From 1e05727072a58d3538dc654c5a3de83ed58874b8 Mon Sep 17 00:00:00 2001 From: Gregory Maxwell Date: Mon, 23 Nov 2015 03:48:54 +0000 Subject: [PATCH] Decide eviction group ties based on time. This corrects a bug the case of tying group size where the code may fail to select the group with the newest member. Since newest time is the final selection criteria, failing to break ties on it on the step before can undermine the final selection. Tied netgroups are very common. (cherry picked from commit 8e09f914f8ec66301257358b250e9a61befadd95) --- src/net.cpp | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/src/net.cpp b/src/net.cpp index 84c5644cc..14e22f6cb 100644 --- a/src/net.cpp +++ b/src/net.cpp @@ -929,15 +929,20 @@ static bool AttemptToEvictConnection(bool fPreferNewConnection) { if (vEvictionCandidates.empty()) return false; - // Identify the network group with the most connections + // Identify the network group with the most connections and youngest member. + // (vEvictionCandidates is already sorted by reverse connect time) std::vector naMostConnections; unsigned int nMostConnections = 0; + int64_t nMostConnectionsTime = 0; std::map, std::vector > mapAddrCounts; BOOST_FOREACH(const CNodeRef &node, vEvictionCandidates) { mapAddrCounts[node->addr.GetGroup()].push_back(node); + int64_t grouptime = mapAddrCounts[node->addr.GetGroup()][0]->nTimeConnected; + size_t groupsize = mapAddrCounts[node->addr.GetGroup()].size(); - if (mapAddrCounts[node->addr.GetGroup()].size() > nMostConnections) { - nMostConnections = mapAddrCounts[node->addr.GetGroup()].size(); + if (groupsize > nMostConnections || (groupsize == nMostConnections && grouptime > nMostConnectionsTime)) { + nMostConnections = groupsize; + nMostConnectionsTime = grouptime; naMostConnections = node->addr.GetGroup(); } } @@ -945,14 +950,13 @@ static bool AttemptToEvictConnection(bool fPreferNewConnection) { // Reduce to the network group with the most connections vEvictionCandidates = mapAddrCounts[naMostConnections]; - // Do not disconnect peers if there is only 1 connection from their network group + // Do not disconnect peers if there is only one unprotected connection from their network group. if (vEvictionCandidates.size() <= 1) // unless we prefer the new connection (for whitelisted peers) if (!fPreferNewConnection) return false; - // Disconnect the most recent connection from the network group with the most connections - std::sort(vEvictionCandidates.begin(), vEvictionCandidates.end(), ReverseCompareNodeTimeConnected); + // Disconnect from the network group with the most connections vEvictionCandidates[0]->fDisconnect = true; return true;