/// <summary>
/// The types of gossip actions that receive gossip has performed.
/// </summary>
public ReceiveGossipType ReceiveGossip(GossipEnvelope envelope)
{
var from = envelope.From;
var remoteGossip = envelope.Gossip;
var localGossip = _latestGossip;
if (remoteGossip.Equals(Gossip.Empty))
{
_log.Debug("Cluster Node [{0}] - Ignoring received gossip from [{1}] to protect against overload",
_cluster.SelfAddress, from);
return ReceiveGossipType.Ignored;
}
if (!envelope.To.Equals(SelfUniqueAddress))
{
_log.Info("Ignoring received gossip intended for someone else, from [{0}] to [{1}]",
from.Address, envelope.To);
return ReceiveGossipType.Ignored;
}
if (!localGossip.Overview.Reachability.IsReachable(SelfUniqueAddress, from))
{
_log.Info("Ignoring received gossip from unreachable [{0}]", from);
return ReceiveGossipType.Ignored;
}
if (localGossip.Members.All(m => !m.UniqueAddress.Equals(from)))
{
_log.Debug("Cluster Node [{0}] - Ignoring received gossip from unknown [{1}]", _cluster.SelfAddress, from);
return ReceiveGossipType.Ignored;
}
if (remoteGossip.Members.All(m => !m.UniqueAddress.Equals(SelfUniqueAddress)))
{
_log.Debug("Ignoring received gossip that does not contain myself, from [{0}]", from);
return ReceiveGossipType.Ignored;
}
var comparison = remoteGossip.Version.CompareTo(localGossip.Version);
Gossip winningGossip;
bool talkback;
ReceiveGossipType gossipType;
switch (comparison)
{
case VectorClock.Ordering.Same:
//same version
winningGossip = remoteGossip.MergeSeen(localGossip);
talkback = !remoteGossip.SeenByNode(SelfUniqueAddress);
gossipType = ReceiveGossipType.Same;
break;
case VectorClock.Ordering.Before:
//local is newer
winningGossip = localGossip;
talkback = true;
gossipType = ReceiveGossipType.Older;
break;
case VectorClock.Ordering.After:
//remote is newer
winningGossip = remoteGossip;
talkback = !remoteGossip.SeenByNode(SelfUniqueAddress);
gossipType = ReceiveGossipType.Newer;
break;
default:
//conflicting versions, merge
winningGossip = remoteGossip.Merge(localGossip);
talkback = true;
gossipType = ReceiveGossipType.Merge;
break;
}
_latestGossip = winningGossip.Seen(SelfUniqueAddress);
// for all new joining nodes we remove them from the failure detector
foreach (var node in _latestGossip.Members)
{
if (node.Status == MemberStatus.Joining && !localGossip.Members.Contains(node))
_cluster.FailureDetector.Remove(node.Address);
}
_log.Debug("Cluster Node [{0}] - Receiving gossip from [{1}]", _cluster.SelfAddress, from);
if (comparison == VectorClock.Ordering.Concurrent)
{
_log.Debug(@"""Couldn't establish a causal relationship between ""remote"" gossip and ""local"" gossip - Remote[{0}] - Local[{1}] - merged them into [{2}]""",
remoteGossip, localGossip, winningGossip);
}
if (_statsEnabled)
{
switch (gossipType)
{
case ReceiveGossipType.Merge:
_gossipStats = _gossipStats.IncrementMergeCount();
break;
case ReceiveGossipType.Same:
_gossipStats = _gossipStats.IncrementSameCount();
break;
case ReceiveGossipType.Newer:
_gossipStats = _gossipStats.IncrementNewerCount();
break;
case ReceiveGossipType.Older:
_gossipStats = _gossipStats.IncrementOlderCount();
break;
}
}
Publish(_latestGossip);
var selfStatus = _latestGossip.GetMember(SelfUniqueAddress).Status;
if (selfStatus == MemberStatus.Exiting || selfStatus == MemberStatus.Down)
Shutdown();
else if (talkback)
{
// send back gossip to sender() when sender() had different view, i.e. merge, or sender() had
// older or sender() had newer
GossipTo(from, Sender);
}
return gossipType;
}
