During reorganisations, it is possible that dependencies get add which
result in clusters that violate limits (count, size), when linking the
new from-block transactions to the old from-mempool transactions.
Unlike RBF scenarios, we cannot simply reject these policy violations
when they are due to received blocks. To accomodate this, add a Trim()
function to TxGraph, which removes transactions (including descendants)
in order to make all resulting clusters satisfy the limits.
In the initial version of the function added here, the following approach
is used:
- Lazily compute a naive linearization for the to-be-merged cluster (using
an O(n log n) algorithm, optimized for far larger groups of transactions
than the normal linearization code).
- Initialize a set of accepted transactions to {}
- Iterate over the transactions in this cluster one by one:
- If adding the transaction to the set makes it exceed the max cluster size
or count limit, stop.
- Add the transaction to the set.
- Remove all transactions from the cluster that were not included in the set
(note that this necessarily includes all descendants too, because they
appear later in the naive linearization).
Co-authored-by: Greg Sanders <gsanders87@gmail.com>
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