fix: make timer operations work with golang 1.23

[gammazero]

In golang 1.23 reading a timer's channel after calling timer.Stop will block forever. This is fixed by looking at the timer's channel capacity to determine if the channel may need to be read following a Stop.

[codecov]

Codecov Report

Attention: Patch coverage is 73.33333% with 4 lines in your changes missing coverage. Please review.

Project coverage is 60.20%. Comparing base (51da02f) to head (789ea52).
Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
mfs/repub.go	84.61%	2 Missing ⚠️
gateway/backend_car_traversal.go	0.00%	0 Missing and 1 partial ⚠️
provider/reprovider.go	0.00%	0 Missing and 1 partial ⚠️

@@            Coverage Diff             @@
##             main     #667      +/-   ##
==========================================
+ Coverage   60.18%   60.20%   +0.01%     
==========================================
  Files         241      241              
  Lines       30707    30707              
==========================================
+ Hits        18482    18486       +4     
+ Misses      10575    10570       -5     
- Partials     1650     1651       +1     

Files with missing lines	Coverage Δ
gateway/backend_car_traversal.go	72.72% <0.00%> (ø)
provider/reprovider.go	68.16% <0.00%> (ø)
mfs/repub.go	80.61% <84.61%> (+1.02%)	⬆️

... and 13 files with indirect coverage changes

[Stebalien]

Note: it looks like go is fixing this upstream, so it might not be worth it to add this workaround.

[gammazero]

Even so, clearing the channel is not necessary. The timeout of 1 hour immediately followed by Stop means the timer will never fire, so no need to read from the channel.

[Stebalien]

Even so, clearing the channel is not necessary. The timeout of 1 hour immediately followed by Stop means the timer will never fire, so no need to read from the channel.

Yeah, but I prefer to make code timing independent. Any reason not to just wait for 1.24, then bump the minimum go requirement to 1.23 to completely fix the race?

[gammazero]

@Stebalien I made the code time independent. This PR is still needed since there are places where the timer channel is read following a Stop, and this breaks with go1.23.

[Stebalien]

@gammazero golang/go#69312? My understanding is that this is going to be fixed in a patch release very soon.

[gammazero]

Will wait for go fix. Until then, the problem can be avoided by running with GODEBUG="asynctimerchan=1"