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0fbaef9676
When calculating the fee for a given tx size from a fee rate, we should always round up to the next satoshi. Otherwise, if we round down (via truncation), the calculated fee may result in a fee with a feerate slightly less than targeted. This is particularly important for coin selection as a slightly lower feerate than expected can result in a variety of issues.
45 lines
1.4 KiB
C++
45 lines
1.4 KiB
C++
// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2020 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <policy/feerate.h>
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#include <tinyformat.h>
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#include <cmath>
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CFeeRate::CFeeRate(const CAmount& nFeePaid, uint32_t num_bytes)
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{
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const int64_t nSize{num_bytes};
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if (nSize > 0) {
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nSatoshisPerK = nFeePaid * 1000 / nSize;
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} else {
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nSatoshisPerK = 0;
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}
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}
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CAmount CFeeRate::GetFee(uint32_t num_bytes) const
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{
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const int64_t nSize{num_bytes};
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// Be explicit that we're converting from a double to int64_t (CAmount) here.
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// We've previously had issues with the silent double->int64_t conversion.
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CAmount nFee{static_cast<CAmount>(std::ceil(nSatoshisPerK * nSize / 1000.0))};
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if (nFee == 0 && nSize != 0) {
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if (nSatoshisPerK > 0) nFee = CAmount(1);
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if (nSatoshisPerK < 0) nFee = CAmount(-1);
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}
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return nFee;
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}
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std::string CFeeRate::ToString(const FeeEstimateMode& fee_estimate_mode) const
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{
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switch (fee_estimate_mode) {
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case FeeEstimateMode::SAT_VB: return strprintf("%d.%03d %s/vB", nSatoshisPerK / 1000, nSatoshisPerK % 1000, CURRENCY_ATOM);
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default: return strprintf("%d.%08d %s/kvB", nSatoshisPerK / COIN, nSatoshisPerK % COIN, CURRENCY_UNIT);
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}
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}
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