llama-stack-mirror/llama_stack/distribution/utils/context.py
Nathan Weinberg bbe0199bb7
chore: update pre-commit hook versions (#2708)
While investigating the `uv.lock` changes made in
https://github.com/meta-llama/llama-stack/pull/2695 I noticed several of
the pre-commit hook versions were out of date

This PR updates them and fixes some new `ruff` errors

---------

Signed-off-by: Nathan Weinberg <nweinber@redhat.com>
2025-07-10 16:47:59 +02:00

40 lines
1.4 KiB
Python

# Copyright (c) Meta Platforms, Inc. and affiliates.
# All rights reserved.
#
# This source code is licensed under the terms described in the LICENSE file in
# the root directory of this source tree.
from collections.abc import AsyncGenerator
from contextvars import ContextVar
def preserve_contexts_async_generator[T](
gen: AsyncGenerator[T, None], context_vars: list[ContextVar]
) -> AsyncGenerator[T, None]:
"""
Wraps an async generator to preserve context variables across iterations.
This is needed because we start a new asyncio event loop for each streaming request,
and we need to preserve the context across the event loop boundary.
"""
# Capture initial context values
initial_context_values = {context_var.name: context_var.get() for context_var in context_vars}
async def wrapper() -> AsyncGenerator[T, None]:
while True:
try:
# Restore context values before any await
for context_var in context_vars:
context_var.set(initial_context_values[context_var.name])
item = await gen.__anext__()
# Update our tracked values with any changes made during this iteration
for context_var in context_vars:
initial_context_values[context_var.name] = context_var.get()
yield item
except StopAsyncIteration:
break
return wrapper()