public ElectionBasedMembershipStrategy(IShard shard, NodeContext context, LocalShardHeartbeatReporting heartbeatTable, ClusterConfigurationManager clusterConfigMgr)
{
this._shard = shard;
this._context = context;
this._clusterConfigMgr = clusterConfigMgr;
Initialize();
}
/// <summary>
/// Authoritative phase:
/// 1. the requesting node acquires an election lock up at the config server.
/// 2. It then proceeds with the election conduction where it asks for votes.
/// 3. Each node checks their world view once more before voting with a yes or no.
/// 4. Its mandatory for a consensus amongst all the nodes for an election term to be successful.
/// 5. One negative vote nullifies the current election term. If such is the case, the entire procedure
/// needs to be repeated.
/// </summary>
/// <param name="reportTable"></param>
/// <returns></returns>
private ElectionResult HoldElection(LocalShardHeartbeatReporting reportTable, Activity activity)
{
ElectionId electionId = null;
ServerNode requestingNode = new ServerNode();
requestingNode.Name = _context.LocalAddress.IpAddress.ToString();
requestingNode.Priority = (int)_manager.LocalServerPriority;
ElectionType type = ElectionType.None;
if (activity == Activity.GeneralElectionsTriggered)
{
type = ElectionType.GeneralElections;
}
else if (activity == Activity.TakeoverElectionsTriggered)
{
type = ElectionType.TakeoverElections;
}
Object response = _context.ConfigurationSession.BeginElection(_context.ClusterName.ToLower(), _context.LocalShardName.ToLower(), requestingNode, type);
if (response != null)
{
electionId = response as ElectionId;
if (electionId != null)
{
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsInfoEnabled)
{
LoggerManager.Instance.ShardLogger.Info("ElectionBasedMembershipStrategy", type + " started for node " + _context.LocalAddress);
}
Address[] activeNodes = reportTable.GetReportTable.Keys.ToArray();
return(_manager.ConductElection(electionId, activeNodes, activity));
}
else
{
//if we get a database exception from the CS, we wait for a configurable amount of time
//before trying to elect a new primary again.
if (response is DatabaseException && ((DatabaseException)response).ErrorCode == ErrorCodes.Cluster.PRIMARY_ALREADY_EXISTS)
{
lock (_mutexOnWait)
{
Monitor.Wait(_mutexOnWait, _waitTimeout);
}
}
}
}
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled)
{
LoggerManager.Instance.ShardLogger.Debug("ElectionBasedMembershipStrategy.HoldElection() ", "Node " + _context.LocalAddress.ToString() + " failed to acquire an election lock on the CS.");
}
return(null);
}
public object OnMessageReceived(object message, Server source, LocalShardHeartbeatReporting heartbeatReport, Membership existingMembership)
{
Election election = message as Election;
if (election != null)
{
HeartbeatInfo localHeartbeat = heartbeatReport.GetHeartbeatInfo(_context.LocalAddress);
if (localHeartbeat != null)
{
return(_manager.CastVote(election, existingMembership, localHeartbeat));
}
}
return(null);
}
public void TriggerElectionMechanism(Activity activity, Server server, LocalShardHeartbeatReporting heartbeatReport, Membership existingMembership)
{
LoggerManager.Instance.SetThreadContext(new LoggerContext()
{
ShardName = _context.LocalShardName != null ? _context.LocalShardName : "", DatabaseName = ""
});
if (existingMembership == null)
{
existingMembership = new Membership();
}
ShardConfiguration sConfig = null;
//Get the shard configuration
if (_clusterConfigMgr != null)
{
sConfig = _clusterConfigMgr.GetShardConfiguration(_context.LocalShardName);
}
IList <Address> activeNodes = null;
MembershipChangeArgs args = new MembershipChangeArgs();
ServerNodes staticServerNodes = null;
if (sConfig == null || sConfig.Servers == null)
{
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsWarnEnabled)
{
LoggerManager.Instance.ShardLogger.Warn("ElectionBasedMembershipStrategy.TiggerElectionMechanism() ", "The shard " + _context.LocalShardName + " does not exist in the configuration.");
}
return;
}
staticServerNodes = sConfig.Servers;
ElectionResult result = null;
if (heartbeatReport != null)
{
activeNodes = heartbeatReport.GetReportTable.Keys.ToList();
}
Address activityNode = null;
if (server == null)
{
activityNode = _context.LocalAddress;
}
else
{
activityNode = server.Address;
}
switch (activity)
{
case Activity.NodeJoining:
if (server == null)
{
return;
}
//On node join, we need to get membership from the config server for the first time.
Membership csMembership = _context.ConfigurationSession.GetMembershipInfo(_context.ClusterName, _context.LocalShardName);
ServerNode joiningNode = sConfig.Servers.GetServerNode(server.Address.IpAddress.ToString());
// If the added node is configured while the cluster is up and running, do the following.
if (joiningNode == null)
{
if (_clusterConfigMgr != null)
{
_clusterConfigMgr.UpdateClusterConfiguration();
sConfig = _clusterConfigMgr.GetShardConfiguration(_context.LocalShardName);
}
if (sConfig == null)
{
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsWarnEnabled)
{
LoggerManager.Instance.ShardLogger.Warn("ElectionBasedMembershipStrategy.TriggerElectionMechanism() ", "The shard " + _context.LocalShardName + " does not exist in the configuration.");
}
return;
}
joiningNode = sConfig.Servers.GetServerNode(server.Address.IpAddress.ToString());
}
if (joiningNode == null)
{
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsWarnEnabled)
{
LoggerManager.Instance.ShardLogger.Warn("ElectionBasedMembershipStrategy.TriggerElectionMechanism() ", "The node " + server.Address + " is not part of the configuration.");
}
return;
}
if (existingMembership == null || existingMembership.Servers == null || !existingMembership.Servers.Contains(joiningNode))
{
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled)
{
LoggerManager.Instance.ShardLogger.Debug("ElectBasedMemSt.TriggerElectMech", "Node joining activity triggered for " + activityNode);
}
}
bool thisNodeIsPrimary = false;
OperationId lastOpId = null;
if (heartbeatReport != null && heartbeatReport.GetReportTable.ContainsKey(server.Address))
{
args.ServerName = _context.LocalAddress;
args.ElectionId = null;
args.ChangeType = MembershipChangeArgs.MembershipChangeType.NodeJoined;
if (server.Address.Equals(_context.LocalAddress))
{
_context.ConfigurationSession.ReportNodeJoining(_context.ClusterName, _context.LocalShardName, sConfig.Servers.GetServerNode(_context.LocalAddress.IpAddress.ToString()));
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsInfoEnabled)
{
LoggerManager.Instance.ShardLogger.Info("electBasedMemSt.TriggerElectMech", server.Address + " reported its joining to the config server. ");
}
//if the primary is not null and the channel is not disconnected, it can be set here.
if ((existingMembership == null || existingMembership.Primary == null) && csMembership.Primary != null && _shard.ActiveChannelsList.Contains(new Server(new Address(csMembership.Primary.Name, sConfig.Port), Status.Initializing)) && ObeysMajorityRule(_shard.ActiveChannelsList.Count, sConfig.Servers.Nodes.Count))
{
args.ServerName = new Address(csMembership.Primary.Name, sConfig.Port);
args.ElectionId = csMembership.ElectionId;
args.ChangeType = MembershipChangeArgs.MembershipChangeType.PrimarySet;
//if the node which was lost comes back up before the CS or the nodes can declare it dead,
//it should resume its status as a primary. There should be no need for an election in this case.
if (args.ServerName.Equals(_context.LocalAddress))
{
thisNodeIsPrimary = true;
}
}
}
if (thisNodeIsPrimary)
{
if (csMembership.ElectionId != null && LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsInfoEnabled)
{
LoggerManager.Instance.ShardLogger.Info("electBasedMemSt.TriggerElectMech", "election_id: " + csMembership.ElectionId.Id + " election time :" + csMembership.ElectionId.ElectionTime);
}
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsInfoEnabled)
{
LoggerManager.Instance.ShardLogger.Info("electBasedMemSt.TriggerElectMech", "I am already declared primary");
}
lastOpId = LastOperationId;
ChangeMembershipShardwide(args);
}
else
{
((LocalShard)_shard).OnMembershipChanged(args);
}
if (server.Address.Equals(_context.LocalAddress))
{
ServerNode sNode = sConfig.Servers.GetServerNode(_context.LocalAddress.IpAddress.ToString());
if (sNode == null)
{
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsWarnEnabled)
{
LoggerManager.Instance.ShardLogger.Warn("ElectionBasedMembershipStrategy.TriggerElectionMechanism() ", "The node " + sNode.Name + " does not exist in the configuration.");
}
return;
}
_context.ConfigurationSession.ReportHeartbeat(_context.ClusterName, _context.LocalShardName, sNode, existingMembership, lastOpId);
}
}
else
{
if (existingMembership.Primary != null && existingMembership.Primary.Name.Equals(server.Address.IpAddress.ToString()))
{
if (sConfig.Servers == null || sConfig.Servers.Nodes == null || !ObeysMajorityRule(activeNodes.Count, sConfig.Servers.Nodes.Count))
{
_context.ConfigurationSession.SetNodeStatus(_context.ClusterName, _context.LocalShardName, existingMembership.Primary, NodeRole.None);
args.ChangeType = MembershipChangeArgs.MembershipChangeType.PrimaryDemoted;
args.ServerName = _context.LocalAddress;
ChangeMembershipShardwide(args);
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsInfoEnabled)
{
LoggerManager.Instance.ShardLogger.Info("electBasedMemSt.TriggerElectMech", " Node addition activity occured. Primary node " + _context.LocalAddress.IpAddress.ToString() + " demoted.");
}
return;
}
}
}
break;
case Activity.NodeLeaving:
if (server == null)
{
return;
}
bool hasMajority = ObeysMajorityRule(activeNodes.Count, staticServerNodes.Nodes.Count);
args.ServerName = server.Address;
args.ChangeType = MembershipChangeArgs.MembershipChangeType.NodeLeft;
_clusterConfigMgr.UpdateClusterConfiguration();
if (existingMembership.Primary != null)
{
// if the existing primary is actually the node lost, we need to update the configuration.
if (existingMembership.Primary.Name == server.Address.IpAddress.ToString())
{
//if Primary leaves, it should be updated locally.
args.ChangeType = MembershipChangeArgs.MembershipChangeType.PrimaryLost;
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled)
{
LoggerManager.Instance.ShardLogger.Debug("electBasedMemSt.TriggerElectMech", "Node leaving activity triggered for " + server.Address + " . Primary lost.");
}
}
else if (existingMembership.Primary.Name == _context.LocalAddress.IpAddress.ToString()) // if the existing primary is the local node, we need to check for possible demotion of the current primary.
{
if (!hasMajority)
{
_context.ConfigurationSession.SetNodeStatus(_context.ClusterName, _context.LocalShardName, existingMembership.Primary, NodeRole.None);
args.ChangeType = MembershipChangeArgs.MembershipChangeType.PrimaryDemoted;
args.ServerName = _context.LocalAddress;
ChangeMembershipShardwide(args);
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled)
{
LoggerManager.Instance.ShardLogger.Debug("electBasedMemSt.TriggerElectMech", " Node leaving activity occurred. Primary node " + _context.LocalAddress.IpAddress.ToString() + " demoted.");
}
return;
}
}
}
((LocalShard)_shard).OnMembershipChanged(args);
break;
case Activity.GeneralElectionsTriggered:
case Activity.TakeoverElectionsTriggered:
// this is where the actual election mechanism takes place.
//Step 1: if no node in the heartbeat table has a primary and there is no primary in the local node's membership, we proceed forward.
//Else if there is a primary but this looks like the takeover election mechanism, we proceed along as well.
if ((activity.Equals(Activity.GeneralElectionsTriggered) && !heartbeatReport.PrimaryExists() && existingMembership.Primary == null) || (activity.Equals(Activity.TakeoverElectionsTriggered) && heartbeatReport.PrimaryExists()))
{
//Step 2: we verify that this node has a majority of the shard nodes connected to it.
if (activeNodes != null && ObeysMajorityRule(activeNodes.Count, staticServerNodes.Nodes.Count))
{
//Step 3: Perform the initial sanity check. (Speculative phase)
if (ShouldIInitiateElection(heartbeatReport, activity))
{
if (existingMembership != null && existingMembership.Primary != null && activity == Activity.GeneralElectionsTriggered)
{
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsInfoEnabled)
{
LoggerManager.Instance.ShardLogger.Info("electBasedMemSt.TriggerElectMech", "A primary has already been selected for "
+ _context.LocalShardName + " hence exiting the election mechanism.");
}
return;
}
//Step 4: The elections take place in real. (Authoritative Phase)
result = HoldElection(heartbeatReport, activity);
if (result != null)
{
if (result.PollingResult == ElectionResult.Result.PrimarySelected)
{
//if the shard is undergoing the takeover election mechanism, the old primary needs to
//be demoted first.
bool oldPrimaryDemoted = false;
if (activity == Activity.TakeoverElectionsTriggered)
{
MembershipChangeArgs args2 = new MembershipChangeArgs();
args2.ChangeType = MembershipChangeArgs.MembershipChangeType.ForcefullyDemotePrimary;
args2.ServerName = _context.LocalAddress;
args2.ElectionId = existingMembership.ElectionId;
Message msg = new Message();
msg.Payload = args2;
msg.MessageType = MessageType.MembershipOperation;
msg.NeedsResponse = true;
ShardRequestBase <bool> request = _shard.CreateUnicastRequest <bool>(new Server(new Address(existingMembership.Primary.Name, sConfig.Port), Status.Running), msg);
IAsyncResult result2 = request.BeginExecute();
oldPrimaryDemoted = request.EndExecute(result2);
}
//Submit the result to the CS.
if (activity == Activity.GeneralElectionsTriggered || (activity == Activity.TakeoverElectionsTriggered && oldPrimaryDemoted))
{
_context.ConfigurationSession.SubmitElectionResult(_context.ClusterName.ToLower(), _context.LocalShardName.ToLower(), result);
}
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled)
{
LoggerManager.Instance.ShardLogger.Debug("electBasedMemSt.TriggerElectMech", "Election result submitted for shard " + _context.LocalShardName.ToString());
}
_context.ElectionResult = result;
args.ServerName = _context.LocalAddress;
args.ElectionId = result.ElectionId;
args.ChangeType = MembershipChangeArgs.MembershipChangeType.PrimarySelected;
//Once, the result is submitted, inform the shard nodes.
ChangeMembershipShardwide(args);
_context.ConfigurationSession.ReportHeartbeat(_context.ClusterName, _context.LocalShardName, result.ElectedPrimary, existingMembership, LastOperationId);
}
//Finally, end this round of elections.
_context.ConfigurationSession.EndElection(_context.ClusterName, _context.LocalShardName, result.ElectionId);
}
}
}
}
break;
case Activity.CSDisconnected:
//this is called whenever a node loses connection with the config server.
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled)
{
LoggerManager.Instance.ShardLogger.Debug("ElectionBasedMembershipStrategy.TriggerElectionMechanism() ", "Config Server disconnected. ");
}
//if the number of configured nodes are even and the primary loses connection with the CS, it needs to demote itself.
if (existingMembership != null && existingMembership.Primary != null && existingMembership.Primary.Name == _context.LocalAddress.IpAddress.ToString() && staticServerNodes.Nodes.Count % 2 == 0)
{
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled)
{
LoggerManager.Instance.ShardLogger.Debug("electBasedMemSt.TriggerElectMech", " Connection of the node " + _context.LocalAddress.ToString() + " with the config server is lost.");
}
args.ServerName = _context.LocalAddress;
args.ElectionId = existingMembership.ElectionId;
args.ChangeType = MembershipChangeArgs.MembershipChangeType.PrimaryDemoted;
ChangeMembershipShardwide(args);
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsInfoEnabled)
{
LoggerManager.Instance.ShardLogger.Info("electBasedMemSt.TriggerElectMech", " Primary node " + _context.LocalAddress.IpAddress.ToString() + " demoted because the primary lost connection with the CS.");
}
}
break;
case Activity.ForcefulPrimaryDemotion:
if (existingMembership != null && existingMembership.Primary != null && existingMembership.Primary.Name == _context.LocalAddress.IpAddress.ToString())
{
_context.ConfigurationSession.SetNodeStatus(_context.ClusterName, _context.LocalShardName, existingMembership.Primary, NodeRole.None);
args.ChangeType = MembershipChangeArgs.MembershipChangeType.PrimaryDemoted;
args.ServerName = _context.LocalAddress;
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsInfoEnabled)
{
LoggerManager.Instance.ShardLogger.Info("electBasedMemSt.TriggerElectMech", "Primary node " + _context.LocalAddress.IpAddress.ToString() + " demoted in order to complete the take over election mechanism. ");
}
((LocalShard)_shard).OnMembershipChanged(args);
}
break;
}
}
/// <summary>
/// Speculative Phase:
/// 1. We search for the node with the latest op-log entry. This detail bears the highest value.
/// 2. Next, if multiple nodes have the same op-log entry, we move onto the next step.
/// 3. All those nodes which have the same op-log entry AND are connected to the CS are considered.
/// 4. Highest priority from amongst these active nodes are taken into consideration.
/// 5. If this node fulfills all of the above, it successfully passes the speculative phase.
/// </summary>
/// <param name="heartbeatReport"></param>
/// <returns></returns>
private bool ShouldIInitiateElection(LocalShardHeartbeatReporting heartbeatReport, Activity activity)
{
IList <Address> activeNodes = null;
if (heartbeatReport != null)
{
activeNodes = heartbeatReport.GetReportTable.Keys.ToList();
OperationId maxOplog = null;
IList <string> matchingOplogServerIPs = new List <string>();
HeartbeatInfo localHeartbeat = heartbeatReport.GetHeartbeatInfo(_context.LocalAddress);
if (localHeartbeat == null)
{
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsWarnEnabled)
{
LoggerManager.Instance.ShardLogger.Warn(
"ElectionBasedMembershipStrategy.ShouldIInititateElections()",
"local node heartbeat is null");
}
return(false);
}
OperationId lastRepId = null;
if (activity.Equals(Activity.TakeoverElectionsTriggered))
{
HeartbeatInfo info = null;
if (_shard != null && _shard.Primary != null)
{
info = heartbeatReport.GetHeartbeatInfo(_shard.Primary.Address);
}
}
else
{
ShardConfiguration sConfig = _clusterConfigMgr.GetShardConfiguration(_context.LocalShardName);
int configuredNodesCount = 0;
OperationId OpIdAtCS = null;
if (sConfig != null && sConfig.Servers != null && sConfig.Servers.Nodes != null)
{
configuredNodesCount = sConfig.Servers.Nodes.Count;
}
if (configuredNodesCount > 0 && activeNodes != null && activeNodes.Count < configuredNodesCount)
{
ShardInfo sInfo = null;
ClusterInfo cInfo = _context.ConfigurationSession.GetDatabaseClusterInfo(_context.ClusterName);
if (cInfo != null)
{
sInfo = cInfo.GetShardInfo(_context.LocalShardName);
}
if (sInfo != null)
{
OpIdAtCS = sInfo.LastOperationId;
}
if (OpIdAtCS > lastRepId)
{
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsInfoEnabled)
{
LoggerManager.Instance.ShardLogger.Info(
"electBasedMemSt.ShouldIInitElections()",
"CS has an operation newer than my operation. Hence, waiting.");
}
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsInfoEnabled)
{
if (OpIdAtCS != null)
{
LoggerManager.Instance.ShardLogger.Info(
"electBasedMemSt.ShouldIInitElections()",
"Operation ID on the CS:- " + OpIdAtCS.ElectionId + ":"
+ OpIdAtCS.ElectionBasedSequenceId);
}
else
{
LoggerManager.Instance.ShardLogger.Info(
"electBasedMemSt.ShouldIInitElections()", "The operation ID at the CS is set to null.");
}
if (lastRepId != null)
{
LoggerManager.Instance.ShardLogger.Info(
"electBasedMemSt.ShouldIInitElections()", "Local node Operation ID:- " + lastRepId.ElectionId +
":" + lastRepId.ElectionBasedSequenceId);
}
else
{
LoggerManager.Instance.ShardLogger.Info(
"electBasedMemSt.ShouldIInitElections()", "The local node operation ID is set to null.");
}
}
//We maintain the last replicated operation log entry with the CS.
//If a node in a shard with older data (usually the previous secondary) is up before the node with the
//latest data(usually the previous primary), it waits for a configurable amount of time (2 minutes for
//now) before proceeding with the election procedure if it is still unable to detect a primary node.
//This way we give the node with the latest data a chance to become primary and therefore avoid data loss.
lock (_mutexOnWait)
{
Monitor.Wait(_mutexOnWait, _waitTimeout);
}
}
}
for (int i = 0; i < activeNodes.Count; i++)
{
HeartbeatInfo info = heartbeatReport.GetHeartbeatInfo(activeNodes[i]);
OperationId currIndexOplog = info.LastOplogOperationId;
if (currIndexOplog > maxOplog)
{
maxOplog = currIndexOplog;
}
if (((localHeartbeat.LastOplogOperationId == null && info.LastOplogOperationId == null) || localHeartbeat.LastOplogOperationId != null && localHeartbeat.LastOplogOperationId.Equals(info.LastOplogOperationId)) &&
info.CSStatus == ConnectivityStatus.Connected)
{
matchingOplogServerIPs.Add(activeNodes[i].IpAddress.ToString());
}
}
}
if (localHeartbeat.LastOplogOperationId != null && maxOplog != null && maxOplog > localHeartbeat.LastOplogOperationId && (lastRepId == null || maxOplog > lastRepId))
{
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled)
{
LoggerManager.Instance.ShardLogger.Debug("electBasedMemSt.ShouldIInitiateElect()", "Local operation log is behind max op log wrt " + _context.LocalShardName + " shard.");
}
if (maxOplog != null && LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled)
{
LoggerManager.Instance.ShardLogger.Debug("electBasedMemSt.ShouldIInitiateElect()", "maxOplog: " + maxOplog.ElectionId + ":" + maxOplog.ElectionBasedSequenceId);
}
if (localHeartbeat.LastOplogOperationId != null && LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled)
{
LoggerManager.Instance.ShardLogger.Debug("electBasedMemSt.ShouldIInitiateElect()", "local opLog (from the heartbeat): " + localHeartbeat.LastOplogOperationId.ElectionId + ":" + localHeartbeat.LastOplogOperationId.ElectionBasedSequenceId);
}
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled && lastRepId != null)
{
LoggerManager.Instance.ShardLogger.Debug("electBasedMemSt.ShouldIInitiateElect()", "LastOpFromOpLog (from the replication module): " + lastRepId.ElectionId + ":" + lastRepId.ElectionBasedSequenceId);
}
return(false);
}
else if (maxOplog == localHeartbeat.LastOplogOperationId || (lastRepId != null && lastRepId.Equals(maxOplog)))
{
//if: there are multiple nodes that have the same oplog entry,
//decision will be made on the basis of the priorities.
//else: the node with the highest oplog entry will be considered eligible.
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled)
{
LoggerManager.Instance.ShardLogger.Debug("electBasedMemSt.ShouldIInitiateElect()", "Local operation log is equal to the max op log wrt " + _context.LocalShardName + " shard.");
}
if (maxOplog != null && (localHeartbeat != null && localHeartbeat.LastOplogOperationId != null))
{
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled)
{
LoggerManager.Instance.ShardLogger.Debug("electBasedMemSt.ShouldIInitiateElect()", "maxOplog: " + maxOplog.ElectionId + ":" + maxOplog.ElectionBasedSequenceId);
}
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled)
{
LoggerManager.Instance.ShardLogger.Debug("electBasedMemSt.ShouldIInitiateElect()", "local opLog (from the heartbeat): " + localHeartbeat.LastOplogOperationId.ElectionId + ":" + localHeartbeat.LastOplogOperationId.ElectionBasedSequenceId);
}
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsDebugEnabled && lastRepId != null)
{
LoggerManager.Instance.ShardLogger.Debug("electBasedMemSt.ShouldIInitiateElect()", "LastOpFromOpLog (from the replication module): " + lastRepId.ElectionId + ":" + lastRepId.ElectionBasedSequenceId);
}
}
if (matchingOplogServerIPs.Count > 0)
{
int highestRunningNodePriority = _manager.GetHighestNodePriority(activeNodes,
matchingOplogServerIPs);
if (highestRunningNodePriority.Equals(_manager.LocalServerPriority))
{
if (LoggerManager.Instance.ShardLogger != null &&
LoggerManager.Instance.ShardLogger.IsDebugEnabled)
{
LoggerManager.Instance.ShardLogger.Debug(
"ElectionBasedMembershipStrategy.ShouldIInitiateElection()",
"Node : " + _context.LocalAddress.IpAddress.ToString() + " in shard: " +
_context.LocalShardName + " is eligible having priority: " +
highestRunningNodePriority + " .");
}
return(true);
}
else
{
return(false);
}
}
}
}
return(false);
}
