PoH use bank_id instead of slot - stronger guarantee on bank not being switcharoo'd

[apfitzge]

Problem

• Alpenglow plans to allow us to switch parent mid slot
• That would lead to a race condition:

1. worker begins executing txs on bank with slot N
2. parent switch initiates
3. "poh" shutdown channel, flushes, switches bank.
4. worker finishes execution, goes to record - succeeds because the slot is the same

• The issue here is that PoH only checks equivalence on Slot.

Summary of Changes

• Use BankId instead of Slot for checks on poh channels && recorder

Fixes #

[codecov-commenter]

Codecov Report

❌ Patch coverage is 98.87640% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 83.2%. Comparing base (ee1b5d0) to head (a69a22f).
⚠️ Report is 39 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #8433   +/-   ##
=======================================
  Coverage    83.2%    83.2%           
=======================================
  Files         839      839           
  Lines      367808   367815    +7     
=======================================
+ Hits       306072   306082   +10     
+ Misses      61736    61733    -3     

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[apfitzge]

As an FYI, afaict this is not a new race introduced by the recent poh changes. Since we've always only gated poh-recording on the working bank's slot.

[bw-solana]

I suppose it's all u64 in the end, but should this be BankId?

[apfitzge]

🫠 I actually wish these were different types because it's really annoying that they can be passed/confused for one another.

Yes.

[apfitzge]

Cool I think there are no more mismatches:

$ rg "Slot" | rg "bank_id"
runtime/src/prioritization_fee_cache.rs:    pub fn finalize_priority_fee(&self, slot: Slot, bank_id: BankId) {
accounts-db/src/accounts_db.rs:    pub fn purge_slot(&self, slot: Slot, bank_id: BankId, is_serialized_with_abs: bool) {
accounts-db/src/accounts_index.rs:    SlotRemoved { slot: Slot, bank_id: BankId },