Fix unbounded event-task leak on the per-connection barrier

lib/librevox/listener/base.rb

@@ -1,8 +1,8 @@
 # frozen_string_literal: true
 
-require 'async/barrier'
 require 'async/semaphore'
 require 'securerandom'
+require 'set'
 
 module Librevox
   module Listener
@@ -21,7 +21,7 @@ def initialize(connection)
         @connection = connection
         @reply_promises = []
         @app_promises = {}
-        @event_barrier = Async::Barrier.new
+        @event_tasks = Set.new
         @write_lock = Async::Semaphore.new(1)
       end
 
@@ -92,9 +92,14 @@ def receive_message(response)
             @app_promises.delete(app_uuid)&.resolve(response)
           end
 
-          @event_barrier.async do
-            on_event(response)
-            invoke_event_hooks(response)
+          Async do |task|
+            @event_tasks << task
+            begin
+              on_event(response)
+              invoke_event_hooks(response)
+            ensure
+              @event_tasks.delete(task)
+            end
           end
         end
       end
@@ -108,7 +113,7 @@ def connection_closed
         @reply_promises.clear
         @app_promises.clear
 
-        @event_barrier.wait
+        @event_tasks.each { |task| task.wait rescue nil }
       rescue ConnectionError
         # Expected — event hooks may have been mid-command when disconnected
       end

test/functional/librevox/listener/base_test.rb

@@ -26,4 +26,21 @@ def test_on_event_with_api_does_not_block_handle_response
 
     assert completed, "Deadlock: on_event with api command blocked handle_response"
   end
+
+  # Regression: a long-lived inbound connection dispatches one event-handler
+  # task per ESL event. These are fire-and-forget, so once finished they must be
+  # released. Previously they were spawned on a per-connection Async::Barrier,
+  # whose task list only shrinks on #wait (called just once, on disconnect) — so
+  # every event leaked a task node for the life of the socket (~GBs over days on
+  # a busy switch). They must not accumulate.
+  def test_completed_event_tasks_are_not_retained
+    Sync do
+      100.times { event "SOME_EVENT" }
+
+      in_flight = @listener.instance_variable_get(:@event_tasks)
+      assert_empty in_flight,
+        "completed event-handler tasks must not accumulate on the listener " \
+        "(got #{in_flight.size} retained after 100 events)"
+    end
+  end
 end