A distributed process registry.

Horde.Registry implements a distributed Registry backed by a δ-CRDT (provided by DeltaCrdt). This CRDT is used for both tracking membership of the cluster and implementing the registry functionality itself. Local changes to the registry will automatically be synced to other nodes in the cluster.

Cluster membership is managed with Horde.Cluster. Joining a cluster can be done with Horde.Cluster.set_members/2. To take a node out of the cluster, call Horde.Cluster.set_members/2 without that node in the list. Alternatively, setting the members startup option to :auto will make Horde auto-manage cluster membership so that all (and only) visible nodes are members of the cluster.

Horde.Registry supports the common "via tuple", described in the documentation for GenServer.

Horde.Registry is API-compatible with Registry, with the following exceptions:

• Horde.Registry does not support keys: :duplicate.
• Horde.Registry does not support partitions.
• Horde.Registry sends an exit signal to a process when it has lost a naming conflict. See Horde.Registry.register/3 for details.

Module-based Registry

Horde supports module-based registries to enable dynamic runtime configuration.

defmodule MyRegistry do
  use Horde.Registry

  def start_link(_) do
    Horde.Registry.start_link(__MODULE__, [keys: :unique], name: __MODULE__)
  end

  def init(init_arg) do
    [members: members()]
    |> Keyword.merge(init_arg)
    |> Horde.Registry.init()
  end

  defp members() do
    [Node.self() | Node.list()]
    |> Enum.map(fn node -> {__MODULE__, node} end)
  end
end

Then you can use MyRegistry.child_spec/1 and MyRegistry.start_link/1 in the same way as you'd use Horde.Registry.child_spec/1 and Horde.Registry.start_link/1.