private (bool HasRemovedFromTopology, long LastAcknowledgedIndex, long LastTruncate, long LastCommit) ApplyLeaderStateToLocalState(Stopwatch sp, ClusterOperationContext context, List <RachisEntry> entries, AppendEntries appendEntries)
{
long lastTruncate;
long lastCommit;
bool removedFromTopology = false;
// we start the tx after we finished reading from the network
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"{ToString()}: Ready to start tx in {sp.Elapsed}");
}
using (var tx = context.OpenWriteTransaction())
{
_engine.ValidateTerm(_term);
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"{ToString()}: Tx running in {sp.Elapsed}");
}
if (entries.Count > 0)
{
var(lastTopology, lastTopologyIndex) = _engine.AppendToLog(context, entries);
using (lastTopology)
{
if (lastTopology != null)
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"Topology changed to {lastTopology}");
}
var topology = JsonDeserializationRachis <ClusterTopology> .Deserialize(lastTopology);
if (topology.Members.ContainsKey(_engine.Tag) ||
topology.Promotables.ContainsKey(_engine.Tag) ||
topology.Watchers.ContainsKey(_engine.Tag))
{
RachisConsensus.SetTopology(_engine, context, topology);
}
else
{
removedFromTopology = true;
_engine.ClearAppendedEntriesAfter(context, lastTopologyIndex);
}
}
}
}
var lastEntryIndexToCommit = Math.Min(
_engine.GetLastEntryIndex(context),
appendEntries.LeaderCommit);
var lastAppliedIndex = _engine.GetLastCommitIndex(context);
var lastAppliedTerm = _engine.GetTermFor(context, lastEntryIndexToCommit);
// we start to commit only after we have any log with a term of the current leader
if (lastEntryIndexToCommit > lastAppliedIndex && lastAppliedTerm == appendEntries.Term)
{
lastAppliedIndex = _engine.Apply(context, lastEntryIndexToCommit, null, sp);
}
lastTruncate = Math.Min(appendEntries.TruncateLogBefore, lastAppliedIndex);
_engine.TruncateLogBefore(context, lastTruncate);
lastCommit = lastAppliedIndex;
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"{ToString()}: Ready to commit in {sp.Elapsed}");
}
tx.Commit();
}
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"{ToString()}: Processing entries request with {entries.Count} entries took {sp.Elapsed}");
}
var lastAcknowledgedIndex = entries.Count == 0 ? appendEntries.PrevLogIndex : entries[entries.Count - 1].Index;
return(HasRemovedFromTopology : removedFromTopology, LastAcknowledgedIndex : lastAcknowledgedIndex, LastTruncate : lastTruncate, LastCommit : lastCommit);
}
/// <summary>
/// This is expected to run for a long time, and it cannot leak exceptions
/// </summary>
private void Run()
{
try
{
var handles = new WaitHandle[]
{
_newEntry,
_voterResponded,
_promotableUpdated,
_shutdownRequested
};
var noopCmd = new DynamicJsonValue
{
["Command"] = "noop"
};
using (_engine.ContextPool.AllocateOperationContext(out TransactionOperationContext context))
using (var tx = context.OpenWriteTransaction())
using (var cmd = context.ReadObject(noopCmd, "noop-cmd"))
{
_engine.InsertToLeaderLog(context, Term, cmd, RachisEntryFlags.Noop);
tx.Commit();
}
_newEntry.Set(); //This is so the noop would register right away
while (_running)
{
switch (WaitHandle.WaitAny(handles, _engine.ElectionTimeout))
{
case 0: // new entry
_newEntry.Reset();
// release any waiting ambassadors to send immediately
TaskExecutor.CompleteAndReplace(ref _newEntriesArrived);
if (_voters.Count == 0)
{
goto case 1;
}
break;
case 1: // voter responded
_voterResponded.Reset();
OnVoterConfirmation();
break;
case 2: // promotable updated
_promotableUpdated.Reset();
CheckPromotables();
break;
case WaitHandle.WaitTimeout:
break;
case 3: // shutdown requested
if (_engine.Log.IsInfoEnabled && _voters.Count != 0)
{
_engine.Log.Info($"{ToString()}: shutting down");
}
_running.Lower();
return;
}
EnsureThatWeHaveLeadership(VotersMajority);
_engine.ReportLeaderTime(LeaderShipDuration);
// don't trancate if we are disposing an old peer
// otherwise he would not recieve notification that he was
// kick out of the cluster
if (_previousPeersWereDisposed > 0) // Not Interlocked, because the race here is not interesting.
{
continue;
}
var lowestIndexInEntireCluster = GetLowestIndexInEntireCluster();
if (lowestIndexInEntireCluster != LowestIndexInEntireCluster)
{
using (_engine.ContextPool.AllocateOperationContext(out TransactionOperationContext context))
using (context.OpenWriteTransaction())
{
_engine.TruncateLogBefore(context, lowestIndexInEntireCluster);
LowestIndexInEntireCluster = lowestIndexInEntireCluster;
context.Transaction.Commit();
}
}
}
}
catch (Exception e)
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info("Error when running leader behavior", e);
}
if (e is VoronErrorException)
{
_engine.Notify(AlertRaised.Create(
null,
"Error when running leader behavior",
e.Message,
AlertType.ClusterTopologyWarning,
NotificationSeverity.Error, details: new ExceptionDetails(e)));
}
try
{
_engine.SwitchToCandidateState("An error occurred during our leadership." + Environment.NewLine + e);
}
catch (Exception e2)
{
if (_engine.Log.IsOperationsEnabled)
{
_engine.Log.Operations("After leadership failure, could not setup switch to candidate state", e2);
}
}
}
}
private void FollowerSteadyState()
{
var entries = new List <RachisEntry>();
long lastCommit = 0, lastTruncate = 0;
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"Follower {_engine.Tag}: Entering steady state");
}
while (true)
{
entries.Clear();
using (_engine.ContextPool.AllocateOperationContext(out TransactionOperationContext context))
{
var appendEntries = _connection.Read <AppendEntries>(context);
if (appendEntries.Term != _engine.CurrentTerm)
{
_connection.Send(context, new AppendEntriesResponse
{
CurrentTerm = _engine.CurrentTerm,
Message = "The current term that I have " + _engine.CurrentTerm + " doesn't match " + appendEntries.Term,
Success = false
});
if (_engine.Log.IsInfoEnabled && entries.Count > 0)
{
_engine.Log.Info($"Follower {_engine.Tag}: Got invalid term {appendEntries.Term} while the current term is {_engine.CurrentTerm}, aborting connection...");
}
return;
}
_engine.Timeout.Defer(_connection.Source);
var sp = Stopwatch.StartNew();
if (appendEntries.EntriesCount != 0)
{
for (int i = 0; i < appendEntries.EntriesCount; i++)
{
entries.Add(_connection.ReadRachisEntry(context));
_engine.Timeout.Defer(_connection.Source);
}
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"Follower {_engine.Tag}: Got non empty append entries request with {entries.Count} entries. Last: ({entries[entries.Count - 1].Index} - {entries[entries.Count - 1].Flags})"
#if DEBUG
+ $"[{string.Join(" ,", entries.Select(x => x.ToString()))}]"
#endif
);
}
}
var lastLogIndex = appendEntries.PrevLogIndex;
// don't start write transaction fro noop
if (lastCommit != appendEntries.LeaderCommit ||
lastTruncate != appendEntries.TruncateLogBefore ||
entries.Count != 0)
{
bool removedFromTopology = false;
// we start the tx after we finished reading from the network
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"Follower {_engine.Tag}: Ready to start tx in {sp.Elapsed}");
}
using (var tx = context.OpenWriteTransaction())
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"Follower {_engine.Tag}: Tx running in {sp.Elapsed}");
}
if (entries.Count > 0)
{
using (var lastTopology = _engine.AppendToLog(context, entries))
{
if (lastTopology != null)
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"Topology changed to {lastTopology}");
}
var topology = JsonDeserializationRachis <ClusterTopology> .Deserialize(lastTopology);
if (topology.Members.ContainsKey(_engine.Tag) ||
topology.Promotables.ContainsKey(_engine.Tag) ||
topology.Watchers.ContainsKey(_engine.Tag))
{
RachisConsensus.SetTopology(_engine, context, topology);
}
else
{
removedFromTopology = true;
}
}
}
}
lastLogIndex = _engine.GetLastEntryIndex(context);
var lastEntryIndexToCommit = Math.Min(
lastLogIndex,
appendEntries.LeaderCommit);
var lastAppliedIndex = _engine.GetLastCommitIndex(context);
if (lastEntryIndexToCommit > lastAppliedIndex)
{
_engine.Apply(context, lastEntryIndexToCommit, null);
}
lastTruncate = Math.Min(appendEntries.TruncateLogBefore, lastEntryIndexToCommit);
_engine.TruncateLogBefore(context, lastTruncate);
lastCommit = lastEntryIndexToCommit;
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"Follower {_engine.Tag}: Ready to commit in {sp.Elapsed}");
}
tx.Commit();
}
if (_engine.Log.IsInfoEnabled && entries.Count > 0)
{
_engine.Log.Info($"Follower {_engine.Tag}: Processing entries request with {entries.Count} entries took {sp.Elapsed}");
}
if (removedFromTopology)
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info("Was notified that I was removed from the node topoloyg, will be moving to passive mode now.");
}
_engine.SetNewState(RachisState.Passive, null, appendEntries.Term,
"I was kicked out of the cluster and moved to passive mode");
return;
}
}
if (appendEntries.ForceElections)
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"Follower {_engine.Tag}: Got a request to become candidate from the leader.");
}
_engine.SwitchToCandidateState("Was asked to do so by my leader", forced: true);
return;
}
_connection.Send(context, new AppendEntriesResponse
{
CurrentTerm = _engine.CurrentTerm,
LastLogIndex = lastLogIndex,
Success = true
});
_engine.Timeout.Defer(_connection.Source);
_engine.ReportLeaderTime(appendEntries.TimeAsLeader);
}
}
}
