Support for custom parenting of processes. See rationale for detailed explanation, and docs for reference.
The following example implements a parent GenServer which starts a child task, and handles its termination by starting another task after one second.
defmodule MyParent do
use Parent.GenServer
require Logger
def start_link(_), do: Parent.GenServer.start_link(__MODULE__, nil)
@impl GenServer
def init(_arg) do
start_job(1)
{:ok, nil}
end
@impl GenServer
def handle_info({:start_job, job_number}, state) do
start_job(job_number)
{:noreply, state}
end
def handle_info(other, state), do: super(other, state)
@impl Parent.GenServer
def handle_child_terminated(:job, job_number, _pid, _reason, state) do
Logger.info("job #{job_number} finished")
Process.send_after(self(), {:start_job, job_number + 1}, :timer.seconds(1))
{:noreply, state}
end
defp start_job(job_number) do
Logger.info("starting job #{job_number}")
Parent.start_child(%{
id: :job,
start: {Task, :start_link, [&run_job/0]},
meta: job_number
})
end
defp run_job() do
Logger.info("processing ...")
# simulates random job duration
Process.sleep(:rand.uniform(5000))
end
end
iex> Supervisor.start_link([MyParent], strategy: :one_for_one)
09:26:28.153 [info] starting job 1
09:26:28.156 [info] processing ...
09:26:32.655 [info] job 1 finished
09:26:33.656 [info] starting job 2
09:26:33.656 [info] processing ...
09:26:37.043 [info] job 2 finished
09:26:38.044 [info] starting job 3
09:26:38.044 [info] processing ...
09:26:40.702 [info] job 3 finished
...This library has been used in the production code, but not extensively.