test(dursto): add snapshots pruning option for long tests

[victor-dumitrescu]

Closes RV-1008.

What

Adds the --keep-epochs N option for the long tests which, upon finishing a test epoch:

• deletes every commit except the N most recent ones from the on-disk repo (for the Database<PersistenceLayer, Normal> and TracedDatabase<PersistenceLayer, Normal>)
• removes every in-memory snapshot except the N most recent ones from the in-memory repo (for the TracedDatabase<InMemoryKeyValueStore, Normal>)

Next:

• test(dursto): run Database long test nightly #1092

Why

Older data is not required for failure replay. This significantly reduces the rate at which the long test uses disk and memory. Another benefit is that it confers a degree of confidence that a future disk GC solution implementing similar behaviour does not cause unexpected failures.

Manually Testing

Run

cargo run --release --features rocksdb,unstable-test-utils --bin database_long_test -- test --epochs 10 --ops-per-epoch 100 --cases-per-epoch 20 --keep-epochs 5

and compare the size of the repo shown at the end of the test with a re-run of the same test (using the seed printed by the previous run) without passing --keep-epochs:

cargo run --release --features rocksdb,unstable-test-utils --bin database_long_test -- test --epochs 10 --ops-per-epoch 100 --cases-per-epoch 20 --seed XXXX

Tasks for the Author

• Link all Linear issues related to this MR using magic words (e.g. part of, relates to, closes).
• Eliminate dead code and other spurious artefacts introduced in your changes.
• Document new public functions, methods and types.
• Make sure the documentation for updated functions, methods, and types is correct.
• Add tests for bugs that have been fixed.
• Explain changes to regression test captures when applicable.
• Write commit messages in agreement with our guidelines.
• Self-review your changes to ensure they are high-quality.
• Complete all of the above before assigning this MR to reviewers.

[codecov]

Codecov Report

❌ Patch coverage is 63.63636% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.92%. Comparing base (8b8098f) to head (2b539a3).

Files with missing lines	Patch %	Lines
durable-storage/src/long_test/mod.rs	62.50%	6 Missing and 3 partials ⚠️
durable-storage/src/bin/database_long_test.rs	0.00%	2 Missing ⚠️
durable-storage/src/storage/in_memory.rs	85.71%	0 Missing and 1 partial ⚠️

❌ Your patch check has failed because the patch coverage (63.63%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1090      +/-   ##
==========================================
- Coverage   89.96%   89.92%   -0.04%     
==========================================
  Files         135      135              
  Lines       29217    29240      +23     
  Branches    29217    29240      +23     
==========================================
+ Hits        26284    26294      +10     
- Misses       2110     2125      +15     
+ Partials      823      821       -2     

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[github-actions]

Benchmark results for revision d79689f:

Metric	Duration	TPS
Mean	1.472130781s	27.172
Worst	1.483211511s	26.969
Best	1.46651951s	27.275
Standard Deviation	±4.67048ms	±0.086

Full results

Run	Transfers	Duration	TPS
1	40	1.480195335s	27.023
2	40	1.480106764s	27.025
3	40	1.474379949s	27.130
4	40	1.483211511s	26.969
5	40	1.469029942s	27.229
6	40	1.471933553s	27.175
7	40	1.473533172s	27.146
8	40	1.469451523s	27.221
9	40	1.471205507s	27.189
10	40	1.468236775s	27.244
11	40	1.474901218s	27.120
12	40	1.46672387s	27.272
13	40	1.46651951s	27.275
14	40	1.466624537s	27.274
15	40	1.470174617s	27.208
16	40	1.468986851s	27.230
17	40	1.469320367s	27.223
18	40	1.475551757s	27.109
19	40	1.473654597s	27.143
20	40	1.468874256s	27.232

Compare the results above with those for the default branch.