Feat: reload from config for up-to-date satoshis_per_byte

[tippenein]

feat #4047

introduces get_satoshis_per_byte fn for fetching most up to date value from config

[CLAassistant]

All committers have signed the CLA.

[tippenein]

I'm not sure if it's desirable to do file reads every time a function needs spb but maybe it's nbd?

[wileyj]

@tippenein can you change the target branch to develop? you may need to rebase

[jcnelson]

Do you think this could be an instance method of Config, and take &self?

[tippenein]

There's one usage on the LeaderBlockCommitFees impl that prevented me from doing this

[jcnelson]

Thank you for sending this PR @tippenein! It looks pretty good to me; just had a few of small comments that are easily addressed. EDIT: Also, I agree with @wileyj that this will need to be rebased on develop, since that's where all new non-consensus-breaking features land (i.e. we follow the gitflow branch model).

Do you think you could add some test coverage? A unit test that verifies that get_satoshis_per_byte() works as intended would suffice. Thanks!

[jcnelson]

@tippenein I'm not sure if it's desirable to do file reads every time a function needs spb but maybe it's nbd?

Given how small the config file is, and how often it'll be loaded, it's probably going to be resident in at least the kernel's block cache in perpetuity. It's not a big deal at all :)

[codecov]

Codecov Report

Attention: 47 lines in your changes are missing coverage. Please review.

Comparison is base (e6d2342) 0.04% compared to head (a6a75f2) 0.04%.
Report is 2 commits behind head on develop.

Files	Patch %	Lines
...-node/src/burnchains/bitcoin_regtest_controller.rs	0.00%	36 Missing ⚠️
testnet/stacks-node/src/config.rs	0.00%	11 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##           develop    #4061    +/-   ##
=========================================
  Coverage     0.04%    0.04%            
=========================================
  Files          401      401            
  Lines       287322   286810   -512     
=========================================
  Hits           136      136            
+ Misses      287186   286674   -512     

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[jcnelson]

LGTM! Thanks for this PR!

[kantai]

This LGTM, but can you add a CHANGELOG.md entry?

[jcnelson]

Congratulations on your first accepted PR @tippenein! 🥳

[cylewitruk]

Congrats, @tippenein :D Welcome :)