DistTest

A POC for handling singleton processes and resolving network splits.

Uses :global to resolve conflicts.

Installation

It's a POC, clone it.

Resolver

To handle singletons, you have to define a module using DistTest.SingletonResolver. This will ensure there's only one instance of the singleton running in cluster, and also handles resolving conflicts if they happen.

defmodule DistTest.Resolver do
  use DistTest.SingletonResolver
  
  @impl true
  def resolver(name, pid1, pid2) do
    # Use your own logic here
    # NOTE: You have to return one of the `pid1` or `pid2` as winner
  end

And to start it in your supervisor

chilren = [
  {DisTest.SingletonResolver, 
    name: DisTest.SomeName, 
    child_opts: [DisTest.Server, []]}
]

name is the name to register the GenServer under, and child_opts is the arguments to pass to GenServer.start_link to start the process.

Splits

When a split happens, the singleton will exist in all of partitions. When the split resolved, your resolve/3 callback is called to determine what process should be killed and what is kept.