private void Received(OrderedCommitNotification msg)
{
//if their previous matches our current, project
//if their previous is less than our current, ignore
//if their previous is > our current, catchup
var comparer = new CheckpointComparer();
var comparision = comparer.Compare(Checkpoint, msg.PreviousCheckpoint);
if (comparision == 0)
{
Project(msg.Commit); //order matched, project
}
else if (comparision > 0)
{
//we are ahead of this commit so no-op, this is a bit odd, so log it
Context.GetLogger().Debug("Received a commit notification (checkpoint {0}) behind our checkpoint ({1})", msg.Commit.CheckpointToken, Checkpoint.Get());
}
else
{
//we are behind the head, should catch up
var fromPoint = Checkpoint.Map(x => x.ToString()).GetOrElse("beginning of time");
Context.GetLogger().Info("Catchup started from checkpoint {0} after receiving out-of-sequence commit with checkpoint {1} and previous checkpoint {2}", fromPoint, msg.Commit.CheckpointToken, msg.PreviousCheckpoint);
Catchup();
Context.GetLogger().Info("Catchup finished from {0} to checkpoint {1} after receiving commit with checkpoint {2}", fromPoint, Checkpoint.Map(x => x.ToString()).GetOrElse("beginning of time"), msg.Commit.CheckpointToken);
}
}
/// <summary>
/// Message sent by the event store poller
/// </summary>
/// <param name="msg"></param>
private void Received(OrderedCommitNotification msg)
{
//guard against old messages being streamed from the poller, we can safely ignore them
if (_orderer.IsNextCheckpoint(_currentCheckpoint, msg))
{
SendCommitToProjectors(msg);
}
}
/// <summary>
/// Sends the commit to the projectors for projection
/// </summary>
/// <param name="msg"></param>
private void SendCommitToProjectors(OrderedCommitNotification msg)
{
_backlogCommitCount = 0; //reset the backlog counter
_currentCheckpoint = msg.Commit.CheckpointToken.ToSome(); //update head pointer
Context.ActorSelection(_projectorsBroadCastRouter).Tell(msg); //pass message on for projection
}
/// <summary>
/// Pass your current checkpoint and a new orderedcommitnotification message to determine if this is the next commit for you to process
/// </summary>
/// <param name="currentCheckpoint"></param>
/// <param name="msg"></param>
/// <returns></returns>
public bool IsNextCheckpoint(Option <long> currentCheckpoint, OrderedCommitNotification msg)
{
return(_comparer.Compare(currentCheckpoint, msg.PreviousCheckpoint) == 0);
}
