fix: process_video silent hang on callback error

[realh4m]

Description

Added exception tracking in process_video so callback errors raised in the worker loop are surfaced after reader/writer threads finish, preventing silent hangs when the callback crashes mid-stream.

Introduced read_finished to avoid draining the read queue unnecessarily once EOF is reached.

• Issue: Fixes the silent failure where process_video could hang without any error when the callback raised an exception.
• Dependencies: None.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

How has this change been tested, please provide a testcase or example of how you tested the change?

Verified locally with a callback that raises an exception.

Any specific deployment considerations

No additional considerations; behavior change only affects process_video error handling.

Docs

• Docs updated? What were the changes:

[CLAassistant]

All committers have signed the CLA.

[Borda]

@realh4m, thank you for your contribution and suggested fix. Could you also include a test to verify that it resolves the issue? 🦩

[Copilot]

Pull request overview

This PR fixes a silent hang issue in process_video when the callback function raises an exception during video processing. The fix ensures that exceptions are caught, the pipeline is properly shut down, and the error is re-raised to the caller.

Changes:

• Added exception tracking (exception_in_worker) to capture and re-raise callback errors
• Introduced read_finished flag to conditionally drain the read queue in the finally block
• Modified the finally block to drain remaining frames from the read queue when an exception occurs, preventing deadlock

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[realh4m]

Thank you for the feedback. I've added unit tests in test/utils/test_video.py to verify that process_video now correctly raises exceptions without hanging. I also included tests for general video utility functions and fixed a minor typo in the process_video docstring. All tests passed successfully.

[codecov]

Codecov Report

❌ Patch coverage is 79.31034% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 60%. Comparing base (7bf03f5) to head (0830888).
⚠️ Report is 5 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #2022   +/-   ##
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+ Coverage       59%     60%   +1%     
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  Files           61      61           
  Lines         7086    7108   +22     
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+ Hits          4193    4287   +94     
+ Misses        2893    2821   -72     

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[SkalskiP]

Hi @realh4m 👋🏻 Thanks a lot for your interest in supervision drafting this PR. I'm actually working on slightly deper rewrite of that whole function, here: #2102.

I want to keep the trace of your contribution so I'll most likely merge my changes into your branch once I'm done, and we will merge it from here.

[realh4m]

Sounds good. I'll wait for your updates. Thanks.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

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[Borda]

@SkalskiP I would be in favor of merging this one as is, since it adds a handful of tests. If you have a better refactor, you can still overwrite/replace it with yours...