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defmodule Nola.Plugins do
require Logger
defmodule Supervisor do
use DynamicSupervisor
require Logger
def start_link() do
DynamicSupervisor.start_link(__MODULE__, [], name: __MODULE__)
end
def start_child(module, opts \\ []) do
Logger.info("Starting #{module}")
spec = %{id: {__MODULE__,module}, start: {__MODULE__, :start_link, [module, opts]}, name: module, restart: :transient}
case DynamicSupervisor.start_child(__MODULE__, spec) do
{:ok, _} = res -> res
:ignore ->
Logger.warn("Ignored #{module}")
:ignore
{:error,_} = res ->
Logger.error("Could not start #{module}: #{inspect(res, pretty: true)}")
res
end
end
@impl true
def init(_init_arg) do
DynamicSupervisor.init(
strategy: :one_for_one,
max_restarts: 10,
max_seconds: 1
)
end
end
def dets(), do: to_charlist(Nola.data_path("/plugins.dets"))
def setup() do
:dets.open_file(dets(), [])
end
def enabled() do
:dets.foldl(fn
{name, true, _}, acc -> [name | acc]
_, acc -> acc
end, [], dets())
end
def start_all() do
for mod <- enabled(), do: {mod, __MODULE__.Supervisor.start_child(mod)}
end
def declare(module) do
case get(module) do
:disabled -> :dets.insert(dets(), {module, true, nil})
_ -> nil
end
end
def start(module, opts \\ []) do
__MODULE__.Supervisor.start_child(module)
end
@doc "Enables a plugin"
def enable(name), do: switch(name, true)
@doc "Disables a plugin"
def disable(name), do: switch(name, false)
@doc "Enables or disables a plugin"
def switch(name, value) when is_boolean(value) do
last = case get(name) do
{:ok, last} -> last
_ -> nil
end
:dets.insert(dets(), {name, value, last})
end
@spec get(module()) :: {:ok, last_start :: nil | non_neg_integer()} | :disabled
def get(name) do
case :dets.lookup(dets(), name) do
[{name, enabled, last_start}] -> {:ok, enabled, last_start}
_ -> :disabled
end
end
def start_link(module, options \\ []) do
with {:disabled, {_, true, last}} <- {:disabled, get(module)},
{:throttled, false} <- {:throttled, false}
do
module.start_link()
else
{error, _} ->
Logger.info("#{__MODULE__}: #{to_string(module)} ignored start: #{to_string(error)}")
:ignore
end
end
end
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