From 31c2a1b7d7b1f248ef515eee9df4338a1d6ee86f Mon Sep 17 00:00:00 2001
From: Aleksey Sabilin <aleksey@sabilin.com>
Date: Sat, 18 Jul 2026 23:33:56 +0300
Subject: [PATCH] fix: subscribe stats_collector after Mnesia tables are ready

Backfill ran during init_tables before wait_for_tables, so dirty reads hit {no_exists,user} and crash-looped eventhub on IFT.
---
 src/eventhub_app.erl          |  2 ++
 src/infra/infra_mnesia.erl    |  2 +-
 src/infra/stats_collector.erl | 21 +++++++++++++++++++--
 src/infra/stats_tops.erl      |  7 ++++++-
 4 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/src/eventhub_app.erl b/src/eventhub_app.erl
index 6a65d3d..051901a 100644
--- a/src/eventhub_app.erl
+++ b/src/eventhub_app.erl
@@ -52,6 +52,8 @@ start_application() ->
       ok = infra_mnesia:init_tables(),
       ok = infra_mnesia:wait_for_tables(),
       ok = migration_engine:ensure_applied(),
+      %% После wait + migrations: иначе backfill ловит {no_exists, user} на ещё не загруженных таблицах.
+      ok = stats_collector:subscribe(),
       calendar_html_renderer:init_cache(),
       application:ensure_all_started(cowboy),
       start_http(),          % Пользовательский API (8080)
diff --git a/src/infra/infra_mnesia.erl b/src/infra/infra_mnesia.erl
index 7d4f968..59b6670 100644
--- a/src/infra/infra_mnesia.erl
+++ b/src/infra/infra_mnesia.erl
@@ -125,7 +125,7 @@ handle_call(init_tables, _From, State) ->
     true -> ok
   end,
   ok = create_indices(),
-  ok = stats_collector:subscribe(),
+  %% stats_collector:subscribe — после wait_for_tables + migrations (eventhub_app)
   ok = start_cleanup_timer(),
   {reply, ok, State};
 
diff --git a/src/infra/stats_collector.erl b/src/infra/stats_collector.erl
index 468c3d4..dcaa72c 100644
--- a/src/infra/stats_collector.erl
+++ b/src/infra/stats_collector.erl
@@ -127,7 +127,18 @@ do_subscribe(State) ->
     false -> stats_tops:rebuild()
   end,
   lists:foreach(fun(Table) ->
-    mnesia:subscribe({table, Table, detailed})
+    case lists:member(Table, mnesia:system_info(tables)) of
+      true ->
+        case mnesia:wait_for_tables([Table], 60000) of
+          ok -> mnesia:subscribe({table, Table, detailed});
+          {timeout, _} ->
+            error_logger:warning_msg(
+              "stats_collector: skip subscribe ~p (wait timeout)~n", [Table])
+        end;
+      false ->
+        error_logger:warning_msg(
+          "stats_collector: skip subscribe ~p (no table)~n", [Table])
+    end
   end, ?SUB_TABLES),
   State#state{ready = true, subscribed = true}.
 
@@ -371,7 +382,13 @@ backfill_all() ->
 
 safe_match(Table, Pattern) ->
   case lists:member(Table, mnesia:system_info(tables)) of
-    true -> mnesia:dirty_match_object(Pattern);
+    true ->
+      try mnesia:dirty_match_object(Pattern) of
+        Rows when is_list(Rows) -> Rows
+      catch
+        exit:{aborted, {no_exists, _}} -> [];
+        error:{aborted, {no_exists, _}} -> []
+      end;
     false -> []
   end.
 
diff --git a/src/infra/stats_tops.erl b/src/infra/stats_tops.erl
index 46925d5..e4eabe1 100644
--- a/src/infra/stats_tops.erl
+++ b/src/infra/stats_tops.erl
@@ -81,7 +81,12 @@ ready() ->
 
 foreach_table(Table, Pattern, Fun) ->
   case lists:member(Table, mnesia:system_info(tables)) of
-    true -> lists:foreach(Fun, mnesia:dirty_match_object(Pattern));
+    true ->
+      try lists:foreach(Fun, mnesia:dirty_match_object(Pattern))
+      catch
+        exit:{aborted, {no_exists, _}} -> ok;
+        error:{aborted, {no_exists, _}} -> ok
+      end;
     false -> ok
   end.