Misson Control Store: Improve performance

[matheusd]

The current implementation of the Misson Control Store has a one second ticker that trims the DB, ensuring only the latest 1000 entries are kept.

That ticker was added in https://github.com/lightningnetwork/lnd/pull/5515 as a way to improve performance by batching and de-duplicating the updates to the db.

However, its current implementation can be significantly improved by doing a few pointed changes. In particular:

1. There is no need to open a db tx when there is no work.
2. The ticker does not need to run continuously, only when there are items in the queue that need to be persisted.
3. The current implementation duplicates the entire in-memory cache of the store, which is not ideal when there are only a few entries that need to be added

This PR improves the situation iteratively on each commit. A set of benchmarks is added to verify the performance improvement.

This is the final result (using a bbolt MC store):

MissionControlStoreFlushing/no_additional_results-7      221µs ±15%       0µs ± 2%   -99.86%  (p=0.000 n=10+10)
MissionControlStoreFlushing/one_additional_result-7      359µs ±40%      44µs ± 8%   -87.87%  (p=0.000 n=10+10)
MissionControlStoreFlushing/ten_additional_results-7     344µs ± 9%     129µs ±29%   -62.61%  (p=0.000 n=9+10)
MissionControlStoreFlushing/100_additional_results-7     987µs ±28%     621µs ±22%   -37.06%  (p=0.000 n=10+10)
MissionControlStoreFlushing/250_additional_results-7    2.02ms ±37%    1.53ms ±41%   -24.62%  (p=0.005 n=10+10)
MissionControlStoreFlushing/500_additional_results-7    2.88ms ±11%    2.84ms ±18%      ~     (p=0.780 n=9+10)

name                                                  old alloc/op   new alloc/op   delta
MissionControlStoreFlushing/no_additional_results-7      139kB ± 0%       0kB       -100.00%  (p=0.000 n=10+10)
MissionControlStoreFlushing/one_additional_result-7      153kB ± 0%      19kB ± 0%   -87.37%  (p=0.000 n=10+10)
MissionControlStoreFlushing/ten_additional_results-7     175kB ± 0%      41kB ± 0%   -76.35%  (p=0.000 n=8+8)
MissionControlStoreFlushing/100_additional_results-7     350kB ± 0%     222kB ± 0%   -36.63%  (p=0.000 n=10+10)
MissionControlStoreFlushing/250_additional_results-7     651kB ± 0%     535kB ± 0%   -17.75%  (p=0.000 n=8+10)
MissionControlStoreFlushing/500_additional_results-7    1.14MB ± 0%    1.04MB ± 0%    -8.57%  (p=0.000 n=10+10)

name                                                  old allocs/op  new allocs/op  delta
MissionControlStoreFlushing/no_additional_results-7      1.06k ± 0%     0.00k       -100.00%  (p=0.000 n=10+10)
MissionControlStoreFlushing/one_additional_result-7      1.15k ± 0%     0.12k ± 0%   -90.02%  (p=0.000 n=10+10)
MissionControlStoreFlushing/ten_additional_results-7     1.49k ± 0%     0.46k ± 0%   -69.36%  (p=0.000 n=10+10)
MissionControlStoreFlushing/100_additional_results-7     4.90k ± 0%     3.87k ± 0%   -21.07%  (p=0.000 n=10+10)
MissionControlStoreFlushing/250_additional_results-7     10.6k ± 0%      9.6k ± 0%    -9.75%  (p=0.000 n=10+10)
MissionControlStoreFlushing/500_additional_results-7     20.1k ± 0%     19.1k ± 0%    -5.15%  (p=0.000 n=9+10)

As can be seen, there is a significant improvement in cpu and memory usage when up to 100 additional results are added (i.e. up to 100 txs/second flowing through the node).

The improvement is specially significant when no new results are added to a full MC store, which is relevant for nodes that have a low or only episodic volument of payments (e.g. a mostly end user node or mobile node).

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[matheusd]

Going through the lint/CI failures now, might need some refactoring to deal with the type checks required from using non-generic *list.List

[matheusd]

Lint issues are fixed, I believe the other CI failures are just flakes.

[matheusd]

@bitromortac sent commit https://github.com/lightningnetwork/lnd/pull/8549/commits/fb4367831fe8766f64e20288a9ab110304ce2f36 to clean up the mission control tests and address your comments.

Also rebased to address the conflict.

[lightninglabs-deploy]

@bitromortac: review reminder @matheusd, remember to re-request review from reviewers when ready

[matheusd]

@ellemouton Thank you for the thorough review! I believe I addressed all of your points.

Also, rebased against current master.

Not sure what to do about the release notes, given the v0.18 RCs are already out (move to v0.19 or v0.18.1 or something else).

[ellemouton]

thanks for the quick turn around! I'll check it out soon.

im also not sure re release notes.... cc @saubyk for that :)

[saubyk]

tagged for 18.1

[saubyk]

tagged for 18.1

On a second thought, 18.1 is already getting bloated and this doesn't seem urgent so moving to 0.19

[matheusd]

Removed commit with type safety and moved release notes to v0.19.0.md.

[ellemouton]

@matheusd - note the failing linter check

[matheusd]

Sorry for the misses. Updated.

[lightninglabs-deploy]

@matheusd, remember to re-request review from reviewers when ready

[ellemouton]

@saubyk - happy for this to be merged? I think it is g2g

[saubyk]

Tagged for 18.1. Release notes need update

[ellemouton]

@matheusd - thanks for your patience 🙏 I think we wanna move this to 0.18.1 instead of 0.19 so do you mind doing one last update and moving the release notes to the 0.18.1 doc pls?

[matheusd]

Updated

[ellemouton]

oh no @matheusd - looks like there is a merge conflict 🙈 one more rebase pls 🙏 will then merge this asap so that this can be the last one!