Sequential processing for group chat participant using SequentialRoutedAgent (#663)

python/packages/autogen-agentchat/src/autogen_agentchat/teams/group_chat/_base_chat_agent_container.py

@@ -1,13 +1,14 @@
 from typing import List
 
 from autogen_core.base import MessageContext
-from autogen_core.components import DefaultTopicId, RoutedAgent, event
+from autogen_core.components import DefaultTopicId, event
 
 from ...agents import BaseChatAgent, MultiModalMessage, StopMessage, TextMessage
 from ._events import ContentPublishEvent, ContentRequestEvent
+from ._sequential_routed_agent import SequentialRoutedAgent
 
 
-class BaseChatAgentContainer(RoutedAgent):
+class BaseChatAgentContainer(SequentialRoutedAgent):
     """A core agent class that delegates message handling to an
     :class:`autogen_agentchat.agents.BaseChatAgent` so that it can be used in a
     group chat team.

python/packages/autogen-agentchat/src/autogen_agentchat/teams/group_chat/_base_group_chat_manager.py

@@ -2,13 +2,14 @@ import sys
 from typing import List
 
 from autogen_core.base import MessageContext, TopicId
-from autogen_core.components import RoutedAgent, event
+from autogen_core.components import event
 
 from ...agents import MultiModalMessage, StopMessage, TextMessage
 from ._events import ContentPublishEvent, ContentRequestEvent
+from ._sequential_routed_agent import SequentialRoutedAgent
 
 
-class BaseGroupChatManager(RoutedAgent):
+class BaseGroupChatManager(SequentialRoutedAgent):
     """Base class for a group chat manager that manages a group chat with multiple participants.
 
     It is the responsibility of the caller to ensure:

python/packages/autogen-agentchat/src/autogen_agentchat/teams/group_chat/_sequential_routed_agent.py

@@ -0,0 +1,51 @@
+import asyncio
+from typing import Any
+
+from autogen_core.base import MessageContext
+from autogen_core.components import RoutedAgent
+
+
+class FIFOLock:
+    """A lock that ensures coroutines acquire the lock in the order they request it."""
+
+    def __init__(self) -> None:
+        self._queue = asyncio.Queue[asyncio.Event]()
+        self._locked = False
+
+    async def acquire(self) -> None:
+        # If the lock is not held by any coroutine, set the lock to be held
+        # by the current coroutine.
+        if not self._locked:
+            self._locked = True
+            return
+
+        # If the lock is held by another coroutine, create an event and put it
+        # in the queue. Wait for the event to be set.
+        event = asyncio.Event()
+        await self._queue.put(event)
+        await event.wait()
+
+    def release(self) -> None:
+        if not self._queue.empty():
+            # If there are events in the queue, get the next event and set it.
+            next_event = self._queue.get_nowait()
+            next_event.set()
+        else:
+            # If there are no events in the queue, release the lock.
+            self._locked = False
+
+
+class SequentialRoutedAgent(RoutedAgent):
+    """A subclass of :class:`autogen_core.components.RoutedAgent` that ensures
+    messages are handled sequentially in the order they arrive."""
+
+    def __init__(self, description: str) -> None:
+        super().__init__(description=description)
+        self._fifo_lock = FIFOLock()
+
+    async def on_message(self, message: Any, ctx: MessageContext) -> Any | None:
+        await self._fifo_lock.acquire()
+        try:
+            return await super().on_message(message, ctx)
+        finally:
+            self._fifo_lock.release()

python/packages/autogen-agentchat/tests/test_sequential_routed_agent.py

@@ -0,0 +1,42 @@
+import asyncio
+import random
+from dataclasses import dataclass
+from typing import List
+
+import pytest
+from autogen_agentchat.teams.group_chat._sequential_routed_agent import SequentialRoutedAgent
+from autogen_core.application import SingleThreadedAgentRuntime
+from autogen_core.base import AgentId, MessageContext
+from autogen_core.components import DefaultTopicId, default_subscription, message_handler
+
+
+@dataclass
+class Message:
+    content: str
+
+
+@default_subscription
+class TestAgent(SequentialRoutedAgent):
+    def __init__(self, description: str) -> None:
+        super().__init__(description=description)
+        self.messages: List[Message] = []
+
+    @message_handler
+    async def handle_content_publish(self, message: Message, ctx: MessageContext) -> None:
+        # Sleep a random amount of time to simulate processing time.
+        await asyncio.sleep(random.random() / 100)
+        self.messages.append(message)
+
+
+@pytest.mark.asyncio
+async def test_sequential_routed_agent() -> None:
+    runtime = SingleThreadedAgentRuntime()
+    runtime.start()
+    await TestAgent.register(runtime, type="test_agent", factory=lambda: TestAgent(description="Test Agent"))
+    test_agent_id = AgentId(type="test_agent", key="default")
+    for i in range(100):
+        await runtime.publish_message(Message(content=f"{i}"), topic_id=DefaultTopicId())
+    await runtime.stop_when_idle()
+    test_agent = await runtime.try_get_underlying_agent_instance(test_agent_id, TestAgent)
+    for i in range(100):
+        assert test_agent.messages[i].content == f"{i}"