framework to preserve optimistic_slot in blockstore

[jbiseda]

Problem

Latest optimistic_slot value is needed when coordinating a restart. This value can be lost if logging is disabled or logs are deleted.

Summary of Changes

blockstore column family changes to support storing optimistic slot information.

See #25311 for follow-on changes.

For release notes:
This change introduces a new rocksdb column family: optimistic_slots. If the validator software is subsequently downgraded the validator will fail to start with the following error:
'Failed to open ledger database: RocksDb(Error { message: "Invalid argument: Column families not opened: optimistic_slots" })'

This can be remedied by dropping the optimistic_slots column family. Use the ldb tool provided with the rocksdb distribution.

Confirm that the database contains the optimistic_slots column family:
ldb --db=<full_path_to_db_directory> list_column_families

Drop the optimistic_slots column family:
ldb --db=<full_path_to_db_directory> drop_column_family optimistic_slots

Fixes #

[codecov]

Codecov Report

Merging #25362 (f2fe1dd) into master (be1d606) will decrease coverage by 0.0%.
The diff coverage is 35.0%.

❗ Current head f2fe1dd differs from pull request most recent head 6116e88. Consider uploading reports for the commit 6116e88 to get more accurate results

@@            Coverage Diff            @@
##           master   #25362     +/-   ##
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- Coverage    82.1%    82.1%   -0.1%     
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  Files         616      616             
  Lines      169469   169489     +20     
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+ Hits       139161   139164      +3     
- Misses      30308    30325     +17     

[steviez]

Thanks for breaking this out into its' own PR - should make backporting much easier!

One thing - I think we should include the blockstore_purge.rs changes in this PR; we have precedent of doing this in the past, such as in #18897. Other than this, I think we're good. I'll hold off on my ship it as a double check for pulling in purge update

[steviez]

Also - I assume this will be end up being backported to v1.10 in order to provide compatibility with v1.11 (assuming the overall change will make it into master in time for v1.11)?

[jbiseda]

One thing - I think we should include the blockstore_purge.rs changes in this PR
I've added the purge changes here.

[steviez]

LGTM

[yhchiang-sol]

LGTM. Thanks for splitting the PRs to allow back-porting.

Left one comment that might be a potential follow-up in the next PR.