From aa815647005bc8467f467c35a9e617794446cd64 Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Mon, 23 Jun 2014 00:00:26 +0200 Subject: [PATCH 1/3] Track peers' available blocks --- src/main.cpp | 46 ++++++++++++++++++++++++++++++++++++++++++++++ src/main.h | 1 + src/rpcnet.cpp | 1 + 3 files changed, 48 insertions(+) diff --git a/src/main.cpp b/src/main.cpp index 336a5a9a8..dc6843128 100644 --- a/src/main.cpp +++ b/src/main.cpp @@ -207,6 +207,10 @@ struct CNodeState { std::string name; // List of asynchronously-determined block rejections to notify this peer about. std::vector rejects; + // The best known block we know this peer has announced. + CBlockIndex *pindexBestKnownBlock; + // The hash of the last unknown block this peer has announced. + uint256 hashLastUnknownBlock; list vBlocksInFlight; int nBlocksInFlight; list vBlocksToDownload; @@ -217,6 +221,8 @@ struct CNodeState { CNodeState() { nMisbehavior = 0; fShouldBan = false; + pindexBestKnownBlock = NULL; + hashLastUnknownBlock = uint256(0); nBlocksToDownload = 0; nBlocksInFlight = 0; nLastBlockReceive = 0; @@ -313,6 +319,39 @@ void MarkBlockAsInFlight(NodeId nodeid, const uint256 &hash) { mapBlocksInFlight[hash] = std::make_pair(nodeid, it); } +/** Check whether the last unknown block a peer advertized is not yet known. */ +void ProcessBlockAvailability(NodeId nodeid) { + CNodeState *state = State(nodeid); + assert(state != NULL); + + if (state->hashLastUnknownBlock != 0) { + map::iterator itOld = mapBlockIndex.find(state->hashLastUnknownBlock); + if (itOld != mapBlockIndex.end() && itOld->second->nChainWork > 0) { + if (state->pindexBestKnownBlock == NULL || itOld->second->nChainWork >= state->pindexBestKnownBlock->nChainWork) + state->pindexBestKnownBlock = itOld->second; + state->hashLastUnknownBlock = uint256(0); + } + } +} + +/** Update tracking information about which blocks a peer is assumed to have. */ +void UpdateBlockAvailability(NodeId nodeid, const uint256 &hash) { + CNodeState *state = State(nodeid); + assert(state != NULL); + + ProcessBlockAvailability(nodeid); + + map::iterator it = mapBlockIndex.find(hash); + if (it != mapBlockIndex.end() && it->second->nChainWork > 0) { + // An actually better block was announced. + if (state->pindexBestKnownBlock == NULL || it->second->nChainWork >= state->pindexBestKnownBlock->nChainWork) + state->pindexBestKnownBlock = it->second; + } else { + // An unknown block was announced; just assume that the latest one is the best one. + state->hashLastUnknownBlock = hash; + } +} + } // anon namespace bool GetNodeStateStats(NodeId nodeid, CNodeStateStats &stats) { @@ -321,6 +360,7 @@ bool GetNodeStateStats(NodeId nodeid, CNodeStateStats &stats) { if (state == NULL) return false; stats.nMisbehavior = state->nMisbehavior; + stats.nSyncHeight = state->pindexBestKnownBlock ? state->pindexBestKnownBlock->nHeight : -1; return true; } @@ -3613,6 +3653,9 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv) PushGetBlocks(pfrom, chainActive.Tip(), GetOrphanRoot(inv.hash)); } + if (inv.type == MSG_BLOCK) + UpdateBlockAvailability(pfrom->GetId(), inv.hash); + // Track requests for our stuff g_signals.Inventory(inv.hash); } @@ -4359,6 +4402,9 @@ bool SendMessages(CNode* pto, bool fSendTrickle) pto->fDisconnect = true; } + // Update knowledge of peer's block availability. + ProcessBlockAvailability(pto->GetId()); + // // Message: getdata (blocks) // diff --git a/src/main.h b/src/main.h index 0332db216..9487078b7 100644 --- a/src/main.h +++ b/src/main.h @@ -185,6 +185,7 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa struct CNodeStateStats { int nMisbehavior; + int nSyncHeight; }; struct CDiskBlockPos diff --git a/src/rpcnet.cpp b/src/rpcnet.cpp index a54872ccc..2d7abb2d5 100644 --- a/src/rpcnet.cpp +++ b/src/rpcnet.cpp @@ -134,6 +134,7 @@ Value getpeerinfo(const Array& params, bool fHelp) obj.push_back(Pair("startingheight", stats.nStartingHeight)); if (fStateStats) { obj.push_back(Pair("banscore", statestats.nMisbehavior)); + obj.push_back(Pair("syncheight", statestats.nSyncHeight)); } obj.push_back(Pair("syncnode", stats.fSyncNode)); From c9a0918330f31dcb1d5e86b56af63c3f521d3cf2 Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Wed, 25 Jun 2014 00:56:47 +0200 Subject: [PATCH 2/3] Add a skiplist to the CBlockIndex structure. This allows fast (O(log n)) access to far predecessor blocks. Use it to speed up CChain::FindFork and CChain::GetLocator. --- src/main.cpp | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++- src/main.h | 12 ++++++++++- 2 files changed, 69 insertions(+), 2 deletions(-) diff --git a/src/main.cpp b/src/main.cpp index dc6843128..41125cb57 100644 --- a/src/main.cpp +++ b/src/main.cpp @@ -414,8 +414,11 @@ CBlockLocator CChain::GetLocator(const CBlockIndex *pindex) const { break; // Exponentially larger steps back, plus the genesis block. int nHeight = std::max(pindex->nHeight - nStep, 0); + // Jump back quickly to the same height as the chain. + if (pindex->nHeight > nHeight) + pindex = pindex->GetAncestor(nHeight); // In case pindex is not in this chain, iterate pindex->pprev to find blocks. - while (pindex->nHeight > nHeight && !Contains(pindex)) + while (!Contains(pindex)) pindex = pindex->pprev; // If pindex is in this chain, use direct height-based access. if (pindex->nHeight > nHeight) @@ -442,6 +445,8 @@ CBlockIndex *CChain::FindFork(const CBlockLocator &locator) const { } CBlockIndex *CChain::FindFork(CBlockIndex *pindex) const { + if (pindex->nHeight > Height()) + pindex = pindex->GetAncestor(Height()); while (pindex && !Contains(pindex)) pindex = pindex->pprev; return pindex; @@ -2151,6 +2156,7 @@ CBlockIndex* AddToBlockIndex(CBlockHeader& block) { pindexNew->pprev = (*miPrev).second; pindexNew->nHeight = pindexNew->pprev->nHeight + 1; + pindexNew->BuildSkip(); } pindexNew->nChainWork = (pindexNew->pprev ? pindexNew->pprev->nChainWork : 0) + pindexNew->GetBlockWork(); pindexNew->RaiseValidity(BLOCK_VALID_TREE); @@ -2508,6 +2514,55 @@ bool CBlockIndex::IsSuperMajority(int minVersion, const CBlockIndex* pstart, uns return (nFound >= nRequired); } +/** Turn the lowest '1' bit in the binary representation of a number into a '0'. */ +int static inline InvertLowestOne(int n) { return n & (n - 1); } + +/** Compute what height to jump back to with the CBlockIndex::pskip pointer. */ +int static inline GetSkipHeight(int height) { + if (height < 2) + return 0; + + // Determine which height to jump back to. Any number strictly lower than height is acceptable, + // but the following expression seems to perform well in simulations (max 110 steps to go back + // up to 2**18 blocks). + return (height & 1) ? InvertLowestOne(InvertLowestOne(height - 1)) + 1 : InvertLowestOne(height); +} + +CBlockIndex* CBlockIndex::GetAncestor(int height) +{ + if (height > nHeight || height < 0) + return NULL; + + CBlockIndex* pindexWalk = this; + int heightWalk = nHeight; + while (heightWalk > height) { + int heightSkip = GetSkipHeight(heightWalk); + int heightSkipPrev = GetSkipHeight(heightWalk - 1); + if (heightSkip == height || + (heightSkip > height && !(heightSkipPrev < heightSkip - 2 && + heightSkipPrev >= height))) { + // Only follow pskip if pprev->pskip isn't better than pskip->pprev. + pindexWalk = pindexWalk->pskip; + heightWalk = heightSkip; + } else { + pindexWalk = pindexWalk->pprev; + heightWalk--; + } + } + return pindexWalk; +} + +const CBlockIndex* CBlockIndex::GetAncestor(int height) const +{ + return const_cast(this)->GetAncestor(height); +} + +void CBlockIndex::BuildSkip() +{ + if (pprev) + pskip = pprev->GetAncestor(GetSkipHeight(nHeight)); +} + void PushGetBlocks(CNode* pnode, CBlockIndex* pindexBegin, uint256 hashEnd) { AssertLockHeld(cs_main); @@ -2858,6 +2913,8 @@ bool static LoadBlockIndexDB() setBlockIndexValid.insert(pindex); if (pindex->nStatus & BLOCK_FAILED_MASK && (!pindexBestInvalid || pindex->nChainWork > pindexBestInvalid->nChainWork)) pindexBestInvalid = pindex; + if (pindex->pprev) + pindex->BuildSkip(); } // Load block file info diff --git a/src/main.h b/src/main.h index 9487078b7..1af86b065 100644 --- a/src/main.h +++ b/src/main.h @@ -677,6 +677,9 @@ public: // pointer to the index of the predecessor of this block CBlockIndex* pprev; + // pointer to the index of some further predecessor of this block + CBlockIndex* pskip; + // height of the entry in the chain. The genesis block has height 0 int nHeight; @@ -716,6 +719,7 @@ public: { phashBlock = NULL; pprev = NULL; + pskip = NULL; nHeight = 0; nFile = 0; nDataPos = 0; @@ -737,6 +741,7 @@ public: { phashBlock = NULL; pprev = NULL; + pskip = NULL; nHeight = 0; nFile = 0; nDataPos = 0; @@ -869,9 +874,14 @@ public: } return false; } -}; + // Build the skiplist pointer for this entry. + void BuildSkip(); + // Efficiently find an ancestor of this block. + CBlockIndex* GetAncestor(int height); + const CBlockIndex* GetAncestor(int height) const; +}; /** Used to marshal pointers into hashes for db storage. */ class CDiskBlockIndex : public CBlockIndex From 236982c2b6de619f0744c9c17ea7208b64a4afb3 Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Sun, 29 Jun 2014 15:26:58 +0200 Subject: [PATCH 3/3] Add skiplist unit tests --- src/Makefile.test.include | 1 + src/test/skiplist_tests.cpp | 45 +++++++++++++++++++++++++++++++++++++ 2 files changed, 46 insertions(+) create mode 100644 src/test/skiplist_tests.cpp diff --git a/src/Makefile.test.include b/src/Makefile.test.include index 4dab1773f..8685452c7 100644 --- a/src/Makefile.test.include +++ b/src/Makefile.test.include @@ -47,6 +47,7 @@ BITCOIN_TESTS =\ test/script_tests.cpp \ test/serialize_tests.cpp \ test/sigopcount_tests.cpp \ + test/skiplist_tests.cpp \ test/test_bitcoin.cpp \ test/transaction_tests.cpp \ test/uint256_tests.cpp \ diff --git a/src/test/skiplist_tests.cpp b/src/test/skiplist_tests.cpp new file mode 100644 index 000000000..ea301685c --- /dev/null +++ b/src/test/skiplist_tests.cpp @@ -0,0 +1,45 @@ +// Copyright (c) 2014 The Bitcoin Core developers +// Distributed under the MIT/X11 software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +#include +#include +#include "main.h" +#include "util.h" + + +#define SKIPLIST_LENGTH 300000 + +BOOST_AUTO_TEST_SUITE(skiplist_tests) + +BOOST_AUTO_TEST_CASE(skiplist_test) +{ + std::vector vIndex(SKIPLIST_LENGTH); + + for (int i=0; i 0) { + BOOST_CHECK(vIndex[i].pskip == &vIndex[vIndex[i].pskip->nHeight]); + BOOST_CHECK(vIndex[i].pskip->nHeight < i); + } else { + BOOST_CHECK(vIndex[i].pskip == NULL); + } + } + + for (int i=0; i < 1000; i++) { + int from = insecure_rand() % (SKIPLIST_LENGTH - 1); + int to = insecure_rand() % (from + 1); + + BOOST_CHECK(vIndex[SKIPLIST_LENGTH - 1].GetAncestor(from) == &vIndex[from]); + BOOST_CHECK(vIndex[from].GetAncestor(to) == &vIndex[to]); + BOOST_CHECK(vIndex[from].GetAncestor(0) == &vIndex[0]); + } +} + +BOOST_AUTO_TEST_SUITE_END() +