private void FollowerSteadyState()
{
var entries = new List <RachisEntry>();
long lastCommit = 0, lastTruncate = 0, lastAcknowledgedIndex = 0;
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"{ToString()}: Entering steady state");
}
while (true)
{
entries.Clear();
using (_engine.ContextPool.AllocateOperationContext(out ClusterOperationContext context))
{
using (context.OpenReadTransaction())
{
if (_engine.RequestSnapshot)
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"{ToString()}: Snapshot was requested, so we close this follower.");
}
return;
}
}
_debugRecorder.Record("Wait for entries");
var appendEntries = _connection.Read <AppendEntries>(context);
var sp = Stopwatch.StartNew();
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)
{
_engine.Log.Info($"{ToString()}: Got invalid term {appendEntries.Term} while the current term is {_engine.CurrentTerm}, aborting connection...");
}
return;
}
ClusterCommandsVersionManager.SetClusterVersion(appendEntries.MinCommandVersion);
_debugRecorder.Record("Got entries");
_engine.Timeout.Defer(_connection.Source);
if (appendEntries.EntriesCount != 0)
{
using (var cts = new CancellationTokenSource())
{
var task = Concurrent_SendAppendEntriesPendingToLeaderAsync(cts, _term, appendEntries.PrevLogIndex);
try
{
for (int i = 0; i < appendEntries.EntriesCount; i++)
{
entries.Add(_connection.ReadRachisEntry(context));
}
}
finally
{
cts.Cancel();
task.Wait(CancellationToken.None);
}
_engine.Timeout.Defer(_connection.Source);
}
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"{ToString()}: Got non empty append entries request with {entries.Count} entries. Last: ({entries[entries.Count - 1].Index} - {entries[entries.Count - 1].Flags})"
#if DEBUG
+ $"[{string.Join(" ,", entries.Select(x => x.ToString()))}]"
#endif
);
}
}
// don't start write transaction for noop
if (lastCommit != appendEntries.LeaderCommit ||
lastTruncate != appendEntries.TruncateLogBefore ||
entries.Count != 0)
{
using (var cts = new CancellationTokenSource())
{
// applying the leader state may take a while, we need to ping
// the server and let us know that we are still there
var task = Concurrent_SendAppendEntriesPendingToLeaderAsync(cts, _term, appendEntries.PrevLogIndex);
try
{
bool hasRemovedFromTopology;
(hasRemovedFromTopology, lastAcknowledgedIndex, lastTruncate, lastCommit) = ApplyLeaderStateToLocalState(sp,
context,
entries,
appendEntries);
if (hasRemovedFromTopology)
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info("Was notified that I was removed from the node topology, will be moving to passive mode now.");
}
_engine.SetNewState(RachisState.Passive, null, appendEntries.Term,
"I was kicked out of the cluster and moved to passive mode");
return;
}
}
catch (RachisInvalidOperationException)
{
// on raft protocol violation propagate the error and close this follower.
throw;
}
catch (ConcurrencyException)
{
// the term was changed
throw;
}
catch (Exception e)
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"Failed to apply leader state to local state with {entries.Count:#,#;;0} entries with leader commit: {appendEntries.LeaderCommit}, term: {appendEntries.Term}. Prev log index: {appendEntries.PrevLogIndex}", e);
}
}
finally
{
// here we need to wait until the concurrent send pending to leader
// is completed to avoid concurrent writes to the leader
cts.Cancel();
task.Wait(CancellationToken.None);
}
}
}
if (appendEntries.ForceElections)
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"{ToString()}: Got a request to become candidate from the leader.");
}
_engine.SwitchToCandidateState("Was asked to do so by my leader", forced: true);
return;
}
_debugRecorder.Record("Processing entries is completed");
_connection.Send(context, new AppendEntriesResponse
{
CurrentTerm = _term,
LastLogIndex = lastAcknowledgedIndex,
Success = true
});
if (sp.Elapsed > _engine.ElectionTimeout / 2)
{
if (_engine.Log.IsInfoEnabled)
{
_engine.Log.Info($"{ToString()}: Took a long time to complete the cycle with {entries.Count} entries: {sp.Elapsed}");
}
}
_engine.Timeout.Defer(_connection.Source);
_engine.ReportLeaderTime(appendEntries.TimeAsLeader);
_debugRecorder.Record("Cycle done");
_debugRecorder.Start();
}
}
}
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);
}
}
}