Coverage Summary for Class: DifficultyCalculator (co.rsk.core)
Class |
Class, %
|
Method, %
|
Line, %
|
DifficultyCalculator |
100%
(1/1)
|
100%
(4/4)
|
82.4%
(28/34)
|
1 /*
2 * This file is part of RskJ
3 * Copyright (C) 2017 RSK Labs Ltd.
4 *
5 * This program is free software: you can redistribute it and/or modify
6 * it under the terms of the GNU Lesser General Public License as published by
7 * the Free Software Foundation, either version 3 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
17 */
18
19 package co.rsk.core;
20
21 import org.ethereum.config.Constants;
22 import org.ethereum.config.blockchain.upgrades.ActivationConfig;
23 import org.ethereum.config.blockchain.upgrades.ConsensusRule;
24 import org.ethereum.core.BlockHeader;
25
26 import java.math.BigInteger;
27
28 import static org.ethereum.util.BIUtil.max;
29
30 public class DifficultyCalculator {
31 private final ActivationConfig activationConfig;
32 private final Constants constants;
33
34 public DifficultyCalculator(ActivationConfig activationConfig, Constants constants) {
35 this.activationConfig = activationConfig;
36 this.constants = constants;
37 }
38
39 public BlockDifficulty calcDifficulty(BlockHeader header, BlockHeader parentHeader) {
40 boolean rskip97Active = activationConfig.isActive(ConsensusRule.RSKIP97, header.getNumber());
41 if (!rskip97Active) {
42 // If more than 10 minutes, reset to minimum difficulty to allow private mining
43 if (header.getTimestamp() >= parentHeader.getTimestamp() + 600) {
44 return constants.getMinimumDifficulty();
45 }
46 }
47
48 return getBlockDifficulty(header, parentHeader);
49 }
50
51 private BlockDifficulty getBlockDifficulty(
52 BlockHeader curBlockHeader,
53 BlockHeader parent) {
54 BlockDifficulty pd = parent.getDifficulty();
55 long parentBlockTS = parent.getTimestamp();
56 int uncleCount = curBlockHeader.getUncleCount();
57 long curBlockTS = curBlockHeader.getTimestamp();
58 int duration = constants.getDurationLimit();
59 BigInteger difDivisor = constants.getDifficultyBoundDivisor(activationConfig.forBlock(curBlockHeader.getNumber()));
60 BlockDifficulty minDif = constants.getMinimumDifficulty();
61 return calcDifficultyWithTimeStamps(curBlockTS, parentBlockTS, pd, uncleCount, duration, difDivisor, minDif);
62 }
63
64 private static BlockDifficulty calcDifficultyWithTimeStamps(
65 long curBlockTS,
66 long parentBlockTS,
67 BlockDifficulty pd,
68 int uncleCount,
69 int duration,
70 BigInteger difDivisor,
71 BlockDifficulty minDif) {
72 long delta = curBlockTS - parentBlockTS;
73 if (delta < 0) {
74 return pd;
75 }
76
77 int calcDur = (1 + uncleCount) * duration;
78 int sign = 0;
79 if (calcDur > delta) {
80 sign = 1;
81 } else if (calcDur < delta) {
82 sign = -1;
83 }
84
85 if (sign == 0) {
86 return pd;
87 }
88
89 BigInteger pdValue = pd.asBigInteger();
90 BigInteger quotient = pdValue.divide(difDivisor);
91
92 BigInteger fromParent;
93 if (sign == 1) {
94 fromParent = pdValue.add(quotient);
95 } else {
96 fromParent = pdValue.subtract(quotient);
97 }
98
99 // If parent difficulty is zero (maybe a genesis block),
100 // then the first child difficulty MUST
101 // be greater or equal getMinimumDifficulty(). That's why the max() is applied in both the add and the sub
102 // cases.
103 // Note that we have to apply max() first in case fromParent ended up being negative.
104 return new BlockDifficulty(max(minDif.asBigInteger(), fromParent));
105 }
106 }