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bbengfort / cloudscope

Simulation and visualization of distributed systems and communications.
http://bbengfort.github.io/cloudscope/
MIT License
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Lamport Version Handling #89

Open bbengfort opened 7 years ago

bbengfort commented 7 years ago

In order to completely implement #79 the replica has to reset it's current version state based on the latest seen from incoming versions (in order to guarantee a Lamport Scalar timestamp).

Number #79 is fixed if the settings are changed so that versioning="lamport" except for the Replica handling.

The reason the replica handling isn't there yet is because globally tracked staleness still requires the global version numbers.

bbengfort commented 7 years ago

Actually as it turns out - a global version number is possible by taking the maximum of all versions for each replica ... see the newly implemented LamportVersion.latest_version class method.

The issue is that this would reduce the staleness counts, since it is possible for a concurrent fork that hasn't been detected to remain unstale.

bbengfort commented 7 years ago

In order to implement this, Replicas simply need to call the LamportVersion.update_version class method on the object they've just received a write from. They can pass in a reference to themselves and the version, and the version numbering will automatically be updated to the maximum value between the remote version and the local counter.

bbengfort commented 7 years ago

While you're doing this, you should probably also refactor the LamportScalar class and embed that logic into the LamportVersion class, similar to the FederatedVersion class!