Skip SSE config updated events if they arrive too fast

Author: hansott

aikido_zen/background_process/realtime/listen_for_config_updates.py

@@ -3,6 +3,7 @@
 """
 
 import json
+import time
 
 from aikido_zen.helpers.token import Token
 from aikido_zen.helpers.logging import logger
@@ -26,6 +27,21 @@ def listen_for_config_updates(connection_manager, event_scheduler):
 
     token = connection_manager.token
     last_updated_at = connection_manager.conf.last_updated_at
+    last_config_refresh_started_at = None
+
+    def config_update_arrived_too_fast():
+        nonlocal last_config_refresh_started_at
+
+        now = time.monotonic()
+        if (
+            last_config_refresh_started_at is not None
+            and now - last_config_refresh_started_at
+            < 9
+        ):
+            return True
+
+        last_config_refresh_started_at = now
+        return False
 
     def on_event(event):
         nonlocal last_updated_at
@@ -43,6 +59,10 @@ def on_event(event):
             logger.debug("SSE config-updated event has invalid payload: %s", event.data)
             return
 
+        if config_update_arrived_too_fast():
+            logger.debug("SSE config-updated event ignored by refresh throttle")
+            return
+
         logger.debug("SSE config-updated event, fetching new config")
 
         try:

aikido_zen/background_process/realtime/listen_for_config_updates_test.py

@@ -188,6 +188,22 @@ def test_updates_last_updated_at_so_a_second_stale_event_is_ignored(
     mock_get_config.assert_called_once()
 
 
+def test_throttles_newer_events(connection_manager):
+    connection_manager.conf.last_updated_at = 100
+    event_scheduler = make_inline_scheduler()
+    on_event = get_on_event(connection_manager, event_scheduler)
+
+    new_config = {"endpoints": [], "configUpdatedAt": 200}
+    with patch(
+        "aikido_zen.background_process.realtime.get_config", return_value=new_config
+    ) as mock_get_config:
+        on_event(make_event(data={"configUpdatedAt": 200}))
+        on_event(make_event(data={"configUpdatedAt": 300}))
+
+    mock_get_config.assert_called_once_with(connection_manager.token)
+    connection_manager.update_firewall_lists.assert_called_once()
+
+
 def test_handles_get_config_failure_gracefully(connection_manager, caplog):
     connection_manager.conf.last_updated_at = 100
     on_event = get_on_event(connection_manager)