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authorGavin Andresen <gavinandresen@gmail.com>2014-06-30 08:21:46 -0400
committerGavin Andresen <gavinandresen@gmail.com>2014-06-30 08:21:46 -0400
commit6fba25ef26649359d8e5962555c0d753b6df51b4 (patch)
tree8b10189b015d4699ad617a56292b06621b648059 /src
parentac26571d2b118b5df9e7fd2585ecac1eeb7ed94d (diff)
parent236982c2b6de619f0744c9c17ea7208b64a4afb3 (diff)
Merge pull request #4420 from sipa/skiplist
Add a skiplist to the CBlockIndex structure.
Diffstat (limited to 'src')
-rw-r--r--src/Makefile.test.include1
-rw-r--r--src/main.cpp105
-rw-r--r--src/main.h13
-rw-r--r--src/rpcnet.cpp1
-rw-r--r--src/test/skiplist_tests.cpp45
5 files changed, 163 insertions, 2 deletions
diff --git a/src/Makefile.test.include b/src/Makefile.test.include
index 4dab1773f4..8685452c7b 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/main.cpp b/src/main.cpp
index 336a5a9a86..41125cb577 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<CBlockReject> 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<QueuedBlock> vBlocksInFlight;
int nBlocksInFlight;
list<uint256> 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<uint256, CBlockIndex*>::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<uint256, CBlockIndex*>::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;
}
@@ -374,8 +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)
@@ -402,6 +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;
@@ -2111,6 +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);
@@ -2468,6 +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<CBlockIndex*>(this)->GetAncestor(height);
+}
+
+void CBlockIndex::BuildSkip()
+{
+ if (pprev)
+ pskip = pprev->GetAncestor(GetSkipHeight(nHeight));
+}
+
void PushGetBlocks(CNode* pnode, CBlockIndex* pindexBegin, uint256 hashEnd)
{
AssertLockHeld(cs_main);
@@ -2818,6 +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
@@ -3613,6 +3710,9 @@ 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 +4459,9 @@ 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 0332db2163..1af86b065f 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
@@ -676,6 +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;
@@ -715,6 +719,7 @@ public:
{
phashBlock = NULL;
pprev = NULL;
+ pskip = NULL;
nHeight = 0;
nFile = 0;
nDataPos = 0;
@@ -736,6 +741,7 @@ public:
{
phashBlock = NULL;
pprev = NULL;
+ pskip = NULL;
nHeight = 0;
nFile = 0;
nDataPos = 0;
@@ -868,9 +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
diff --git a/src/rpcnet.cpp b/src/rpcnet.cpp
index a54872ccc4..2d7abb2d58 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));
diff --git a/src/test/skiplist_tests.cpp b/src/test/skiplist_tests.cpp
new file mode 100644
index 0000000000..ea301685c9
--- /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 <boost/test/unit_test.hpp>
+#include <vector>
+#include "main.h"
+#include "util.h"
+
+
+#define SKIPLIST_LENGTH 300000
+
+BOOST_AUTO_TEST_SUITE(skiplist_tests)
+
+BOOST_AUTO_TEST_CASE(skiplist_test)
+{
+ std::vector<CBlockIndex> vIndex(SKIPLIST_LENGTH);
+
+ for (int i=0; i<SKIPLIST_LENGTH; i++) {
+ vIndex[i].nHeight = i;
+ vIndex[i].pprev = (i == 0) ? NULL : &vIndex[i - 1];
+ vIndex[i].BuildSkip();
+ }
+
+ for (int i=0; i<SKIPLIST_LENGTH; i++) {
+ if (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()
+