Also improve test coverage for removeForReorg by creating a scenario where
there are in-mempool descendants that are only invalidated due to an in-mempool
parent no longer spending a mature coin.
Previously we would sanity check the -maxmempool configuration based on a
multiple of the descendant size limit, but with cluster mempool the maximum
evicted size is now the cluster size limit, so use that instead.
Also allow -maxmempool=0 in general (and not just if
-limitdescendantsize/-limitclustersize is set to 0).
We use CompareMiningScoreWithTopology() for sorting transaction announcements
during tx relay, and we use GetSortedScoreWithTopology() in
CTxMemPool::check().
Calculating mempool ancestors for a new transaction should not be done until
after cluster size limits have been enforced, to limit CPU DoS potential.
Achieve this by reworking TRUC and RBF validation logic:
- TRUC policy enforcement is now done using only mempool parents of
new transactions, not all mempool ancestors (note that it's fine to calculate
ancestors of in-mempool transactions, if the number of such calls is
reasonably bounded).
- RBF replacement checks are performed earlier (which allows for checking
cluster size limits earlier, because cluster size checks cannot happen until
after all conflicts are staged for removal).
- Verifying that a new transaction doesn't conflict with an ancestor now
happens later, in AcceptSingleTransaction() rather than in PreChecks(). This
means that the test is not performed at all in AcceptMultipleTransactions(),
but in package acceptance we already disallow RBF in situations where a
package transaction has in-mempool parents.
Also to ensure that all RBF validation logic is applied in both the single
transaction and multiple transaction cases, remove the optimization that skips
the PackageMempoolChecks() in the case of a single transaction being validated
in AcceptMultipleTransactions().
Now that ancestor calculation never fails (due to ancestor/descendant limits
being eliminated), we can eliminate the error handling from
CalculateMemPoolAncestors.
With the descendant size limits removed, replace the concept of "max number of
descendants of any ancestor of a given tx" with the cluster count of the cluster
that the transaction belongs to.
The mempool clusters and linearization permit sorting the mempool topologically
without making use of ancestor counts (as long as the graph is not oversized).
Co-authored-by: Pieter Wuille <pieter@wuille.net>
Previously, transaction batches were first sorted by ancestor count and then
feerate, to ensure transactions are announced in a topologically valid order,
while prioritizing higher feerate transactions. Ancestor count is a crude
topological sort criteria, so replace this with linearization order so that the
highest feerate transactions (as would be observed by the mining algorithm) are
relayed before lower feerate ones, in a topologically valid way.
This also fixes a test that only worked due to the ancestor-count-based sort
order.
With a total ordering on mempool transactions, we are now able to calculate a
transaction's mining score at all times. Use this to improve the RBF logic:
- we no longer enforce a "no new unconfirmed parents" rule
- we now require that the mempool's feerate diagram must improve in order
to accept a replacement
- the topology restrictions for conflicts in the package rbf setting have been
eliminated
Revert the temporary change to mempool_ephemeral_dust.py that were previously
made due to RBF validation checks being reordered.
Co-authored-by: Gregory Sanders <gsanders87@gmail.com>, glozow <gloriajzhao@gmail.com>
Rather than evicting the transactions with the lowest descendant feerate,
instead evict transactions that have the lowest chunk feerate.
Once mining is implemented based on choosing transactions with highest chunk
feerate (see next commit), mining and eviction will be opposites, so that we
will evict the transactions that would be mined last.
Include an adjustment to mempool_tests.cpp due to the additional memory used by
txgraph.
Includes a temporary change to the mempool_ephemeral_dust.py functional test,
due to validation checks being reordered. This change will revert once the RBF
rules are changed in a later commit.
