Lease API & integration

[zbynek001]

Note: this depends on Timers (#3778), will rebase it when it's merged

• Lease API
• Singleton Integration
• Sharding Integration

Open quesions:

• where to put the api, right now it's directly in Akka project, should it be moved somewhere else?

migrated from akka/akka#26629

[zbynek001]

sharding integration would be better to do after Timers API (#3778)

[Aaronontheweb]

@zbynek001 is #3778 good to go?

[zbynek001]

@Aaronontheweb in theory yes. There is only the open question if the code in ActorBase.AroundReceive will have any performance implication

[Aaronontheweb]

@zbynek001 ok, got it - I'll review the PR then benchmark it.

[Aaronontheweb]

@zbynek001 reviewed #3778 - do you need to address those before this PR gets finished?

[Aaronontheweb]

Working on reviewing this now that #3778 has been merged. Might take a bit as I'm familiarizing myself with the API as I go.

Going to need to add documentation for this too if the API is public.

[Aaronontheweb]

Overall looks good - have some questions, but we really need to move the leasing code out of the core Akka module and into its own project instead: Akka.Coordination.

[Aaronontheweb]

So, removing a lot of this business logic from the cluster singleton implementation itself and moving it to the leasing system - ok, that makes sense.

[Aaronontheweb]

Oh I see - it's been moved to the state rather than the event-handling methods themselves.

[Aaronontheweb]

One question I have that wasn't totally clear to me based on what I reviewed - do any of these leasing messages go over the wire? Didn't look that way when I first looked but it might be implementation-specific for things like Akka.Cluster.Tools.Singleton

[Aaronontheweb]

@zbynek001 this will be a great addition to Akka.NET - happy to do it once we can address these comments.

[zbynek001]

@Aaronontheweb basically no messages here go over wire, this is just adding API to create your own Lease implementation.
And the specific Lease implementation would then internally communicate with some external system to create the lease, e.g. redis cache.

[zbynek001]

@Aaronontheweb I think all changes should be done. Not sure about the new projects, if there is something else to change in build script or somewhere else

[Aaronontheweb]

@zbynek001 I'll check that now.

[Aaronontheweb]

Code looks great - just need some help with meta-data, XML-DOC, and copyright headers in a couple of areas.

[Aaronontheweb]

Nice work @zbynek001

[Lutando]

General question about this, this a timed lease that works similar to Azure Blob leases? ie Only one actor/process can hold a reference to an actor in a bounded time period?

[Aaronontheweb]

@Lutando that's correct - you could implement a lease that is backed by Azure blobs, a Redis object, etc...