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Merge #12118: Sort mempool by min(feerate, ancestor_feerate)

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0a22a52 Use mempool's ancestor sort in transaction selection (Suhas Daftuar)
7abfa53 Add test for new ancestor feerate sort behavior (Suhas Daftuar)
9a51319 Sort mempool by min(feerate, ancestor_feerate) (Suhas Daftuar)
6773f92 Refactor CompareTxMemPoolEntryByDescendantScore (Suhas Daftuar)

Pull request description:

  This more closely approximates the desirability of a given transaction for
  mining, and should result in less re-sorting when transactions get removed from
  the mempool after being mined.

  I measured this as approximately a 5% speedup in removeForBlock.

Tree-SHA512: ffa36b567c5dfe3e8908c545a459b6a5ec0de26e7dc81b1050dd235cac9046564b4409a3f8c5ba97bd8b30526e8fec8f78480a912e317979467f32305c3dd37b
This commit is contained in:
Wladimir J. van der Laan 2018-01-15 15:36:25 +01:00
commit 44080a90a2
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GPG key ID: 1E4AED62986CD25D
4 changed files with 71 additions and 37 deletions
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2
src/miner.cpp
View file

@ -352,7 +352,7 @@ void BlockAssembler::addPackageTxs(int &nPackagesSelected, int &nDescendantsUpda
// Try to compare the mapTx entry to the mapModifiedTx entry
iter = mempool.mapTx.project<0>(mi);
if (modit != mapModifiedTx.get<ancestor_score>().end() &&
CompareModifiedEntry()(*modit, CTxMemPoolModifiedEntry(iter))) {
CompareTxMemPoolEntryByAncestorFee()(*modit, CTxMemPoolModifiedEntry(iter))) {
// The best entry in mapModifiedTx has higher score
// than the one from mapTx.
// Switch which transaction (package) to consider

23
src/miner.h
View file

@ -41,6 +41,12 @@ struct CTxMemPoolModifiedEntry {
nSigOpCostWithAncestors = entry->GetSigOpCostWithAncestors();
}
int64_t GetModifiedFee() const { return iter->GetModifiedFee(); }
uint64_t GetSizeWithAncestors() const { return nSizeWithAncestors; }
CAmount GetModFeesWithAncestors() const { return nModFeesWithAncestors; }
size_t GetTxSize() const { return iter->GetTxSize(); }
const CTransaction& GetTx() const { return iter->GetTx(); }
CTxMemPool::txiter iter;
uint64_t nSizeWithAncestors;
CAmount nModFeesWithAncestors;
@ -67,21 +73,6 @@ struct modifiedentry_iter {
}
};
// This matches the calculation in CompareTxMemPoolEntryByAncestorFee,
// except operating on CTxMemPoolModifiedEntry.
// TODO: refactor to avoid duplication of this logic.
struct CompareModifiedEntry {
bool operator()(const CTxMemPoolModifiedEntry &a, const CTxMemPoolModifiedEntry &b) const
{
double f1 = (double)a.nModFeesWithAncestors * b.nSizeWithAncestors;
double f2 = (double)b.nModFeesWithAncestors * a.nSizeWithAncestors;
if (f1 == f2) {
return CTxMemPool::CompareIteratorByHash()(a.iter, b.iter);
}
return f1 > f2;
}
};
// A comparator that sorts transactions based on number of ancestors.
// This is sufficient to sort an ancestor package in an order that is valid
// to appear in a block.
@ -106,7 +97,7 @@ typedef boost::multi_index_container<
// Reuse same tag from CTxMemPool's similar index
boost::multi_index::tag<ancestor_score>,
boost::multi_index::identity<CTxMemPoolModifiedEntry>,
CompareModifiedEntry
CompareTxMemPoolEntryByAncestorFee
>
>
> indexed_modified_transaction_set;

17
src/test/mempool_tests.cpp
View file

@ -398,6 +398,23 @@ BOOST_AUTO_TEST_CASE(MempoolAncestorIndexingTest)
sortedOrder.erase(sortedOrder.end()-2);
sortedOrder.insert(sortedOrder.begin(), tx7.GetHash().ToString());
CheckSort<ancestor_score>(pool, sortedOrder);
// High-fee parent, low-fee child
// tx7 -> tx8
CMutableTransaction tx8 = CMutableTransaction();
tx8.vin.resize(1);
tx8.vin[0].prevout = COutPoint(tx7.GetHash(), 0);
tx8.vin[0].scriptSig = CScript() << OP_11;
tx8.vout.resize(1);
tx8.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
tx8.vout[0].nValue = 10*COIN;
// Check that we sort by min(feerate, ancestor_feerate):
// set the fee so that the ancestor feerate is above tx1/5,
// but the transaction's own feerate is lower
pool.addUnchecked(tx8.GetHash(), entry.Fee(5000LL).FromTx(tx8));
sortedOrder.insert(sortedOrder.end()-1, tx8.GetHash().ToString());
CheckSort<ancestor_score>(pool, sortedOrder);
}

66
src/txmempool.h
View file

@ -206,18 +206,14 @@ class CompareTxMemPoolEntryByDescendantScore
public:
bool operator()(const CTxMemPoolEntry& a, const CTxMemPoolEntry& b) const
{
bool fUseADescendants = UseDescendantScore(a);
bool fUseBDescendants = UseDescendantScore(b);
double a_mod_fee, a_size, b_mod_fee, b_size;
double aModFee = fUseADescendants ? a.GetModFeesWithDescendants() : a.GetModifiedFee();
double aSize = fUseADescendants ? a.GetSizeWithDescendants() : a.GetTxSize();
double bModFee = fUseBDescendants ? b.GetModFeesWithDescendants() : b.GetModifiedFee();
double bSize = fUseBDescendants ? b.GetSizeWithDescendants() : b.GetTxSize();
GetModFeeAndSize(a, a_mod_fee, a_size);
GetModFeeAndSize(b, b_mod_fee, b_size);
// Avoid division by rewriting (a/b > c/d) as (a*d > c*b).
double f1 = aModFee * bSize;
double f2 = aSize * bModFee;
double f1 = a_mod_fee * b_size;
double f2 = a_size * b_mod_fee;
if (f1 == f2) {
return a.GetTime() >= b.GetTime();
@ -225,12 +221,21 @@ public:
return f1 < f2;
}
// Calculate which score to use for an entry (avoiding division).
bool UseDescendantScore(const CTxMemPoolEntry &a) const
// Return the fee/size we're using for sorting this entry.
void GetModFeeAndSize(const CTxMemPoolEntry &a, double &mod_fee, double &size) const
{
// Compare feerate with descendants to feerate of the transaction, and
// return the fee/size for the max.
double f1 = (double)a.GetModifiedFee() * a.GetSizeWithDescendants();
double f2 = (double)a.GetModFeesWithDescendants() * a.GetTxSize();
return f2 > f1;
if (f2 > f1) {
mod_fee = a.GetModFeesWithDescendants();
size = a.GetSizeWithDescendants();
} else {
mod_fee = a.GetModifiedFee();
size = a.GetTxSize();
}
}
};
@ -261,27 +266,48 @@ public:
}
};
/** \class CompareTxMemPoolEntryByAncestorScore
*
* Sort an entry by min(score/size of entry's tx, score/size with all ancestors).
*/
class CompareTxMemPoolEntryByAncestorFee
{
public:
bool operator()(const CTxMemPoolEntry& a, const CTxMemPoolEntry& b) const
template<typename T>
bool operator()(const T& a, const T& b) const
{
double aFees = a.GetModFeesWithAncestors();
double aSize = a.GetSizeWithAncestors();
double a_mod_fee, a_size, b_mod_fee, b_size;
double bFees = b.GetModFeesWithAncestors();
double bSize = b.GetSizeWithAncestors();
GetModFeeAndSize(a, a_mod_fee, a_size);
GetModFeeAndSize(b, b_mod_fee, b_size);
// Avoid division by rewriting (a/b > c/d) as (a*d > c*b).
double f1 = aFees * bSize;
double f2 = aSize * bFees;
double f1 = a_mod_fee * b_size;
double f2 = a_size * b_mod_fee;
if (f1 == f2) {
return a.GetTx().GetHash() < b.GetTx().GetHash();
}
return f1 > f2;
}
// Return the fee/size we're using for sorting this entry.
template <typename T>
void GetModFeeAndSize(const T &a, double &mod_fee, double &size) const
{
// Compare feerate with ancestors to feerate of the transaction, and
// return the fee/size for the min.
double f1 = (double)a.GetModifiedFee() * a.GetSizeWithAncestors();
double f2 = (double)a.GetModFeesWithAncestors() * a.GetTxSize();
if (f1 > f2) {
mod_fee = a.GetModFeesWithAncestors();
size = a.GetSizeWithAncestors();
} else {
mod_fee = a.GetModifiedFee();
size = a.GetTxSize();
}
}
};
// Multi_index tag names