Remove the ancestor and descendant indices from the mempool

diff --git a/src/test/mempool_tests.cpp b/src/test/mempool_tests.cpp
index ec3bbd15..2271e7b8 100644
--- a/src/test/mempool_tests.cpp
+++ b/src/test/mempool_tests.cpp
@@ -115,322 +115,6 @@ BOOST_AUTO_TEST_CASE(MempoolRemoveTest)
     BOOST_CHECK_EQUAL(testPool.size(), 0U);
 }
 
-template <typename name>
-static void CheckSort(CTxMemPool& pool, std::vector<std::string>& sortedOrder) EXCLUSIVE_LOCKS_REQUIRED(pool.cs)
-{
-    BOOST_CHECK_EQUAL(pool.size(), sortedOrder.size());
-    typename CTxMemPool::indexed_transaction_set::index<name>::type::iterator it = pool.mapTx.get<name>().begin();
-    int count = 0;
-    for (; it != pool.mapTx.get<name>().end(); ++it, ++count) {
-        BOOST_CHECK_EQUAL(it->GetTx().GetHash().ToString(), sortedOrder[count]);
-    }
-}
-
-BOOST_AUTO_TEST_CASE(MempoolIndexingTest)
-{
-    CTxMemPool& pool = *Assert(m_node.mempool);
-    LOCK2(cs_main, pool.cs);
-    TestMemPoolEntryHelper entry;
-
-    /* 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;
-    AddToMempool(pool, entry.Fee(10000LL).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;
-    AddToMempool(pool, entry.Fee(20000LL).FromTx(tx2));
-
-    /* lowest fee */
-    CMutableTransaction tx3 = CMutableTransaction();
-    tx3.vout.resize(1);
-    tx3.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
-    tx3.vout[0].nValue = 5 * COIN;
-    AddToMempool(pool, entry.Fee(0LL).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;
-    AddToMempool(pool, entry.Fee(15000LL).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;
-    entry.time = NodeSeconds{1s};
-    AddToMempool(pool, entry.Fee(10000LL).FromTx(tx5));
-    BOOST_CHECK_EQUAL(pool.size(), 5U);
-
-    std::vector<std::string> sortedOrder;
-    sortedOrder.resize(5);
-    sortedOrder[0] = tx3.GetHash().ToString(); // 0
-    sortedOrder[1] = tx5.GetHash().ToString(); // 10000
-    sortedOrder[2] = tx1.GetHash().ToString(); // 10000
-    sortedOrder[3] = tx4.GetHash().ToString(); // 15000
-    sortedOrder[4] = tx2.GetHash().ToString(); // 20000
-    CheckSort<descendant_score>(pool, sortedOrder);
-
-    /* low fee but with high fee child */
-    /* tx6 -> tx7 -> tx8, tx9 -> tx10 */
-    CMutableTransaction tx6 = CMutableTransaction();
-    tx6.vout.resize(1);
-    tx6.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
-    tx6.vout[0].nValue = 20 * COIN;
-    AddToMempool(pool, entry.Fee(0LL).FromTx(tx6));
-    BOOST_CHECK_EQUAL(pool.size(), 6U);
-    // Check that at this point, tx6 is sorted low
-    sortedOrder.insert(sortedOrder.begin(), tx6.GetHash().ToString());
-    CheckSort<descendant_score>(pool, sortedOrder);
-
-    CTxMemPool::setEntries setAncestors;
-    setAncestors.insert(pool.GetIter(tx6.GetHash()).value());
-    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(2);
-    tx7.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
-    tx7.vout[0].nValue = 10 * COIN;
-    tx7.vout[1].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
-    tx7.vout[1].nValue = 1 * COIN;
-
-    {
-        auto ancestors_calculated{pool.CalculateMemPoolAncestors(entry.Fee(2000000LL).FromTx(tx7), CTxMemPool::Limits::NoLimits())};
-        BOOST_REQUIRE(ancestors_calculated.has_value());
-        BOOST_CHECK(*ancestors_calculated == setAncestors);
-    }
-
-    AddToMempool(pool, entry.FromTx(tx7));
-    BOOST_CHECK_EQUAL(pool.size(), 7U);
-
-    // Now tx6 should be sorted higher (high fee child): tx7, tx6, tx2, ...
-    sortedOrder.erase(sortedOrder.begin());
-    sortedOrder.push_back(tx6.GetHash().ToString());
-    sortedOrder.push_back(tx7.GetHash().ToString());
-    CheckSort<descendant_score>(pool, sortedOrder);
-
-    /* low fee child of tx7 */
-    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;
-    setAncestors.insert(pool.GetIter(tx7.GetHash()).value());
-    AddToMempool(pool, entry.Fee(0LL).Time(NodeSeconds{2s}).FromTx(tx8));
-
-    // Now tx8 should be sorted low, but tx6/tx both high
-    sortedOrder.insert(sortedOrder.begin(), tx8.GetHash().ToString());
-    CheckSort<descendant_score>(pool, sortedOrder);
-
-    /* low fee child of tx7 */
-    CMutableTransaction tx9 = CMutableTransaction();
-    tx9.vin.resize(1);
-    tx9.vin[0].prevout = COutPoint(tx7.GetHash(), 1);
-    tx9.vin[0].scriptSig = CScript() << OP_11;
-    tx9.vout.resize(1);
-    tx9.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
-    tx9.vout[0].nValue = 1 * COIN;
-    AddToMempool(pool, entry.Fee(0LL).Time(NodeSeconds{3s}).FromTx(tx9));
-
-    // tx9 should be sorted low
-    BOOST_CHECK_EQUAL(pool.size(), 9U);
-    sortedOrder.insert(sortedOrder.begin(), tx9.GetHash().ToString());
-    CheckSort<descendant_score>(pool, sortedOrder);
-
-    std::vector<std::string> snapshotOrder = sortedOrder;
-
-    setAncestors.insert(pool.GetIter(tx8.GetHash()).value());
-    setAncestors.insert(pool.GetIter(tx9.GetHash()).value());
-    /* tx10 depends on tx8 and tx9 and has a high fee*/
-    CMutableTransaction tx10 = CMutableTransaction();
-    tx10.vin.resize(2);
-    tx10.vin[0].prevout = COutPoint(tx8.GetHash(), 0);
-    tx10.vin[0].scriptSig = CScript() << OP_11;
-    tx10.vin[1].prevout = COutPoint(tx9.GetHash(), 0);
-    tx10.vin[1].scriptSig = CScript() << OP_11;
-    tx10.vout.resize(1);
-    tx10.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
-    tx10.vout[0].nValue = 10 * COIN;
-
-    {
-        auto ancestors_calculated{pool.CalculateMemPoolAncestors(entry.Fee(200000LL).Time(NodeSeconds{4s}).FromTx(tx10), CTxMemPool::Limits::NoLimits())};
-        BOOST_REQUIRE(ancestors_calculated);
-        BOOST_CHECK(*ancestors_calculated == setAncestors);
-    }
-
-    AddToMempool(pool, entry.FromTx(tx10));
-
-    /**
-     *  tx8 and tx9 should both now be sorted higher
-     *  Final order after tx10 is added:
-     *
-     *  tx3 = 0 (1)
-     *  tx5 = 10000 (1)
-     *  tx1 = 10000 (1)
-     *  tx4 = 15000 (1)
-     *  tx2 = 20000 (1)
-     *  tx9 = 200k (2 txs)
-     *  tx8 = 200k (2 txs)
-     *  tx10 = 200k (1 tx)
-     *  tx6 = 2.2M (5 txs)
-     *  tx7 = 2.2M (4 txs)
-     */
-    sortedOrder.erase(sortedOrder.begin(), sortedOrder.begin()+2); // take out tx9, tx8 from the beginning
-    sortedOrder.insert(sortedOrder.begin()+5, tx9.GetHash().ToString());
-    sortedOrder.insert(sortedOrder.begin()+6, tx8.GetHash().ToString());
-    sortedOrder.insert(sortedOrder.begin()+7, tx10.GetHash().ToString()); // tx10 is just before tx6
-    CheckSort<descendant_score>(pool, sortedOrder);
-
-    // there should be 10 transactions in the mempool
-    BOOST_CHECK_EQUAL(pool.size(), 10U);
-
-    // Now try removing tx10 and verify the sort order returns to normal
-    pool.removeRecursive(*Assert(pool.get(tx10.GetHash())), REMOVAL_REASON_DUMMY);
-    CheckSort<descendant_score>(pool, snapshotOrder);
-
-    pool.removeRecursive(*Assert(pool.get(tx9.GetHash())), REMOVAL_REASON_DUMMY);
-    pool.removeRecursive(*Assert(pool.get(tx8.GetHash())), REMOVAL_REASON_DUMMY);
-}
-
-BOOST_AUTO_TEST_CASE(MempoolAncestorIndexingTest)
-{
-    CTxMemPool& pool = *Assert(m_node.mempool);
-    LOCK2(cs_main, pool.cs);
-    TestMemPoolEntryHelper entry;
-
-    /* 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;
-    AddToMempool(pool, entry.Fee(10000LL).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;
-    AddToMempool(pool, entry.Fee(20000LL).FromTx(tx2));
-    uint64_t tx2Size = GetVirtualTransactionSize(CTransaction(tx2));
-
-    /* lowest fee */
-    CMutableTransaction tx3 = CMutableTransaction();
-    tx3.vout.resize(1);
-    tx3.vout[0].scriptPubKey = CScript() << OP_11 << OP_EQUAL;
-    tx3.vout[0].nValue = 5 * COIN;
-    AddToMempool(pool, entry.Fee(0LL).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;
-    AddToMempool(pool, entry.Fee(15000LL).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;
-    AddToMempool(pool, entry.Fee(10000LL).FromTx(tx5));
-    BOOST_CHECK_EQUAL(pool.size(), 5U);
-
-    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 = GetVirtualTransactionSize(CTransaction(tx6));
-
-    AddToMempool(pool, entry.Fee(0LL).FromTx(tx6));
-    BOOST_CHECK_EQUAL(pool.size(), 6U);
-    // Ties are broken by hash
-    if (tx3.GetHash() < tx6.GetHash())
-        sortedOrder.push_back(tx6.GetHash().ToString());
-    else
-        sortedOrder.insert(sortedOrder.end()-1,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 = GetVirtualTransactionSize(CTransaction(tx7));
-
-    /* set the fee to just below tx2's feerate when including ancestor */
-    CAmount fee = (20000/tx2Size)*(tx7Size + tx6Size) - 1;
-
-    AddToMempool(pool, entry.Fee(fee).FromTx(tx7));
-    BOOST_CHECK_EQUAL(pool.size(), 7U);
-    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.push_back(MakeTransactionRef(tx6));
-    pool.removeForBlock(vtx, 1);
-
-    sortedOrder.erase(sortedOrder.begin()+1);
-    // Ties are broken by hash
-    if (tx3.GetHash() < tx6.GetHash())
-        sortedOrder.pop_back();
-    else
-        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
-    AddToMempool(pool, entry.Fee(5000LL).FromTx(tx8));
-    sortedOrder.insert(sortedOrder.end()-1, tx8.GetHash().ToString());
-    CheckSort<ancestor_score>(pool, sortedOrder);
-}
-
-
 BOOST_AUTO_TEST_CASE(MempoolSizeLimitTest)
 {
     auto& pool = static_cast<MemPoolTest&>(*Assert(m_node.mempool));
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index 15b25081..f2a63c26 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -1057,8 +1057,8 @@ void CCoinsViewMemPool::Reset()
 
 size_t CTxMemPool::DynamicMemoryUsage() const {
     LOCK(cs);
-    // 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) + 15 * sizeof(void*)) * mapTx.size() + memusage::DynamicUsage(mapNextTx) + memusage::DynamicUsage(mapDeltas) + memusage::DynamicUsage(txns_randomized) + m_txgraph->GetMainMemoryUsage() + cachedInnerUsage;
+    // Estimate the overhead of mapTx to be 9 pointers (3 pointers per index) + an allocation, as no exact formula for boost::multi_index_contained is implemented.
+    return memusage::MallocUsage(sizeof(CTxMemPoolEntry) + 9 * sizeof(void*)) * mapTx.size() + memusage::DynamicUsage(mapNextTx) + memusage::DynamicUsage(mapDeltas) + memusage::DynamicUsage(txns_randomized) + m_txgraph->GetMainMemoryUsage() + cachedInnerUsage;
 }
 
 void CTxMemPool::RemoveUnbroadcastTx(const Txid& txid, const bool unchecked) {
diff --git a/src/txmempool.h b/src/txmempool.h
index 1750596c..5834cd00 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -90,37 +90,6 @@ struct mempoolentry_wtxid
     }
 };
 
-
-/** \class CompareTxMemPoolEntryByDescendantScore
- *
- *  Sort an entry by max(score/size of entry's tx, score/size with all descendants).
- */
-class CompareTxMemPoolEntryByDescendantScore
-{
-public:
-    bool operator()(const CTxMemPoolEntry& a, const CTxMemPoolEntry& b) const
-    {
-        FeeFrac f1 = GetModFeeAndSize(a);
-        FeeFrac f2 = GetModFeeAndSize(b);
-
-        if (FeeRateCompare(f1, f2) == 0) {
-            return a.GetTime() >= b.GetTime();
-        }
-        return f1 < f2;
-    }
-
-    // Return the fee/size we're using for sorting this entry.
-    FeeFrac GetModFeeAndSize(const CTxMemPoolEntry &a) const
-    {
-        // Compare feerate with descendants to feerate of the transaction, and
-        // return the fee/size for the max.
-        return std::max<FeeFrac>(
-            FeeFrac(a.GetModFeesWithDescendants(), a.GetSizeWithDescendants()),
-            FeeFrac(a.GetModifiedFee(), a.GetTxSize())
-        );
-    }
-};
-
 /** \class CompareTxMemPoolEntryByScore
  *
  *  Sort by feerate of entry (fee/size) in descending order
@@ -151,42 +120,8 @@ public:
     }
 };
 
-/** \class CompareTxMemPoolEntryByAncestorScore
- *
- *  Sort an entry by min(score/size of entry's tx, score/size with all ancestors).
- */
-class CompareTxMemPoolEntryByAncestorFee
-{
-public:
-    template<typename T>
-    bool operator()(const T& a, const T& b) const
-    {
-        FeeFrac f1 = GetModFeeAndSize(a);
-        FeeFrac f2 = GetModFeeAndSize(b);
-
-        if (FeeRateCompare(f1, f2) == 0) {
-            return a.GetTx().GetHash() < b.GetTx().GetHash();
-        }
-        return f1 > f2;
-    }
-
-    // Return the fee/size we're using for sorting this entry.
-    template <typename T>
-    FeeFrac GetModFeeAndSize(const T &a) const
-    {
-        // Compare feerate with ancestors to feerate of the transaction, and
-        // return the fee/size for the min.
-        return std::min<FeeFrac>(
-            FeeFrac(a.GetModFeesWithAncestors(), a.GetSizeWithAncestors()),
-            FeeFrac(a.GetModifiedFee(), a.GetTxSize())
-        );
-    }
-};
-
 // Multi_index tag names
-struct descendant_score {};
 struct entry_time {};
-struct ancestor_score {};
 struct index_by_wtxid {};
 
 /**
@@ -321,23 +256,11 @@ public:
                 mempoolentry_wtxid,
                 SaltedWtxidHasher
             >,
-            // sorted by fee rate
-            boost::multi_index::ordered_non_unique<
-                boost::multi_index::tag<descendant_score>,
-                boost::multi_index::identity<CTxMemPoolEntry>,
-                CompareTxMemPoolEntryByDescendantScore
-            >,
             // sorted by entry time
             boost::multi_index::ordered_non_unique<
                 boost::multi_index::tag<entry_time>,
                 boost::multi_index::identity<CTxMemPoolEntry>,
                 CompareTxMemPoolEntryByEntryTime
-            >,
-            // sorted by fee rate with ancestors
-            boost::multi_index::ordered_non_unique<
-                boost::multi_index::tag<ancestor_score>,
-                boost::multi_index::identity<CTxMemPoolEntry>,
-                CompareTxMemPoolEntryByAncestorFee
             >
         >
         {};