introduce UninterruptibleFrame frames

src/pipecat/frames/frames.py

@@ -186,6 +186,20 @@ class ControlFrame(Frame):
 #
 
 
+@dataclass
+class UninterruptibleFrame:
+    """A marker for data or control frames that must not be interrupted.
+
+    Frames with this mixin are still ordered normally, but unlike other frames,
+    they are preserved during interruptions: they remain in internal queues and
+    any task processing them will not be cancelled. This ensures the frame is
+    always delivered and processed to completion.
+
+    """
+
+    pass
+
+
 @dataclass
 class AudioRawFrame:
     """A frame containing a chunk of raw audio.

src/pipecat/processors/frame_processor.py

@@ -33,6 +33,7 @@ from pipecat.frames.frames import (
     InterruptionTaskFrame,
     StartFrame,
     SystemFrame,
+    UninterruptibleFrame,
 )
 from pipecat.metrics.metrics import LLMTokenUsage, MetricsData
 from pipecat.observers.base_observer import BaseObserver, FrameProcessed, FramePushed
@@ -211,6 +212,7 @@ class FrameProcessor(BaseObject):
         # The input task that handles all types of frames. It processes system
         # frames right away and queues non-system frames for later processing.
         self.__should_block_system_frames = False
+        self.__input_queue = FrameProcessorQueue()
         self.__input_event: Optional[asyncio.Event] = None
         self.__input_frame_task: Optional[asyncio.Task] = None
 
@@ -220,8 +222,10 @@ class FrameProcessor(BaseObject):
         # called. To resume processing frames we need to call
         # `resume_processing_frames()` which will wake up the event.
         self.__should_block_frames = False
+        self.__process_queue = asyncio.Queue()
         self.__process_event: Optional[asyncio.Event] = None
         self.__process_frame_task: Optional[asyncio.Task] = None
+        self.__process_current_frame: Optional[Frame] = None
 
         # To interrupt a pipeline, we push an `InterruptionTaskFrame` upstream.
         # Then we wait for the corresponding `InterruptionFrame` to travel from
@@ -805,8 +809,12 @@ class FrameProcessor(BaseObject):
                 # interruption). Instead we just drain the queue because this is
                 # an interruption.
                 self.__reset_process_task()
+            elif isinstance(self.__process_current_frame, UninterruptibleFrame):
+                # We don't want to cancel UninterruptibleFrame, so we simply
+                # cleanup the queue.
+                self.__reset_process_queue()
             else:
-                # Cancel and re-create the process task including the queue.
+                # Cancel and re-create the process task.
                 await self.__cancel_process_task()
                 self.__create_process_task()
         except Exception as e:
@@ -872,7 +880,6 @@ class FrameProcessor(BaseObject):
 
         if not self.__input_frame_task:
             self.__input_event = asyncio.Event()
-            self.__input_queue = FrameProcessorQueue()
             self.__input_frame_task = self.create_task(self.__input_frame_task_handler())
 
     async def __cancel_input_task(self):
@@ -890,9 +897,7 @@ class FrameProcessor(BaseObject):
             return
 
         if not self.__process_frame_task:
-            self.__should_block_frames = False
-            self.__process_event = asyncio.Event()
-            self.__process_queue = asyncio.Queue()
+            self.__reset_process_task()
             self.__process_frame_task = self.create_task(self.__process_frame_task_handler())
 
     def __reset_process_task(self):
@@ -902,10 +907,26 @@ class FrameProcessor(BaseObject):
 
         self.__should_block_frames = False
         self.__process_event = asyncio.Event()
+        self.__reset_process_queue()
+
+    def __reset_process_queue(self):
+        """Reset non-system frame processing queue."""
+        # Create a new queue to insert UninterruptibleFrame frames.
+        new_queue = asyncio.Queue()
+
+        # Process current queue and keep UninterruptibleFrame frames.
         while not self.__process_queue.empty():
-            self.__process_queue.get_nowait()
+            item = self.__process_queue.get_nowait()
+            if isinstance(item, UninterruptibleFrame):
+                new_queue.put_nowait(item)
             self.__process_queue.task_done()
 
+        # Put back UninterruptibleFrame frames into our process queue.
+        while not new_queue.empty():
+            item = new_queue.get_nowait()
+            self.__process_queue.put_nowait(item)
+            new_queue.task_done()
+
     async def __cancel_process_task(self):
         """Cancel the non-system frame processing task."""
         if self.__process_frame_task:
@@ -959,8 +980,12 @@ class FrameProcessor(BaseObject):
     async def __process_frame_task_handler(self):
         """Handle non-system frames from the process queue."""
         while True:
+            self.__process_current_frame = None
+
             (frame, direction, callback) = await self.__process_queue.get()
 
+            self.__process_current_frame = frame
+
             if self.__should_block_frames and self.__process_event:
                 logger.trace(f"{self}: frame processing paused")
                 await self.__process_event.wait()