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Merge pull request #4470

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f4b00be Add CChain::GetLocator() unit test (Pieter Wuille)
3c85d2e Fix CChain::GetLocator (Pieter Wuille)
This commit is contained in:
Wladimir J. van der Laan 2014-07-07 10:24:20 +02:00
commit 5e1b7a23b0
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2 changed files with 62 additions and 8 deletions
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14
src/main.cpp
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@ -423,15 +423,13 @@ 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 (!Contains(pindex))
pindex = pindex->pprev;
// If pindex is in this chain, use direct height-based access.
if (pindex->nHeight > nHeight)
if (Contains(pindex)) {
// Use O(1) CChain index if possible.
pindex = (*this)[nHeight];
} else {
// Otherwise, use O(log n) skiplist.
pindex = pindex->GetAncestor(nHeight);
}
if (vHave.size() > 10)
nStep *= 2;
}

56
src/test/skiplist_tests.cpp
View file

@ -41,5 +41,61 @@ BOOST_AUTO_TEST_CASE(skiplist_test)
}
}
BOOST_AUTO_TEST_CASE(getlocator_test)
{
// Build a main chain 100000 blocks long.
std::vector<uint256> vHashMain(100000);
std::vector<CBlockIndex> vBlocksMain(100000);
for (unsigned int i=0; i<vBlocksMain.size(); i++) {
vHashMain[i] = i; // Set the hash equal to the height, so we can quickly check the distances.
vBlocksMain[i].nHeight = i;
vBlocksMain[i].pprev = i ? &vBlocksMain[i - 1] : NULL;
vBlocksMain[i].phashBlock = &vHashMain[i];
vBlocksMain[i].BuildSkip();
BOOST_CHECK_EQUAL((int)vBlocksMain[i].GetBlockHash().GetLow64(), vBlocksMain[i].nHeight);
BOOST_CHECK(vBlocksMain[i].pprev == NULL || vBlocksMain[i].nHeight == vBlocksMain[i].pprev->nHeight + 1);
}
// Build a branch that splits off at block 49999, 50000 blocks long.
std::vector<uint256> vHashSide(50000);
std::vector<CBlockIndex> vBlocksSide(50000);
for (unsigned int i=0; i<vBlocksSide.size(); i++) {
vHashSide[i] = i + 50000 + (uint256(1) << 128); // Add 1<<128 to the hashes, so GetLow64() still returns the height.
vBlocksSide[i].nHeight = i + 50000;
vBlocksSide[i].pprev = i ? &vBlocksSide[i - 1] : &vBlocksMain[49999];
vBlocksSide[i].phashBlock = &vHashSide[i];
vBlocksSide[i].BuildSkip();
BOOST_CHECK_EQUAL((int)vBlocksSide[i].GetBlockHash().GetLow64(), vBlocksSide[i].nHeight);
BOOST_CHECK(vBlocksSide[i].pprev == NULL || vBlocksSide[i].nHeight == vBlocksSide[i].pprev->nHeight + 1);
}
// Build a CChain for the main branch.
CChain chain;
chain.SetTip(&vBlocksMain.back());
// Test 100 random starting points for locators.
for (int n=0; n<100; n++) {
int r = insecure_rand() % 150000;
CBlockIndex* tip = (r < 100000) ? &vBlocksMain[r] : &vBlocksSide[r - 100000];
CBlockLocator locator = chain.GetLocator(tip);
// The first result must be the block itself, the last one must be genesis.
BOOST_CHECK(locator.vHave.front() == tip->GetBlockHash());
BOOST_CHECK(locator.vHave.back() == vBlocksMain[0].GetBlockHash());
// Entries 1 through 11 (inclusive) go back one step each.
for (unsigned int i = 1; i < 12 && i < locator.vHave.size() - 1; i++) {
BOOST_CHECK_EQUAL(locator.vHave[i].GetLow64(), tip->nHeight - i);
}
// The further ones (excluding the last one) go back with exponential steps.
unsigned int dist = 2;
for (unsigned int i = 12; i < locator.vHave.size() - 1; i++) {
BOOST_CHECK_EQUAL(locator.vHave[i - 1].GetLow64() - locator.vHave[i].GetLow64(), dist);
dist *= 2;
}
}
}
BOOST_AUTO_TEST_SUITE_END()