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authorWladimir J. van der Laan <laanwj@gmail.com>2019-07-19 19:56:12 +0200
committerWladimir J. van der Laan <laanwj@gmail.com>2019-07-19 20:00:12 +0200
commit51a6e2c4192913c9c18507d8dfb3302500b26cc3 (patch)
treeed1f4ddc01217aa66b0359d11a8b28e488e72e85 /src/validation.cpp
parentf4b1fe7165c84d7ed4ef84cac7e0dc6804973fa5 (diff)
parent50cede3f5a4d4fbfbb7c420b94e661a6a159bced (diff)
Merge #15681: [mempool] Allow one extra single-ancestor transaction per package
50cede3f5a4d4fbfbb7c420b94e661a6a159bced [mempool] Allow one extra single-ancestor transaction per package (Matt Corallo) Pull request description: This implements the proposed policy change from [1], which allows certain classes of contract protocols involving revocation punishments to use CPFP. Note that some such use-cases may still want some form of one-deep package relay, though even this alone may greatly simplify some lightning fee negotiation. [1] https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2018-November/016518.html ACKs for top commit: ajtowns: ACK 50cede3f5a4d4fbfbb7c420b94e661a6a159bced -- looked over code again, compared with previous commit, compiles, etc. sdaftuar: ACK 50cede3f5a4d4fbfbb7c420b94e661a6a159bced ryanofsky: utACK 50cede3f5a4d4fbfbb7c420b94e661a6a159bced. Changes since last review: adding EXTRA_DESCENDANT_TX_SIZE_LIMIT constant, changing max ancestor size from 1,000,000 to nLimitAncestorSize constant (101,000), fixing test comment and getting rid of unused test node. Tree-SHA512: b052c2a0f384855572b4579310131897b612201214b5abbb225167224e4f550049e300b471dbf320928652571e92ca2d650050b7cf39ac92b3bc1d2bcd386c1c
Diffstat (limited to 'src/validation.cpp')
-rw-r--r--src/validation.cpp16
1 files changed, 15 insertions, 1 deletions
diff --git a/src/validation.cpp b/src/validation.cpp
index 0bc6167bad..f585bc7d2d 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -616,7 +616,21 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
size_t nLimitDescendantSize = gArgs.GetArg("-limitdescendantsize", DEFAULT_DESCENDANT_SIZE_LIMIT)*1000;
std::string errString;
if (!pool.CalculateMemPoolAncestors(entry, setAncestors, nLimitAncestors, nLimitAncestorSize, nLimitDescendants, nLimitDescendantSize, errString)) {
- return state.Invalid(ValidationInvalidReason::TX_MEMPOOL_POLICY, false, REJECT_NONSTANDARD, "too-long-mempool-chain", errString);
+ setAncestors.clear();
+ // If the new transaction is relatively small (up to 40k weight)
+ // and has at most one ancestor (ie ancestor limit of 2, including
+ // the new transaction), allow it if its parent has exactly the
+ // descendant limit descendants.
+ //
+ // This allows protocols which rely on distrusting counterparties
+ // being able to broadcast descendants of an unconfirmed transaction
+ // to be secure by simply only having two immediately-spendable
+ // outputs - one for each counterparty. For more info on the uses for
+ // this, see https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2018-November/016518.html
+ if (nSize > EXTRA_DESCENDANT_TX_SIZE_LIMIT ||
+ !pool.CalculateMemPoolAncestors(entry, setAncestors, 2, nLimitAncestorSize, nLimitDescendants + 1, nLimitDescendantSize + EXTRA_DESCENDANT_TX_SIZE_LIMIT, errString)) {
+ return state.Invalid(ValidationInvalidReason::TX_MEMPOOL_POLICY, false, REJECT_NONSTANDARD, "too-long-mempool-chain", errString);
+ }
}
// A transaction that spends outputs that would be replaced by it is invalid. Now