Muawiya-contact opened a new pull request, #363:
URL: https://github.com/apache/hugegraph-ai/pull/363
## Summary
Fixes a control-flow fall-through in `Scheduler.schedule_stream_flow` that
caused
the flow to be built, run, and streamed **twice** when no reusable pipeline
exists (`manager.fetch()` returns `None`).
Closes #360.
## Root cause
The `if pipeline is None:` branch builds a fresh pipeline, runs it, streams
the
result via `post_deal_stream`, and caches it with `manager.add(pipeline)` —
but
it was missing a `return` at the end. Execution therefore fell straight
through
into the reuse `try` block below, where the just-built (now non-`None`)
pipeline
was prepared and run a second time.
Impact: duplicate pipeline execution, extra LLM calls, and doubled streaming
output on the first call for a given flow.
The synchronous counterpart `schedule_flow` does not have this bug because
its
`if pipeline is None:` branch ends with an explicit `return res`.
## Fix
Add a bare `return` after `manager.add(pipeline)` in the `if pipeline is
None:`
branch, so the build/run/stream path terminates instead of falling through.
A bare `return` is used (not `return res`) because `schedule_stream_flow` is
an
async generator, where `return <value>` is not allowed.
## Tests
Adds `hugegraph-llm/src/tests/flows/test_scheduler.py` (Layer A / `unit`
marker,
no Docker, network, or real LLM):
- `test_stream_flow_runs_once_when_no_reusable_pipeline` — forces
`manager.fetch()` to return `None` and asserts the flow is built,
initialized,
run, and streamed **exactly once**, the stream output is not duplicated,
`manager.add` is called once, and the reuse/release path (`prepare` /
`release`) is never entered. This test fails on the previous code and
passes
with the fix.
- `test_stream_flow_rejects_unknown_flow_name` — covers the `ValueError`
guard
for unsupported flow names.
The `Scheduler` is instantiated via `__new__` with a single mocked pool
entry to
avoid eagerly constructing every real flow/manager in `__init__`.
## How to verify locally
```bash
uv sync --extra llm --extra dev
uv run pytest hugegraph-llm/src/tests/flows/test_scheduler.py -v
uv run ruff format --check .
uv run ruff check .
```
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