feat: Add async streaming support in HuggingFaceLocalChatGenerator

[mdrazak2001]

Related Issues

• fixes In HuggingFaceLocalChatGenerator add an async version of HFTokenStreamHandler and update type signature for async streaming callback #9391

Proposed Changes:

• added async version of hugging face local streaming handler.

How did you test it?

• added a unit tes

Notes for the reviewer

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test: and added ! in case the PR includes breaking changes.
• I documented my code
• I ran pre-commit hooks and fixed any issue

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Pull Request Test Coverage Report for Build 15217439421

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Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 324 unchanged lines in 29 files lost coverage.
• Overall coverage decreased (-0.2%) to 90.258%

---

Files with Coverage Reduction	New Missed Lines	%
components/agents/init.py	1	75.0%
components/builders/answer_builder.py	1	98.53%
components/evaluators/sas_evaluator.py	1	62.3%
components/embedders/sentence_transformers_document_embedder.py	2	96.88%
components/embedders/sentence_transformers_text_embedder.py	2	96.43%
components/rankers/init.py	2	50.0%
tools/parameters_schema_utils.py	2	94.87%
utils/init.py	2	33.33%
components/converters/multi_file_converter.py	4	92.73%
components/generators/hugging_face_local.py	4	91.76%

Totals
Change from base Build 15067128089:	-0.2%
Covered Lines:	11387
Relevant Lines:	12616

---

💛 - Coveralls

[sjrl]

To make mypy happy could we add an assert here asserting that streaming_callback is of type AsyncStreamingCallbackT?

or update AsyncHFTokenStreamingHandler such that the type hint for stream_handler is StreamingCallbackT

[mpangrazzi]

I've left a comment below!

[mpangrazzi]

This method returns a coroutine, but if I look at this, it seems that TextStreamer will call it synchronously (and so coroutine will be not awaited).

In the test below I see you're working around this:

loop.call_soon_threadsafe(
    lambda: asyncio.create_task(streamer.on_finalized_text("Hello", stream_end=False))
)

but TextStreamer will call it like:

streamer.on_finalized_text("Hello", stream_end=False) 

I might be wrong, but have you tried testing it manually? You might need to do something like:

def on_finalized_text(self, word: str, stream_end: bool = False):
    word_to_send = word + "\n" if stream_end else word
    if word_to_send.strip() not in self.stop_words:
        # Schedule the async callback without returning the coroutine
        asyncio.create_task(self.token_handler(StreamingChunk(content=word_to_send)))

[mdrazak2001]

@mpangrazzi thank you for noticing and pointing out, had really missed this crucial implementation step!
have made the required change as well!