diff --git a/src/primitives/transaction.cpp b/src/primitives/transaction.cpp
index 93bef75f8..91725ecc1 100644
--- a/src/primitives/transaction.cpp
+++ b/src/primitives/transaction.cpp
@@ -1,133 +1,103 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <primitives/transaction.h>
 
 #include <hash.h>
 #include <tinyformat.h>
 #include <util/strencodings.h>
 
 std::string COutPoint::ToString() const {
     return strprintf("COutPoint(%s, %u)", txid.ToString().substr(0, 10), n);
 }
 
 std::string CTxIn::ToString() const {
     std::string str;
     str += "CTxIn(";
     str += prevout.ToString();
     if (prevout.IsNull()) {
         str += strprintf(", coinbase %s", HexStr(scriptSig));
     } else {
         str += strprintf(", scriptSig=%s", HexStr(scriptSig).substr(0, 24));
     }
     if (nSequence != SEQUENCE_FINAL) {
         str += strprintf(", nSequence=%u", nSequence);
     }
     str += ")";
     return str;
 }
 
 std::string CTxOut::ToString() const {
     return strprintf("CTxOut(nValue=%d.%08d, scriptPubKey=%s)", nValue / COIN,
                      (nValue % COIN) / SATOSHI,
                      HexStr(scriptPubKey).substr(0, 30));
 }
 
 CMutableTransaction::CMutableTransaction()
     : nVersion(CTransaction::CURRENT_VERSION), nLockTime(0) {}
 CMutableTransaction::CMutableTransaction(const CTransaction &tx)
     : vin(tx.vin), vout(tx.vout), nVersion(tx.nVersion),
       nLockTime(tx.nLockTime) {}
 
 static uint256 ComputeCMutableTransactionHash(const CMutableTransaction &tx) {
     return SerializeHash(tx, SER_GETHASH, 0);
 }
 
 TxId CMutableTransaction::GetId() const {
     return TxId(ComputeCMutableTransactionHash(*this));
 }
 
 TxHash CMutableTransaction::GetHash() const {
     return TxHash(ComputeCMutableTransactionHash(*this));
 }
 
 uint256 CTransaction::ComputeHash() const {
     return SerializeHash(*this, SER_GETHASH, 0);
 }
 
 /**
  * For backward compatibility, the hash is initialized to 0.
  * TODO: remove the need for this default constructor entirely.
  */
 CTransaction::CTransaction()
     : vin(), vout(), nVersion(CTransaction::CURRENT_VERSION), nLockTime(0),
       hash() {}
 CTransaction::CTransaction(const CMutableTransaction &tx)
     : vin(tx.vin), vout(tx.vout), nVersion(tx.nVersion),
       nLockTime(tx.nLockTime), hash(ComputeHash()) {}
 CTransaction::CTransaction(CMutableTransaction &&tx)
     : vin(std::move(tx.vin)), vout(std::move(tx.vout)), nVersion(tx.nVersion),
       nLockTime(tx.nLockTime), hash(ComputeHash()) {}
 
 Amount CTransaction::GetValueOut() const {
     Amount nValueOut = Amount::zero();
     for (const auto &tx_out : vout) {
         nValueOut += tx_out.nValue;
         if (!MoneyRange(tx_out.nValue) || !MoneyRange(nValueOut)) {
             throw std::runtime_error(std::string(__func__) +
                                      ": value out of range");
         }
     }
     return nValueOut;
 }
 
-double CTransaction::ComputePriority(double dPriorityInputs,
-                                     unsigned int nTxSize) const {
-    nTxSize = CalculateModifiedSize(nTxSize);
-    if (nTxSize == 0) {
-        return 0.0;
-    }
-
-    return dPriorityInputs / nTxSize;
-}
-
-unsigned int CTransaction::CalculateModifiedSize(unsigned int nTxSize) const {
-    // In order to avoid disincentivizing cleaning up the UTXO set we don't
-    // count the constant overhead for each txin and up to 110 bytes of
-    // scriptSig (which is enough to cover a compressed pubkey p2sh redemption)
-    // for priority. Providing any more cleanup incentive than making additional
-    // inputs free would risk encouraging people to create junk outputs to
-    // redeem later.
-    if (nTxSize == 0) {
-        nTxSize = GetTotalSize();
-    }
-    for (const auto &nVin : vin) {
-        unsigned int offset =
-            41U + std::min(110U, (unsigned int)nVin.scriptSig.size());
-        if (nTxSize > offset) {
-            nTxSize -= offset;
-        }
-    }
-    return nTxSize;
-}
-
 unsigned int CTransaction::GetTotalSize() const {
     return ::GetSerializeSize(*this, PROTOCOL_VERSION);
 }
 
 std::string CTransaction::ToString() const {
     std::string str;
     str += strprintf("CTransaction(txid=%s, ver=%d, vin.size=%u, vout.size=%u, "
                      "nLockTime=%u)\n",
                      GetId().ToString().substr(0, 10), nVersion, vin.size(),
                      vout.size(), nLockTime);
     for (const auto &nVin : vin) {
         str += "    " + nVin.ToString() + "\n";
     }
     for (const auto &nVout : vout) {
         str += "    " + nVout.ToString() + "\n";
     }
     return str;
 }
diff --git a/src/primitives/transaction.h b/src/primitives/transaction.h
index 1bde8150e..9fe5d0309 100644
--- a/src/primitives/transaction.h
+++ b/src/primitives/transaction.h
@@ -1,367 +1,359 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Copyright (c) 2017-2018 The Bitcoin developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_PRIMITIVES_TRANSACTION_H
 #define BITCOIN_PRIMITIVES_TRANSACTION_H
 
 #include <amount.h>
 #include <feerate.h>
 #include <primitives/txid.h>
 #include <script/script.h>
 #include <serialize.h>
 
 static const int SERIALIZE_TRANSACTION = 0x00;
 
 /**
  * An outpoint - a combination of a transaction hash and an index n into its
  * vout.
  */
 class COutPoint {
 private:
     TxId txid;
     uint32_t n;
 
 public:
     COutPoint() : txid(), n(-1) {}
     COutPoint(TxId txidIn, uint32_t nIn) : txid(txidIn), n(nIn) {}
 
     ADD_SERIALIZE_METHODS;
 
     template <typename Stream, typename Operation>
     inline void SerializationOp(Stream &s, Operation ser_action) {
         READWRITE(txid);
         READWRITE(n);
     }
 
     bool IsNull() const { return txid.IsNull() && n == uint32_t(-1); }
 
     const TxId &GetTxId() const { return txid; }
     uint32_t GetN() const { return n; }
 
     friend bool operator<(const COutPoint &a, const COutPoint &b) {
         int cmp = a.txid.Compare(b.txid);
         return cmp < 0 || (cmp == 0 && a.n < b.n);
     }
 
     friend bool operator==(const COutPoint &a, const COutPoint &b) {
         return (a.txid == b.txid && a.n == b.n);
     }
 
     friend bool operator!=(const COutPoint &a, const COutPoint &b) {
         return !(a == b);
     }
 
     std::string ToString() const;
 };
 
 /**
  * An input of a transaction. It contains the location of the previous
  * transaction's output that it claims and a signature that matches the output's
  * public key.
  */
 class CTxIn {
 public:
     COutPoint prevout;
     CScript scriptSig;
     uint32_t nSequence;
 
     /**
      * Setting nSequence to this value for every input in a transaction disables
      * nLockTime.
      */
     static const uint32_t SEQUENCE_FINAL = 0xffffffff;
 
     /* Below flags apply in the context of BIP 68*/
     /**
      * If this flag set, CTxIn::nSequence is NOT interpreted as a relative
      * lock-time.
      */
     static const uint32_t SEQUENCE_LOCKTIME_DISABLE_FLAG = (1U << 31);
 
     /**
      * If CTxIn::nSequence encodes a relative lock-time and this flag is set,
      * the relative lock-time has units of 512 seconds, otherwise it specifies
      * blocks with a granularity of 1.
      */
     static const uint32_t SEQUENCE_LOCKTIME_TYPE_FLAG = (1 << 22);
 
     /**
      * If CTxIn::nSequence encodes a relative lock-time, this mask is applied to
      * extract that lock-time from the sequence field.
      */
     static const uint32_t SEQUENCE_LOCKTIME_MASK = 0x0000ffff;
 
     /**
      * In order to use the same number of bits to encode roughly the same
      * wall-clock duration, and because blocks are naturally limited to occur
      * every 600s on average, the minimum granularity for time-based relative
      * lock-time is fixed at 512 seconds. Converting from CTxIn::nSequence to
      * seconds is performed by multiplying by 512 = 2^9, or equivalently
      * shifting up by 9 bits.
      */
     static const int SEQUENCE_LOCKTIME_GRANULARITY = 9;
 
     CTxIn() { nSequence = SEQUENCE_FINAL; }
 
     explicit CTxIn(COutPoint prevoutIn, CScript scriptSigIn = CScript(),
                    uint32_t nSequenceIn = SEQUENCE_FINAL)
         : prevout(prevoutIn), scriptSig(scriptSigIn), nSequence(nSequenceIn) {}
     CTxIn(TxId prevTxId, uint32_t nOut, CScript scriptSigIn = CScript(),
           uint32_t nSequenceIn = SEQUENCE_FINAL)
         : CTxIn(COutPoint(prevTxId, nOut), scriptSigIn, nSequenceIn) {}
 
     ADD_SERIALIZE_METHODS;
 
     template <typename Stream, typename Operation>
     inline void SerializationOp(Stream &s, Operation ser_action) {
         READWRITE(prevout);
         READWRITE(scriptSig);
         READWRITE(nSequence);
     }
 
     friend bool operator==(const CTxIn &a, const CTxIn &b) {
         return (a.prevout == b.prevout && a.scriptSig == b.scriptSig &&
                 a.nSequence == b.nSequence);
     }
 
     friend bool operator!=(const CTxIn &a, const CTxIn &b) { return !(a == b); }
 
     std::string ToString() const;
 };
 
 /**
  * An output of a transaction.  It contains the public key that the next input
  * must be able to sign with to claim it.
  */
 class CTxOut {
 public:
     Amount nValue;
     CScript scriptPubKey;
 
     CTxOut() { SetNull(); }
 
     CTxOut(Amount nValueIn, CScript scriptPubKeyIn)
         : nValue(nValueIn), scriptPubKey(scriptPubKeyIn) {}
 
     ADD_SERIALIZE_METHODS;
 
     template <typename Stream, typename Operation>
     inline void SerializationOp(Stream &s, Operation ser_action) {
         READWRITE(nValue);
         READWRITE(scriptPubKey);
     }
 
     void SetNull() {
         nValue = -SATOSHI;
         scriptPubKey.clear();
     }
 
     bool IsNull() const { return nValue == -SATOSHI; }
 
     friend bool operator==(const CTxOut &a, const CTxOut &b) {
         return (a.nValue == b.nValue && a.scriptPubKey == b.scriptPubKey);
     }
 
     friend bool operator!=(const CTxOut &a, const CTxOut &b) {
         return !(a == b);
     }
 
     std::string ToString() const;
 };
 
 class CMutableTransaction;
 
 /**
  * Basic transaction serialization format:
  * - int32_t nVersion
  * - std::vector<CTxIn> vin
  * - std::vector<CTxOut> vout
  * - uint32_t nLockTime
  */
 template <typename Stream, typename TxType>
 inline void UnserializeTransaction(TxType &tx, Stream &s) {
     s >> tx.nVersion;
     tx.vin.clear();
     tx.vout.clear();
     /* Try to read the vin. In case the dummy is there, this will be read as an
      * empty vector. */
     s >> tx.vin;
     /* We read a non-empty vin. Assume a normal vout follows. */
     s >> tx.vout;
     s >> tx.nLockTime;
 }
 
 template <typename Stream, typename TxType>
 inline void SerializeTransaction(const TxType &tx, Stream &s) {
     s << tx.nVersion;
     s << tx.vin;
     s << tx.vout;
     s << tx.nLockTime;
 }
 
 /**
  * The basic transaction that is broadcasted on the network and contained in
  * blocks. A transaction can contain multiple inputs and outputs.
  */
 class CTransaction {
 public:
     // Default transaction version.
     static const int32_t CURRENT_VERSION = 2;
 
     // Changing the default transaction version requires a two step process:
     // first adapting relay policy by bumping MAX_STANDARD_VERSION, and then
     // later date bumping the default CURRENT_VERSION at which point both
     // CURRENT_VERSION and MAX_STANDARD_VERSION will be equal.
     static const int32_t MAX_STANDARD_VERSION = 2;
 
     // The local variables are made const to prevent unintended modification
     // without updating the cached hash value. However, CTransaction is not
     // actually immutable; deserialization and assignment are implemented,
     // and bypass the constness. This is safe, as they update the entire
     // structure, including the hash.
     const std::vector<CTxIn> vin;
     const std::vector<CTxOut> vout;
     const int32_t nVersion;
     const uint32_t nLockTime;
 
 private:
     /** Memory only. */
     const uint256 hash;
 
     uint256 ComputeHash() const;
 
 public:
     /** Construct a CTransaction that qualifies as IsNull() */
     CTransaction();
 
     /** Convert a CMutableTransaction into a CTransaction. */
     explicit CTransaction(const CMutableTransaction &tx);
     explicit CTransaction(CMutableTransaction &&tx);
 
     template <typename Stream> inline void Serialize(Stream &s) const {
         SerializeTransaction(*this, s);
     }
 
     /**
      * This deserializing constructor is provided instead of an Unserialize
      * method. Unserialize is not possible, since it would require overwriting
      * const fields.
      */
     template <typename Stream>
     CTransaction(deserialize_type, Stream &s)
         : CTransaction(CMutableTransaction(deserialize, s)) {}
 
     bool IsNull() const { return vin.empty() && vout.empty(); }
 
     const TxId GetId() const { return TxId(hash); }
     const TxHash GetHash() const { return TxHash(hash); }
 
     // Return sum of txouts.
     Amount GetValueOut() const;
     // GetValueIn() is a method on CCoinsViewCache, because
     // inputs must be known to compute value in.
 
-    // Compute priority, given priority of inputs and (optionally) tx size
-    double ComputePriority(double dPriorityInputs,
-                           unsigned int nTxSize = 0) const;
-
-    // Compute modified tx size for priority calculation (optionally given tx
-    // size)
-    unsigned int CalculateModifiedSize(unsigned int nTxSize = 0) const;
-
     /**
      * Get the total transaction size in bytes.
      * @return Total transaction size in bytes
      */
     unsigned int GetTotalSize() const;
 
     bool IsCoinBase() const {
         return (vin.size() == 1 && vin[0].prevout.IsNull());
     }
 
     friend bool operator==(const CTransaction &a, const CTransaction &b) {
         return a.GetHash() == b.GetHash();
     }
 
     friend bool operator!=(const CTransaction &a, const CTransaction &b) {
         return !(a == b);
     }
 
     std::string ToString() const;
 };
 #if defined(__x86_64__)
 static_assert(sizeof(CTransaction) == 88,
               "sizeof CTransaction is expected to be 88 bytes");
 #endif
 
 /**
  * A mutable version of CTransaction.
  */
 class CMutableTransaction {
 public:
     std::vector<CTxIn> vin;
     std::vector<CTxOut> vout;
     int32_t nVersion;
     uint32_t nLockTime;
 
     CMutableTransaction();
     explicit CMutableTransaction(const CTransaction &tx);
 
     template <typename Stream> inline void Serialize(Stream &s) const {
         SerializeTransaction(*this, s);
     }
 
     template <typename Stream> inline void Unserialize(Stream &s) {
         UnserializeTransaction(*this, s);
     }
 
     template <typename Stream>
     CMutableTransaction(deserialize_type, Stream &s) {
         Unserialize(s);
     }
 
     /**
      * Compute the id and hash of this CMutableTransaction. This is computed on
      * the fly, as opposed to GetId() and GetHash() in CTransaction, which uses
      * a cached result.
      */
     TxId GetId() const;
     TxHash GetHash() const;
 
     friend bool operator==(const CMutableTransaction &a,
                            const CMutableTransaction &b) {
         return a.GetHash() == b.GetHash();
     }
 };
 #if defined(__x86_64__)
 static_assert(sizeof(CMutableTransaction) == 56,
               "sizeof CMutableTransaction is expected to be 56 bytes");
 #endif
 
 typedef std::shared_ptr<const CTransaction> CTransactionRef;
 static inline CTransactionRef MakeTransactionRef() {
     return std::make_shared<const CTransaction>();
 }
 template <typename Tx>
 static inline CTransactionRef MakeTransactionRef(Tx &&txIn) {
     return std::make_shared<const CTransaction>(std::forward<Tx>(txIn));
 }
 
 /** Precompute sighash midstate to avoid quadratic hashing */
 struct PrecomputedTransactionData {
     uint256 hashPrevouts, hashSequence, hashOutputs;
 
     PrecomputedTransactionData()
         : hashPrevouts(), hashSequence(), hashOutputs() {}
 
     PrecomputedTransactionData(const PrecomputedTransactionData &txdata)
         : hashPrevouts(txdata.hashPrevouts), hashSequence(txdata.hashSequence),
           hashOutputs(txdata.hashOutputs) {}
 
     template <class T> explicit PrecomputedTransactionData(const T &tx);
 };
 
 #endif // BITCOIN_PRIMITIVES_TRANSACTION_H
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index 21d345bbd..e8e5da32e 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -1,1400 +1,1399 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <txmempool.h>
 
 #include <chain.h>
 #include <chainparams.h> // for GetConsensus.
 #include <clientversion.h>
 #include <config.h>
 #include <consensus/consensus.h>
 #include <consensus/tx_verify.h>
 #include <consensus/validation.h>
 #include <policy/fees.h>
 #include <policy/policy.h>
 #include <reverse_iterator.h>
 #include <streams.h>
 #include <timedata.h>
 #include <util/moneystr.h>
 #include <util/system.h>
 #include <util/time.h>
 #include <validation.h>
 #include <version.h>
 
 #include <algorithm>
 
 CTxMemPoolEntry::CTxMemPoolEntry(const CTransactionRef &_tx, const Amount _nFee,
                                  int64_t _nTime, unsigned int _entryHeight,
                                  bool _spendsCoinbase, int64_t _sigOpsCount,
                                  LockPoints lp)
     : tx(_tx), nFee(_nFee), nTime(_nTime), entryHeight(_entryHeight),
       spendsCoinbase(_spendsCoinbase), sigOpCount(_sigOpsCount),
       lockPoints(lp) {
     nTxSize = tx->GetTotalSize();
-    nModSize = tx->CalculateModifiedSize(GetTxSize());
     nUsageSize = RecursiveDynamicUsage(tx);
 
     nCountWithDescendants = 1;
     nSizeWithDescendants = GetTxSize();
     nModFeesWithDescendants = nFee;
 
     feeDelta = Amount::zero();
 
     nCountWithAncestors = 1;
     nSizeWithAncestors = GetTxSize();
     nModFeesWithAncestors = nFee;
     nSigOpCountWithAncestors = sigOpCount;
 }
 
 void CTxMemPoolEntry::UpdateFeeDelta(Amount newFeeDelta) {
     nModFeesWithDescendants += newFeeDelta - feeDelta;
     nModFeesWithAncestors += newFeeDelta - feeDelta;
     feeDelta = newFeeDelta;
 }
 
 void CTxMemPoolEntry::UpdateLockPoints(const LockPoints &lp) {
     lockPoints = lp;
 }
 
 // Update the given tx for any in-mempool descendants.
 // Assumes that setMemPoolChildren is correct for the given tx and all
 // descendants.
 void CTxMemPool::UpdateForDescendants(txiter updateIt,
                                       cacheMap &cachedDescendants,
                                       const std::set<TxId> &setExclude) {
     setEntries stageEntries, setAllDescendants;
     stageEntries = GetMemPoolChildren(updateIt);
 
     while (!stageEntries.empty()) {
         const txiter cit = *stageEntries.begin();
         setAllDescendants.insert(cit);
         stageEntries.erase(cit);
         const setEntries &setChildren = GetMemPoolChildren(cit);
         for (txiter childEntry : setChildren) {
             cacheMap::iterator cacheIt = cachedDescendants.find(childEntry);
             if (cacheIt != cachedDescendants.end()) {
                 // We've already calculated this one, just add the entries for
                 // this set but don't traverse again.
                 for (txiter cacheEntry : cacheIt->second) {
                     setAllDescendants.insert(cacheEntry);
                 }
             } else if (!setAllDescendants.count(childEntry)) {
                 // Schedule for later processing
                 stageEntries.insert(childEntry);
             }
         }
     }
     // setAllDescendants now contains all in-mempool descendants of updateIt.
     // Update and add to cached descendant map
     int64_t modifySize = 0;
     int64_t modifyCount = 0;
     Amount modifyFee = Amount::zero();
     for (txiter cit : setAllDescendants) {
         if (!setExclude.count(cit->GetTx().GetId())) {
             modifySize += cit->GetTxSize();
             modifyFee += cit->GetModifiedFee();
             modifyCount++;
             cachedDescendants[updateIt].insert(cit);
             // Update ancestor state for each descendant
             mapTx.modify(cit,
                          update_ancestor_state(updateIt->GetTxSize(),
                                                updateIt->GetModifiedFee(), 1,
                                                updateIt->GetSigOpCount()));
         }
     }
     mapTx.modify(updateIt,
                  update_descendant_state(modifySize, modifyFee, modifyCount));
 }
 
 // txidsToUpdate is the set of transaction hashes from a disconnected block
 // which has been re-added to the mempool. For each entry, look for descendants
 // that are outside txidsToUpdate, and add fee/size information for such
 // descendants to the parent. For each such descendant, also update the ancestor
 // state to include the parent.
 void CTxMemPool::UpdateTransactionsFromBlock(
     const std::vector<TxId> &txidsToUpdate) {
     LOCK(cs);
     // For each entry in txidsToUpdate, store the set of in-mempool, but not
     // in-txidsToUpdate transactions, so that we don't have to recalculate
     // descendants when we come across a previously seen entry.
     cacheMap mapMemPoolDescendantsToUpdate;
 
     // Use a set for lookups into txidsToUpdate (these entries are already
     // accounted for in the state of their ancestors)
     std::set<TxId> setAlreadyIncluded(txidsToUpdate.begin(),
                                       txidsToUpdate.end());
 
     // Iterate in reverse, so that whenever we are looking at a transaction
     // we are sure that all in-mempool descendants have already been processed.
     // This maximizes the benefit of the descendant cache and guarantees that
     // setMemPoolChildren will be updated, an assumption made in
     // UpdateForDescendants.
     for (const TxId &txid : reverse_iterate(txidsToUpdate)) {
         // we cache the in-mempool children to avoid duplicate updates
         setEntries setChildren;
         // calculate children from mapNextTx
         txiter it = mapTx.find(txid);
         if (it == mapTx.end()) {
             continue;
         }
 
         auto iter = mapNextTx.lower_bound(COutPoint(txid, 0));
         // First calculate the children, and update setMemPoolChildren to
         // include them, and update their setMemPoolParents to include this tx.
         for (; iter != mapNextTx.end() && iter->first->GetTxId() == txid;
              ++iter) {
             const TxId &childTxId = iter->second->GetId();
             txiter childIter = mapTx.find(childTxId);
             assert(childIter != mapTx.end());
             // We can skip updating entries we've encountered before or that are
             // in the block (which are already accounted for).
             if (setChildren.insert(childIter).second &&
                 !setAlreadyIncluded.count(childTxId)) {
                 UpdateChild(it, childIter, true);
                 UpdateParent(childIter, it, true);
             }
         }
         UpdateForDescendants(it, mapMemPoolDescendantsToUpdate,
                              setAlreadyIncluded);
     }
 }
 
 bool CTxMemPool::CalculateMemPoolAncestors(
     const CTxMemPoolEntry &entry, setEntries &setAncestors,
     uint64_t limitAncestorCount, uint64_t limitAncestorSize,
     uint64_t limitDescendantCount, uint64_t limitDescendantSize,
     std::string &errString, bool fSearchForParents /* = true */) const {
     setEntries parentHashes;
     const CTransaction &tx = entry.GetTx();
 
     if (fSearchForParents) {
         // Get parents of this transaction that are in the mempool
         // GetMemPoolParents() is only valid for entries in the mempool, so we
         // iterate mapTx to find parents.
         for (const CTxIn &in : tx.vin) {
             boost::optional<txiter> piter = GetIter(in.prevout.GetTxId());
             if (!piter) {
                 continue;
             }
             parentHashes.insert(*piter);
             if (parentHashes.size() + 1 > limitAncestorCount) {
                 errString =
                     strprintf("too many unconfirmed parents [limit: %u]",
                               limitAncestorCount);
                 return false;
             }
         }
     } else {
         // If we're not searching for parents, we require this to be an entry in
         // the mempool already.
         txiter it = mapTx.iterator_to(entry);
         parentHashes = GetMemPoolParents(it);
     }
 
     size_t totalSizeWithAncestors = entry.GetTxSize();
 
     while (!parentHashes.empty()) {
         txiter stageit = *parentHashes.begin();
 
         setAncestors.insert(stageit);
         parentHashes.erase(stageit);
         totalSizeWithAncestors += stageit->GetTxSize();
 
         if (stageit->GetSizeWithDescendants() + entry.GetTxSize() >
             limitDescendantSize) {
             errString = strprintf(
                 "exceeds descendant size limit for tx %s [limit: %u]",
                 stageit->GetTx().GetId().ToString(), limitDescendantSize);
             return false;
         }
 
         if (stageit->GetCountWithDescendants() + 1 > limitDescendantCount) {
             errString = strprintf("too many descendants for tx %s [limit: %u]",
                                   stageit->GetTx().GetId().ToString(),
                                   limitDescendantCount);
             return false;
         }
 
         if (totalSizeWithAncestors > limitAncestorSize) {
             errString = strprintf("exceeds ancestor size limit [limit: %u]",
                                   limitAncestorSize);
             return false;
         }
 
         const setEntries &setMemPoolParents = GetMemPoolParents(stageit);
         for (txiter phash : setMemPoolParents) {
             // If this is a new ancestor, add it.
             if (setAncestors.count(phash) == 0) {
                 parentHashes.insert(phash);
             }
             if (parentHashes.size() + setAncestors.size() + 1 >
                 limitAncestorCount) {
                 errString =
                     strprintf("too many unconfirmed ancestors [limit: %u]",
                               limitAncestorCount);
                 return false;
             }
         }
     }
 
     return true;
 }
 
 void CTxMemPool::UpdateAncestorsOf(bool add, txiter it,
                                    setEntries &setAncestors) {
     setEntries parentIters = GetMemPoolParents(it);
     // add or remove this tx as a child of each parent
     for (txiter piter : parentIters) {
         UpdateChild(piter, it, add);
     }
     const int64_t updateCount = (add ? 1 : -1);
     const int64_t updateSize = updateCount * it->GetTxSize();
     const Amount updateFee = updateCount * it->GetModifiedFee();
     for (txiter ancestorIt : setAncestors) {
         mapTx.modify(ancestorIt, update_descendant_state(updateSize, updateFee,
                                                          updateCount));
     }
 }
 
 void CTxMemPool::UpdateEntryForAncestors(txiter it,
                                          const setEntries &setAncestors) {
     int64_t updateCount = setAncestors.size();
     int64_t updateSize = 0;
     int64_t updateSigOpsCount = 0;
     Amount updateFee = Amount::zero();
 
     for (txiter ancestorIt : setAncestors) {
         updateSize += ancestorIt->GetTxSize();
         updateFee += ancestorIt->GetModifiedFee();
         updateSigOpsCount += ancestorIt->GetSigOpCount();
     }
     mapTx.modify(it, update_ancestor_state(updateSize, updateFee, updateCount,
                                            updateSigOpsCount));
 }
 
 void CTxMemPool::UpdateChildrenForRemoval(txiter it) {
     const setEntries &setMemPoolChildren = GetMemPoolChildren(it);
     for (txiter updateIt : setMemPoolChildren) {
         UpdateParent(updateIt, it, false);
     }
 }
 
 void CTxMemPool::UpdateForRemoveFromMempool(const setEntries &entriesToRemove,
                                             bool updateDescendants) {
     // For each entry, walk back all ancestors and decrement size associated
     // with this transaction.
     const uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
     if (updateDescendants) {
         // updateDescendants should be true whenever we're not recursively
         // removing a tx and all its descendants, eg when a transaction is
         // confirmed in a block. Here we only update statistics and not data in
         // mapLinks (which we need to preserve until we're finished with all
         // operations that need to traverse the mempool).
         for (txiter removeIt : entriesToRemove) {
             setEntries setDescendants;
             CalculateDescendants(removeIt, setDescendants);
             setDescendants.erase(removeIt); // don't update state for self
             int64_t modifySize = -int64_t(removeIt->GetTxSize());
             Amount modifyFee = -1 * removeIt->GetModifiedFee();
             int modifySigOps = -removeIt->GetSigOpCount();
             for (txiter dit : setDescendants) {
                 mapTx.modify(dit, update_ancestor_state(modifySize, modifyFee,
                                                         -1, modifySigOps));
             }
         }
     }
 
     for (txiter removeIt : entriesToRemove) {
         setEntries setAncestors;
         const CTxMemPoolEntry &entry = *removeIt;
         std::string dummy;
         // Since this is a tx that is already in the mempool, we can call CMPA
         // with fSearchForParents = false.  If the mempool is in a consistent
         // state, then using true or false should both be correct, though false
         // should be a bit faster.
         // However, if we happen to be in the middle of processing a reorg, then
         // the mempool can be in an inconsistent state. In this case, the set of
         // ancestors reachable via mapLinks will be the same as the set of
         // ancestors whose packages include this transaction, because when we
         // add a new transaction to the mempool in addUnchecked(), we assume it
         // has no children, and in the case of a reorg where that assumption is
         // false, the in-mempool children aren't linked to the in-block tx's
         // until UpdateTransactionsFromBlock() is called. So if we're being
         // called during a reorg, ie before UpdateTransactionsFromBlock() has
         // been called, then mapLinks[] will differ from the set of mempool
         // parents we'd calculate by searching, and it's important that we use
         // the mapLinks[] notion of ancestor transactions as the set of things
         // to update for removal.
         CalculateMemPoolAncestors(entry, setAncestors, nNoLimit, nNoLimit,
                                   nNoLimit, nNoLimit, dummy, false);
         // Note that UpdateAncestorsOf severs the child links that point to
         // removeIt in the entries for the parents of removeIt.
         UpdateAncestorsOf(false, removeIt, setAncestors);
     }
     // After updating all the ancestor sizes, we can now sever the link between
     // each transaction being removed and any mempool children (ie, update
     // setMemPoolParents for each direct child of a transaction being removed).
     for (txiter removeIt : entriesToRemove) {
         UpdateChildrenForRemoval(removeIt);
     }
 }
 
 void CTxMemPoolEntry::UpdateDescendantState(int64_t modifySize,
                                             Amount modifyFee,
                                             int64_t modifyCount) {
     nSizeWithDescendants += modifySize;
     assert(int64_t(nSizeWithDescendants) > 0);
     nModFeesWithDescendants += modifyFee;
     nCountWithDescendants += modifyCount;
     assert(int64_t(nCountWithDescendants) > 0);
 }
 
 void CTxMemPoolEntry::UpdateAncestorState(int64_t modifySize, Amount modifyFee,
                                           int64_t modifyCount,
                                           int modifySigOps) {
     nSizeWithAncestors += modifySize;
     assert(int64_t(nSizeWithAncestors) > 0);
     nModFeesWithAncestors += modifyFee;
     nCountWithAncestors += modifyCount;
     assert(int64_t(nCountWithAncestors) > 0);
     nSigOpCountWithAncestors += modifySigOps;
     assert(int(nSigOpCountWithAncestors) >= 0);
 }
 
 CTxMemPool::CTxMemPool() : nTransactionsUpdated(0) {
     // lock free clear
     _clear();
 
     // Sanity checks off by default for performance, because otherwise accepting
     // transactions becomes O(N^2) where N is the number of transactions in the
     // pool
     nCheckFrequency = 0;
 }
 
 CTxMemPool::~CTxMemPool() {}
 
 bool CTxMemPool::isSpent(const COutPoint &outpoint) const {
     LOCK(cs);
     return mapNextTx.count(outpoint);
 }
 
 unsigned int CTxMemPool::GetTransactionsUpdated() const {
     LOCK(cs);
     return nTransactionsUpdated;
 }
 
 void CTxMemPool::AddTransactionsUpdated(unsigned int n) {
     LOCK(cs);
     nTransactionsUpdated += n;
 }
 
 void CTxMemPool::addUnchecked(const TxId &txid, const CTxMemPoolEntry &entry,
                               setEntries &setAncestors) {
     NotifyEntryAdded(entry.GetSharedTx());
     // Add to memory pool without checking anything.
     // Used by AcceptToMemoryPool(), which DOES do all the appropriate checks.
     indexed_transaction_set::iterator newit = mapTx.insert(entry).first;
     mapLinks.insert(make_pair(newit, TxLinks()));
 
     // Update transaction for any feeDelta created by PrioritiseTransaction
     // TODO: refactor so that the fee delta is calculated before inserting into
     // mapTx.
     double priorityDelta = 0;
     Amount feeDelta = Amount::zero();
     ApplyDeltas(entry.GetTx().GetId(), priorityDelta, feeDelta);
     if (feeDelta != Amount::zero()) {
         mapTx.modify(newit, update_fee_delta(feeDelta));
     }
 
     // Update cachedInnerUsage to include contained transaction's usage.
     // (When we update the entry for in-mempool parents, memory usage will be
     // further updated.)
     cachedInnerUsage += entry.DynamicMemoryUsage();
 
     const CTransaction &tx = newit->GetTx();
     std::set<TxId> setParentTransactions;
     for (const CTxIn &in : tx.vin) {
         mapNextTx.insert(std::make_pair(&in.prevout, &tx));
         setParentTransactions.insert(in.prevout.GetTxId());
     }
     // Don't bother worrying about child transactions of this one. Normal case
     // of a new transaction arriving is that there can't be any children,
     // because such children would be orphans. An exception to that is if a
     // transaction enters that used to be in a block. In that case, our
     // disconnect block logic will call UpdateTransactionsFromBlock to clean up
     // the mess we're leaving here.
 
     // Update ancestors with information about this tx
     for (const auto &pit : GetIterSet(setParentTransactions)) {
         UpdateParent(newit, pit, true);
     }
     UpdateAncestorsOf(true, newit, setAncestors);
     UpdateEntryForAncestors(newit, setAncestors);
 
     nTransactionsUpdated++;
     totalTxSize += entry.GetTxSize();
 
     vTxHashes.emplace_back(tx.GetHash(), newit);
     newit->vTxHashesIdx = vTxHashes.size() - 1;
 }
 
 void CTxMemPool::removeUnchecked(txiter it, MemPoolRemovalReason reason) {
     NotifyEntryRemoved(it->GetSharedTx(), reason);
     for (const CTxIn &txin : it->GetTx().vin) {
         mapNextTx.erase(txin.prevout);
     }
 
     if (vTxHashes.size() > 1) {
         vTxHashes[it->vTxHashesIdx] = std::move(vTxHashes.back());
         vTxHashes[it->vTxHashesIdx].second->vTxHashesIdx = it->vTxHashesIdx;
         vTxHashes.pop_back();
         if (vTxHashes.size() * 2 < vTxHashes.capacity()) {
             vTxHashes.shrink_to_fit();
         }
     } else {
         vTxHashes.clear();
     }
 
     totalTxSize -= it->GetTxSize();
     cachedInnerUsage -= it->DynamicMemoryUsage();
     cachedInnerUsage -= memusage::DynamicUsage(mapLinks[it].parents) +
                         memusage::DynamicUsage(mapLinks[it].children);
     mapLinks.erase(it);
     mapTx.erase(it);
     nTransactionsUpdated++;
 }
 
 // Calculates descendants of entry that are not already in setDescendants, and
 // adds to setDescendants. Assumes entryit is already a tx in the mempool and
 // setMemPoolChildren is correct for tx and all descendants. Also assumes that
 // if an entry is in setDescendants already, then all in-mempool descendants of
 // it are already in setDescendants as well, so that we can save time by not
 // iterating over those entries.
 void CTxMemPool::CalculateDescendants(txiter entryit,
                                       setEntries &setDescendants) const {
     setEntries stage;
     if (setDescendants.count(entryit) == 0) {
         stage.insert(entryit);
     }
     // Traverse down the children of entry, only adding children that are not
     // accounted for in setDescendants already (because those children have
     // either already been walked, or will be walked in this iteration).
     while (!stage.empty()) {
         txiter it = *stage.begin();
         setDescendants.insert(it);
         stage.erase(it);
 
         const setEntries &setChildren = GetMemPoolChildren(it);
         for (txiter childiter : setChildren) {
             if (!setDescendants.count(childiter)) {
                 stage.insert(childiter);
             }
         }
     }
 }
 
 void CTxMemPool::removeRecursive(const CTransaction &origTx,
                                  MemPoolRemovalReason reason) {
     // Remove transaction from memory pool.
     LOCK(cs);
     setEntries txToRemove;
     txiter origit = mapTx.find(origTx.GetId());
     if (origit != mapTx.end()) {
         txToRemove.insert(origit);
     } else {
         // When recursively removing but origTx isn't in the mempool be sure to
         // remove any children that are in the pool. This can happen during
         // chain re-orgs if origTx isn't re-accepted into the mempool for any
         // reason.
         for (size_t i = 0; i < origTx.vout.size(); i++) {
             auto it = mapNextTx.find(COutPoint(origTx.GetId(), i));
             if (it == mapNextTx.end()) {
                 continue;
             }
 
             txiter nextit = mapTx.find(it->second->GetId());
             assert(nextit != mapTx.end());
             txToRemove.insert(nextit);
         }
     }
 
     setEntries setAllRemoves;
     for (txiter it : txToRemove) {
         CalculateDescendants(it, setAllRemoves);
     }
 
     RemoveStaged(setAllRemoves, false, reason);
 }
 
 void CTxMemPool::removeForReorg(const Config &config,
                                 const CCoinsViewCache *pcoins,
                                 unsigned int nMemPoolHeight, int flags) {
     // Remove transactions spending a coinbase which are now immature and
     // no-longer-final transactions.
     LOCK(cs);
     setEntries txToRemove;
     for (indexed_transaction_set::const_iterator it = mapTx.begin();
          it != mapTx.end(); it++) {
         const CTransaction &tx = it->GetTx();
         LockPoints lp = it->GetLockPoints();
         bool validLP = TestLockPointValidity(&lp);
 
         CValidationState state;
         if (!ContextualCheckTransactionForCurrentBlock(
                 config.GetChainParams().GetConsensus(), tx, state, flags) ||
             !CheckSequenceLocks(*this, tx, flags, &lp, validLP)) {
             // Note if CheckSequenceLocks fails the LockPoints may still be
             // invalid. So it's critical that we remove the tx and not depend on
             // the LockPoints.
             txToRemove.insert(it);
         } else if (it->GetSpendsCoinbase()) {
             for (const CTxIn &txin : tx.vin) {
                 indexed_transaction_set::const_iterator it2 =
                     mapTx.find(txin.prevout.GetTxId());
                 if (it2 != mapTx.end()) {
                     continue;
                 }
 
                 const Coin &coin = pcoins->AccessCoin(txin.prevout);
                 if (nCheckFrequency != 0) {
                     assert(!coin.IsSpent());
                 }
 
                 if (coin.IsSpent() ||
                     (coin.IsCoinBase() &&
                      int64_t(nMemPoolHeight) - coin.GetHeight() <
                          COINBASE_MATURITY)) {
                     txToRemove.insert(it);
                     break;
                 }
             }
         }
         if (!validLP) {
             mapTx.modify(it, update_lock_points(lp));
         }
     }
     setEntries setAllRemoves;
     for (txiter it : txToRemove) {
         CalculateDescendants(it, setAllRemoves);
     }
     RemoveStaged(setAllRemoves, false, MemPoolRemovalReason::REORG);
 }
 
 void CTxMemPool::removeConflicts(const CTransaction &tx) {
     // Remove transactions which depend on inputs of tx, recursively
     AssertLockHeld(cs);
     for (const CTxIn &txin : tx.vin) {
         auto it = mapNextTx.find(txin.prevout);
         if (it != mapNextTx.end()) {
             const CTransaction &txConflict = *it->second;
             if (txConflict != tx) {
                 ClearPrioritisation(txConflict.GetId());
                 removeRecursive(txConflict, MemPoolRemovalReason::CONFLICT);
             }
         }
     }
 }
 
 /**
  * Called when a block is connected. Removes from mempool and updates the miner
  * fee estimator.
  */
 void CTxMemPool::removeForBlock(const std::vector<CTransactionRef> &vtx,
                                 unsigned int nBlockHeight) {
     LOCK(cs);
 
     DisconnectedBlockTransactions disconnectpool;
     disconnectpool.addForBlock(vtx);
 
     std::vector<const CTxMemPoolEntry *> entries;
     for (const CTransactionRef &tx :
          reverse_iterate(disconnectpool.GetQueuedTx().get<insertion_order>())) {
         const TxId &txid = tx->GetId();
 
         indexed_transaction_set::iterator i = mapTx.find(txid);
         if (i != mapTx.end()) {
             entries.push_back(&*i);
         }
     }
 
     for (const CTransactionRef &tx :
          reverse_iterate(disconnectpool.GetQueuedTx().get<insertion_order>())) {
         txiter it = mapTx.find(tx->GetId());
         if (it != mapTx.end()) {
             setEntries stage;
             stage.insert(it);
             RemoveStaged(stage, true, MemPoolRemovalReason::BLOCK);
         }
         removeConflicts(*tx);
         ClearPrioritisation(tx->GetId());
     }
 
     disconnectpool.clear();
 
     lastRollingFeeUpdate = GetTime();
     blockSinceLastRollingFeeBump = true;
 }
 
 void CTxMemPool::_clear() {
     mapLinks.clear();
     mapTx.clear();
     mapNextTx.clear();
     vTxHashes.clear();
     totalTxSize = 0;
     cachedInnerUsage = 0;
     lastRollingFeeUpdate = GetTime();
     blockSinceLastRollingFeeBump = false;
     rollingMinimumFeeRate = 0;
     ++nTransactionsUpdated;
 }
 
 void CTxMemPool::clear() {
     LOCK(cs);
     _clear();
 }
 
 static void CheckInputsAndUpdateCoins(const CTransaction &tx,
                                       CCoinsViewCache &mempoolDuplicate,
                                       const int64_t spendheight) {
     CValidationState state;
     Amount txfee = Amount::zero();
     bool fCheckResult =
         tx.IsCoinBase() || Consensus::CheckTxInputs(tx, state, mempoolDuplicate,
                                                     spendheight, txfee);
     assert(fCheckResult);
     UpdateCoins(mempoolDuplicate, tx, std::numeric_limits<int>::max());
 }
 
 void CTxMemPool::check(const CCoinsViewCache *pcoins) const {
     LOCK(cs);
     if (nCheckFrequency == 0) {
         return;
     }
 
     if (GetRand(std::numeric_limits<uint32_t>::max()) >= nCheckFrequency) {
         return;
     }
 
     LogPrint(BCLog::MEMPOOL,
              "Checking mempool with %u transactions and %u inputs\n",
              (unsigned int)mapTx.size(), (unsigned int)mapNextTx.size());
 
     uint64_t checkTotal = 0;
     uint64_t innerUsage = 0;
 
     CCoinsViewCache mempoolDuplicate(const_cast<CCoinsViewCache *>(pcoins));
     const int64_t spendheight = GetSpendHeight(mempoolDuplicate);
 
     std::list<const CTxMemPoolEntry *> waitingOnDependants;
     for (indexed_transaction_set::const_iterator it = mapTx.begin();
          it != mapTx.end(); it++) {
         unsigned int i = 0;
         checkTotal += it->GetTxSize();
         innerUsage += it->DynamicMemoryUsage();
         const CTransaction &tx = it->GetTx();
         txlinksMap::const_iterator linksiter = mapLinks.find(it);
         assert(linksiter != mapLinks.end());
         const TxLinks &links = linksiter->second;
         innerUsage += memusage::DynamicUsage(links.parents) +
                       memusage::DynamicUsage(links.children);
         bool fDependsWait = false;
         setEntries setParentCheck;
         for (const CTxIn &txin : tx.vin) {
             // Check that every mempool transaction's inputs refer to available
             // coins, or other mempool tx's.
             indexed_transaction_set::const_iterator it2 =
                 mapTx.find(txin.prevout.GetTxId());
             if (it2 != mapTx.end()) {
                 const CTransaction &tx2 = it2->GetTx();
                 assert(tx2.vout.size() > txin.prevout.GetN() &&
                        !tx2.vout[txin.prevout.GetN()].IsNull());
                 fDependsWait = true;
                 setParentCheck.insert(it2);
             } else {
                 assert(pcoins->HaveCoin(txin.prevout));
             }
             // Check whether its inputs are marked in mapNextTx.
             auto it3 = mapNextTx.find(txin.prevout);
             assert(it3 != mapNextTx.end());
             assert(it3->first == &txin.prevout);
             assert(it3->second == &tx);
             i++;
         }
         assert(setParentCheck == GetMemPoolParents(it));
         // Verify ancestor state is correct.
         setEntries setAncestors;
         uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
         std::string dummy;
         CalculateMemPoolAncestors(*it, setAncestors, nNoLimit, nNoLimit,
                                   nNoLimit, nNoLimit, dummy);
         uint64_t nCountCheck = setAncestors.size() + 1;
         uint64_t nSizeCheck = it->GetTxSize();
         Amount nFeesCheck = it->GetModifiedFee();
         int64_t nSigOpCheck = it->GetSigOpCount();
 
         for (txiter ancestorIt : setAncestors) {
             nSizeCheck += ancestorIt->GetTxSize();
             nFeesCheck += ancestorIt->GetModifiedFee();
             nSigOpCheck += ancestorIt->GetSigOpCount();
         }
 
         assert(it->GetCountWithAncestors() == nCountCheck);
         assert(it->GetSizeWithAncestors() == nSizeCheck);
         assert(it->GetSigOpCountWithAncestors() == nSigOpCheck);
         assert(it->GetModFeesWithAncestors() == nFeesCheck);
 
         // Check children against mapNextTx
         CTxMemPool::setEntries setChildrenCheck;
         auto iter = mapNextTx.lower_bound(COutPoint(it->GetTx().GetId(), 0));
         uint64_t child_sizes = 0;
         for (; iter != mapNextTx.end() &&
                iter->first->GetTxId() == it->GetTx().GetId();
              ++iter) {
             txiter childit = mapTx.find(iter->second->GetId());
             // mapNextTx points to in-mempool transactions
             assert(childit != mapTx.end());
             if (setChildrenCheck.insert(childit).second) {
                 child_sizes += childit->GetTxSize();
             }
         }
         assert(setChildrenCheck == GetMemPoolChildren(it));
         // Also check to make sure size is greater than sum with immediate
         // children. Just a sanity check, not definitive that this calc is
         // correct...
         assert(it->GetSizeWithDescendants() >= child_sizes + it->GetTxSize());
 
         if (fDependsWait) {
             waitingOnDependants.push_back(&(*it));
         } else {
             CheckInputsAndUpdateCoins(tx, mempoolDuplicate, spendheight);
         }
     }
 
     unsigned int stepsSinceLastRemove = 0;
     while (!waitingOnDependants.empty()) {
         const CTxMemPoolEntry *entry = waitingOnDependants.front();
         waitingOnDependants.pop_front();
         if (!mempoolDuplicate.HaveInputs(entry->GetTx())) {
             waitingOnDependants.push_back(entry);
             stepsSinceLastRemove++;
             assert(stepsSinceLastRemove < waitingOnDependants.size());
         } else {
             CheckInputsAndUpdateCoins(entry->GetTx(), mempoolDuplicate,
                                       spendheight);
             stepsSinceLastRemove = 0;
         }
     }
 
     for (auto it = mapNextTx.cbegin(); it != mapNextTx.cend(); it++) {
         const TxId &txid = it->second->GetId();
         indexed_transaction_set::const_iterator it2 = mapTx.find(txid);
         const CTransaction &tx = it2->GetTx();
         assert(it2 != mapTx.end());
         assert(&tx == it->second);
     }
 
     assert(totalTxSize == checkTotal);
     assert(innerUsage == cachedInnerUsage);
 }
 
 bool CTxMemPool::CompareDepthAndScore(const TxId &txida, const TxId &txidb) {
     LOCK(cs);
     indexed_transaction_set::const_iterator i = mapTx.find(txida);
     if (i == mapTx.end()) {
         return false;
     }
     indexed_transaction_set::const_iterator j = mapTx.find(txidb);
     if (j == mapTx.end()) {
         return true;
     }
     uint64_t counta = i->GetCountWithAncestors();
     uint64_t countb = j->GetCountWithAncestors();
     if (counta == countb) {
         return CompareTxMemPoolEntryByScore()(*i, *j);
     }
     return counta < countb;
 }
 
 namespace {
 class DepthAndScoreComparator {
 public:
     bool
     operator()(const CTxMemPool::indexed_transaction_set::const_iterator &a,
                const CTxMemPool::indexed_transaction_set::const_iterator &b) {
         uint64_t counta = a->GetCountWithAncestors();
         uint64_t countb = b->GetCountWithAncestors();
         if (counta == countb) {
             return CompareTxMemPoolEntryByScore()(*a, *b);
         }
         return counta < countb;
     }
 };
 } // namespace
 
 std::vector<CTxMemPool::indexed_transaction_set::const_iterator>
 CTxMemPool::GetSortedDepthAndScore() const {
     std::vector<indexed_transaction_set::const_iterator> iters;
     AssertLockHeld(cs);
 
     iters.reserve(mapTx.size());
     for (indexed_transaction_set::iterator mi = mapTx.begin();
          mi != mapTx.end(); ++mi) {
         iters.push_back(mi);
     }
 
     std::sort(iters.begin(), iters.end(), DepthAndScoreComparator());
     return iters;
 }
 
 void CTxMemPool::queryHashes(std::vector<uint256> &vtxid) const {
     LOCK(cs);
     auto iters = GetSortedDepthAndScore();
 
     vtxid.clear();
     vtxid.reserve(mapTx.size());
 
     for (auto it : iters) {
         vtxid.push_back(it->GetTx().GetId());
     }
 }
 
 static TxMempoolInfo
 GetInfo(CTxMemPool::indexed_transaction_set::const_iterator it) {
     return TxMempoolInfo{it->GetSharedTx(), it->GetTime(),
                          CFeeRate(it->GetFee(), it->GetTxSize()),
                          it->GetModifiedFee() - it->GetFee()};
 }
 
 std::vector<TxMempoolInfo> CTxMemPool::infoAll() const {
     LOCK(cs);
     auto iters = GetSortedDepthAndScore();
 
     std::vector<TxMempoolInfo> ret;
     ret.reserve(mapTx.size());
     for (auto it : iters) {
         ret.push_back(GetInfo(it));
     }
 
     return ret;
 }
 
 CTransactionRef CTxMemPool::get(const TxId &txid) const {
     LOCK(cs);
     indexed_transaction_set::const_iterator i = mapTx.find(txid);
     if (i == mapTx.end()) {
         return nullptr;
     }
 
     return i->GetSharedTx();
 }
 
 TxMempoolInfo CTxMemPool::info(const TxId &txid) const {
     LOCK(cs);
     indexed_transaction_set::const_iterator i = mapTx.find(txid);
     if (i == mapTx.end()) {
         return TxMempoolInfo();
     }
 
     return GetInfo(i);
 }
 
 CFeeRate CTxMemPool::estimateFee() const {
     LOCK(cs);
 
     uint64_t maxMempoolSize =
         gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000;
     // minerPolicy uses recent blocks to figure out a reasonable fee.  This
     // may disagree with the rollingMinimumFeerate under certain scenarios
     // where the mempool  increases rapidly, or blocks are being mined which
     // do not contain propagated transactions.
     return std::max(::minRelayTxFee, GetMinFee(maxMempoolSize));
 }
 
 void CTxMemPool::PrioritiseTransaction(const TxId &txid, double dPriorityDelta,
                                        const Amount nFeeDelta) {
     {
         LOCK(cs);
         TXModifier &deltas = mapDeltas[txid];
         deltas.first += dPriorityDelta;
         deltas.second += nFeeDelta;
         txiter it = mapTx.find(txid);
         if (it != mapTx.end()) {
             mapTx.modify(it, update_fee_delta(deltas.second));
             // Now update all ancestors' modified fees with descendants
             setEntries setAncestors;
             uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
             std::string dummy;
             CalculateMemPoolAncestors(*it, setAncestors, nNoLimit, nNoLimit,
                                       nNoLimit, nNoLimit, dummy, false);
             for (txiter ancestorIt : setAncestors) {
                 mapTx.modify(ancestorIt,
                              update_descendant_state(0, nFeeDelta, 0));
             }
 
             // Now update all descendants' modified fees with ancestors
             setEntries setDescendants;
             CalculateDescendants(it, setDescendants);
             setDescendants.erase(it);
             for (txiter descendantIt : setDescendants) {
                 mapTx.modify(descendantIt,
                              update_ancestor_state(0, nFeeDelta, 0, 0));
             }
             ++nTransactionsUpdated;
         }
     }
     LogPrintf("PrioritiseTransaction: %s priority += %f, fee += %d\n",
               txid.ToString(), dPriorityDelta, FormatMoney(nFeeDelta));
 }
 
 void CTxMemPool::ApplyDeltas(const TxId &txid, double &dPriorityDelta,
                              Amount &nFeeDelta) const {
     LOCK(cs);
     std::map<TxId, TXModifier>::const_iterator pos = mapDeltas.find(txid);
     if (pos == mapDeltas.end()) {
         return;
     }
 
     const TXModifier &deltas = pos->second;
     dPriorityDelta += deltas.first;
     nFeeDelta += deltas.second;
 }
 
 void CTxMemPool::ClearPrioritisation(const TxId &txid) {
     LOCK(cs);
     mapDeltas.erase(txid);
 }
 
 const CTransaction *CTxMemPool::GetConflictTx(const COutPoint &prevout) const {
     const auto it = mapNextTx.find(prevout);
     return it == mapNextTx.end() ? nullptr : it->second;
 }
 
 boost::optional<CTxMemPool::txiter>
 CTxMemPool::GetIter(const TxId &txid) const {
     auto it = mapTx.find(txid);
     if (it != mapTx.end()) {
         return it;
     }
     return boost::optional<txiter>{};
 }
 
 CTxMemPool::setEntries
 CTxMemPool::GetIterSet(const std::set<TxId> &txids) const {
     CTxMemPool::setEntries ret;
     for (const auto &txid : txids) {
         const auto mi = GetIter(txid);
         if (mi) {
             ret.insert(*mi);
         }
     }
     return ret;
 }
 
 bool CTxMemPool::HasNoInputsOf(const CTransaction &tx) const {
     for (const CTxIn &in : tx.vin) {
         if (exists(in.prevout.GetTxId())) {
             return false;
         }
     }
 
     return true;
 }
 
 CCoinsViewMemPool::CCoinsViewMemPool(CCoinsView *baseIn,
                                      const CTxMemPool &mempoolIn)
     : CCoinsViewBacked(baseIn), mempool(mempoolIn) {}
 
 bool CCoinsViewMemPool::GetCoin(const COutPoint &outpoint, Coin &coin) const {
     // If an entry in the mempool exists, always return that one, as it's
     // guaranteed to never conflict with the underlying cache, and it cannot
     // have pruned entries (as it contains full) transactions. First checking
     // the underlying cache risks returning a pruned entry instead.
     CTransactionRef ptx = mempool.get(outpoint.GetTxId());
     if (ptx) {
         if (outpoint.GetN() < ptx->vout.size()) {
             coin = Coin(ptx->vout[outpoint.GetN()], MEMPOOL_HEIGHT, false);
             return true;
         }
         return false;
     }
     return base->GetCoin(outpoint, coin);
 }
 
 size_t CTxMemPool::DynamicMemoryUsage() const {
     LOCK(cs);
     // Estimate the overhead of mapTx to be 12 pointers + an allocation, as no
     // exact formula for boost::multi_index_contained is implemented.
     return memusage::MallocUsage(sizeof(CTxMemPoolEntry) +
                                  12 * sizeof(void *)) *
                mapTx.size() +
            memusage::DynamicUsage(mapNextTx) +
            memusage::DynamicUsage(mapDeltas) +
            memusage::DynamicUsage(mapLinks) +
            memusage::DynamicUsage(vTxHashes) + cachedInnerUsage;
 }
 
 void CTxMemPool::RemoveStaged(setEntries &stage, bool updateDescendants,
                               MemPoolRemovalReason reason) {
     AssertLockHeld(cs);
     UpdateForRemoveFromMempool(stage, updateDescendants);
     for (txiter it : stage) {
         removeUnchecked(it, reason);
     }
 }
 
 int CTxMemPool::Expire(int64_t time) {
     LOCK(cs);
     indexed_transaction_set::index<entry_time>::type::iterator it =
         mapTx.get<entry_time>().begin();
     setEntries toremove;
     while (it != mapTx.get<entry_time>().end() && it->GetTime() < time) {
         toremove.insert(mapTx.project<0>(it));
         it++;
     }
 
     setEntries stage;
     for (txiter removeit : toremove) {
         CalculateDescendants(removeit, stage);
     }
 
     RemoveStaged(stage, false, MemPoolRemovalReason::EXPIRY);
     return stage.size();
 }
 
 void CTxMemPool::LimitSize(size_t limit, unsigned long age) {
     int expired = Expire(GetTime() - age);
     if (expired != 0) {
         LogPrint(BCLog::MEMPOOL,
                  "Expired %i transactions from the memory pool\n", expired);
     }
 
     std::vector<COutPoint> vNoSpendsRemaining;
     TrimToSize(limit, &vNoSpendsRemaining);
     for (const COutPoint &removed : vNoSpendsRemaining) {
         pcoinsTip->Uncache(removed);
     }
 }
 
 void CTxMemPool::addUnchecked(const TxId &txid, const CTxMemPoolEntry &entry) {
     setEntries setAncestors;
     uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
     std::string dummy;
     CalculateMemPoolAncestors(entry, setAncestors, nNoLimit, nNoLimit, nNoLimit,
                               nNoLimit, dummy);
     return addUnchecked(txid, entry, setAncestors);
 }
 
 void CTxMemPool::UpdateChild(txiter entry, txiter child, bool add) {
     setEntries s;
     if (add && mapLinks[entry].children.insert(child).second) {
         cachedInnerUsage += memusage::IncrementalDynamicUsage(s);
     } else if (!add && mapLinks[entry].children.erase(child)) {
         cachedInnerUsage -= memusage::IncrementalDynamicUsage(s);
     }
 }
 
 void CTxMemPool::UpdateParent(txiter entry, txiter parent, bool add) {
     setEntries s;
     if (add && mapLinks[entry].parents.insert(parent).second) {
         cachedInnerUsage += memusage::IncrementalDynamicUsage(s);
     } else if (!add && mapLinks[entry].parents.erase(parent)) {
         cachedInnerUsage -= memusage::IncrementalDynamicUsage(s);
     }
 }
 
 const CTxMemPool::setEntries &
 CTxMemPool::GetMemPoolParents(txiter entry) const {
     assert(entry != mapTx.end());
     txlinksMap::const_iterator it = mapLinks.find(entry);
     assert(it != mapLinks.end());
     return it->second.parents;
 }
 
 const CTxMemPool::setEntries &
 CTxMemPool::GetMemPoolChildren(txiter entry) const {
     assert(entry != mapTx.end());
     txlinksMap::const_iterator it = mapLinks.find(entry);
     assert(it != mapLinks.end());
     return it->second.children;
 }
 
 CFeeRate CTxMemPool::GetMinFee(size_t sizelimit) const {
     LOCK(cs);
     if (!blockSinceLastRollingFeeBump || rollingMinimumFeeRate == 0) {
         return CFeeRate(int64_t(ceill(rollingMinimumFeeRate)) * SATOSHI);
     }
 
     int64_t time = GetTime();
     if (time > lastRollingFeeUpdate + 10) {
         double halflife = ROLLING_FEE_HALFLIFE;
         if (DynamicMemoryUsage() < sizelimit / 4) {
             halflife /= 4;
         } else if (DynamicMemoryUsage() < sizelimit / 2) {
             halflife /= 2;
         }
 
         rollingMinimumFeeRate =
             rollingMinimumFeeRate /
             pow(2.0, (time - lastRollingFeeUpdate) / halflife);
         lastRollingFeeUpdate = time;
     }
     return CFeeRate(int64_t(ceill(rollingMinimumFeeRate)) * SATOSHI);
 }
 
 void CTxMemPool::trackPackageRemoved(const CFeeRate &rate) {
     AssertLockHeld(cs);
     if ((rate.GetFeePerK() / SATOSHI) > rollingMinimumFeeRate) {
         rollingMinimumFeeRate = rate.GetFeePerK() / SATOSHI;
         blockSinceLastRollingFeeBump = false;
     }
 }
 
 void CTxMemPool::TrimToSize(size_t sizelimit,
                             std::vector<COutPoint> *pvNoSpendsRemaining) {
     LOCK(cs);
 
     unsigned nTxnRemoved = 0;
     CFeeRate maxFeeRateRemoved(Amount::zero());
     while (!mapTx.empty() && DynamicMemoryUsage() > sizelimit) {
         indexed_transaction_set::index<descendant_score>::type::iterator it =
             mapTx.get<descendant_score>().begin();
 
         // We set the new mempool min fee to the feerate of the removed set,
         // plus the "minimum reasonable fee rate" (ie some value under which we
         // consider txn to have 0 fee). This way, we don't allow txn to enter
         // mempool with feerate equal to txn which were removed with no block in
         // between.
         CFeeRate removed(it->GetModFeesWithDescendants(),
                          it->GetSizeWithDescendants());
         removed += MEMPOOL_FULL_FEE_INCREMENT;
 
         trackPackageRemoved(removed);
         maxFeeRateRemoved = std::max(maxFeeRateRemoved, removed);
 
         setEntries stage;
         CalculateDescendants(mapTx.project<0>(it), stage);
         nTxnRemoved += stage.size();
 
         std::vector<CTransaction> txn;
         if (pvNoSpendsRemaining) {
             txn.reserve(stage.size());
             for (txiter iter : stage) {
                 txn.push_back(iter->GetTx());
             }
         }
         RemoveStaged(stage, false, MemPoolRemovalReason::SIZELIMIT);
         if (pvNoSpendsRemaining) {
             for (const CTransaction &tx : txn) {
                 for (const CTxIn &txin : tx.vin) {
                     if (exists(txin.prevout.GetTxId())) {
                         continue;
                     }
                     pvNoSpendsRemaining->push_back(txin.prevout);
                 }
             }
         }
     }
 
     if (maxFeeRateRemoved > CFeeRate(Amount::zero())) {
         LogPrint(BCLog::MEMPOOL,
                  "Removed %u txn, rolling minimum fee bumped to %s\n",
                  nTxnRemoved, maxFeeRateRemoved.ToString());
     }
 }
 
 uint64_t CTxMemPool::CalculateDescendantMaximum(txiter entry) const {
     // find parent with highest descendant count
     std::vector<txiter> candidates;
     setEntries counted;
     candidates.push_back(entry);
     uint64_t maximum = 0;
     while (candidates.size()) {
         txiter candidate = candidates.back();
         candidates.pop_back();
         if (!counted.insert(candidate).second) {
             continue;
         }
         const setEntries &parents = GetMemPoolParents(candidate);
         if (parents.size() == 0) {
             maximum = std::max(maximum, candidate->GetCountWithDescendants());
         } else {
             for (txiter i : parents) {
                 candidates.push_back(i);
             }
         }
     }
     return maximum;
 }
 
 void CTxMemPool::GetTransactionAncestry(const TxId &txid, size_t &ancestors,
                                         size_t &descendants) const {
     LOCK(cs);
     auto it = mapTx.find(txid);
     ancestors = descendants = 0;
     if (it != mapTx.end()) {
         ancestors = it->GetCountWithAncestors();
         descendants = CalculateDescendantMaximum(it);
     }
 }
 
 bool CTxMemPool::IsLoaded() const {
     LOCK(cs);
     return m_is_loaded;
 }
 
 void CTxMemPool::SetIsLoaded(bool loaded) {
     LOCK(cs);
     m_is_loaded = loaded;
 }
 
 SaltedTxidHasher::SaltedTxidHasher()
     : k0(GetRand(std::numeric_limits<uint64_t>::max())),
       k1(GetRand(std::numeric_limits<uint64_t>::max())) {}
 
 /** Maximum bytes for transactions to store for processing during reorg */
 static const size_t MAX_DISCONNECTED_TX_POOL_SIZE = 20 * DEFAULT_MAX_BLOCK_SIZE;
 
 void DisconnectedBlockTransactions::addForBlock(
     const std::vector<CTransactionRef> &vtx) {
     for (const auto &tx : reverse_iterate(vtx)) {
         // If we already added it, just skip.
         auto it = queuedTx.find(tx->GetId());
         if (it != queuedTx.end()) {
             continue;
         }
 
         // Insert the transaction into the pool.
         addTransaction(tx);
 
         // Fill in the set of parents.
         std::unordered_set<TxId, SaltedTxidHasher> parents;
         for (const CTxIn &in : tx->vin) {
             parents.insert(in.prevout.GetTxId());
         }
 
         // In order to make sure we keep things in topological order, we check
         // if we already know of the parent of the current transaction. If so,
         // we remove them from the set and then add them back.
         while (parents.size() > 0) {
             std::unordered_set<TxId, SaltedTxidHasher> worklist(
                 std::move(parents));
             parents.clear();
 
             for (const TxId &txid : worklist) {
                 // If we do not have that txid in the set, nothing needs to be
                 // done.
                 auto pit = queuedTx.find(txid);
                 if (pit == queuedTx.end()) {
                     continue;
                 }
 
                 // We have parent in our set, we reinsert them at the right
                 // position.
                 const CTransactionRef ptx = *pit;
                 queuedTx.erase(pit);
                 queuedTx.insert(ptx);
 
                 // And we make sure ancestors are covered.
                 for (const CTxIn &in : ptx->vin) {
                     parents.insert(in.prevout.GetTxId());
                 }
             }
         }
     }
 
     // Keep the size under control.
     while (DynamicMemoryUsage() > MAX_DISCONNECTED_TX_POOL_SIZE) {
         // Drop the earliest entry, and remove its children from the
         // mempool.
         auto it = queuedTx.get<insertion_order>().begin();
         g_mempool.removeRecursive(**it, MemPoolRemovalReason::REORG);
         removeEntry(it);
     }
 }
 
 void DisconnectedBlockTransactions::importMempool(CTxMemPool &pool) {
     // addForBlock's algorithm sorts a vector of transactions back into
     // topological order. We use it in a separate object to create a valid
     // ordering of all mempool transactions, which we then splice in front of
     // the current queuedTx. This results in a valid sequence of transactions to
     // be reprocessed in updateMempoolForReorg.
 
     // We create vtx in order of the entry_time index to facilitate for
     // addForBlocks (which iterates in reverse order), as vtx probably end in
     // the correct ordering for queuedTx.
     std::vector<CTransactionRef> vtx;
     {
         LOCK(pool.cs);
         vtx.reserve(pool.mapTx.size());
         for (const CTxMemPoolEntry &e : pool.mapTx.get<entry_time>()) {
             vtx.push_back(e.GetSharedTx());
         }
         pool.clear();
     }
 
     // Use addForBlocks to sort the transactions and then splice them in front
     // of queuedTx
     DisconnectedBlockTransactions orderedTxnPool;
     orderedTxnPool.addForBlock(vtx);
     cachedInnerUsage += orderedTxnPool.cachedInnerUsage;
     queuedTx.get<insertion_order>().splice(
         queuedTx.get<insertion_order>().begin(),
         orderedTxnPool.queuedTx.get<insertion_order>());
 
     // We limit memory usage because we can't know if more blocks will be
     // disconnected
     while (DynamicMemoryUsage() > MAX_DISCONNECTED_TX_POOL_SIZE) {
         // Drop the earliest entry which, by definition, has no children
         removeEntry(queuedTx.get<insertion_order>().begin());
     }
 }
 
 void DisconnectedBlockTransactions::updateMempoolForReorg(const Config &config,
                                                           bool fAddToMempool) {
     AssertLockHeld(cs_main);
     std::vector<TxId> txidsUpdate;
 
     // disconnectpool's insertion_order index sorts the entries from oldest to
     // newest, but the oldest entry will be the last tx from the latest mined
     // block that was disconnected.
     // Iterate disconnectpool in reverse, so that we add transactions back to
     // the mempool starting with the earliest transaction that had been
     // previously seen in a block.
     for (const CTransactionRef &tx :
          reverse_iterate(queuedTx.get<insertion_order>())) {
         // ignore validation errors in resurrected transactions
         CValidationState stateDummy;
         if (!fAddToMempool || tx->IsCoinBase() ||
             !AcceptToMemoryPool(config, g_mempool, stateDummy, tx,
                                 nullptr /* pfMissingInputs */,
                                 true /* bypass_limits */,
                                 Amount::zero() /* nAbsurdFee */)) {
             // If the transaction doesn't make it in to the mempool, remove any
             // transactions that depend on it (which would now be orphans).
             g_mempool.removeRecursive(*tx, MemPoolRemovalReason::REORG);
         } else if (g_mempool.exists(tx->GetId())) {
             txidsUpdate.push_back(tx->GetId());
         }
     }
 
     queuedTx.clear();
 
     // AcceptToMemoryPool/addUnchecked all assume that new mempool entries have
     // no in-mempool children, which is generally not true when adding
     // previously-confirmed transactions back to the mempool.
     // UpdateTransactionsFromBlock finds descendants of any transactions in the
     // disconnectpool that were added back and cleans up the mempool state.
     g_mempool.UpdateTransactionsFromBlock(txidsUpdate);
 
     // We also need to remove any now-immature transactions
     g_mempool.removeForReorg(config, pcoinsTip.get(),
                              chainActive.Tip()->nHeight + 1,
                              STANDARD_LOCKTIME_VERIFY_FLAGS);
 
     // Re-limit mempool size, in case we added any transactions
     g_mempool.LimitSize(
         gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000,
         gArgs.GetArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY) * 60 * 60);
 }
diff --git a/src/txmempool.h b/src/txmempool.h
index 4f141fcc7..cd60b5006 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -1,977 +1,975 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_TXMEMPOOL_H
 #define BITCOIN_TXMEMPOOL_H
 
 #include <amount.h>
 #include <coins.h>
 #include <crypto/siphash.h>
 #include <indirectmap.h>
 #include <primitives/transaction.h>
 #include <random.h>
 #include <sync.h>
 
 #include <boost/multi_index/hashed_index.hpp>
 #include <boost/multi_index/ordered_index.hpp>
 #include <boost/multi_index/sequenced_index.hpp>
 #include <boost/multi_index_container.hpp>
 #include <boost/signals2/signal.hpp>
 
 #include <map>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 class CBlockIndex;
 class Config;
 
 extern CCriticalSection cs_main;
 
 /**
  * Fake height value used in Coins to signify they are only in the memory
  * pool(since 0.8)
  */
 static const uint32_t MEMPOOL_HEIGHT = 0x7FFFFFFF;
 
 struct LockPoints {
     // Will be set to the blockchain height and median time past values that
     // would be necessary to satisfy all relative locktime constraints (BIP68)
     // of this tx given our view of block chain history
     int height;
     int64_t time;
     // As long as the current chain descends from the highest height block
     // containing one of the inputs used in the calculation, then the cached
     // values are still valid even after a reorg.
     CBlockIndex *maxInputBlock;
 
     LockPoints() : height(0), time(0), maxInputBlock(nullptr) {}
 };
 
 class CTxMemPool;
 
 /** \class CTxMemPoolEntry
  *
  * CTxMemPoolEntry stores data about the corresponding transaction, as well as
  * data about all in-mempool transactions that depend on the transaction
  * ("descendant" transactions).
  *
  * When a new entry is added to the mempool, we update the descendant state
  * (nCountWithDescendants, nSizeWithDescendants, and nModFeesWithDescendants)
  * for all ancestors of the newly added transaction.
  */
 
 class CTxMemPoolEntry {
 private:
     CTransactionRef tx;
     //!< Cached to avoid expensive parent-transaction lookups
     Amount nFee;
     //!< ... and avoid recomputing tx size
     size_t nTxSize;
-    //!< ... and modified size for priority
-    size_t nModSize;
     //!< ... and total memory usage
     size_t nUsageSize;
     //!< Local time when entering the mempool
     int64_t nTime;
     //!< Chain height when entering the mempool
     unsigned int entryHeight;
     //!< keep track of transactions that spend a coinbase
     bool spendsCoinbase;
     //!< Total sigop plus P2SH sigops count
     int64_t sigOpCount;
     //!< Used for determining the priority of the transaction for mining in a
     //! block
     Amount feeDelta;
     //!< Track the height and time at which tx was final
     LockPoints lockPoints;
 
     // Information about descendants of this transaction that are in the
     // mempool; if we remove this transaction we must remove all of these
     // descendants as well.
     //!< number of descendant transactions
     uint64_t nCountWithDescendants;
     //!< ... and size
     uint64_t nSizeWithDescendants;
 
     //!< ... and total fees (all including us)
     Amount nModFeesWithDescendants;
 
     // Analogous statistics for ancestor transactions
     uint64_t nCountWithAncestors;
     uint64_t nSizeWithAncestors;
     Amount nModFeesWithAncestors;
     int64_t nSigOpCountWithAncestors;
 
 public:
     CTxMemPoolEntry(const CTransactionRef &_tx, const Amount _nFee,
                     int64_t _nTime, unsigned int _entryHeight,
                     bool spendsCoinbase, int64_t nSigOpsCost, LockPoints lp);
 
     const CTransaction &GetTx() const { return *this->tx; }
     CTransactionRef GetSharedTx() const { return this->tx; }
     const Amount GetFee() const { return nFee; }
     size_t GetTxSize() const { return nTxSize; }
 
     int64_t GetTime() const { return nTime; }
     unsigned int GetHeight() const { return entryHeight; }
     int64_t GetSigOpCount() const { return sigOpCount; }
     Amount GetModifiedFee() const { return nFee + feeDelta; }
     size_t DynamicMemoryUsage() const { return nUsageSize; }
     const LockPoints &GetLockPoints() const { return lockPoints; }
 
     // Adjusts the descendant state.
     void UpdateDescendantState(int64_t modifySize, Amount modifyFee,
                                int64_t modifyCount);
     // Adjusts the ancestor state
     void UpdateAncestorState(int64_t modifySize, Amount modifyFee,
                              int64_t modifyCount, int modifySigOps);
     // Updates the fee delta used for mining priority score, and the
     // modified fees with descendants.
     void UpdateFeeDelta(Amount feeDelta);
     // Update the LockPoints after a reorg
     void UpdateLockPoints(const LockPoints &lp);
 
     uint64_t GetCountWithDescendants() const { return nCountWithDescendants; }
     uint64_t GetSizeWithDescendants() const { return nSizeWithDescendants; }
     Amount GetModFeesWithDescendants() const { return nModFeesWithDescendants; }
 
     bool GetSpendsCoinbase() const { return spendsCoinbase; }
 
     uint64_t GetCountWithAncestors() const { return nCountWithAncestors; }
     uint64_t GetSizeWithAncestors() const { return nSizeWithAncestors; }
     Amount GetModFeesWithAncestors() const { return nModFeesWithAncestors; }
     int64_t GetSigOpCountWithAncestors() const {
         return nSigOpCountWithAncestors;
     }
 
     //!< Index in mempool's vTxHashes
     mutable size_t vTxHashesIdx;
 };
 
 // Helpers for modifying CTxMemPool::mapTx, which is a boost multi_index.
 struct update_descendant_state {
     update_descendant_state(int64_t _modifySize, Amount _modifyFee,
                             int64_t _modifyCount)
         : modifySize(_modifySize), modifyFee(_modifyFee),
           modifyCount(_modifyCount) {}
 
     void operator()(CTxMemPoolEntry &e) {
         e.UpdateDescendantState(modifySize, modifyFee, modifyCount);
     }
 
 private:
     int64_t modifySize;
     Amount modifyFee;
     int64_t modifyCount;
 };
 
 struct update_ancestor_state {
     update_ancestor_state(int64_t _modifySize, Amount _modifyFee,
                           int64_t _modifyCount, int64_t _modifySigOpsCost)
         : modifySize(_modifySize), modifyFee(_modifyFee),
           modifyCount(_modifyCount), modifySigOpsCost(_modifySigOpsCost) {}
 
     void operator()(CTxMemPoolEntry &e) {
         e.UpdateAncestorState(modifySize, modifyFee, modifyCount,
                               modifySigOpsCost);
     }
 
 private:
     int64_t modifySize;
     Amount modifyFee;
     int64_t modifyCount;
     int64_t modifySigOpsCost;
 };
 
 struct update_fee_delta {
     explicit update_fee_delta(Amount _feeDelta) : feeDelta(_feeDelta) {}
 
     void operator()(CTxMemPoolEntry &e) { e.UpdateFeeDelta(feeDelta); }
 
 private:
     Amount feeDelta;
 };
 
 struct update_lock_points {
     explicit update_lock_points(const LockPoints &_lp) : lp(_lp) {}
 
     void operator()(CTxMemPoolEntry &e) { e.UpdateLockPoints(lp); }
 
 private:
     const LockPoints &lp;
 };
 
 // extracts a transaction id from CTxMemPoolEntry or CTransactionRef
 struct mempoolentry_txid {
     typedef TxId result_type;
     result_type operator()(const CTxMemPoolEntry &entry) const {
         return entry.GetTx().GetId();
     }
 
     result_type operator()(const CTransactionRef &tx) const {
         return tx->GetId();
     }
 };
 
 /** \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 {
         double a_mod_fee, a_size, b_mod_fee, b_size;
 
         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 = a_mod_fee * b_size;
         double f2 = a_size * b_mod_fee;
 
         if (f1 == f2) {
             return a.GetTime() >= b.GetTime();
         }
         return f1 < f2;
     }
 
     // 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 = a.GetSizeWithDescendants() * (a.GetModifiedFee() / SATOSHI);
         double f2 = a.GetTxSize() * (a.GetModFeesWithDescendants() / SATOSHI);
 
         if (f2 > f1) {
             mod_fee = a.GetModFeesWithDescendants() / SATOSHI;
             size = a.GetSizeWithDescendants();
         } else {
             mod_fee = a.GetModifiedFee() / SATOSHI;
             size = a.GetTxSize();
         }
     }
 };
 
 /** \class CompareTxMemPoolEntryByScore
  *
  *  Sort by feerate of entry (fee/size) in descending order
  *  This is only used for transaction relay, so we use GetFee()
  *  instead of GetModifiedFee() to avoid leaking prioritization
  *  information via the sort order.
  */
 class CompareTxMemPoolEntryByScore {
 public:
     bool operator()(const CTxMemPoolEntry &a, const CTxMemPoolEntry &b) const {
         double f1 = b.GetTxSize() * (a.GetFee() / SATOSHI);
         double f2 = a.GetTxSize() * (b.GetFee() / SATOSHI);
         if (f1 == f2) {
             return b.GetTx().GetId() < a.GetTx().GetId();
         }
         return f1 > f2;
     }
 };
 
 class CompareTxMemPoolEntryByEntryTime {
 public:
     bool operator()(const CTxMemPoolEntry &a, const CTxMemPoolEntry &b) const {
         return a.GetTime() < b.GetTime();
     }
 };
 
 /** \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 {
         double a_mod_fee, a_size, b_mod_fee, b_size;
 
         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 = a_mod_fee * b_size;
         double f2 = a_size * b_mod_fee;
 
         if (f1 == f2) {
             return a.GetTx().GetId() < b.GetTx().GetId();
         }
         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 = a.GetSizeWithAncestors() * (a.GetModifiedFee() / SATOSHI);
         double f2 = a.GetTxSize() * (a.GetModFeesWithAncestors() / SATOSHI);
 
         if (f1 > f2) {
             mod_fee = a.GetModFeesWithAncestors() / SATOSHI;
             size = a.GetSizeWithAncestors();
         } else {
             mod_fee = a.GetModifiedFee() / SATOSHI;
             size = a.GetTxSize();
         }
     }
 };
 
 // Multi_index tag names
 struct descendant_score {};
 struct entry_time {};
 struct ancestor_score {};
 
 /**
  * Information about a mempool transaction.
  */
 struct TxMempoolInfo {
     /** The transaction itself */
     CTransactionRef tx;
 
     /** Time the transaction entered the mempool. */
     int64_t nTime;
 
     /** Feerate of the transaction. */
     CFeeRate feeRate;
 
     /** The fee delta. */
     Amount nFeeDelta;
 };
 
 /**
  * Reason why a transaction was removed from the mempool, this is passed to the
  * notification signal.
  */
 enum class MemPoolRemovalReason {
     //!< Manually removed or unknown reason
     UNKNOWN = 0,
     //!< Expired from mempool
     EXPIRY,
     //!< Removed in size limiting
     SIZELIMIT,
     //!< Removed for reorganization
     REORG,
     //!< Removed for block
     BLOCK,
     //!< Removed for conflict with in-block transaction
     CONFLICT,
     //!< Removed for replacement
     REPLACED
 };
 
 class SaltedTxidHasher {
 private:
     /** Salt */
     const uint64_t k0, k1;
 
 public:
     SaltedTxidHasher();
 
     size_t operator()(const TxId &txid) const {
         return SipHashUint256(k0, k1, txid);
     }
 };
 
 typedef std::pair<double, Amount> TXModifier;
 
 /**
  * CTxMemPool stores valid-according-to-the-current-best-chain transactions that
  * may be included in the next block.
  *
  * Transactions are added when they are seen on the network (or created by the
  * local node), but not all transactions seen are added to the pool. For
  * example, the following new transactions will not be added to the mempool:
  * - a transaction which doesn't meet the minimum fee requirements.
  * - a new transaction that double-spends an input of a transaction already in
  * the pool where the new transaction does not meet the Replace-By-Fee
  * requirements as defined in BIP 125.
  * - a non-standard transaction.
  *
  * CTxMemPool::mapTx, and CTxMemPoolEntry bookkeeping:
  *
  * mapTx is a boost::multi_index that sorts the mempool on 4 criteria:
  * - transaction hash
  * - descendant feerate [we use max(feerate of tx, feerate of tx with all
  * descendants)]
  * - time in mempool
  * - ancestor feerate [we use min(feerate of tx, feerate of tx with all
  * unconfirmed ancestors)]
  *
  * Note: the term "descendant" refers to in-mempool transactions that depend on
  * this one, while "ancestor" refers to in-mempool transactions that a given
  * transaction depends on.
  *
  * In order for the feerate sort to remain correct, we must update transactions
  * in the mempool when new descendants arrive. To facilitate this, we track the
  * set of in-mempool direct parents and direct children in mapLinks. Within each
  * CTxMemPoolEntry, we track the size and fees of all descendants.
  *
  * Usually when a new transaction is added to the mempool, it has no in-mempool
  * children (because any such children would be an orphan). So in
  * addUnchecked(), we:
  * - update a new entry's setMemPoolParents to include all in-mempool parents
  * - update the new entry's direct parents to include the new tx as a child
  * - update all ancestors of the transaction to include the new tx's size/fee
  *
  * When a transaction is removed from the mempool, we must:
  * - update all in-mempool parents to not track the tx in setMemPoolChildren
  * - update all ancestors to not include the tx's size/fees in descendant state
  * - update all in-mempool children to not include it as a parent
  *
  * These happen in UpdateForRemoveFromMempool(). (Note that when removing a
  * transaction along with its descendants, we must calculate that set of
  * transactions to be removed before doing the removal, or else the mempool can
  * be in an inconsistent state where it's impossible to walk the ancestors of a
  * transaction.)
  *
  * In the event of a reorg, the assumption that a newly added tx has no
  * in-mempool children is false.  In particular, the mempool is in an
  * inconsistent state while new transactions are being added, because there may
  * be descendant transactions of a tx coming from a disconnected block that are
  * unreachable from just looking at transactions in the mempool (the linking
  * transactions may also be in the disconnected block, waiting to be added).
  * Because of this, there's not much benefit in trying to search for in-mempool
  * children in addUnchecked(). Instead, in the special case of transactions
  * being added from a disconnected block, we require the caller to clean up the
  * state, to account for in-mempool, out-of-block descendants for all the
  * in-block transactions by calling UpdateTransactionsFromBlock(). Note that
  * until this is called, the mempool state is not consistent, and in particular
  * mapLinks may not be correct (and therefore functions like
  * CalculateMemPoolAncestors() and CalculateDescendants() that rely on them to
  * walk the mempool are not generally safe to use).
  *
  * Computational limits:
  *
  * Updating all in-mempool ancestors of a newly added transaction can be slow,
  * if no bound exists on how many in-mempool ancestors there may be.
  * CalculateMemPoolAncestors() takes configurable limits that are designed to
  * prevent these calculations from being too CPU intensive.
  */
 class CTxMemPool {
 private:
     //!< Value n means that n times in 2^32 we check.
     uint32_t nCheckFrequency GUARDED_BY(cs);
     //!< Used by getblocktemplate to trigger CreateNewBlock() invocation
     unsigned int nTransactionsUpdated;
 
     //!< sum of all mempool tx's virtual sizes.
     uint64_t totalTxSize;
     //!< sum of dynamic memory usage of all the map elements (NOT the maps
     //! themselves)
     uint64_t cachedInnerUsage;
 
     mutable int64_t lastRollingFeeUpdate;
     mutable bool blockSinceLastRollingFeeBump;
     //!< minimum fee to get into the pool, decreases exponentially
     mutable double rollingMinimumFeeRate;
 
     void trackPackageRemoved(const CFeeRate &rate) EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     bool m_is_loaded GUARDED_BY(cs){false};
 
 public:
     // public only for testing
     static const int ROLLING_FEE_HALFLIFE = 60 * 60 * 12;
 
     typedef boost::multi_index_container<
         CTxMemPoolEntry, boost::multi_index::indexed_by<
                              // sorted by txid
                              boost::multi_index::hashed_unique<
                                  mempoolentry_txid, SaltedTxidHasher>,
                              // 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>>>
         indexed_transaction_set;
 
     /**
      * This mutex needs to be locked when accessing `mapTx` or other members
      * that are guarded by it.
      *
      * @par Consistency guarantees
      *
      * By design, it is guaranteed that:
      *
      * 1. Locking both `cs_main` and `mempool.cs` will give a view of mempool
      *    that is consistent with current chain tip (`chainActive` and
      *    `pcoinsTip`) and is fully populated. Fully populated means that if the
      *    current active chain is missing transactions that were present in a
      *    previously active chain, all the missing transactions will have been
      *    re-added to the mempool and should be present if they meet size and
      *    consistency constraints.
      *
      * 2. Locking `mempool.cs` without `cs_main` will give a view of a mempool
      *    consistent with some chain that was active since `cs_main` was last
      *    locked, and that is fully populated as described above. It is ok for
      *    code that only needs to query or remove transactions from the mempool
      *    to lock just `mempool.cs` without `cs_main`.
      *
      * To provide these guarantees, it is necessary to lock both `cs_main` and
      * `mempool.cs` whenever adding transactions to the mempool and whenever
      * changing the chain tip. It's necessary to keep both mutexes locked until
      * the mempool is consistent with the new chain tip and fully populated.
      *
      * @par Consistency bug
      *
      * The second guarantee above is not currently enforced, but
      * https://github.com/bitcoin/bitcoin/pull/14193 will fix it. No known code
      * in bitcoin currently depends on second guarantee, but it is important to
      * fix for third party code that needs be able to frequently poll the
      * mempool without locking `cs_main` and without encountering missing
      * transactions during reorgs.
      */
     mutable RecursiveMutex cs;
     indexed_transaction_set mapTx GUARDED_BY(cs);
 
     typedef indexed_transaction_set::nth_index<0>::type::iterator txiter;
     //!< All tx hashes/entries in mapTx, in random order
     std::vector<std::pair<TxHash, txiter>> vTxHashes;
 
     struct CompareIteratorById {
         bool operator()(const txiter &a, const txiter &b) const {
             return a->GetTx().GetId() < b->GetTx().GetId();
         }
     };
     typedef std::set<txiter, CompareIteratorById> setEntries;
 
     const setEntries &GetMemPoolParents(txiter entry) const
         EXCLUSIVE_LOCKS_REQUIRED(cs);
     const setEntries &GetMemPoolChildren(txiter entry) const
         EXCLUSIVE_LOCKS_REQUIRED(cs);
     uint64_t CalculateDescendantMaximum(txiter entry) const
         EXCLUSIVE_LOCKS_REQUIRED(cs);
 
 private:
     typedef std::map<txiter, setEntries, CompareIteratorById> cacheMap;
 
     struct TxLinks {
         setEntries parents;
         setEntries children;
     };
 
     typedef std::map<txiter, TxLinks, CompareIteratorById> txlinksMap;
     txlinksMap mapLinks;
 
     void UpdateParent(txiter entry, txiter parent, bool add);
     void UpdateChild(txiter entry, txiter child, bool add);
 
     std::vector<indexed_transaction_set::const_iterator>
     GetSortedDepthAndScore() const EXCLUSIVE_LOCKS_REQUIRED(cs);
 
 public:
     indirectmap<COutPoint, const CTransaction *> mapNextTx GUARDED_BY(cs);
     std::map<TxId, TXModifier> mapDeltas;
 
     /**
      * Create a new CTxMemPool.
      */
     CTxMemPool();
     ~CTxMemPool();
 
     /**
      * If sanity-checking is turned on, check makes sure the pool is consistent
      * (does not contain two transactions that spend the same inputs, all inputs
      * are in the mapNextTx array). If sanity-checking is turned off, check does
      * nothing.
      */
     void check(const CCoinsViewCache *pcoins) const;
     void setSanityCheck(double dFrequency = 1.0) {
         LOCK(cs);
         nCheckFrequency = static_cast<uint32_t>(dFrequency * 4294967295.0);
     }
 
     // addUnchecked must updated state for all ancestors of a given transaction,
     // to track size/count of descendant transactions. First version of
     // addUnchecked can be used to have it call CalculateMemPoolAncestors(), and
     // then invoke the second version.
     // Note that addUnchecked is ONLY called from ATMP outside of tests
     // and any other callers may break wallet's in-mempool tracking (due to
     // lack of CValidationInterface::TransactionAddedToMempool callbacks).
     void addUnchecked(const TxId &txid, const CTxMemPoolEntry &entry)
         EXCLUSIVE_LOCKS_REQUIRED(cs, cs_main);
     void addUnchecked(const TxId &txid, const CTxMemPoolEntry &entry,
                       setEntries &setAncestors)
         EXCLUSIVE_LOCKS_REQUIRED(cs, cs_main);
 
     void removeRecursive(
         const CTransaction &tx,
         MemPoolRemovalReason reason = MemPoolRemovalReason::UNKNOWN);
     void removeForReorg(const Config &config, const CCoinsViewCache *pcoins,
                         unsigned int nMemPoolHeight, int flags)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
     void removeConflicts(const CTransaction &tx) EXCLUSIVE_LOCKS_REQUIRED(cs);
     void removeForBlock(const std::vector<CTransactionRef> &vtx,
                         unsigned int nBlockHeight);
 
     void clear();
     // lock free
     void _clear() EXCLUSIVE_LOCKS_REQUIRED(cs);
     bool CompareDepthAndScore(const TxId &txida, const TxId &txidb);
     void queryHashes(std::vector<uint256> &vtxid) const;
     bool isSpent(const COutPoint &outpoint) const;
     unsigned int GetTransactionsUpdated() const;
     void AddTransactionsUpdated(unsigned int n);
     /**
      * Check that none of this transactions inputs are in the mempool, and thus
      * the tx is not dependent on other mempool transactions to be included in a
      * block.
      */
     bool HasNoInputsOf(const CTransaction &tx) const;
 
     /** Affect CreateNewBlock prioritisation of transactions */
     void PrioritiseTransaction(const TxId &txid, double dPriorityDelta,
                                const Amount nFeeDelta);
     void ApplyDeltas(const TxId &txid, double &dPriorityDelta,
                      Amount &nFeeDelta) const;
     void ClearPrioritisation(const TxId &txid);
 
     /** Get the transaction in the pool that spends the same prevout */
     const CTransaction *GetConflictTx(const COutPoint &prevout) const
         EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /** Returns an iterator to the given txid, if found */
     boost::optional<txiter> GetIter(const TxId &txid) const
         EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /**
      * Translate a set of txids into a set of pool iterators to avoid repeated
      * lookups.
      */
     setEntries GetIterSet(const std::set<TxId> &txids) const
         EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /**
      * Remove a set of transactions from the mempool. If a transaction is in
      * this set, then all in-mempool descendants must also be in the set, unless
      * this transaction is being removed for being in a block. Set
      * updateDescendants to true when removing a tx that was in a block, so that
      * any in-mempool descendants have their ancestor state updated.
      */
     void
     RemoveStaged(setEntries &stage, bool updateDescendants,
                  MemPoolRemovalReason reason = MemPoolRemovalReason::UNKNOWN)
         EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /**
      * When adding transactions from a disconnected block back to the mempool,
      * new mempool entries may have children in the mempool (which is generally
      * not the case when otherwise adding transactions).
      * UpdateTransactionsFromBlock() will find child transactions and update the
      * descendant state for each transaction in txidsToUpdate (excluding any
      * child transactions present in txidsToUpdate, which are already accounted
      * for).
      * Note: txidsToUpdate should be the set of transactions from the
      * disconnected block that have been accepted back into the mempool.
      */
     void UpdateTransactionsFromBlock(const std::vector<TxId> &txidsToUpdate)
         EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
     /**
      * Try to calculate all in-mempool ancestors of entry.
      *  (these are all calculated including the tx itself)
      *  limitAncestorCount = max number of ancestors
      *  limitAncestorSize = max size of ancestors
      *  limitDescendantCount = max number of descendants any ancestor can have
      *  limitDescendantSize = max size of descendants any ancestor can have
      *  errString = populated with error reason if any limits are hit
      * fSearchForParents = whether to search a tx's vin for in-mempool parents,
      * or look up parents from mapLinks. Must be true for entries not in the
      * mempool
      */
     bool CalculateMemPoolAncestors(
         const CTxMemPoolEntry &entry, setEntries &setAncestors,
         uint64_t limitAncestorCount, uint64_t limitAncestorSize,
         uint64_t limitDescendantCount, uint64_t limitDescendantSize,
         std::string &errString, bool fSearchForParents = true) const
         EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /**
      * Populate setDescendants with all in-mempool descendants of hash.
      * Assumes that setDescendants includes all in-mempool descendants of
      * anything already in it.
      */
     void CalculateDescendants(txiter it, setEntries &setDescendants) const
         EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /**
      * The minimum fee to get into the mempool, which may itself not be enough
      * for larger-sized transactions. The incrementalRelayFee policy variable is
      * used to bound the time it takes the fee rate to go back down all the way
      * to 0. When the feerate would otherwise be half of this, it is set to 0
      * instead.
      */
     CFeeRate GetMinFee(size_t sizelimit) const;
 
     /**
      * Remove transactions from the mempool until its dynamic size is <=
      * sizelimit. pvNoSpendsRemaining, if set, will be populated with the list
      * of outpoints which are not in mempool which no longer have any spends in
      * this mempool.
      */
     void TrimToSize(size_t sizelimit,
                     std::vector<COutPoint> *pvNoSpendsRemaining = nullptr);
 
     /**
      * Expire all transaction (and their dependencies) in the mempool older than
      * time. Return the number of removed transactions.
      */
     int Expire(int64_t time);
 
     /**
      * Reduce the size of the mempool by expiring and then trimming the mempool.
      */
     void LimitSize(size_t limit, unsigned long age);
 
     /**
      * Calculate the ancestor and descendant count for the given transaction.
      * The counts include the transaction itself.
      */
     void GetTransactionAncestry(const TxId &txid, size_t &ancestors,
                                 size_t &descendants) const;
 
     /** @returns true if the mempool is fully loaded */
     bool IsLoaded() const;
 
     /** Sets the current loaded state */
     void SetIsLoaded(bool loaded);
 
     unsigned long size() const {
         LOCK(cs);
         return mapTx.size();
     }
 
     uint64_t GetTotalTxSize() const {
         LOCK(cs);
         return totalTxSize;
     }
 
     bool exists(const TxId &txid) const {
         LOCK(cs);
         return mapTx.count(txid) != 0;
     }
 
     CTransactionRef get(const TxId &txid) const;
     TxMempoolInfo info(const TxId &txid) const;
     std::vector<TxMempoolInfo> infoAll() const;
 
     CFeeRate estimateFee() const;
 
     size_t DynamicMemoryUsage() const;
 
     boost::signals2::signal<void(CTransactionRef)> NotifyEntryAdded;
     boost::signals2::signal<void(CTransactionRef, MemPoolRemovalReason)>
         NotifyEntryRemoved;
 
 private:
     /**
      * UpdateForDescendants is used by UpdateTransactionsFromBlock to update the
      * descendants for a single transaction that has been added to the mempool
      * but may have child transactions in the mempool, eg during a chain reorg.
      * setExclude is the set of descendant transactions in the mempool that must
      * not be accounted for (because any descendants in setExclude were added to
      * the mempool after the transaction being updated and hence their state is
      * already reflected in the parent state).
      *
      * cachedDescendants will be updated with the descendants of the transaction
      * being updated, so that future invocations don't need to walk the same
      * transaction again, if encountered in another transaction chain.
      */
     void UpdateForDescendants(txiter updateIt, cacheMap &cachedDescendants,
                               const std::set<TxId> &setExclude)
         EXCLUSIVE_LOCKS_REQUIRED(cs);
     /**
      * Update ancestors of hash to add/remove it as a descendant transaction.
      */
     void UpdateAncestorsOf(bool add, txiter hash, setEntries &setAncestors)
         EXCLUSIVE_LOCKS_REQUIRED(cs);
     /** Set ancestor state for an entry */
     void UpdateEntryForAncestors(txiter it, const setEntries &setAncestors)
         EXCLUSIVE_LOCKS_REQUIRED(cs);
     /**
      * For each transaction being removed, update ancestors and any direct
      * children. If updateDescendants is true, then also update in-mempool
      * descendants' ancestor state.
      */
     void UpdateForRemoveFromMempool(const setEntries &entriesToRemove,
                                     bool updateDescendants)
         EXCLUSIVE_LOCKS_REQUIRED(cs);
     /** Sever link between specified transaction and direct children. */
     void UpdateChildrenForRemoval(txiter entry) EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     /**
      * Before calling removeUnchecked for a given transaction,
      * UpdateForRemoveFromMempool must be called on the entire (dependent) set
      * of transactions being removed at the same time. We use each
      * CTxMemPoolEntry's setMemPoolParents in order to walk ancestors of a given
      * transaction that is removed, so we can't remove intermediate transactions
      * in a chain before we've updated all the state for the removal.
      */
     void
     removeUnchecked(txiter entry,
                     MemPoolRemovalReason reason = MemPoolRemovalReason::UNKNOWN)
         EXCLUSIVE_LOCKS_REQUIRED(cs);
 };
 
 /**
  * CCoinsView that brings transactions from a mempool into view.
  * It does not check for spendings by memory pool transactions.
  * Instead, it provides access to all Coins which are either unspent in the
  * base CCoinsView, or are outputs from any mempool transaction!
  * This allows transaction replacement to work as expected, as you want to
  * have all inputs "available" to check signatures, and any cycles in the
  * dependency graph are checked directly in AcceptToMemoryPool.
  * It also allows you to sign a double-spend directly in
  * signrawtransactionwithkey and signrawtransactionwithwallet,
  * as long as the conflicting transaction is not yet confirmed.
  */
 class CCoinsViewMemPool : public CCoinsViewBacked {
 protected:
     const CTxMemPool &mempool;
 
 public:
     CCoinsViewMemPool(CCoinsView *baseIn, const CTxMemPool &mempoolIn);
     bool GetCoin(const COutPoint &outpoint, Coin &coin) const override;
 };
 
 /**
  * DisconnectedBlockTransactions
  *
  * During the reorg, it's desirable to re-add previously confirmed transactions
  * to the mempool, so that anything not re-confirmed in the new chain is
  * available to be mined. However, it's more efficient to wait until the reorg
  * is complete and process all still-unconfirmed transactions at that time,
  * since we expect most confirmed transactions to (typically) still be
  * confirmed in the new chain, and re-accepting to the memory pool is expensive
  * (and therefore better to not do in the middle of reorg-processing).
  * Instead, store the disconnected transactions (in order!) as we go, remove any
  * that are included in blocks in the new chain, and then process the remaining
  * still-unconfirmed transactions at the end.
  *
  * It also enables efficient reprocessing of current mempool entries, useful
  * when (de)activating forks that result in in-mempool transactions becoming
  * invalid
  */
 // multi_index tag names
 struct txid_index {};
 struct insertion_order {};
 
 class DisconnectedBlockTransactions {
 private:
     typedef boost::multi_index_container<
         CTransactionRef, boost::multi_index::indexed_by<
                              // sorted by txid
                              boost::multi_index::hashed_unique<
                                  boost::multi_index::tag<txid_index>,
                                  mempoolentry_txid, SaltedTxidHasher>,
                              // sorted by order in the blockchain
                              boost::multi_index::sequenced<
                                  boost::multi_index::tag<insertion_order>>>>
         indexed_disconnected_transactions;
 
     indexed_disconnected_transactions queuedTx;
     uint64_t cachedInnerUsage = 0;
 
     void addTransaction(const CTransactionRef &tx) {
         queuedTx.insert(tx);
         cachedInnerUsage += RecursiveDynamicUsage(tx);
     }
 
 public:
     // It's almost certainly a logic bug if we don't clear out queuedTx before
     // destruction, as we add to it while disconnecting blocks, and then we
     // need to re-process remaining transactions to ensure mempool consistency.
     // For now, assert() that we've emptied out this object on destruction.
     // This assert() can always be removed if the reorg-processing code were
     // to be refactored such that this assumption is no longer true (for
     // instance if there was some other way we cleaned up the mempool after a
     // reorg, besides draining this object).
     ~DisconnectedBlockTransactions() { assert(queuedTx.empty()); }
 
     // Estimate the overhead of queuedTx to be 6 pointers + an allocation, as
     // no exact formula for boost::multi_index_contained is implemented.
     size_t DynamicMemoryUsage() const {
         return memusage::MallocUsage(sizeof(CTransactionRef) +
                                      6 * sizeof(void *)) *
                    queuedTx.size() +
                cachedInnerUsage;
     }
 
     const indexed_disconnected_transactions &GetQueuedTx() const {
         return queuedTx;
     }
 
     // Import mempool entries in topological order into queuedTx and clear the
     // mempool. Caller should call updateMempoolForReorg to reprocess these
     // transactions
     void importMempool(CTxMemPool &pool);
 
     // Add entries for a block while reconstructing the topological ordering so
     // they can be added back to the mempool simply.
     void addForBlock(const std::vector<CTransactionRef> &vtx);
 
     // Remove entries based on txid_index, and update memory usage.
     void removeForBlock(const std::vector<CTransactionRef> &vtx) {
         // Short-circuit in the common case of a block being added to the tip
         if (queuedTx.empty()) {
             return;
         }
         for (auto const &tx : vtx) {
             auto it = queuedTx.find(tx->GetId());
             if (it != queuedTx.end()) {
                 cachedInnerUsage -= RecursiveDynamicUsage(*it);
                 queuedTx.erase(it);
             }
         }
     }
 
     // Remove an entry by insertion_order index, and update memory usage.
     void removeEntry(indexed_disconnected_transactions::index<
                      insertion_order>::type::iterator entry) {
         cachedInnerUsage -= RecursiveDynamicUsage(*entry);
         queuedTx.get<insertion_order>().erase(entry);
     }
 
     bool isEmpty() const { return queuedTx.empty(); }
 
     void clear() {
         cachedInnerUsage = 0;
         queuedTx.clear();
     }
 
     /**
      * Make mempool consistent after a reorg, by re-adding or recursively
      * erasing disconnected block transactions from the mempool, and also
      * removing any other transactions from the mempool that are no longer valid
      * given the new tip/height.
      *
      * Note: we assume that disconnectpool only contains transactions that are
      * NOT confirmed in the current chain nor already in the mempool (otherwise,
      * in-mempool descendants of such transactions would be removed).
      *
      * Passing fAddToMempool=false will skip trying to add the transactions
      * back, and instead just erase from the mempool as needed.
      */
     void updateMempoolForReorg(const Config &config, bool fAddToMempool);
 };
 
 #endif // BITCOIN_TXMEMPOOL_H