEOUT, 30000). % 30 секунд неактивности
+
+start_link() ->
+  gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
+
+get_archive_node(Day) ->
+  gen_server:call(?MODULE, {get_node, Day}).
+
+init([]) ->
+  {ok, #{}}.
+
+handle_call({get_node, Day}, _From, State) ->
+  Node = list_to_atom("eventhub_archive_" ++ Day ++ "@" ++ host()),
+  case maps:find(Node, State) of
+    {ok, _Info} ->   % переменная не используется, ок
+      {reply, {ok, Node}, update_access(State, Node)};
+    error ->
+      case start_archive_node(Day) of
+        {ok, Node} ->
+          Ref = erlang:send_after(?TIMEOUT, self(), {release, Node}),
+          NewState = State#{Node => #{timer => Ref, last_access => erlang:monotonic_time()}},
+          {reply, {ok, Node}, NewState};
+        {error, Reason} ->
+          {reply, {error, Reason}, State}
+      end
+  end.
+
+handle_cast(_, State) -> {noreply, State}.
+
+handle_info({release, Node}, State) ->
+  case maps:find(Node, State) of
+    {ok, #{last_access := Last}} ->
+      Now = erlang:monotonic_time(),
+      if Now - Last >= (?TIMEOUT * 1000) ->
+        stop_archive_node(Node),
+        {noreply, maps:remove(Node, State)};
+        true ->
+          Ref = erlang:send_after(?TIMEOUT, self(), {release, Node}),
+          {noreply, State#{Node => #{timer => Ref, last_access => Last}}}
+      end;
+    error ->
+      {noreply, State}
+  end;
+handle_info(_, State) -> {noreply, State}.
+
+update_access(State, Node) ->
+  Info = maps:get(Node, State),
+  Ref = erlang:send_after(?TIMEOUT, self(), {release, Node}),
+  State#{Node => Info#{timer => Ref, last_access => erlang:monotonic_time()}}.
+
+start_archive_node(Day) ->
+  Node = list_to_atom("eventhub_archive_" ++ Day ++ "@" ++ host()),
+  case slave:start(host(), Node) of
+    {ok, _} ->
+      rpc:call(Node, mnesia, start, []),
+      {ok, Node};
+    Error -> Error
+  end.
+
+stop_archive_node(Node) ->
+  rpc:cast(Node, init, stop, []).
+
+host() ->
+  {ok, Name} = inet:gethostname(),
+  Name.