/// <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 Clone()
{
ElectionId electionId = new ElectionId();
electionId.Id = Id;
electionId.UID = UID;
electionId.RequestingNode = RequestingNode;
electionId.ElectionTime = ElectionTime;
electionId.AllowedDuration = AllowedDuration;
electionId.TimeTaken = TimeTaken;
return(electionId);
}
public Election(ElectionId id, ElectionType electionType)
{
ElectionId = id;
ElectionType = electionType;
}
