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/*
This file is part of cpp-ethereum.
cpp-ethereum is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
cpp-ethereum is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with cpp-ethereum. If not, see <http://www.gnu.org/licenses/>.
*/
/** @file BasicGasPricer.cpp
* @author Gav Wood <i@gavwood.com>
* @date 2015
*/
#include <boost/math/distributions/normal.hpp>
#include "BasicGasPricer.h"
#include "BlockChain.h"
using namespace std;
using namespace dev;
using namespace dev::eth;
void BasicGasPricer::update(BlockChain const& _bc)
{
unsigned c = 0;
h256 p = _bc.currentHash();
m_gasPerBlock = _bc.info(p).gasLimit();
map<u256, u256> dist;
u256 total = 0;
// make gasPrice versus gasUsed distribution for the last 1000 blocks
while (c < 1000 && p)
{
BlockInfo bi = _bc.info(p);
if (bi.transactionsRoot() != EmptyTrie)
{
auto bb = _bc.block(p);
RLP r(bb);
BlockReceipts brs(_bc.receipts(bi.hash()));
size_t i = 0;
for (auto const& tr: r[1])
{
Transaction tx(tr.data(), CheckTransaction::None);
u256 gu = brs.receipts[i].gasUsed();
dist[tx.gasPrice()] += gu;
total += gu;
i++;
}
}
p = bi.parentHash();
++c;
}
// fill m_octiles with weighted gasPrices
if (total > 0)
{
m_octiles[0] = dist.begin()->first;
// calc mean
u256 mean = 0;
for (auto const& i: dist)
mean += i.first * i.second;
mean /= total;
// calc standard deviation
u256 sdSquared = 0;
for (auto const& i: dist)
sdSquared += i.second * (i.first - mean) * (i.first - mean);
sdSquared /= total;
if (sdSquared)
{
long double sd = sqrt(sdSquared.convert_to<long double>());
long double normalizedSd = sd / mean.convert_to<long double>();
// calc octiles normalized to gaussian distribution
boost::math::normal gauss(1.0, (normalizedSd > 0.01) ? normalizedSd : 0.01);
for (size_t i = 1; i < 8; i++)
m_octiles[i] = u256(mean.convert_to<long double>() * boost::math::quantile(gauss, i / 8.0));
m_octiles[8] = dist.rbegin()->first;
}
else
{
for (size_t i = 0; i < 9; i++)
m_octiles[i] = (i + 1) * mean / 5;
}
}
}