Add system event listeners for monitoring (#6929)

openhands/server/monitoring.py

@@ -0,0 +1,38 @@
+from openhands.core.config.app_config import AppConfig
+from openhands.events.event import Event
+
+
+class MonitoringListener:
+    """
+    Allow tracking of application activity for monitoring purposes.
+
+    Implementations should be non-disruptive, do not raise or block to perform I/O.
+    """
+
+    def on_session_event(self, event: Event) -> None:
+        """
+        Track metrics about events being added to a Session's EventStream.
+        """
+        pass
+
+    def on_agent_session_start(self, success: bool, duration: float) -> None:
+        """
+        Track an agent session start.
+        Success is true if startup completed without error.
+        Duration is start time in seconds observed by AgentSession.
+        """
+        pass
+
+    def on_create_conversation(self) -> None:
+        """
+        Track the beginning of conversation creation.
+        Does not currently capture whether it succeed.
+        """
+        pass
+
+    @classmethod
+    def get_instance(
+        cls,
+        config: AppConfig,
+    ) -> 'MonitoringListener':
+        return cls()