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src/chain.cpp
// Copyright (c) 2009-2010 Satoshi Nakamoto | // Copyright (c) 2009-2010 Satoshi Nakamoto | ||||
// Copyright (c) 2009-2016 The Bitcoin Core developers | // Copyright (c) 2009-2016 The Bitcoin Core developers | ||||
// Distributed under the MIT software license, see the accompanying | // Distributed under the MIT software license, see the accompanying | ||||
// file COPYING or http://www.opensource.org/licenses/mit-license.php. | // file COPYING or http://www.opensource.org/licenses/mit-license.php. | ||||
#include "chain.h" | #include "chain.h" | ||||
/** | /** | ||||
* CChain implementation | * CChain implementation | ||||
*/ | */ | ||||
void CChain::SetTip(CBlockIndex *pindex) { | void CChain::SetTip(CBlockIndex *pindex) { | ||||
if (pindex == nullptr) { | if (pindex == nullptr) { | ||||
vChain.clear(); | vChain.clear(); | ||||
return; | return; | ||||
} | } | ||||
vChain.resize(pindex->nHeight + 1); | vChain.resize(pindex->nHeight + 1); | ||||
while (pindex && vChain[pindex->nHeight] != pindex) { | while (pindex && vChain[pindex->nHeight] != pindex) { | ||||
vChain[pindex->nHeight] = pindex; | vChain[pindex->nHeight] = pindex; | ||||
pindex = pindex->pprev; | pindex = pindex->pprev; | ||||
} | } | ||||
} | } | ||||
CBlockLocator CChain::GetLocator(const CBlockIndex *pindex) const { | CBlockLocator CChain::GetLocator(const CBlockIndex *pindex) const { | ||||
int nStep = 1; | int nStep = 1; | ||||
std::vector<uint256> vHave; | std::vector<uint256> vHave; | ||||
vHave.reserve(32); | vHave.reserve(32); | ||||
if (!pindex) pindex = Tip(); | if (!pindex) { | ||||
pindex = Tip(); | |||||
} | |||||
while (pindex) { | while (pindex) { | ||||
vHave.push_back(pindex->GetBlockHash()); | vHave.push_back(pindex->GetBlockHash()); | ||||
// Stop when we have added the genesis block. | // Stop when we have added the genesis block. | ||||
if (pindex->nHeight == 0) break; | if (pindex->nHeight == 0) { | ||||
break; | |||||
} | |||||
// Exponentially larger steps back, plus the genesis block. | // Exponentially larger steps back, plus the genesis block. | ||||
int nHeight = std::max(pindex->nHeight - nStep, 0); | int nHeight = std::max(pindex->nHeight - nStep, 0); | ||||
if (Contains(pindex)) { | if (Contains(pindex)) { | ||||
// Use O(1) CChain index if possible. | // Use O(1) CChain index if possible. | ||||
pindex = (*this)[nHeight]; | pindex = (*this)[nHeight]; | ||||
} else { | } else { | ||||
// Otherwise, use O(log n) skiplist. | // Otherwise, use O(log n) skiplist. | ||||
pindex = pindex->GetAncestor(nHeight); | pindex = pindex->GetAncestor(nHeight); | ||||
} | } | ||||
if (vHave.size() > 10) nStep *= 2; | if (vHave.size() > 10) { | ||||
nStep *= 2; | |||||
} | |||||
} | } | ||||
return CBlockLocator(vHave); | return CBlockLocator(vHave); | ||||
} | } | ||||
const CBlockIndex *CChain::FindFork(const CBlockIndex *pindex) const { | const CBlockIndex *CChain::FindFork(const CBlockIndex *pindex) const { | ||||
if (pindex == nullptr) { | if (pindex == nullptr) { | ||||
return nullptr; | return nullptr; | ||||
} | } | ||||
if (pindex->nHeight > Height()) pindex = pindex->GetAncestor(Height()); | if (pindex->nHeight > Height()) { | ||||
while (pindex && !Contains(pindex)) | pindex = pindex->GetAncestor(Height()); | ||||
} | |||||
while (pindex && !Contains(pindex)) { | |||||
pindex = pindex->pprev; | pindex = pindex->pprev; | ||||
} | |||||
return pindex; | return pindex; | ||||
} | } | ||||
CBlockIndex *CChain::FindEarliestAtLeast(int64_t nTime) const { | CBlockIndex *CChain::FindEarliestAtLeast(int64_t nTime) const { | ||||
std::vector<CBlockIndex *>::const_iterator lower = | std::vector<CBlockIndex *>::const_iterator lower = | ||||
std::lower_bound(vChain.begin(), vChain.end(), nTime, | std::lower_bound(vChain.begin(), vChain.end(), nTime, | ||||
[](CBlockIndex *pBlock, const int64_t &time) -> bool { | [](CBlockIndex *pBlock, const int64_t &time) -> bool { | ||||
return pBlock->GetBlockTimeMax() < time; | return pBlock->GetBlockTimeMax() < time; | ||||
}); | }); | ||||
return (lower == vChain.end() ? nullptr : *lower); | return (lower == vChain.end() ? nullptr : *lower); | ||||
} | } | ||||
/** Turn the lowest '1' bit in the binary representation of a number into a '0'. | /** Turn the lowest '1' bit in the binary representation of a number into a '0'. | ||||
*/ | */ | ||||
static inline int InvertLowestOne(int n) { | static inline int InvertLowestOne(int n) { | ||||
return n & (n - 1); | return n & (n - 1); | ||||
} | } | ||||
/** Compute what height to jump back to with the CBlockIndex::pskip pointer. */ | /** Compute what height to jump back to with the CBlockIndex::pskip pointer. */ | ||||
static inline int GetSkipHeight(int height) { | static inline int GetSkipHeight(int height) { | ||||
if (height < 2) return 0; | if (height < 2) { | ||||
return 0; | |||||
} | |||||
// Determine which height to jump back to. Any number strictly lower than | // Determine which height to jump back to. Any number strictly lower than | ||||
// height is acceptable, but the following expression seems to perform well | // height is acceptable, but the following expression seems to perform well | ||||
// in simulations (max 110 steps to go back up to 2**18 blocks). | // in simulations (max 110 steps to go back up to 2**18 blocks). | ||||
return (height & 1) ? InvertLowestOne(InvertLowestOne(height - 1)) + 1 | return (height & 1) ? InvertLowestOne(InvertLowestOne(height - 1)) + 1 | ||||
: InvertLowestOne(height); | : InvertLowestOne(height); | ||||
} | } | ||||
CBlockIndex *CBlockIndex::GetAncestor(int height) { | CBlockIndex *CBlockIndex::GetAncestor(int height) { | ||||
if (height > nHeight || height < 0) return nullptr; | if (height > nHeight || height < 0) { | ||||
return nullptr; | |||||
} | |||||
CBlockIndex *pindexWalk = this; | CBlockIndex *pindexWalk = this; | ||||
int heightWalk = nHeight; | int heightWalk = nHeight; | ||||
while (heightWalk > height) { | while (heightWalk > height) { | ||||
int heightSkip = GetSkipHeight(heightWalk); | int heightSkip = GetSkipHeight(heightWalk); | ||||
int heightSkipPrev = GetSkipHeight(heightWalk - 1); | int heightSkipPrev = GetSkipHeight(heightWalk - 1); | ||||
if (pindexWalk->pskip != nullptr && | if (pindexWalk->pskip != nullptr && | ||||
(heightSkip == height || (heightSkip > height && | (heightSkip == height || (heightSkip > height && | ||||
Show All 11 Lines | CBlockIndex *CBlockIndex::GetAncestor(int height) { | ||||
return pindexWalk; | return pindexWalk; | ||||
} | } | ||||
const CBlockIndex *CBlockIndex::GetAncestor(int height) const { | const CBlockIndex *CBlockIndex::GetAncestor(int height) const { | ||||
return const_cast<CBlockIndex *>(this)->GetAncestor(height); | return const_cast<CBlockIndex *>(this)->GetAncestor(height); | ||||
} | } | ||||
void CBlockIndex::BuildSkip() { | void CBlockIndex::BuildSkip() { | ||||
if (pprev) pskip = pprev->GetAncestor(GetSkipHeight(nHeight)); | if (pprev) { | ||||
pskip = pprev->GetAncestor(GetSkipHeight(nHeight)); | |||||
} | |||||
} | } | ||||
arith_uint256 GetBlockProof(const CBlockIndex &block) { | arith_uint256 GetBlockProof(const CBlockIndex &block) { | ||||
arith_uint256 bnTarget; | arith_uint256 bnTarget; | ||||
bool fNegative; | bool fNegative; | ||||
bool fOverflow; | bool fOverflow; | ||||
bnTarget.SetCompact(block.nBits, &fNegative, &fOverflow); | bnTarget.SetCompact(block.nBits, &fNegative, &fOverflow); | ||||
if (fNegative || fOverflow || bnTarget == 0) return 0; | if (fNegative || fOverflow || bnTarget == 0) { | ||||
return 0; | |||||
} | |||||
// We need to compute 2**256 / (bnTarget+1), but we can't represent 2**256 | // We need to compute 2**256 / (bnTarget+1), but we can't represent 2**256 | ||||
// as it's too large for a arith_uint256. However, as 2**256 is at least as | // as it's too large for a arith_uint256. However, as 2**256 is at least as | ||||
// large as bnTarget+1, it is equal to ((2**256 - bnTarget - 1) / | // large as bnTarget+1, it is equal to ((2**256 - bnTarget - 1) / | ||||
// (bnTarget+1)) + 1, or ~bnTarget / (nTarget+1) + 1. | // (bnTarget+1)) + 1, or ~bnTarget / (nTarget+1) + 1. | ||||
return (~bnTarget / (bnTarget + 1)) + 1; | return (~bnTarget / (bnTarget + 1)) + 1; | ||||
} | } | ||||
int64_t GetBlockProofEquivalentTime(const CBlockIndex &to, | int64_t GetBlockProofEquivalentTime(const CBlockIndex &to, | ||||
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