Simplify JoinSplit priority calculation. refs 1896
Signed-off-by: Daira Hopwood <daira@jacaranda.org>
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@ -7,6 +7,7 @@
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#include "memusage.h"
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#include "random.h"
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#include "version.h"
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#include "policy/fees.h"
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#include <assert.h>
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@ -443,7 +444,17 @@ double CCoinsViewCache::GetPriority(const CTransaction &tx, int nHeight) const
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{
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if (tx.IsCoinBase())
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return 0.0;
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CAmount nTotalIn = 0;
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// Joinsplits do not reveal any information about the value or age of a note, so we
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// cannot apply the priority algorithm used for transparent utxos. Instead, we just
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// use the maximum priority whenever a transaction contains any JoinSplits.
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// (Note that coinbase transactions cannot contain JoinSplits.)
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// FIXME: this logic is partially duplicated between here and CreateNewBlock in miner.cpp.
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if (tx.vjoinsplit.size() > 0) {
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return MAX_PRIORITY;
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}
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double dResult = 0.0;
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BOOST_FOREACH(const CTxIn& txin, tx.vin)
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{
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@ -452,34 +463,9 @@ double CCoinsViewCache::GetPriority(const CTransaction &tx, int nHeight) const
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if (!coins->IsAvailable(txin.prevout.n)) continue;
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if (coins->nHeight < nHeight) {
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dResult += coins->vout[txin.prevout.n].nValue * (nHeight-coins->nHeight);
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nTotalIn += coins->vout[txin.prevout.n].nValue;
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}
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}
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// If a transaction contains a joinsplit, we boost the priority of the transaction.
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// Joinsplits do not reveal any information about the value or age of a note, so we
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// cannot apply the priority algorithm used for transparent utxos. Instead, we pick a
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// very large number and multiply it by the transaction's fee per 1000 bytes of data.
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// One trillion, 1000000000000, is equivalent to 1 ZEC utxo * 10000 blocks (~17 days).
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if (tx.vjoinsplit.size() > 0) {
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unsigned int nTxSize = ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION);
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nTotalIn += tx.GetJoinSplitValueIn();
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CAmount fee = nTotalIn - tx.GetValueOut();
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CFeeRate feeRate(fee, nTxSize);
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CAmount feePerK = feeRate.GetFeePerK();
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if (feePerK == 0) {
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feePerK = 1;
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}
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dResult += 1000000000000 * double(feePerK);
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// We cast feePerK from int64_t to double because if feePerK is a large number, say
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// close to MAX_MONEY, the multiplication operation will result in an integer overflow.
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// The variable dResult should never overflow since a 64-bit double in C++ is typically
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// a double-precision floating-point number as specified by IEE 754, with a maximum
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// value DBL_MAX of 1.79769e+308.
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}
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return tx.ComputePriority(dResult);
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}
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