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Use EraseLastKElements() throughout SelectNodeToEvict()

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Co-authored-by: Vasil Dimov <vd@FreeBSD.org>
This commit is contained in:
Jon Atack
2020-10-20 08:28:56 +02:00
parent 8b1e156143
commit 8f1a53eb02
1 changed files with 15 additions and 12 deletions
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27
src/net.cpp
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@@ -870,13 +870,15 @@ static bool CompareNodeBlockRelayOnlyTime(const NodeEvictionCandidate &a, const
return a.nTimeConnected > b.nTimeConnected;
}
//! Sort an array by the specified comparator, then erase the last K elements.
template<typename T, typename Comparator>
static void EraseLastKElements(std::vector<T> &elements, Comparator comparator, size_t k)
//! Sort an array by the specified comparator, then erase the last K elements where predicate is true.
template <typename T, typename Comparator>
static void EraseLastKElements(
std::vector<T>& elements, Comparator comparator, size_t k,
std::function<bool(const NodeEvictionCandidate&)> predicate = [](const NodeEvictionCandidate& n) { return true; })
{
std::sort(elements.begin(), elements.end(), comparator);
size_t eraseSize = std::min(k, elements.size());
elements.erase(elements.end() - eraseSize, elements.end());
elements.erase(std::remove_if(elements.end() - eraseSize, elements.end(), predicate), elements.end());
}
void ProtectEvictionCandidatesByRatio(std::vector<NodeEvictionCandidate>& vEvictionCandidates)
@@ -886,13 +888,14 @@ void ProtectEvictionCandidatesByRatio(std::vector<NodeEvictionCandidate>& vEvict
// Reserve half of these protected spots for localhost peers, even if
// they're not longest-uptime overall. This helps protect tor peers, which
// tend to be otherwise disadvantaged under our eviction criteria.
size_t initial_size = vEvictionCandidates.size();
const size_t initial_size = vEvictionCandidates.size();
size_t total_protect_size = initial_size / 2;
// Pick out up to 1/4 peers that are localhost, sorted by longest uptime.
std::sort(vEvictionCandidates.begin(), vEvictionCandidates.end(), CompareLocalHostTimeConnected);
size_t local_erase_size = total_protect_size / 2;
vEvictionCandidates.erase(std::remove_if(vEvictionCandidates.end() - local_erase_size, vEvictionCandidates.end(), [](NodeEvictionCandidate const &n) { return n.m_is_local; }), vEvictionCandidates.end());
const size_t local_erase_size = total_protect_size / 2;
EraseLastKElements(vEvictionCandidates, CompareLocalHostTimeConnected, local_erase_size,
[](const NodeEvictionCandidate& n) { return n.m_is_local; });
// Calculate how many we removed, and update our total number of peers that
// we want to protect based on uptime accordingly.
total_protect_size -= initial_size - vEvictionCandidates.size();
@@ -913,9 +916,9 @@ void ProtectEvictionCandidatesByRatio(std::vector<NodeEvictionCandidate>& vEvict
// An attacker cannot manipulate this metric without performing useful work.
EraseLastKElements(vEvictionCandidates, CompareNodeTXTime, 4);
// Protect up to 8 non-tx-relay peers that have sent us novel blocks.
std::sort(vEvictionCandidates.begin(), vEvictionCandidates.end(), CompareNodeBlockRelayOnlyTime);
size_t erase_size = std::min(size_t(8), vEvictionCandidates.size());
vEvictionCandidates.erase(std::remove_if(vEvictionCandidates.end() - erase_size, vEvictionCandidates.end(), [](NodeEvictionCandidate const &n) { return !n.fRelayTxes && n.fRelevantServices; }), vEvictionCandidates.end());
const size_t erase_size = std::min(size_t(8), vEvictionCandidates.size());
EraseLastKElements(vEvictionCandidates, CompareNodeBlockRelayOnlyTime, erase_size,
[](const NodeEvictionCandidate& n) { return !n.fRelayTxes && n.fRelevantServices; });
// Protect 4 nodes that most recently sent us novel blocks.
// An attacker cannot manipulate this metric without performing useful work.
@@ -944,7 +947,7 @@ void ProtectEvictionCandidatesByRatio(std::vector<NodeEvictionCandidate>& vEvict
for (const NodeEvictionCandidate &node : vEvictionCandidates) {
std::vector<NodeEvictionCandidate> &group = mapNetGroupNodes[node.nKeyedNetGroup];
group.push_back(node);
int64_t grouptime = group[0].nTimeConnected;
const int64_t grouptime = group[0].nTimeConnected;
if (group.size() > nMostConnections || (group.size() == nMostConnections && grouptime > nMostConnectionsTime)) {
nMostConnections = group.size();