Refactor event system and add third-party event listeners

- Move event_bus import to correct module paths
- Introduce BaseEventListener abstract base class
- Add AgentOpsListener for third-party event tracking
- Update event listener initialization and setup
- Clean up event-related imports and exports

src/crewai/agents/crew_agent_executor.py

@@ -18,11 +18,11 @@ from crewai.tools.base_tool import BaseTool
 from crewai.tools.tool_usage import ToolUsage, ToolUsageErrorException
 from crewai.utilities import I18N, Printer
 from crewai.utilities.constants import MAX_LLM_RETRY, TRAINING_DATA_FILE
-from crewai.utilities.events import event_bus
 from crewai.utilities.events.agent_events import (
     AgentExecutionError,
     AgentExecutionStarted,
 )
+from crewai.utilities.events.event_bus import event_bus
 from crewai.utilities.exceptions.context_window_exceeding_exception import (
     LLMContextLengthExceededException,
 )

src/crewai/crew.py

@@ -43,7 +43,6 @@ from crewai.utilities import I18N, FileHandler, Logger, RPMController
 from crewai.utilities.constants import TRAINING_DATA_FILE
 from crewai.utilities.evaluators.crew_evaluator_handler import CrewEvaluator
 from crewai.utilities.evaluators.task_evaluator import TaskEvaluator
-from crewai.utilities.events import event_bus
 from crewai.utilities.events.crew_events import (
     CrewKickoffCompleted,
     CrewKickoffFailed,
@@ -55,6 +54,7 @@ from crewai.utilities.events.crew_events import (
     CrewTrainFailed,
     CrewTrainStarted,
 )
+from crewai.utilities.events.event_bus import event_bus
 from crewai.utilities.formatter import (
     aggregate_raw_outputs_from_task_outputs,
     aggregate_raw_outputs_from_tasks,
@@ -471,8 +471,6 @@ class Crew(BaseModel):
                         )
         return self
 
-
-
     @property
     def key(self) -> str:
         source = [agent.key for agent in self.agents] + [
@@ -970,13 +968,13 @@ class Crew(BaseModel):
     def _create_crew_output(self, task_outputs: List[TaskOutput]) -> CrewOutput:
         if not task_outputs:
             raise ValueError("No task outputs available to create crew output.")
-            
+
         # Filter out empty outputs and get the last valid one as the main output
         valid_outputs = [t for t in task_outputs if t.raw]
         if not valid_outputs:
             raise ValueError("No valid task outputs available to create crew output.")
         final_task_output = valid_outputs[-1]
-            
+
         final_string_output = final_task_output.raw
         self._finish_execution(final_string_output)
         token_usage = self.calculate_usage_metrics()

src/crewai/flow/flow.py

@@ -28,8 +28,8 @@ from crewai.utilities.events import (
     FlowStarted,
     MethodExecutionFinished,
     MethodExecutionStarted,
-    event_bus,
 )
+from crewai.utilities.events.event_bus import event_bus
 from crewai.utilities.printer import Printer
 
 logger = logging.getLogger(__name__)

src/crewai/tools/tool_usage.py

@@ -17,7 +17,7 @@ from crewai.tools import BaseTool
 from crewai.tools.structured_tool import CrewStructuredTool
 from crewai.tools.tool_calling import InstructorToolCalling, ToolCalling
 from crewai.utilities import I18N, Converter, ConverterError, Printer
-from crewai.utilities.events import event_bus
+from crewai.utilities.events.event_bus import event_bus
 from crewai.utilities.events.event_types import (
     ToolUsageError,
     ToolUsageFinished,

src/crewai/utilities/events/__init__.py

@@ -6,13 +6,14 @@ from .crew_events import (
 from .agent_events import AgentExecutionStarted, AgentExecutionCompleted
 from .task_events import TaskStarted, TaskCompleted, TaskFailed
 from .flow_events import FlowStarted, FlowFinished, MethodExecutionStarted, MethodExecutionFinished
-from .event_bus import event_bus, EventTypes
+from .event_bus import EventTypes, EventBus
 from .events import emit, on
-from .event_bus import EventBus
-from .event_listener import EventListener
 from .tool_usage_events import ToolUsageFinished, ToolUsageError
-event_bus = EventBus()
+
-event_listener = EventListener()
+# events
+from .event_listener import EventListener
+from .third_party.agentops_listener import agentops_listener
+
 
 __all__ = [
     AgentExecutionStarted,
@@ -29,10 +30,11 @@ __all__ = [
     MethodExecutionFinished,
     EventTypes,
     emit,
-    on,
+    on, 
     event_bus,
     ToolUsageFinished,
     ToolUsageError,
+    EventBus
 ]
 
 

src/crewai/utilities/events/base_event_listener.py

@@ -0,0 +1,13 @@
+from abc import ABC, abstractmethod
+
+from crewai.utilities.events.event_bus import EventBus, event_bus
+
+
+class BaseEventListener(ABC):
+    def __init__(self):
+        super().__init__()
+        self.setup_listeners(event_bus)
+
+    @abstractmethod
+    def setup_listeners(self, event_bus: EventBus):
+        pass

src/crewai/utilities/events/event_bus.py

@@ -29,6 +29,7 @@ class EventBus:
         self._signal = Signal("event_bus")
         self._handlers: Dict[Type[EventTypes], List[Callable]] = {}
 
+    # TODO: generic types
     def on(self, event_type: Type[EventTypes]) -> Callable:
         """
         Decorator to register an event handler for a specific event type.

src/crewai/utilities/events/event_listener.py

@@ -1,5 +1,8 @@
+from pydantic import PrivateAttr
+
 from crewai.telemetry.telemetry import Telemetry
 from crewai.utilities.evaluators.task_evaluator import TaskEvaluator
+from crewai.utilities.events.base_event_listener import BaseEventListener
 
 from .agent_events import (
     AgentExecutionCompleted,
@@ -11,7 +14,6 @@ from .crew_events import (
     CrewTestCompleted,
     CrewTestStarted,
 )
-from .event_bus import EventBus
 from .flow_events import (
     FlowFinished,
     FlowStarted,
@@ -21,16 +23,15 @@ from .flow_events import (
 from .task_events import TaskCompleted, TaskStarted
 
 
-class EventListener:
+class EventListener(BaseEventListener):
-    _telemetry = Telemetry()
+    _telemetry: Telemetry = PrivateAttr(default_factory=lambda: Telemetry())
 
     def __init__(self):
-        self._setup_listeners()
+        super().__init__()
+        self._telemetry = Telemetry()
         self._telemetry.set_tracer()
 
-    def _setup_listeners(self):
+    def setup_listeners(self, event_bus):
-        event_bus = EventBus()
-
         @event_bus.on(CrewKickoffStarted)
         def on_crew_started(source, event):
             print(f"🚀 Crew '{event.crew_name}' started", event.timestamp)
@@ -95,3 +96,6 @@ class EventListener:
         @event_bus.on(MethodExecutionFinished)
         def on_method_execution_finished(source, event):
             print(f"👍 Flow Method Finished: '{event.method_name}'")
+
+
+event_listener = EventListener()

src/crewai/utilities/events/third_party/__init__.py

@@ -0,0 +1 @@
+from .agentops_listener import agentops_listener

src/crewai/utilities/events/third_party/agentops_listener.py

@@ -0,0 +1,25 @@
+from crewai.utilities.events.agent_events import AgentExecutionStarted
+from crewai.utilities.events.base_event_listener import BaseEventListener
+
+try:
+    import agentops
+
+    AGENTOPS_INSTALLED = True
+except ImportError:
+    AGENTOPS_INSTALLED = False
+
+
+class AgentOpsListener(BaseEventListener):
+    def __init__(self):
+        super().__init__()
+        print("AgentOpsListener init")
+
+    def setup_listeners(self, event_bus):
+        if AGENTOPS_INSTALLED:
+
+            @event_bus.on(AgentExecutionStarted)
+            def on_agent_started(source, event: AgentExecutionStarted):
+                print("AGENTOPS WORKS !!!", event.agent)
+
+
+agentops_listener = AgentOpsListener()

tests/utilities/test_events.py

@@ -1,5 +1,4 @@
 from datetime import datetime
-from unittest import mock
 from unittest.mock import patch
 
 import pytest