Line data    Source code

       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/time.h>
       9             : 
      10           1 : std::string CBlockFileInfo::ToString() const
      11             : {
      12           1 :     return strprintf("CBlockFileInfo(blocks=%u, size=%u, heights=%u...%u, time=%s...%s)", nBlocks, nSize, nHeightFirst, nHeightLast, FormatISO8601Date(nTimeFirst), FormatISO8601Date(nTimeLast));
      13           0 : }
      14             : 
      15           0 : std::string CBlockIndex::ToString() const
      16             : {
      17           0 :     return strprintf("CBlockIndex(pprev=%p, nHeight=%d, merkle=%s, hashBlock=%s)",
      18           0 :                      pprev, nHeight, hashMerkleRoot.ToString(), GetBlockHash().ToString());
      19           0 : }
      20             : 
      21         201 : void CChain::SetTip(CBlockIndex& block)
      22             : {
      23         201 :     CBlockIndex* pindex = &block;
      24         201 :     vChain.resize(pindex->nHeight + 1);
      25         402 :     while (pindex && vChain[pindex->nHeight] != pindex) {
      26         201 :         vChain[pindex->nHeight] = pindex;
      27         201 :         pindex = pindex->pprev;
      28             :     }
      29         201 : }
      30             : 
      31           0 : std::vector<uint256> LocatorEntries(const CBlockIndex* index)
      32             : {
      33           0 :     int step = 1;
      34           0 :     std::vector<uint256> have;
      35           0 :     if (index == nullptr) return have;
      36             : 
      37           0 :     have.reserve(32);
      38           0 :     while (index) {
      39           0 :         have.emplace_back(index->GetBlockHash());
      40           0 :         if (index->nHeight == 0) break;
      41             :         // Exponentially larger steps back, plus the genesis block.
      42           0 :         int height = std::max(index->nHeight - step, 0);
      43             :         // Use skiplist.
      44           0 :         index = index->GetAncestor(height);
      45           0 :         if (have.size() > 10) step *= 2;
      46             :     }
      47           0 :     return have;
      48           0 : }
      49             : 
      50           0 : CBlockLocator GetLocator(const CBlockIndex* index)
      51             : {
      52           0 :     return CBlockLocator{LocatorEntries(index)};
      53           0 : }
      54             : 
      55           0 : CBlockLocator CChain::GetLocator() const
      56             : {
      57           0 :     return ::GetLocator(Tip());
      58             : }
      59             : 
      60         402 : const CBlockIndex *CChain::FindFork(const CBlockIndex *pindex) const {
      61         402 :     if (pindex == nullptr) {
      62           1 :         return nullptr;
      63             :     }
      64         401 :     if (pindex->nHeight > Height())
      65         201 :         pindex = pindex->GetAncestor(Height());
      66         401 :     while (pindex && !Contains(pindex))
      67           0 :         pindex = pindex->pprev;
      68         401 :     return pindex;
      69         402 : }
      70             : 
      71           0 : CBlockIndex* CChain::FindEarliestAtLeast(int64_t nTime, int height) const
      72             : {
      73           0 :     std::pair<int64_t, int> blockparams = std::make_pair(nTime, height);
      74           2 :     std::vector<CBlockIndex*>::const_iterator lower = std::lower_bound(vChain.begin(), vChain.end(), blockparams,
      75           0 :         [](CBlockIndex* pBlock, const std::pair<int64_t, int>& blockparams) -> bool { return pBlock->GetBlockTimeMax() < blockparams.first || pBlock->nHeight < blockparams.second; });
      76           0 :     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      398177 : 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      265474 : int static inline GetSkipHeight(int height) {
      84      265474 :     if (height < 2)
      85          21 :         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      265453 :     return (height & 1) ? InvertLowestOne(InvertLowestOne(height - 1)) + 1 : InvertLowestOne(height);
      91      265474 : }
      92             : 
      93       19250 : const CBlockIndex* CBlockIndex::GetAncestor(int height) const
      94             : {
      95       19250 :     if (height > nHeight || height < 0) {
      96         147 :         return nullptr;
      97             :     }
      98             : 
      99       19103 :     const CBlockIndex* pindexWalk = this;
     100       19103 :     int heightWalk = nHeight;
     101      151740 :     while (heightWalk > height) {
     102      132637 :         int heightSkip = GetSkipHeight(heightWalk);
     103      132637 :         int heightSkipPrev = GetSkipHeight(heightWalk - 1);
     104      133721 :         if (pindexWalk->pskip != nullptr &&
     105      130865 :             (heightSkip == height ||
     106      119286 :              (heightSkip > height && !(heightSkipPrev < heightSkip - 2 &&
     107        1084 :                                        heightSkipPrev >= height)))) {
     108             :             // Only follow pskip if pprev->pskip isn't better than pskip->pprev.
     109       83672 :             pindexWalk = pindexWalk->pskip;
     110       83672 :             heightWalk = heightSkip;
     111       83672 :         } else {
     112       48965 :             assert(pindexWalk->pprev);
     113       48965 :             pindexWalk = pindexWalk->pprev;
     114       48965 :             heightWalk--;
     115             :         }
     116             :     }
     117       19103 :     return pindexWalk;
     118       19250 : }
     119             : 
     120       12217 : CBlockIndex* CBlockIndex::GetAncestor(int height)
     121             : {
     122       12217 :     return const_cast<CBlockIndex*>(static_cast<const CBlockIndex*>(this)->GetAncestor(height));
     123             : }
     124             : 
     125         200 : void CBlockIndex::BuildSkip()
     126             : {
     127         200 :     if (pprev)
     128         200 :         pskip = pprev->GetAncestor(GetSkipHeight(nHeight));
     129         200 : }
     130             : 
     131         201 : arith_uint256 GetBlockProof(const CBlockIndex& block)
     132             : {
     133         201 :     arith_uint256 bnTarget;
     134             :     bool fNegative;
     135             :     bool fOverflow;
     136         201 :     bnTarget.SetCompact(block.nBits, &fNegative, &fOverflow);
     137         201 :     if (fNegative || fOverflow || bnTarget == 0)
     138           0 :         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         201 :     return (~bnTarget / (bnTarget + 1)) + 1;
     144         201 : }
     145             : 
     146           0 : int64_t GetBlockProofEquivalentTime(const CBlockIndex& to, const CBlockIndex& from, const CBlockIndex& tip, const Consensus::Params& params)
     147             : {
     148           0 :     arith_uint256 r;
     149           0 :     int sign = 1;
     150           0 :     if (to.nChainWork > from.nChainWork) {
     151           0 :         r = to.nChainWork - from.nChainWork;
     152           0 :     } else {
     153           0 :         r = from.nChainWork - to.nChainWork;
     154           0 :         sign = -1;
     155             :     }
     156           0 :     r = r * arith_uint256(params.nPowTargetSpacing) / GetBlockProof(tip);
     157           0 :     if (r.bits() > 63) {
     158           0 :         return sign * std::numeric_limits<int64_t>::max();
     159             :     }
     160           0 :     return sign * int64_t(r.GetLow64());
     161           0 : }
     162             : 
     163             : /** Find the last common ancestor two blocks have.
     164             :  *  Both pa and pb must be non-nullptr. */
     165           0 : const CBlockIndex* LastCommonAncestor(const CBlockIndex* pa, const CBlockIndex* pb) {
     166           0 :     if (pa->nHeight > pb->nHeight) {
     167           0 :         pa = pa->GetAncestor(pb->nHeight);
     168           0 :     } else if (pb->nHeight > pa->nHeight) {
     169           0 :         pb = pb->GetAncestor(pa->nHeight);
     170           0 :     }
     171             : 
     172           0 :     while (pa != pb && pa && pb) {
     173           0 :         pa = pa->pprev;
     174           0 :         pb = pb->pprev;
     175             :     }
     176             : 
     177             :     // Eventually all chain branches meet at the genesis block.
     178           0 :     assert(pa == pb);
     179           0 :     return pa;
     180             : }