Attempt to skip redundant startup account verification

[bw-solana]

Problem

We potentially run accounts hash/capitalization verification from two places at almost the same time, which seems wasteful and appears to slow down startup by ~30 seconds (Takes ~2 minutes on current master and ~1.5 minutes after this change). Here is the call stack for each:

Summary of Changes

Wait for any existing verifications to complete. Only check capitalization from process_blockstore_from_root in the event we loaded frozen bank forks

[steviez]

Only check capitalization from process_blockstore_from_root in the event we loaded frozen bank forks

I think this is right / a valid adjustment to make:

• Unpacking the snapshot will check cap. on the snapshot slot
• So, we only need to check cap again on BankForks::root_bank() in the scenario that the root bank has been updated in load_frozen_forks()

Hypothetically, we could have a SlotMeta for snapshot slot, but not be able to process any further (ie incomplete slots). Something you could do to cover this case would be to

• Grab the new root_bank after calling load_frozen_forks()
• Run the cap. check only if new_root_bank.slot() != start_slot, recalling that start_slot is the slot from root_bank at the start of things

instead of moving the cap. check inside the if let Some(start_meta_slot) ... block

[jeffwashington]

I'd like to separate out the wait for the bg hash calc:
#27145
This keeps the 2 issues separate and makes both prs simple.

Pull request has been modified.

[jeffwashington]

@carllin I roped you in.

[carllin]

Yeah this seems fine, good catch! The redundant check in blockstore_processor was added here: #11927

at which time the existing snapshot verification also already existed https://github.com/ryoqun/solana/blob/95cb371ecd6ba8dfb0527ee4e828081c1d0e937f/runtime/src/snapshot_utils.rs#L591