Add ancestor feerate index to mempool

src/test/mempool_tests.cpp

@@ -316,6 +316,110 @@ BOOST_AUTO_TEST_CASE(MempoolIndexingTest)
     CheckSort<mining_score>(pool, sortedOrder);
 }
 
+BOOST_AUTO_TEST_CASE(MempoolAncestorIndexingTest)
+{
+    CTxMemPool pool(CFeeRate(0));
+    TestMemPoolEntryHelper entry;
+    entry.hadNoDependencies = true;
+
+    /* 3rd highest fee */
+    CMutableTransaction tx1 = CMutableTransaction();
+    tx1.vout.resize(1);
+    tx1.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
+    tx1.vout[0].nValue = 10 * COIN;
+    pool.addUnchecked(tx1.GetHash(), entry.Fee(10000LL).Priority(10.0).FromTx(tx1));
+
+    /* highest fee */
+    CMutableTransaction tx2 = CMutableTransaction();
+    tx2.vout.resize(1);
+    tx2.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
+    tx2.vout[0].nValue = 2 * COIN;
+    pool.addUnchecked(tx2.GetHash(), entry.Fee(20000LL).Priority(9.0).FromTx(tx2));
+    uint64_t tx2Size = ::GetSerializeSize(tx2, SER_NETWORK, PROTOCOL_VERSION);
+
+    /* lowest fee */
+    CMutableTransaction tx3 = CMutableTransaction();
+    tx3.vout.resize(1);
+    tx3.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
+    tx3.vout[0].nValue = 5 * COIN;
+    pool.addUnchecked(tx3.GetHash(), entry.Fee(0LL).Priority(100.0).FromTx(tx3));
+
+    /* 2nd highest fee */
+    CMutableTransaction tx4 = CMutableTransaction();
+    tx4.vout.resize(1);
+    tx4.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
+    tx4.vout[0].nValue = 6 * COIN;
+    pool.addUnchecked(tx4.GetHash(), entry.Fee(15000LL).Priority(1.0).FromTx(tx4));
+
+    /* equal fee rate to tx1, but newer */
+    CMutableTransaction tx5 = CMutableTransaction();
+    tx5.vout.resize(1);
+    tx5.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
+    tx5.vout[0].nValue = 11 * COIN;
+    pool.addUnchecked(tx5.GetHash(), entry.Fee(10000LL).FromTx(tx5));
+    BOOST_CHECK_EQUAL(pool.size(), 5);
+
+    std::vector<std::string> sortedOrder;
+    sortedOrder.resize(5);
+    sortedOrder[0] = tx2.GetHash().ToString(); // 20000
+    sortedOrder[1] = tx4.GetHash().ToString(); // 15000
+    // tx1 and tx5 are both 10000
+    // Ties are broken by hash, not timestamp, so determine which
+    // hash comes first.
+    if (tx1.GetHash() < tx5.GetHash()) {
+        sortedOrder[2] = tx1.GetHash().ToString();
+        sortedOrder[3] = tx5.GetHash().ToString();
+    } else {
+        sortedOrder[2] = tx5.GetHash().ToString();
+        sortedOrder[3] = tx1.GetHash().ToString();
+    }
+    sortedOrder[4] = tx3.GetHash().ToString(); // 0
+
+    CheckSort<ancestor_score>(pool, sortedOrder);
+
+    /* low fee parent with high fee child */
+    /* tx6 (0) -> tx7 (high) */
+    CMutableTransaction tx6 = CMutableTransaction();
+    tx6.vout.resize(1);
+    tx6.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
+    tx6.vout[0].nValue = 20 * COIN;
+    uint64_t tx6Size = ::GetSerializeSize(tx6, SER_NETWORK, PROTOCOL_VERSION);
+
+    pool.addUnchecked(tx6.GetHash(), entry.Fee(0LL).FromTx(tx6));
+    BOOST_CHECK_EQUAL(pool.size(), 6);
+    sortedOrder.push_back(tx6.GetHash().ToString());
+    CheckSort<ancestor_score>(pool, sortedOrder);
+
+    CMutableTransaction tx7 = CMutableTransaction();
+    tx7.vin.resize(1);
+    tx7.vin[0].prevout = COutPoint(tx6.GetHash(), 0);
+    tx7.vin[0].scriptSig = CScript() << OP_11;
+    tx7.vout.resize(1);
+    tx7.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
+    tx7.vout[0].nValue = 10 * COIN;
+    uint64_t tx7Size = ::GetSerializeSize(tx7, SER_NETWORK, PROTOCOL_VERSION);
+
+    /* set the fee to just below tx2's feerate when including ancestor */
+    CAmount fee = (20000/tx2Size)*(tx7Size + tx6Size) - 1;
+
+    //CTxMemPoolEntry entry7(tx7, fee, 2, 10.0, 1, true);
+    pool.addUnchecked(tx7.GetHash(), entry.Fee(fee).FromTx(tx7));
+    BOOST_CHECK_EQUAL(pool.size(), 7);
+    sortedOrder.insert(sortedOrder.begin()+1, tx7.GetHash().ToString());
+    CheckSort<ancestor_score>(pool, sortedOrder);
+
+    /* after tx6 is mined, tx7 should move up in the sort */
+    std::vector<CTransactionRef> vtx;
+    vtx.emplace_back(MakeTransactionRef(tx6));
+    std::list<CTransactionRef> dummy;
+    pool.removeForBlock(vtx, 1, dummy, false);
+
+    sortedOrder.erase(sortedOrder.begin()+1);
+    sortedOrder.pop_back();
+    sortedOrder.insert(sortedOrder.begin(), tx7.GetHash().ToString());
+    CheckSort<ancestor_score>(pool, sortedOrder);
+}
+
 
 BOOST_AUTO_TEST_CASE(MempoolSizeLimitTest)
 {

src/txmempool.cpp

@@ -967,9 +967,9 @@ bool CCoinsViewMemPool::GetNullifier(const uint256& nullifier) const
 size_t CTxMemPool::DynamicMemoryUsage() const
 {
     LOCK(cs);
-    // Estimate the overhead of mapTx to be 12 pointers + an allocation, as no exact formula for
+    // Estimate the overhead of mapTx to be 15 pointers + an allocation, as no exact formula for
     // boost::multi_index_contained is implemented.
-    return memusage::MallocUsage(sizeof(CTxMemPoolEntry) + 12 * sizeof(void*)) * mapTx.size() +
+    return memusage::MallocUsage(sizeof(CTxMemPoolEntry) + 15 * sizeof(void*)) * mapTx.size() +
             memusage::DynamicUsage(mapNextTx) +
             memusage::DynamicUsage(mapDeltas) +
             memusage::DynamicUsage(mapLinks) +

src/txmempool.h

@@ -254,10 +254,34 @@ class CompareTxMemPoolEntryByEntryTime
     }
 };
 
+class CompareTxMemPoolEntryByAncestorFee
+{
+public:
+    bool operator()(const CTxMemPoolEntry& a, const CTxMemPoolEntry& b) const
+    {
+        double aFees = a.GetModFeesWithAncestors();
+        double aSize = a.GetSizeWithAncestors();
+
+        double bFees = b.GetModFeesWithAncestors();
+        double bSize = b.GetSizeWithAncestors();
+
+        // Avoid division by rewriting (a/b > c/d) as (a*d > c*b).
+        double f1 = aFees * bSize;
+        double f2 = aSize * bFees;
+
+        if (f1 == f2) {
+            return a.GetTx().GetHash() < b.GetTx().GetHash();
+        }
+
+        return f1 > f2;
+    }
+};
+
 // Multi_index tag names
 struct descendant_score {};
 struct entry_time {};
 struct mining_score {};
+struct ancestor_score {};
 
 class CBlockPolicyEstimator;
 
@@ -410,6 +434,12 @@ class CTxMemPool
                 boost::multi_index::tag<mining_score>,
                 boost::multi_index::identity<CTxMemPoolEntry>,
                 CompareTxMemPoolEntryByScore
+            >,
+            // sorted by fee rate with ancestors
+            boost::multi_index::ordered_non_unique<
+                boost::multi_index::tag<ancestor_score>,
+                boost::multi_index::identity<CTxMemPoolEntry>,
+                CompareTxMemPoolEntryByAncestorFee
             >
         >
     > indexed_transaction_set;