[cleanup] Remove coin age priority completely.

Remove GetPriority and ComputePriority.  Remove internal machinery for tracking priority in CTxMemPoolEntry.

Author: morcos

src/bench/mempool_eviction.cpp

@@ -12,14 +12,13 @@
 static void AddTx(const CTransaction& tx, const CAmount& nFee, CTxMemPool& pool)
 {
     int64_t nTime = 0;
-    double dPriority = 10.0;
     unsigned int nHeight = 1;
     bool spendsCoinbase = false;
     unsigned int sigOpCost = 4;
     LockPoints lp;
     pool.addUnchecked(tx.GetHash(), CTxMemPoolEntry(
-                                        MakeTransactionRef(tx), nFee, nTime, dPriority, nHeight,
-                                        tx.GetValueOut(), spendsCoinbase, sigOpCost, lp));
+                                        MakeTransactionRef(tx), nFee, nTime, nHeight,
+                                        spendsCoinbase, sigOpCost, lp));
 }
 
 // Right now this is only testing eviction performance in an extremely small

src/coins.cpp

@@ -295,25 +295,6 @@ bool CCoinsViewCache::HaveInputs(const CTransaction& tx) const
     return true;
 }
 
-double CCoinsViewCache::GetPriority(const CTransaction &tx, int nHeight, CAmount &inChainInputValue) const
-{
-    inChainInputValue = 0;
-    if (tx.IsCoinBase())
-        return 0.0;
-    double dResult = 0.0;
-    BOOST_FOREACH(const CTxIn& txin, tx.vin)
-    {
-        const CCoins* coins = AccessCoins(txin.prevout.hash);
-        assert(coins);
-        if (!coins->IsAvailable(txin.prevout.n)) continue;
-        if (coins->nHeight <= nHeight) {
-            dResult += (double)(coins->vout[txin.prevout.n].nValue) * (nHeight-coins->nHeight);
-            inChainInputValue += coins->vout[txin.prevout.n].nValue;
-        }
-    }
-    return tx.ComputePriority(dResult);
-}
-
 CCoinsModifier::CCoinsModifier(CCoinsViewCache& cache_, CCoinsMap::iterator it_, size_t usage) : cache(cache_), it(it_), cachedCoinUsage(usage) {
     assert(!cache.hasModifier);
     cache.hasModifier = true;

src/coins.h

@@ -460,13 +460,6 @@ class CCoinsViewCache : public CCoinsViewBacked
     //! Check whether all prevouts of the transaction are present in the UTXO set represented by this view
     bool HaveInputs(const CTransaction& tx) const;
 
-    /**
-     * Return priority of tx at height nHeight. Also calculate the sum of the values of the inputs
-     * that are already in the chain.  These are the inputs that will age and increase priority as
-     * new blocks are added to the chain.
-     */
-    double GetPriority(const CTransaction &tx, int nHeight, CAmount &inChainInputValue) const;
-
     const CTxOut &GetOutputFor(const CTxIn& input) const;
 
     friend class CCoinsModifier;

src/primitives/transaction.cpp

@@ -89,32 +89,6 @@ CAmount CTransaction::GetValueOut() const
     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 = (GetTransactionWeight(*this) + WITNESS_SCALE_FACTOR - 1) / WITNESS_SCALE_FACTOR;
-    for (std::vector<CTxIn>::const_iterator it(vin.begin()); it != vin.end(); ++it)
-    {
-        unsigned int offset = 41U + std::min(110U, (unsigned int)it->scriptSig.size());
-        if (nTxSize > offset)
-            nTxSize -= offset;
-    }
-    return nTxSize;
-}
-
 unsigned int CTransaction::GetTotalSize() const
 {
     return ::GetSerializeSize(*this, SER_NETWORK, PROTOCOL_VERSION);

src/primitives/transaction.h

@@ -361,12 +361,6 @@ class CTransaction
     // 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, including witness data.
      * "Total Size" defined in BIP141 and BIP144.

src/test/mempool_tests.cpp

@@ -407,7 +407,6 @@ BOOST_AUTO_TEST_CASE(MempoolAncestorIndexingTest)
     /* set the fee to just below tx2's feerate when including ancestor */
     CAmount fee = (20000/tx2Size)*(tx7Size + tx6Size) - 1;
 
-    //CTxMemPoolEntry entry7(tx7, fee, 2, 10.0, 1, true);
     pool.addUnchecked(tx7.GetHash(), entry.Fee(fee).FromTx(tx7));
     BOOST_CHECK_EQUAL(pool.size(), 7);
     sortedOrder.insert(sortedOrder.begin()+1, tx7.GetHash().ToString());

src/test/test_bitcoin.cpp

@@ -147,8 +147,8 @@ CTxMemPoolEntry TestMemPoolEntryHelper::FromTx(const CMutableTransaction &tx) {
 }
 
 CTxMemPoolEntry TestMemPoolEntryHelper::FromTx(const CTransaction &txn) {
-    return CTxMemPoolEntry(MakeTransactionRef(txn), nFee, nTime, 0.0, nHeight,
-                           0, spendsCoinbase, sigOpCost, lp);
+    return CTxMemPoolEntry(MakeTransactionRef(txn), nFee, nTime, nHeight,
+                           spendsCoinbase, sigOpCost, lp);
 }
 
 void Shutdown(void* parg)

src/txmempool.cpp

@@ -19,22 +19,17 @@
 #include "version.h"
 
 CTxMemPoolEntry::CTxMemPoolEntry(const CTransactionRef& _tx, const CAmount& _nFee,
-                                 int64_t _nTime, double _entryPriority, unsigned int _entryHeight,
-                                 CAmount _inChainInputValue,
+                                 int64_t _nTime, unsigned int _entryHeight,
                                  bool _spendsCoinbase, int64_t _sigOpsCost, LockPoints lp):
-    tx(_tx), nFee(_nFee), nTime(_nTime), entryPriority(_entryPriority), entryHeight(_entryHeight),
-    inChainInputValue(_inChainInputValue),
+    tx(_tx), nFee(_nFee), nTime(_nTime), entryHeight(_entryHeight),
     spendsCoinbase(_spendsCoinbase), sigOpCost(_sigOpsCost), lockPoints(lp)
 {
     nTxWeight = GetTransactionWeight(*tx);
-    nModSize = tx->CalculateModifiedSize(GetTxSize());
     nUsageSize = RecursiveDynamicUsage(*tx) + memusage::DynamicUsage(tx);
 
     nCountWithDescendants = 1;
     nSizeWithDescendants = GetTxSize();
     nModFeesWithDescendants = nFee;
-    CAmount nValueIn = tx->GetValueOut()+nFee;
-    assert(inChainInputValue <= nValueIn);
 
     feeDelta = 0;
 
@@ -49,16 +44,6 @@ CTxMemPoolEntry::CTxMemPoolEntry(const CTxMemPoolEntry& other)
     *this = other;
 }
 
-double
-CTxMemPoolEntry::GetPriority(unsigned int currentHeight) const
-{
-    double deltaPriority = ((double)(currentHeight-entryHeight)*inChainInputValue)/nModSize;
-    double dResult = entryPriority + deltaPriority;
-    if (dResult < 0) // This should only happen if it was called with a height below entry height
-        dResult = 0;
-    return dResult;
-}
-
 void CTxMemPoolEntry::UpdateFeeDelta(int64_t newFeeDelta)
 {
     nModFeesWithDescendants += newFeeDelta - feeDelta;

src/txmempool.h

@@ -73,12 +73,9 @@ class CTxMemPoolEntry
     CTransactionRef tx;
     CAmount nFee;              //!< Cached to avoid expensive parent-transaction lookups
     size_t nTxWeight;          //!< ... and avoid recomputing tx weight (also used for GetTxSize())
-    size_t nModSize;           //!< ... and modified size for priority
     size_t nUsageSize;         //!< ... and total memory usage
     int64_t nTime;             //!< Local time when entering the mempool
-    double entryPriority;      //!< Priority when entering the mempool
     unsigned int entryHeight;  //!< Chain height when entering the mempool
-    CAmount inChainInputValue; //!< Sum of all txin values that are already in blockchain
     bool spendsCoinbase;       //!< keep track of transactions that spend a coinbase
     int64_t sigOpCost;         //!< Total sigop cost
     int64_t feeDelta;          //!< Used for determining the priority of the transaction for mining in a block
@@ -101,19 +98,14 @@ class CTxMemPoolEntry
 
 public:
     CTxMemPoolEntry(const CTransactionRef& _tx, const CAmount& _nFee,
-                    int64_t _nTime, double _entryPriority, unsigned int _entryHeight,
-                    CAmount _inChainInputValue, bool spendsCoinbase,
+                    int64_t _nTime, unsigned int _entryHeight,
+                    bool spendsCoinbase,
                     int64_t nSigOpsCost, LockPoints lp);
 
     CTxMemPoolEntry(const CTxMemPoolEntry& other);
 
     const CTransaction& GetTx() const { return *this->tx; }
     CTransactionRef GetSharedTx() const { return this->tx; }
-    /**
-     * Fast calculation of lower bound of current priority as update
-     * from entry priority. Only inputs that were originally in-chain will age.
-     */
-    double GetPriority(unsigned int currentHeight) const;
     const CAmount& GetFee() const { return nFee; }
     size_t GetTxSize() const;
     size_t GetTxWeight() const { return nTxWeight; }

src/validation.cpp

@@ -722,9 +722,6 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const C
         CAmount nModifiedFees = nFees;
         pool.ApplyDelta(hash, nModifiedFees);
 
-        CAmount inChainInputValue;
-        double dPriority = view.GetPriority(tx, chainActive.Height(), inChainInputValue);
-
         // Keep track of transactions that spend a coinbase, which we re-scan
         // during reorgs to ensure COINBASE_MATURITY is still met.
         bool fSpendsCoinbase = false;
@@ -736,8 +733,8 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const C
             }
         }
 
-        CTxMemPoolEntry entry(ptx, nFees, nAcceptTime, dPriority, chainActive.Height(),
-                              inChainInputValue, fSpendsCoinbase, nSigOpsCost, lp);
+        CTxMemPoolEntry entry(ptx, nFees, nAcceptTime, chainActive.Height(),
+                              fSpendsCoinbase, nSigOpsCost, lp);
         unsigned int nSize = entry.GetTxSize();
 
         // Check that the transaction doesn't have an excessive number of