Define a Python source which receives a reference to a subscriber

[dagardner-nv]

Description

• Allows a Python generator source to check if the subscriber is still subscribed.
• Define a class SubscriberFuncWrapper for Python sources rather than just a lambda. The reason is that python objects captured by the lambda need to be destroyed while the gil is held, which causes a problem if the lambda is destroyed unexpectedly.
• Update conftest.py to set the loglevel to DEBUG if the GLOG_v environment variable is defined.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[mdemoret-nv]

/merge

[codecov]

Codecov Report

Attention: Patch coverage is 73.07692% with 7 lines in your changes missing coverage. Please review.

Project coverage is 74.09%. Comparing base (ca8a73f) to head (4995873).
Report is 1 commits behind head on branch-24.10.

Files with missing lines	Patch %	Lines
python/mrc/_pymrc/src/segment.cpp	70.83%	7 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff                @@
##           branch-24.10     #496      +/-   ##
================================================
+ Coverage         74.06%   74.09%   +0.03%     
================================================
  Files               403      403              
  Lines             14403    14424      +21     
  Branches           1132     1134       +2     
================================================
+ Hits              10667    10688      +21     
  Misses             3736     3736              

Flag	Coverage Δ
cpp	70.69% <7.69%> (-0.12%)	⬇️
py	42.59% <79.16%> (+0.76%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
python/mrc/_pymrc/include/pymrc/segment.hpp	62.50% <ø> (ø)
python/mrc/core/segment.cpp	95.83% <100.00%> (+0.08%)	⬆️
python/mrc/_pymrc/src/segment.cpp	80.22% <70.83%> (-1.48%)	⬇️

... and 5 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ca8a73f...4995873. Read the comment docs.