Prior to cluster mempool, a policy was in place that
disallowed non-TRUC transactions from being
TX_RECONSIDERABLE in a package setting if it was below
minrelay. This was meant to simplify reasoning about mempool
trimming requirements with non-trivial transaction
topologies in the mempool. This is no longer a concern
post-cluster mempool, so this is relaxed.
In effect, this makes 0-value parent transactions relayable
through the network without the TRUC restrictions and
thus the anti-pinning protections.
This rule was originally introduced along with a very early proposal for
package relay as a way to verify that the "correct"
child-with-unconfirmed-parents package was provided for a transaction,
where correctness was defined as all of the transactions unconfirmed
parents. However, we are not planning to introduce a protocol where
peers would be asked to send these packages.
This rule has downsides: if a transaction has multiple parents but only
1 that requires package CPFP to be accepted, the current rule prevents
us from accepting that package. Even if the other parents are already in
mempool, the p2p logic will only submit the 1p1c package, which fails
this check. See the test in p2p_1p1c_network.py
32fc59796f74a2941772b5ec2755b1319132cd9c rpc: Allow single transaction through submitpackage (glozow)
Pull request description:
There's no particular reason to restrict single transaction submissions with submitpackage. This change relaxes the RPC checks as enables the `AcceptPackage` flow to accept packages of a single transaction.
Resolves#31085
ACKs for top commit:
naumenkogs:
ACK 32fc59796f
achow101:
ACK 32fc59796f74a2941772b5ec2755b1319132cd9c
glozow:
ACK 32fc59796f74a2941772b5ec2755b1319132cd9c
Tree-SHA512: ffed353bfdca610ffcfd53b40b76da05ffc26df6bac4b0421492e067bede930380e03399d2e2d1d17f0e88fb91cd8eb376e3aabebbabcc724590bf068d09807c
And under the hood suppoert single transactions
in AcceptPackage. This simplifies user experience
and paves the way for reducing number of codepaths
for transaction acceptance in the future.
Co-Authored-By: instagibbs <gsanders87@gmail.com>
The behavior is not new, but this rule exits earlier than before.
Previously, a carve out could have been granted in PreChecks() but then
nullified in PackageMempoolChecks() when CheckPackageLimits() is called
with the default limits.
While allowing submitted packages to be slightly larger than what
may be allowed in the mempool to allow simpler reasoning
about contextual-less checks vs chain limits.
Avoid adding transactions below min relay feerate because, even if they
were bumped through CPFP when entering the mempool, we do not have a
DoS-resistant way of ensuring they always remain bumped. In the future,
this rule can be relaxed (e.g. to allow packages to bump 0-fee
transactions) if we find a way to do so.
Our RBF policy is different from the rules specified in BIP125. For
example, the BIP does not mention Rule 6, and our Rule 4 uses the
(configurable) incremental relay feerate (distinct from the
minimum relay feerate). Those interested in our policy should refer to
doc/policy/mempool-replacements.md instead. These rules may also
continue to diverge with package RBF and other RBF improvements. Keep
references to the BIP125 signaling wrt sequence numbers, since that is
still correct and widely used. It is helpful to refer to this as "BIP125
signaling" since it is unambiguous and succint, especially if we have
multiple ways to signal replaceability in the future.
The rule numbers in doc/policy/mempool-replacements.md correspond
largely to those of BIP 125, so we can still refer to them like "Rule 5."
