Enables hot reloading of mining configuration file

[xoloki]

Enables hot reloading of mining configuration file.

Prior to every mining burnchain transaction, the config file will be reloaded if its modified time is newer and the following settings will be reloaded:

burnchain.burn_fee_cap
burnchain.satoshis_per_byte
burnchain.rbf_fee_increment
burnchain.max_rbf
node.microblock_frequency
node.wait_time_for_microblocks

The following config file items, if missing, will be read from environment variables:

node.seed => STACKS_NODE_SEED
burnchain.username => STACKS_BURNCHAIN_USERNAME
burnchain.password => STACKS_BURNCHAIN_PASSWORD 

Addresses the following issues:

• Ability to change burn_fee_cap and satoshis_per_byte in config without restarting #2629
• Changing STX Mining Burn fee on the fly #3181

[codecov]

Codecov Report

Merging #3385 (29dd595) into develop (a4d4c3b) will decrease coverage by 1.65%.
The diff coverage is 51.20%.

@@             Coverage Diff             @@
##           develop    #3385      +/-   ##
===========================================
- Coverage    32.35%   30.69%   -1.66%     
===========================================
  Files          262      262              
  Lines       212722   212884     +162     
===========================================
- Hits         68816    65348    -3468     
- Misses      143906   147536    +3630     

Impacted Files	Coverage Δ
testnet/stacks-node/src/main.rs	0.52% <0.00%> (-0.02%)	⬇️
testnet/stacks-node/src/config.rs	45.41% <31.78%> (-3.57%)	⬇️
testnet/stacks-node/src/run_loop/neon.rs	79.76% <50.00%> (-0.59%)	⬇️
testnet/stacks-node/src/tests/neon_integrations.rs	62.99% <76.00%> (-22.02%)	⬇️
...-node/src/burnchains/bitcoin_regtest_controller.rs	85.47% <97.95%> (+0.24%)	⬆️
testnet/stacks-node/src/neon_node.rs	81.04% <100.00%> (-2.80%)	⬇️
testnet/stacks-node/src/tests/epoch_205.rs	98.03% <100.00%> (+<0.01%)	⬆️
src/cost_estimates/fee_medians.rs	0.00% <0.00%> (-92.38%)	⬇️
src/cost_estimates/fee_rate_fuzzer.rs	0.00% <0.00%> (-60.87%)	⬇️
... and 54 more

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[igorsyl]

Can you run stacks-node with a mock miner configuration to test the config reloading?

[xoloki]

Can you run stacks-node with a mock miner configuration to test the config reloading?

Sure, do you want me to write an integration test or just run it by hand and check?

[igorsyl]

Sure, do you want me to write an integration test or just run it by hand and check?

Integration test would be sweet!

[jcnelson]

You probably don't need (or want) RefCell here.

[xoloki]

RefCell removed from ConfigHandle and ConfigLoaderHandle.

[jcnelson]

On the whole, it's not clear to me why there needs to be a shared ConfigHandle structure. The miner thread could simply load up the config file itself each time it gets spawned, which would obviate the need for any shared state in RAM. It's not like it takes an extraordinary amount of time (especially when compared to mining).

[pavitthrap]

Closing for now, might resume progress in future.