Merge pull request #4017 from ethereum/eip100

EIP100 - Difficulty adjustment including uncles

libethashseal/Ethash.cpp

@@ -194,8 +194,14 @@ u256 Ethash::calculateDifficulty(BlockHeader const& _bi, BlockHeader const& _par
 		// Frontier-era difficulty adjustment
 		target = _bi.timestamp() >= _parent.timestamp() + durationLimit ? _parent.difficulty() - (_parent.difficulty() / difficultyBoundDivisor) : (_parent.difficulty() + (_parent.difficulty() / difficultyBoundDivisor));
 	else
-		// Homestead-era difficulty adjustment
-		target = _parent.difficulty() + _parent.difficulty() / 2048 * max<bigint>(1 - (bigint(_bi.timestamp()) - _parent.timestamp()) / 10, -99);
+	{
+		bigint const timestampDiff = bigint(_bi.timestamp()) - _parent.timestamp();
+		bigint const adjFactor = _bi.number() < chainParams().u256Param("metropolisForkBlock") ?
+			max<bigint>(1 - timestampDiff / 10, -99) : // Homestead-era difficulty adjustment
+			max<bigint>((_parent.hasUncles() ? 2 : 1) - timestampDiff / 9, -99); // Metropolis-era difficulty adjustment
+
+		target = _parent.difficulty() + _parent.difficulty() / 2048 * adjFactor;
+	}
 
 	bigint o = target;
 	unsigned periodCount = unsigned(_parent.number() + 1) / c_expDiffPeriod;

libethcore/BlockHeader.h

@@ -153,6 +153,7 @@ class BlockHeader
 
 	h256 const& parentHash() const { return m_parentHash; }
 	h256 const& sha3Uncles() const { return m_sha3Uncles; }
+	bool hasUncles() const { return m_sha3Uncles != EmptyListSHA3; }
 	u256 const& timestamp() const { return m_timestamp; }
 	Address const& author() const { return m_author; }
 	h256 const& stateRoot() const { return m_stateRoot; }

test/unittests/libethashseal/EthashTest.cpp

@@ -0,0 +1,99 @@
+/*
+	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 ethash.cpp
+ * Ethash class testing.
+ */
+
+#include <boost/test/unit_test.hpp>
+#include <test/tools/libtesteth/TestHelper.h>
+#include <libethashseal/Ethash.h>
+
+using namespace std;
+using namespace dev;
+using namespace dev::eth;
+using namespace dev::test;
+
+BOOST_FIXTURE_TEST_SUITE(EthashTests, TestOutputHelper)
+
+BOOST_AUTO_TEST_CASE(calculateDifficultyMetropolisWithoutUncles)
+{
+	ChainOperationParams params;
+	params.otherParams["metropolisForkBlock"] = "0x1000";
+
+	Ethash ethash;
+	ethash.setChainParams(params);
+
+	BlockHeader parentHeader;
+	parentHeader.clear();
+	parentHeader.setNumber(0x2000);
+	parentHeader.setTimestamp(100);
+	parentHeader.setDifficulty(1000000);
+
+	BlockHeader header;
+	header.clear();
+	header.setNumber(0x2001);
+	header.setTimestamp(130);
+
+	BOOST_REQUIRE_EQUAL(ethash.calculateDifficulty(header, parentHeader), 999024);
+}
+
+BOOST_AUTO_TEST_CASE(calculateDifficultyMetropolisWithUncles)
+{
+	ChainOperationParams params;
+	params.otherParams["metropolisForkBlock"] = "0x1000";
+
+	Ethash ethash;
+	ethash.setChainParams(params);
+
+	BlockHeader parentHeader;
+	parentHeader.clear();
+	parentHeader.setNumber(0x2000);
+	parentHeader.setTimestamp(100);
+	parentHeader.setDifficulty(1000000);
+	parentHeader.setSha3Uncles(h256("0x949d991d685738352398dff73219ab19c62c06e6f8ce899fbae755d5127ed1ef"));
+
+	BlockHeader header;
+	header.clear();
+	header.setNumber(0x2001);
+	header.setTimestamp(130);
+
+	BOOST_REQUIRE_EQUAL(ethash.calculateDifficulty(header, parentHeader), 999512);
+}
+
+BOOST_AUTO_TEST_CASE(calculateDifficultyMetropolisMaxAdjustment)
+{
+	ChainOperationParams params;
+	params.otherParams["metropolisForkBlock"] = "0x1000";
+
+	Ethash ethash;
+	ethash.setChainParams(params);
+
+	BlockHeader parentHeader;
+	parentHeader.clear();
+	parentHeader.setNumber(0x2000);
+	parentHeader.setTimestamp(100);
+	parentHeader.setDifficulty(1000000);
+
+	BlockHeader header;
+	header.clear();
+	header.setNumber(0x2001);
+	header.setTimestamp(1100);
+
+	BOOST_REQUIRE_EQUAL(ethash.calculateDifficulty(header, parentHeader), 951688);
+}
+
+BOOST_AUTO_TEST_SUITE_END()