[pamod-madubashana]

Fixes #1459

What changed

Honours Python signal handlers (e.g. Ctrl+C / KeyboardInterrupt) while scanning from Python by calling py.check_signals() at iteration boundaries in vortex-python/src/iter/:

• PyArrayIterator::__next__ now checks signals with the GIL held before and after the detached chunk fetch, so each next() raises promptly if a signal arrived.
• read_all now pulls chunks one at a time, checking signals before each chunk (plus a final check), instead of running the whole scan inside a single detach with no signal checks.
• The to_arrow RecordBatchReader closure checks signals via Python::attach before converting each chunk, so pyarrow readers are interruptible too.
• PythonArrayIterator::next now implements the signal check its comment always promised, mapping a PyErr into a VortexError since only VortexResult is available there.

Why

Long scans run inside py.detach(...), which releases the GIL, so Python signal handlers never run and Ctrl+C appears to hang until the scan finishes. Checking signals wherever we already hold the GIL at chunk boundaries lets the interpreter raise KeyboardInterrupt between chunks without changing any scan semantics.

Verification

• cargo fmt -p vortex-python -- --check: clean (only stable-channel warnings about nightly-only options, no diff).
• cargo clippy -p vortex-python --all-targets -- -D warnings: could not compile in this environment — vortex-array's build script fails with failed to run flatc: No such file or directory (os error 2), a pre-existing missing FlatBuffers compiler unrelated to this change. For the same reason no Python test requiring the built extension could be run.

[robert3005]

I think this needs some testing?

[pamod-madubashana]

Added vortex-python/test/test_iter_signals.py covering all four check_signals sites: next(), read_all() (pending-signal early-abort plus a mid-scan SIGINT timing test), and the to_arrow record-batch reader. Each test queues a real SIGINT against a counting Python iterator and asserts the scan surfaces it promptly without consuming every chunk first. Note I could not run the suite locally (no built extension / flatc in this environment), so CI verification would be appreciated.

[github-actions]

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[pamod-madubashana]

Rebased onto latest develop and resolved the merge conflict in vortex-python/src/iter/mod.rs. Also fixed a type-inference error in PyArrayIterator::__next__ (annotated the py.detach closure as VortexResult<Option<PyArrayRef>>) and made test_iter_signals.py runnable (the original signal.raise_signal fired synchronously and aborted pytest; switched to background-thread delivery). Built the extension, ran cargo fmt/clippy (clean), and all 4 signal tests pass. Force-pushed the resolved branch.