catchup: pause on round

[algoganesh]

Summary

We want the ability to pause a node on a particular round.

• goal node start --round <round>
• algod -round <round> Starts the node and only catches up to the block number <round>

Test Plan

[codecov[bot]]

Codecov Report

Merging #4060 (6258402) into master (9237316) will decrease coverage by 0.05%. The diff coverage is 43.18%.

@@            Coverage Diff             @@
##           master    #4060      +/-   ##
==========================================
- Coverage   54.55%   54.49%   -0.06%     
==========================================
  Files         391      391              
  Lines       48665    48707      +42     
==========================================
- Hits        26549    26545       -4     
- Misses      19890    19932      +42     
- Partials     2226     2230       +4     

Impacted Files	Coverage Δ
cmd/algod/main.go	0.00% <0.00%> (ø)
daemon/algod/server.go	4.96% <0.00%> (-0.04%)	:arrow_down:
node/node.go	23.01% <0.00%> (-1.95%)	:arrow_down:
nodecontrol/NodeController.go	22.85% <ø> (ø)
nodecontrol/algodControl.go	3.92% <0.00%> (-0.08%)	:arrow_down:
cmd/goal/node.go	11.14% <50.00%> (+0.23%)	:arrow_up:
catchup/service.go	68.11% <58.06%> (-1.27%)	:arrow_down:
ledger/roundlru.go	90.56% <0.00%> (-5.67%)	:arrow_down:
ledger/tracker.go	74.45% <0.00%> (-2.17%)	:arrow_down:
agreement/cryptoVerifier.go	67.60% <0.00%> (-2.12%)	:arrow_down:
... and 6 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 9237316...6258402. Read the comment docs.

[algonautshant]

This is a very intrusive change in a critical path of the node's function. Is there a document making the business case for this feature?

[winder]

This is a very intrusive change in a critical path of the node's function. Is there a document making the business case for this feature?

Thanks for looking Shant. Do you know of a less intrusive way?

This feature solves several problems:

1. We would use it for Indexer, where we need to initialize a ledger to a particular round.
2. People who need to observe account state at a particular round would now be able to do so.
3. When troubleshooting issues, it's frequently useful to setup a node to a particular round before attaching a debugger and inspecting the behavior.
4. Automated tests could leverage this functionality to be more deterministic.

[algonautshant]

In order to achieve these objectives, stopping/pausing at the catchup will work as long as the node is behind the most recent block. Once at the edge, the agreement service will start adding blocks to the ledger.

[algorandskiy]

What we want to accomplish with this? To allow developers to debug their contracts at round? Or something else?

[winder]

What we want to accomplish with this? To allow developers to debug their contracts at round? Or something else?

@algorandskiy It's an added capability like dev-mode that gives us more control over algod. Here are some use cases: https://github.com/algorand/go-algorand/pull/4060#issuecomment-1150351779