public Task Handle(CompleteTaskCommand command)
{
var @event = new TaskFinished
{
Number = command.TaskNumber,
Timestamp = DateTimeOffset.UtcNow
};
// If some other process magically zips
// in and updates this project event stream
// between the call to AppendOptimistic()
// and SaveChangesAsync(), Marten will detect
// that and reject the transaction
_session.Events.AppendOptimistic(
command.ProjectId,
@event);
return(_session.SaveChangesAsync());
}
public Task Handle(CompleteTaskCommand command)
{
var @event = new TaskFinished
{
Number = command.TaskNumber,
Timestamp = DateTimeOffset.UtcNow
};
// This tries to acquire an exclusive
// lock on the stream identified by
// command.ProjectId in the database
// so that only one process at a time
// can update this event stream
_session.Events.AppendExclusive(
command.ProjectId,
@event);
return(_session.SaveChangesAsync());
}
public Task Handle(CompleteTaskCommand command)
{
var @event = new TaskFinished
{
Number = command.TaskNumber,
Timestamp = DateTimeOffset.UtcNow
};
_session.Events.Append(
command.ProjectId,
// Using this overload will make Marten do
// an optimistic concurrency check against
// the existing version of the project event
// stream as it commits
command.ExpectedVersion,
@event);
return(_session.SaveChangesAsync());
}