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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2020 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 <wallet/fees.h>
#include <wallet/coincontrol.h>
#include <wallet/wallet.h>
namespace wallet {
CAmount GetRequiredFee(const CWallet& wallet, unsigned int nTxBytes)
{
return GetRequiredFeeRate(wallet).GetFee(nTxBytes);
}
CAmount GetMinimumFee(const CWallet& wallet, unsigned int nTxBytes, const CCoinControl& coin_control, FeeCalculation* feeCalc)
{
return GetMinimumFeeRate(wallet, coin_control, feeCalc).GetFee(nTxBytes);
}
CFeeRate GetRequiredFeeRate(const CWallet& wallet)
{
return std::max(wallet.m_min_fee, wallet.chain().relayMinFee());
}
CFeeRate GetMinimumFeeRate(const CWallet& wallet, const CCoinControl& coin_control, FeeCalculation* feeCalc)
{
/* User control of how to calculate fee uses the following parameter precedence:
1. coin_control.m_feerate
2. coin_control.m_confirm_target
3. m_pay_tx_fee (user-set member variable of wallet)
4. m_confirm_target (user-set member variable of wallet)
The first parameter that is set is used.
*/
CFeeRate feerate_needed;
if (coin_control.m_feerate) { // 1.
feerate_needed = *(coin_control.m_feerate);
if (feeCalc) feeCalc->reason = FeeReason::PAYTXFEE;
// Allow to override automatic min/max check over coin control instance
if (coin_control.fOverrideFeeRate) return feerate_needed;
}
else if (!coin_control.m_confirm_target && wallet.m_pay_tx_fee != CFeeRate(0)) { // 3. TODO: remove magic value of 0 for wallet member m_pay_tx_fee
feerate_needed = wallet.m_pay_tx_fee;
if (feeCalc) feeCalc->reason = FeeReason::PAYTXFEE;
}
else { // 2. or 4.
// We will use smart fee estimation
unsigned int target = coin_control.m_confirm_target ? *coin_control.m_confirm_target : wallet.m_confirm_target;
// By default estimates are economical iff we are signaling opt-in-RBF
bool conservative_estimate = !coin_control.m_signal_bip125_rbf.value_or(wallet.m_signal_rbf);
// Allow to override the default fee estimate mode over the CoinControl instance
if (coin_control.m_fee_mode == FeeEstimateMode::CONSERVATIVE) conservative_estimate = true;
else if (coin_control.m_fee_mode == FeeEstimateMode::ECONOMICAL) conservative_estimate = false;
feerate_needed = wallet.chain().estimateSmartFee(target, conservative_estimate, feeCalc);
if (feerate_needed == CFeeRate(0)) {
// if we don't have enough data for estimateSmartFee, then use fallback fee
feerate_needed = wallet.m_fallback_fee;
if (feeCalc) feeCalc->reason = FeeReason::FALLBACK;
// directly return if fallback fee is disabled (feerate 0 == disabled)
if (wallet.m_fallback_fee == CFeeRate(0)) return feerate_needed;
}
// Obey mempool min fee when using smart fee estimation
CFeeRate min_mempool_feerate = wallet.chain().mempoolMinFee();
if (feerate_needed < min_mempool_feerate) {
feerate_needed = min_mempool_feerate;
if (feeCalc) feeCalc->reason = FeeReason::MEMPOOL_MIN;
}
}
// prevent user from paying a fee below the required fee rate
CFeeRate required_feerate = GetRequiredFeeRate(wallet);
if (required_feerate > feerate_needed) {
feerate_needed = required_feerate;
if (feeCalc) feeCalc->reason = FeeReason::REQUIRED;
}
return feerate_needed;
}
CFeeRate GetDiscardRate(const CWallet& wallet)
{
unsigned int highest_target = wallet.chain().estimateMaxBlocks();
CFeeRate discard_rate = wallet.chain().estimateSmartFee(highest_target, /*conservative=*/false);
// Don't let discard_rate be greater than longest possible fee estimate if we get a valid fee estimate
discard_rate = (discard_rate == CFeeRate(0)) ? wallet.m_discard_rate : std::min(discard_rate, wallet.m_discard_rate);
// Discard rate must be at least dust relay feerate
discard_rate = std::max(discard_rate, wallet.chain().relayDustFee());
return discard_rate;
}
} // namespace wallet
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