Consistency level in projector and store

[cottinisimone]

Closes: #82

[emturner]

Hi @cottinisimone! Hope you're well 😄

I think that possibly, while this address #82, the implementation is misleading?

Regardless of whether consistency is set to strong or weak, the projectors are still running to completion within the transaction -
The only difference here, is whether projectors are 'allowed' to fail? So while this does allow you to 'opt in' to allowing projectors to fail, I think the notion of 'consistency' here is perhaps misleading?

Perhaps if consistency is weak, all the projectors should be run separately, in an ideal world? @matteosister
But possibly this is more effort, as could require larger restructuring of the crate?

(If a projector panics, for any reason, then clearly the event doesn't get persisted at all, but maybe that's not an issue).

[cottinisimone]

Hi @cottinisimone! Hope you're well smile

I think that possibly, while this address #82, the implementation is misleading?

Regardless of whether consistency is set to strong or weak, the projectors are still running to completion within the transaction - The only difference here, is whether projectors are 'allowed' to fail? So while this does allow you to 'opt in' to allowing projectors to fail, I think the notion of 'consistency' here is perhaps misleading?

Perhaps if consistency is weak, all the projectors should be run separately, in an ideal world? @matteosister But possibly this is more effort, as could require larger restructuring of the crate?

(If a projector panics, for any reason, then clearly the event doesn't get persisted at all, but maybe that's not an issue).

Ops. I've already merged. So what could be a better name for this? Failability? Fallibility? Don't know honestly

[emturner]

Don't worry! My fault for being a bit slow responding to github notifications 😆

I am also not sure - perhaps something like:

/// Governs the relationship of an event to a resulting projection.
pub enum ParentEventRelationship {
   ///  This projector must succeed, for the parent event to be persisted.
   Blocking,
   /// This projector is allowed to fail, and doesn't block persisting the parent event.
   Fallible
}

Though I'm not sold on this enum name either!

[cottinisimone]

I open an issue for that in order to discuss about that. Thank you very much Emma :)