Repair messages_count triggers in one SQLite write transaction

ensure! now rechecks trigger presence under BEGIN IMMEDIATE, backfills drifted rooms.messages_count, and reinstalls all three triggers before commit so concurrent writers and concurrent boot repairs cannot observe a partial install or keep a wrong total. install! uses the same immediate write lock for drop/recreate. Lifecycle regressions cover missing/partial trigger drift, concurrent ensure!, and writes racing repair. Co-authored-by: Thomas Klemm <github@tklemm.eu>
2026-10-09 00:00:12 +09:00 · 2026-10-07 20:58:32 +00:00
parent 32748e7fd6
commit b4ab2df20f
2 changed files with 198 additions and 32 deletions
@@ -21,25 +21,24 @@ class Room::MessagesCountLifecycleTest < ActiveSupport::TestCase
    Room::MessagesCount.backfill!
  end

-  test "ensure! installs missing triggers without changing existing counts" do
+  test "ensure! installs missing triggers and keeps accurate counts" do
    before = @room.reload.messages_count
    Room::MessagesCount.uninstall!

-    assert_not Room::MessagesCount.trigger_installed?(ActiveRecord::Base.connection, Room::MessagesCount::INSERT_TRIGGER)
+    assert_not Room::MessagesCount.triggers_installed?

    Room::MessagesCount.ensure!

-    assert Room::MessagesCount::TRIGGERS.all? { |name|
-      Room::MessagesCount.trigger_installed?(ActiveRecord::Base.connection, name)
-    }
+    assert Room::MessagesCount.triggers_installed?
    assert_equal before, @room.reload.messages_count
+    assert_equal @room.messages.count, @room.messages_count

    assert_difference -> { @room.reload.messages_count }, +1 do
      @room.messages.create!(creator: users(:jason), body: "After ensure", client_message_id: "count-ensure")
    end
  end

-  test "ensure! repairs a partial trigger install" do
+  test "ensure! repairs a partial trigger install and backfills drifted counts" do
    Room::MessagesCount.uninstall!
    ActiveRecord::Base.connection.execute <<~SQL
      CREATE TRIGGER #{Room::MessagesCount::INSERT_TRIGGER} AFTER INSERT ON messages
@@ -51,11 +50,147 @@ class Room::MessagesCountLifecycleTest < ActiveSupport::TestCase
    assert Room::MessagesCount.trigger_installed?(ActiveRecord::Base.connection, Room::MessagesCount::INSERT_TRIGGER)
    assert_not Room::MessagesCount.trigger_installed?(ActiveRecord::Base.connection, Room::MessagesCount::DELETE_TRIGGER)

+    # Delete fires with no delete trigger → counter drifts high.
+    drifted = @room.messages.create!(creator: users(:jason), body: "Drift", client_message_id: "count-partial-drift")
+    ActiveRecord::Base.connection.execute("DELETE FROM messages WHERE id = #{drifted.id}")
+    assert_operator @room.reload.messages_count, :>, @room.messages.count
+
    Room::MessagesCount.ensure!

-    assert Room::MessagesCount::TRIGGERS.all? { |name|
-      Room::MessagesCount.trigger_installed?(ActiveRecord::Base.connection, name)
-    }
+    assert Room::MessagesCount.triggers_installed?
+    assert_equal @room.messages.count, @room.reload.messages_count
+  end
+
+  test "ensure! backfills writes that landed while the insert trigger was missing" do
+    Room::MessagesCount.uninstall!
+    before_count = @room.messages.count
+    before_cached = @room.reload.messages_count
+    assert_equal before_count, before_cached
+
+    path = File.expand_path(ActiveRecord::Base.connection_db_config.database)
+    now = Time.current.utc.strftime("%Y-%m-%d %H:%M:%S.%6N")
+    ActiveRecord::Base.connection_pool.release_connection
+
+    SQLite3::Database.new(path) do |db|
+      db.busy_timeout = 5_000
+      db.execute(
+        "INSERT INTO messages (room_id, creator_id, client_message_id, created_at, updated_at) VALUES (?, ?, ?, ?, ?)",
+        [ @room.id, users(:david).id, "count-missing-insert", now, now ]
+      )
+    end
+
+    assert_equal before_count + 1, @room.messages.count
+    assert_equal before_cached, @room.reload.messages_count
+
+    Room::MessagesCount.ensure!
+
+    assert Room::MessagesCount.triggers_installed?
+    assert_equal @room.messages.count, @room.reload.messages_count
+    assert_equal before_cached + 1, @room.messages_count
+  end
+
+  test "concurrent ensure! repairs leave triggers installed and counts accurate" do
+    Room::MessagesCount.uninstall!
+    path = File.expand_path(ActiveRecord::Base.connection_db_config.database)
+    now = Time.current.utc.strftime("%Y-%m-%d %H:%M:%S.%6N")
+    ActiveRecord::Base.connection_pool.release_connection
+
+    SQLite3::Database.new(path) do |db|
+      db.busy_timeout = 5_000
+      db.execute(
+        "INSERT INTO messages (room_id, creator_id, client_message_id, created_at, updated_at) VALUES (?, ?, ?, ?, ?)",
+        [ @room.id, users(:david).id, "count-concurrent-drift", now, now ]
+      )
+    end
+
+    assert_not_equal @room.messages.count, @room.reload.messages_count
+
+    errors = []
+    errors_mutex = Mutex.new
+
+    workers = 2.times.map do
+      Thread.new do
+        ActiveRecord::Base.connection_pool.with_connection do |connection|
+          Room::MessagesCount.ensure!(connection)
+        end
+      rescue => error
+        errors_mutex.synchronize { errors << error }
+      end
+    end
+
+    workers.each(&:join)
+
+    assert_empty errors, -> { errors.map(&:full_message).join("\n") }
+    assert Room::MessagesCount.triggers_installed?
+    assert_equal @room.messages.count, @room.reload.messages_count
+  end
+
+  test "writes concurrent with ensure! repair leave accurate counts" do
+    Room::MessagesCount.uninstall!
+    path = File.expand_path(ActiveRecord::Base.connection_db_config.database)
+    now = Time.current.utc.strftime("%Y-%m-%d %H:%M:%S.%6N")
+    ActiveRecord::Base.connection_pool.release_connection
+
+    errors = []
+    errors_mutex = Mutex.new
+
+    ensure_thread = Thread.new do
+      ActiveRecord::Base.connection_pool.with_connection do |connection|
+        Room::MessagesCount.ensure!(connection)
+      end
+    rescue => error
+      errors_mutex.synchronize { errors << error }
+    end
+
+    insert_thread = Thread.new do
+      SQLite3::Database.new(path) do |db|
+        db.busy_timeout = 10_000
+        db.execute(
+          "INSERT INTO messages (room_id, creator_id, client_message_id, created_at, updated_at) VALUES (?, ?, ?, ?, ?)",
+          [ @room.id, users(:david).id, "count-during-repair", now, now ]
+        )
+      end
+    rescue => error
+      errors_mutex.synchronize { errors << error }
+    end
+
+    [ ensure_thread, insert_thread ].each(&:join)
+
+    assert_empty errors, -> { errors.map(&:full_message).join("\n") }
+    assert Room::MessagesCount.triggers_installed?
+    assert_equal @room.messages.count, @room.reload.messages_count
+    assert Message.exists?(client_message_id: "count-during-repair")
+  end
+
+  test "install! never exposes a partial trigger set to other connections" do
+    Room::MessagesCount.uninstall!
+    path = File.expand_path(ActiveRecord::Base.connection_db_config.database)
+    ActiveRecord::Base.connection_pool.release_connection
+
+    stop = false
+    partial_snapshots = []
+    snapshots_mutex = Mutex.new
+
+    watcher = Thread.new do
+      SQLite3::Database.new(path) do |db|
+        db.busy_timeout = 5_000
+        until stop
+          names = db.execute(
+            "SELECT name FROM sqlite_master WHERE type = 'trigger' AND name IN (#{Room::MessagesCount::TRIGGERS.map { "'#{it}'" }.join(", ")})"
+          ).flatten
+          if names.any? && names.sort != Room::MessagesCount::TRIGGERS.sort
+            snapshots_mutex.synchronize { partial_snapshots << names.sort }
+          end
+        end
+      end
+    end
+
+    25.times { Room::MessagesCount.install! }
+    stop = true
+    watcher.join
+
+    assert_empty partial_snapshots
+    assert Room::MessagesCount.triggers_installed?
  end

  test "foreign SQLite connections keep the counter in step" do