INDY-1924: Catchup and audit design proposal

[skhoroshavin]

Signed-off-by: Sergey Khoroshavin sergey.khoroshavin@dsr-corporation.com

[sovbot]

Can one of the admins verify this patch?

[skhoroshavin]

(ci) test this please

[lovesh]

Why create a separate ledger? Why not persist viewNo and ppSeqNo in the respective ledger apart from storing other ledger's root hash if it had changed. Then building a total order across txns is same as building a single sorted list from multiple sorted lists. So for example domain ledger looks like this

Domain ledger Batch1
     (viewNo1, ppSeqNo1, pool root, config root)  // part of domain ledger merkle tree as a leaf, like any other txn but with some special designator to differentiate it from txns.
     domain txn 1
     domain txn 2
Domain ledger Batch2
     (viewNo1, ppSeqNo2)    // no change in pool or config ledger
     domain txn 3
     domain txn 4
     domain txn 5
Domain ledger Batch4    // batch 3 was for config ledger
     (viewNo1, ppSeqNo4, config root)    // config ledger changed config; ledger new root (part of domain ledger merkle tree a leaf, like any other txn)
     domain txn 6
     domain txn 7