The scaffold implementation to dynamically manage many similar tasks running as processes.

It creates a main supervisor, managing the GenServer holding the state and DynamicSupervisor handling chidren. It has a strategy :rest_for_one, assuming that if the process holding the state crashes, the children will be restarted.

Typically one calls use Tarearbol.DynamicManager and implements at least children_specs/0 callback and receives back supervised tree with a state and many processes controlled by DynamicSupervisor.

To see how it works you might try

defmodule DynamicManager do
  use Tarearbol.DynamicManager

  def children_specs do
    for i <- 1..10, do: {"foo_#{i}", []}, into: %{}
  end
end

{:ok, pid} = DynamicManager.start_link()

The above would spawn 10 children with IDs "foo_1".."foo_10".

Workers Management

DynamicManager allows dynamic workers management. It exports three functions

@spec get(id :: id()) :: Enum.t()
@spec put(id :: id(), opts :: Enum.t()) :: pid()
@spec del(id :: id()) :: :ok
@spec restart(id :: id()) :: :ok

The semantics of put/2 arguments is the same as a single child_spec, del/1 and get/1 receive the unique ID of the child and shutdown it or return it’s payload respectively.

Workers Callbacks

Workers are allowed to implement several callbacks to be used to pass messages to them.

• peform/2 is called periodically by the library internals; the interval is set upon worker initialization via children_specs/1 (static) or put/2 (dynamic); the interval set to 0 suppresses periodic invocations
• call/3 to handle synchronous message send to worker
• cast/2 to handle asynchronous message send to worker
• terminate/2 to handle worker process termination

All the above should return a value of Tarearbol.DynamicManager.response/0 type.

Also, the implementing module might use a custom initialization function to e. g. dynamically build payload. Is should be passed to use DynamicManager as a parameter init: handler and might be a tuple {module(), function(), arity()} or a captured function &MyMod.my_init/1. Arities 0, 1 and 2 are allowed, as described by Tarearbol.DynamicManager.init_handler/0 type.

The worker process will call this function from GenServer.handle_continue/2 callback.