Convenience wrapper library around Erlang's global
module to ensure
a single instance of a process is kept running on a cluster of nodes.
The package can be installed as:
- Add
singleton
to your list of dependencies inmix.exs
:
def deps do
[{:singleton, "~> 1.0.0"}]
end
- Ensure
Singleton.Supervisor
is added to your application's supervision tree:
If your application includes a supervision tree in application.ex
, you can simply add Singleton.Supervisor
to the list of children.
children = [
# ...,
{Singleton.Supervisor, name: MyApp.Sinlgeton}
]
supervisor = Supervisor.start_link(children, opts)
Use Singleton.start_child/3
to start a unique GenServer process.
Singleton.start_child(MyApp.Sinlgeton, MyServer, [1], {:myserver, 1})
Execute this command on all nodes. The MyServer
GenServer is now
globally registered under the name {:global, {:myserver, 1}}
.
As soon as you connect nodes together, you'll see logger messages like:
04:56:29.003 [info] global: Name conflict terminating {MyServer, #PID<12501.68.0>}
When you now stop (or disconnect) the node on which the singleton process runs, you'll see it get started on one of the other nodes.