/// <summary>
/// Creates ServerNodes list from _settings.
/// </summary>
private void CreateServerNodes()
{
foreach (var server in _settings.Servers)
{
ServerNodes.Add(server.Name, new NGRIDServerNode(server.Name));
}
}
/// <summary>
/// Gets adjacent nodes from settings and joins servers in ServerNodes.
/// </summary>
private void JoinNodes()
{
//Gets adjacents of all nodes
var adjacentsOfServers = new SortedList <string, string>();
foreach (var server in _settings.Servers)
{
adjacentsOfServers.Add(server.Name, server.Adjacents);
}
//Join adjacents of all nodes
foreach (var serverName in adjacentsOfServers.Keys)
{
//Create adjacent list
ServerNodes[serverName].Adjacents = new SortedList <string, NGRIDServerNode>();
//Get adjacent names
var adjacents = adjacentsOfServers[serverName].Split(',');
//Add nodes as adjacent
foreach (var adjacent in adjacents)
{
var trimmedAdjacentName = adjacent.Trim();
if (string.IsNullOrEmpty(trimmedAdjacentName))
{
continue;
}
if (!ServerNodes.ContainsKey(trimmedAdjacentName))
{
throw new NGRIDException("Adjacent server (" + trimmedAdjacentName + ") of server (" + serverName + ") can not be found in servers list.");
}
ServerNodes[serverName].Adjacents.Add(trimmedAdjacentName, ServerNodes[trimmedAdjacentName]);
}
}
}
/// <summary>
/// Sets ThisServerNode field according to _settings and ServerNodes
/// </summary>
private void SetCurrentServer()
{
if (ServerNodes.ContainsKey(_settings.ThisServerName))
{
ThisServerNode = ServerNodes[_settings.ThisServerName];
}
else
{
throw new NGRIDException("Current server is not defined in settings file.");
}
}
public List <ServerNode> GetActiveServerNodes(ServerNodes serverNodes)
{
IList <Address> list = _heartbeatReporter.Keys.ToList();
List <ServerNode> activeNodes = new List <ServerNode>();
foreach (var node in list)
{
activeNodes.Add(serverNodes.GetServerNode(node.IpAddress.ToString()));
}
return(activeNodes);
}
/// <summary>
/// Sets ThisServerNode field according to _settings and ServerNodes
/// </summary>
private void SetCurrentServer()
{
if (ServerNodes.ContainsKey(_settings.ThisServerName))
{
ThisServerNode = ServerNodes[_settings.ThisServerName];
}
//else
//{
// throw new MDSException("Current server is not defined in settings file.");
//}
}
internal int GetHighestNodePriority(IList <Address> nodes, IList <string> maxOplogAddress)
{
LoggerManager.Instance.SetThreadContext(new LoggerContext()
{
ShardName = _context.LocalShardName != null ? _context.LocalShardName : "", DatabaseName = ""
});
ShardConfiguration sConfig = null;
if (_clusterConfigMgr != null)
{
sConfig = _clusterConfigMgr.GetShardConfiguration(_context.LocalShardName);
}
if (sConfig == null || sConfig.Servers == null)
{
if (LoggerManager.Instance.ShardLogger != null && LoggerManager.Instance.ShardLogger.IsWarnEnabled)
{
LoggerManager.Instance.ShardLogger.Warn("ElectionManager.GetHeighestNodePriority() ", "The shard (or the nodes of the shard) " + _context.LocalShardName + " does not exist in the configuration.");
}
return(0);
}
ServerNodes staticNodes = sConfig.Servers;
int maxPriority = Int32.MaxValue;
if (nodes != null)
{
foreach (Address node in nodes)
{
ServerNode serverNode = staticNodes.GetServerNode(node.IpAddress.ToString());
if (serverNode != null)
{
int thisPriority = serverNode.Priority;
if ((thisPriority < maxPriority) && maxOplogAddress.Contains(serverNode.Name))
{
maxPriority = thisPriority;
}
}
}
return(maxPriority);
}
else
{
throw new Exception("Membership is null.");
}
}
private string PickOneServer()
{
if (string.IsNullOrEmpty(ServerNodes))
{
throw new ArgumentNullException("ServerNodes");
}
var servers = ServerNodes.Split(',');
if (servers.Length == 1)
{
return(servers[0]);
}
var index = new Random().Next(0, servers.Length);
return(servers[index]);
}
private void FillAssignNodes()
{
DataTable NodesDataTable = new DataTable();
NodesDataTable = VSWebBL.SecurityBL.NodesBL.Ins.GetAllData();
DataRow row = NodesDataTable.NewRow();
row["ID"] = "-1";
row["Name"] = "";
NodesDataTable.Rows.InsertAt(row, 0);
if (NodesDataTable.Rows.Count > 0)
{
ServerNodes.DataSource = NodesDataTable;
ServerNodes.TextField = "Name";
ServerNodes.ValueField = "ID";
ServerNodes.DataBind();
ServerNodes.Items[0].Selected = true;
}
}
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;
}
}
public ActionResult <Task> Update([FromBody] ServerNode model) => ServerNodes.Update(model);
public ActionResult <List <ServerNode> > FindAll() => ServerNodes.FindAll();
public ActionResult <ServerNode> FindById([FromQuery] string id) => ServerNodes.FindById(id);
public ActionResult <Task> DeleteClusterNode([FromBody] ServerNode model) => ServerNodes.DeleteServerNode(model);
public ActionResult <Task> CreateCluster([FromBody] ServerNode model) => ServerNodes.AddServerNode(model);