[Feat] Facilitate RocksDB's secondary instances

[ljedrz]

This PR enables support for RocksDB's secondary instances. This could be used by all sorts of tools that require an insight into the storage of a running node.

Filing as a draft, as it depends on a pending aleo-std PR.

[vicsn]

secondary instances.

Very cool. Any evidence on how stable this is, or whether "read-only" instance historically had less bugs?

[ljedrz]

Any evidence on how stable this is

It has been stable since at least 2021.

whether "read-only" instance historically had less bugs?

Compared to a read-only primary instance? I don't think either is any more stable, and I'm not sure if a read-only primary instance can be used while a primary read/write session is in progress. Secondary instances are also better suited for continued use (via try_catch_up_with_primary).

[ljedrz]

The stability question reminded me that we're actually a bit behind in terms of the version of RocksDB we're using. I pushed a commit updating it to 0.24; I've also confirmed that snarkOS builds with it.

[ljedrz]

Hmm, not sure why the CI jobs are failing with a clang-related build error, it works for me locally, even without CXXFLAGS = "-include cstdint" (commented out in .cargo/config.toml).

In any case, an update isn't required for this feature; if I don't find a solution, I'll revert back to 0.21 when updating the aleo-std branch.