v19.12.0

This release contains some stability improvements, and enables priority flooding for Soroban.

Stability improvements

• Switch LedgerTxn instances to read-only in overlay
• Soroban flooding and tx set construction followup
• Add max tx count for Soroban network settings
• Cleanup functions used in test builds only

New features

• Flooding, tx limiting and tx set construction strategy for Soroban
  This change enables Core to throttle and prioritize Soroban specific transactions. During flooding and tx set building, Soroban transactions are compared with each other, separate from classic transactions.

Soroban (only enabled in vNext, not enabled in default build)

• Disable autobump by default
• bump env for wasmi bump
• Expire entries
• Update default network configs for contract costs; bump limits
• RestoreFootprintOp
• Update env and xdr
• Bump Soroban env & XDR.
• Bump XDR in Core and fix build.
• Wire up soroban PRNG seed from txset hash, tx and op numbers.
• State expiration v5 rebased
• Ensure we can always find txs to evict in tx limiter
• Updates corresponding to the Soroban auth XDR changes.
• Bump env and add xdr mismatch check back in

Breaking changes

None