Line data    Source code

       1             : // Copyright (c) 2009-2010 Satoshi Nakamoto
       2             : // Copyright (c) 2009-2019 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 <util/time.h>
       8             : 
       9             : #include <tinyformat.h>
      10             : 
      11        3020 : std::string CBlockFileInfo::ToString() const
      12             : {
      13        3020 :     return strprintf("CBlockFileInfo(blocks=%u, size=%u, heights=%u...%u, time=%s...%s)", nBlocks, nSize, nHeightFirst, nHeightLast, FormatISO8601Date(nTimeFirst), FormatISO8601Date(nTimeLast));
      14           0 : }
      15             : 
      16           0 : std::string CBlockIndex::ToString() const
      17             : {
      18           0 :     return strprintf("CBlockIndex(pprev=%p, nHeight=%d, merkle=%s, hashBlock=%s)",
      19           0 :                      pprev, nHeight, hashMerkleRoot.ToString(), GetBlockHash().ToString());
      20           0 : }
      21             : 
      22      269769 : void CChain::SetTip(CBlockIndex& block)
      23             : {
      24      269769 :     CBlockIndex* pindex = &block;
      25      269769 :     vChain.resize(pindex->nHeight + 1);
      26     1044197 :     while (pindex && vChain[pindex->nHeight] != pindex) {
      27      774428 :         vChain[pindex->nHeight] = pindex;
      28      774428 :         pindex = pindex->pprev;
      29             :     }
      30      269769 : }
      31             : 
      32       41089 : CBlockLocator CChain::GetLocator(const CBlockIndex *pindex) const {
      33       41089 :     int nStep = 1;
      34       41089 :     std::vector<uint256> vHave;
      35       41089 :     vHave.reserve(32);
      36             : 
      37       41089 :     if (!pindex)
      38        8981 :         pindex = Tip();
      39      710692 :     while (pindex) {
      40      710688 :         vHave.push_back(pindex->GetBlockHash());
      41             :         // Stop when we have added the genesis block.
      42      710688 :         if (pindex->nHeight == 0)
      43       41085 :             break;
      44             :         // Exponentially larger steps back, plus the genesis block.
      45      669603 :         int nHeight = std::max(pindex->nHeight - nStep, 0);
      46      669603 :         if (Contains(pindex)) {
      47             :             // Use O(1) CChain index if possible.
      48      491083 :             pindex = (*this)[nHeight];
      49      491083 :         } else {
      50             :             // Otherwise, use O(log n) skiplist.
      51      178520 :             pindex = pindex->GetAncestor(nHeight);
      52             :         }
      53      669603 :         if (vHave.size() > 10)
      54      301295 :             nStep *= 2;
      55             :     }
      56             : 
      57       41089 :     return CBlockLocator(vHave);
      58       41089 : }
      59             : 
      60      491786 : const CBlockIndex *CChain::FindFork(const CBlockIndex *pindex) const {
      61      491786 :     if (pindex == nullptr) {
      62        1074 :         return nullptr;
      63             :     }
      64      490712 :     if (pindex->nHeight > Height())
      65      245486 :         pindex = pindex->GetAncestor(Height());
      66      507652 :     while (pindex && !Contains(pindex))
      67       16940 :         pindex = pindex->pprev;
      68      490712 :     return pindex;
      69      491786 : }
      70             : 
      71       11406 : CBlockIndex* CChain::FindEarliestAtLeast(int64_t nTime, int height) const
      72             : {
      73       11406 :     std::pair<int64_t, int> blockparams = std::make_pair(nTime, height);
      74       11406 :     std::vector<CBlockIndex*>::const_iterator lower = std::lower_bound(vChain.begin(), vChain.end(), blockparams,
      75      175079 :         [](CBlockIndex* pBlock, const std::pair<int64_t, int>& blockparams) -> bool { return pBlock->GetBlockTimeMax() < blockparams.first || pBlock->nHeight < blockparams.second; });
      76       11406 :     return (lower == vChain.end() ? nullptr : *lower);
      77             : }
      78             : 
      79             : /** Turn the lowest '1' bit in the binary representation of a number into a '0'. */
      80   296240088 : int static inline InvertLowestOne(int n) { return n & (n - 1); }
      81             : 
      82             : /** Compute what height to jump back to with the CBlockIndex::pskip pointer. */
      83   197615482 : int static inline GetSkipHeight(int height) {
      84   197615482 :     if (height < 2)
      85      119455 :         return 0;
      86             : 
      87             :     // Determine which height to jump back to. Any number strictly lower than height is acceptable,
      88             :     // but the following expression seems to perform well in simulations (max 110 steps to go back
      89             :     // up to 2**18 blocks).
      90   197496027 :     return (height & 1) ? InvertLowestOne(InvertLowestOne(height - 1)) + 1 : InvertLowestOne(height);
      91   197615482 : }
      92             : 
      93    22422140 : const CBlockIndex* CBlockIndex::GetAncestor(int height) const
      94             : {
      95    22422140 :     if (height > nHeight || height < 0) {
      96     3668998 :         return nullptr;
      97             :     }
      98             : 
      99    18753142 :     const CBlockIndex* pindexWalk = this;
     100    18753142 :     int heightWalk = nHeight;
     101   114227417 :     while (heightWalk > height) {
     102    95474275 :         int heightSkip = GetSkipHeight(heightWalk);
     103    95474275 :         int heightSkipPrev = GetSkipHeight(heightWalk - 1);
     104   102957090 :         if (pindexWalk->pskip != nullptr &&
     105    95371553 :             (heightSkip == height ||
     106    90043593 :              (heightSkip > height && !(heightSkipPrev < heightSkip - 2 &&
     107     7482815 :                                        heightSkipPrev >= height)))) {
     108             :             // Only follow pskip if pprev->pskip isn't better than pskip->pprev.
     109    45611044 :             pindexWalk = pindexWalk->pskip;
     110    45611044 :             heightWalk = heightSkip;
     111    45611044 :         } else {
     112    49863231 :             assert(pindexWalk->pprev);
     113    49863231 :             pindexWalk = pindexWalk->pprev;
     114    49863231 :             heightWalk--;
     115             :         }
     116             :     }
     117    18753142 :     return pindexWalk;
     118    22422140 : }
     119             : 
     120     7564308 : CBlockIndex* CBlockIndex::GetAncestor(int height)
     121             : {
     122     7564308 :     return const_cast<CBlockIndex*>(static_cast<const CBlockIndex*>(this)->GetAncestor(height));
     123             : }
     124             : 
     125     6667466 : void CBlockIndex::BuildSkip()
     126             : {
     127     6667466 :     if (pprev)
     128     6667136 :         pskip = pprev->GetAncestor(GetSkipHeight(nHeight));
     129     6667466 : }
     130             : 
     131      629360 : arith_uint256 GetBlockProof(const CBlockIndex& block)
     132             : {
     133      629360 :     arith_uint256 bnTarget;
     134             :     bool fNegative;
     135             :     bool fOverflow;
     136      629360 :     bnTarget.SetCompact(block.nBits, &fNegative, &fOverflow);
     137      629360 :     if (fNegative || fOverflow || bnTarget == 0)
     138          48 :         return 0;
     139             :     // We need to compute 2**256 / (bnTarget+1), but we can't represent 2**256
     140             :     // as it's too large for an arith_uint256. However, as 2**256 is at least as large
     141             :     // as bnTarget+1, it is equal to ((2**256 - bnTarget - 1) / (bnTarget+1)) + 1,
     142             :     // or ~bnTarget / (bnTarget+1) + 1.
     143      629312 :     return (~bnTarget / (bnTarget + 1)) + 1;
     144      629360 : }
     145             : 
     146        1421 : int64_t GetBlockProofEquivalentTime(const CBlockIndex& to, const CBlockIndex& from, const CBlockIndex& tip, const Consensus::Params& params)
     147             : {
     148        1421 :     arith_uint256 r;
     149        1421 :     int sign = 1;
     150        1421 :     if (to.nChainWork > from.nChainWork) {
     151         916 :         r = to.nChainWork - from.nChainWork;
     152         916 :     } else {
     153         505 :         r = from.nChainWork - to.nChainWork;
     154         505 :         sign = -1;
     155             :     }
     156        1421 :     r = r * arith_uint256(params.nPowTargetSpacing) / GetBlockProof(tip);
     157        1421 :     if (r.bits() > 63) {
     158           0 :         return sign * std::numeric_limits<int64_t>::max();
     159             :     }
     160        1421 :     return sign * int64_t(r.GetLow64());
     161        1421 : }
     162             : 
     163             : /** Find the last common ancestor two blocks have.
     164             :  *  Both pa and pb must be non-nullptr. */
     165     1174177 : const CBlockIndex* LastCommonAncestor(const CBlockIndex* pa, const CBlockIndex* pb) {
     166     1174177 :     if (pa->nHeight > pb->nHeight) {
     167           0 :         pa = pa->GetAncestor(pb->nHeight);
     168     1174177 :     } else if (pb->nHeight > pa->nHeight) {
     169      281674 :         pb = pb->GetAncestor(pa->nHeight);
     170      281674 :     }
     171             : 
     172     1188394 :     while (pa != pb && pa && pb) {
     173       14217 :         pa = pa->pprev;
     174       14217 :         pb = pb->pprev;
     175             :     }
     176             : 
     177             :     // Eventually all chain branches meet at the genesis block.
     178     1174177 :     assert(pa == pb);
     179     1174177 :     return pa;
     180             : }