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1 : : // Copyright (c) 2009-2010 Satoshi Nakamoto
2 : : // Copyright (c) 2009-2022 The Bitcoin Core developers
3 : : // Distributed under the MIT software license, see the accompanying
4 : : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
5 : :
6 : : #include <chain.h>
7 : : #include <tinyformat.h>
8 : : #include <util/check.h>
9 : : #include <util/time.h>
10 : :
11 : 1688 : std::string CBlockFileInfo::ToString() const
12 : : {
13 [ + - + - ]: 3376 : return strprintf("CBlockFileInfo(blocks=%u, size=%u, heights=%u...%u, time=%s...%s)", nBlocks, nSize, nHeightFirst, nHeightLast, FormatISO8601Date(nTimeFirst), FormatISO8601Date(nTimeLast));
14 : : }
15 : :
16 : 208 : std::string CBlockIndex::ToString() const
17 : : {
18 : 208 : return strprintf("CBlockIndex(pprev=%p, nHeight=%d, merkle=%s, hashBlock=%s)",
19 [ + - + - ]: 416 : pprev, nHeight, hashMerkleRoot.ToString(), GetBlockHash().ToString());
20 : : }
21 : :
22 : 609768 : void CChain::SetTip(CBlockIndex& block)
23 : : {
24 : 609768 : CBlockIndex* pindex = █
25 : 609768 : vChain.resize(pindex->nHeight + 1);
26 [ + + + + ]: 34886376 : while (pindex && vChain[pindex->nHeight] != pindex) {
27 : 33666840 : vChain[pindex->nHeight] = pindex;
28 : 33666840 : pindex = pindex->pprev;
29 : : }
30 : 609768 : }
31 : :
32 : 374414 : std::vector<uint256> LocatorEntries(const CBlockIndex* index)
33 : : {
34 : 374414 : int step = 1;
35 : 374414 : std::vector<uint256> have;
36 [ + - ]: 374414 : if (index == nullptr) return have;
37 : :
38 [ + - ]: 374414 : have.reserve(32);
39 [ + - ]: 1689340 : while (index) {
40 [ + - ]: 1689340 : have.emplace_back(index->GetBlockHash());
41 [ + + ]: 1689340 : if (index->nHeight == 0) break;
42 : : // Exponentially larger steps back, plus the genesis block.
43 [ + + ]: 1314926 : int height = std::max(index->nHeight - step, 0);
44 : : // Use skiplist.
45 [ + - ]: 1314926 : index = index->GetAncestor(height);
46 [ - + + + ]: 1314926 : if (have.size() > 10) step *= 2;
47 : : }
48 : : return have;
49 : 0 : }
50 : :
51 : 111672 : CBlockLocator GetLocator(const CBlockIndex* index)
52 : : {
53 : 111672 : return CBlockLocator{LocatorEntries(index)};
54 : : }
55 : :
56 : 226173 : const CBlockIndex *CChain::FindFork(const CBlockIndex *pindex) const {
57 [ + + ]: 226173 : if (pindex == nullptr) {
58 : : return nullptr;
59 : : }
60 [ - + + + ]: 224485 : if (pindex->nHeight > Height())
61 : 113842 : pindex = pindex->GetAncestor(Height());
62 [ + + - + ]: 224485 : while (pindex && !Contains(pindex))
63 : 0 : pindex = pindex->pprev;
64 : : return pindex;
65 : : }
66 : :
67 : 0 : CBlockIndex* CChain::FindEarliestAtLeast(int64_t nTime, int height) const
68 : : {
69 : 0 : std::pair<int64_t, int> blockparams = std::make_pair(nTime, height);
70 : 0 : std::vector<CBlockIndex*>::const_iterator lower = std::lower_bound(vChain.begin(), vChain.end(), blockparams,
71 [ # # # # ]: 0 : [](CBlockIndex* pBlock, const std::pair<int64_t, int>& blockparams) -> bool { return pBlock->GetBlockTimeMax() < blockparams.first || pBlock->nHeight < blockparams.second; });
72 [ # # ]: 0 : return (lower == vChain.end() ? nullptr : *lower);
73 : : }
74 : :
75 : : /** Turn the lowest '1' bit in the binary representation of a number into a '0'. */
76 : 22374197 : int static inline InvertLowestOne(int n) { return n & (n - 1); }
77 : :
78 : : /** Compute what height to jump back to with the CBlockIndex::pskip pointer. */
79 : 22593338 : int static inline GetSkipHeight(int height) {
80 [ + + ]: 22593338 : if (height < 2)
81 : : return 0;
82 : :
83 : : // Determine which height to jump back to. Any number strictly lower than height is acceptable,
84 : : // but the following expression seems to perform well in simulations (max 110 steps to go back
85 : : // up to 2**18 blocks).
86 [ + + ]: 22374197 : return (height & 1) ? InvertLowestOne(InvertLowestOne(height - 1)) + 1 : InvertLowestOne(height);
87 : : }
88 : :
89 : 5102805 : const CBlockIndex* CBlockIndex::GetAncestor(int height) const
90 : : {
91 [ + + + + ]: 5102805 : if (height > nHeight || height < 0) {
92 : : return nullptr;
93 : : }
94 : :
95 : : const CBlockIndex* pindexWalk = this;
96 : : int heightWalk = nHeight;
97 [ + + ]: 14342799 : while (heightWalk > height) {
98 : 11160404 : int heightSkip = GetSkipHeight(heightWalk);
99 : 11160404 : int heightSkipPrev = GetSkipHeight(heightWalk - 1);
100 [ + + + + ]: 11160404 : if (pindexWalk->pskip != nullptr &&
101 [ + + ]: 9761239 : (heightSkip == height ||
102 [ + + + + ]: 4447233 : (heightSkip > height && !(heightSkipPrev < heightSkip - 2 &&
103 : : heightSkipPrev >= height)))) {
104 : : // Only follow pskip if pprev->pskip isn't better than pskip->pprev.
105 : : pindexWalk = pindexWalk->pskip;
106 : : heightWalk = heightSkip;
107 : : } else {
108 [ - + ]: 5901725 : assert(pindexWalk->pprev);
109 : : pindexWalk = pindexWalk->pprev;
110 : : heightWalk--;
111 : : }
112 : : }
113 : : return pindexWalk;
114 : : }
115 : :
116 : 2274832 : CBlockIndex* CBlockIndex::GetAncestor(int height)
117 : : {
118 : 2274832 : return const_cast<CBlockIndex*>(static_cast<const CBlockIndex*>(this)->GetAncestor(height));
119 : : }
120 : :
121 : 272894 : void CBlockIndex::BuildSkip()
122 : : {
123 [ + + ]: 272894 : if (pprev)
124 : 272530 : pskip = pprev->GetAncestor(GetSkipHeight(nHeight));
125 : 272894 : }
126 : :
127 : 1141745 : arith_uint256 GetBlockProof(const CBlockIndex& block)
128 : : {
129 : 1141745 : arith_uint256 bnTarget;
130 : 1141745 : bool fNegative;
131 : 1141745 : bool fOverflow;
132 : 1141745 : bnTarget.SetCompact(block.nBits, &fNegative, &fOverflow);
133 [ + + + + : 2129135 : if (fNegative || fOverflow || bnTarget == 0)
+ + ]
134 : 212956 : return 0;
135 : : // We need to compute 2**256 / (bnTarget+1), but we can't represent 2**256
136 : : // as it's too large for an arith_uint256. However, as 2**256 is at least as large
137 : : // as bnTarget+1, it is equal to ((2**256 - bnTarget - 1) / (bnTarget+1)) + 1,
138 : : // or ~bnTarget / (bnTarget+1) + 1.
139 : 1857578 : return (~bnTarget / (bnTarget + 1)) + 1;
140 : : }
141 : :
142 : 150784 : int64_t GetBlockProofEquivalentTime(const CBlockIndex& to, const CBlockIndex& from, const CBlockIndex& tip, const Consensus::Params& params)
143 : : {
144 : 150784 : arith_uint256 r;
145 : 150784 : int sign = 1;
146 [ + + ]: 150784 : if (to.nChainWork > from.nChainWork) {
147 : 42900 : r = to.nChainWork - from.nChainWork;
148 : : } else {
149 : 107884 : r = from.nChainWork - to.nChainWork;
150 : 107884 : sign = -1;
151 : : }
152 : 301568 : r = r * arith_uint256(params.nPowTargetSpacing) / GetBlockProof(tip);
153 [ + + ]: 70716 : if (r.bits() > 63) {
154 : 28936 : return sign * std::numeric_limits<int64_t>::max();
155 : : }
156 : 41780 : return sign * int64_t(r.GetLow64());
157 : : }
158 : :
159 : : /** Find the last common ancestor two blocks have.
160 : : * Both pa and pb must be non-nullptr. */
161 : 0 : const CBlockIndex* LastCommonAncestor(const CBlockIndex* pa, const CBlockIndex* pb) {
162 : : // First rewind to the last common height (the forking point cannot be past one of the two).
163 [ # # ]: 0 : if (pa->nHeight > pb->nHeight) {
164 : 0 : pa = pa->GetAncestor(pb->nHeight);
165 [ # # ]: 0 : } else if (pb->nHeight > pa->nHeight) {
166 : 0 : pb = pb->GetAncestor(pa->nHeight);
167 : : }
168 [ # # ]: 0 : while (pa != pb) {
169 : : // Jump back until pa and pb have a common "skip" ancestor.
170 [ # # ]: 0 : while (pa->pskip != pb->pskip) {
171 : : // This logic relies on the property that equal-height blocks have equal-height skip
172 : : // pointers.
173 : 0 : Assume(pa->nHeight == pb->nHeight);
174 : 0 : Assume(pa->pskip->nHeight == pb->pskip->nHeight);
175 : 0 : pa = pa->pskip;
176 : 0 : pb = pb->pskip;
177 : : }
178 : : // At this point, pa and pb are different, but have equal pskip. The forking point lies in
179 : : // between pa/pb on the one end, and pa->pskip/pb->pskip on the other end.
180 : 0 : pa = pa->pprev;
181 : 0 : pb = pb->pprev;
182 : : }
183 : 0 : return pa;
184 : : }
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