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https://github.com/run-llama/create-llama.git
synced 2026-07-18 21:14:37 -04:00
Huu Le
67 lines
2.1 KiB
Python
67 lines
2.1 KiB
Python
import logging
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from typing import List, Optional
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from llama_index.core.workflow.handler import WorkflowHandler
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from app.api.callbacks.base import EventCallback
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logger = logging.getLogger("uvicorn")
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class StreamHandler:
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"""
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Streams events from a workflow handler through a chain of callbacks.
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"""
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def __init__(
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self,
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workflow_handler: WorkflowHandler,
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callbacks: Optional[List[EventCallback]] = None,
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):
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self.workflow_handler = workflow_handler
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self.callbacks = callbacks or []
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self.accumulated_text = ""
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def vercel_stream(self):
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"""Create a streaming response with Vercel format."""
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from app.api.routers.vercel_response import VercelStreamResponse
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return VercelStreamResponse(stream_handler=self)
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async def cancel_run(self):
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"""Cancel the workflow handler."""
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await self.workflow_handler.cancel_run()
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async def stream_events(self):
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"""Stream events through the processor chain."""
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try:
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async for event in self.workflow_handler.stream_events():
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# Process the event through each processor
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for callback in self.callbacks:
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event = await callback.run(event)
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yield event
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# After all events are processed, call on_complete for each callback
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for callback in self.callbacks:
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result = await callback.on_complete(self.accumulated_text)
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if result:
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yield result
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except Exception as e:
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# Make sure to cancel the workflow on error
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await self.workflow_handler.cancel_run()
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raise e
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async def accumulate_text(self, text: str):
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"""Accumulate text from the workflow handler."""
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self.accumulated_text += text
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@classmethod
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def from_default(
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cls,
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handler: WorkflowHandler,
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callbacks: Optional[List[EventCallback]] = None,
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) -> "StreamHandler":
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"""Create a new instance with the given workflow handler and callbacks."""
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return cls(workflow_handler=handler, callbacks=callbacks)
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