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#
# lkn.core: an entity-component-system (ecs) implementation for lyxan
# Copyright (C) 2017 Thomas Letan <contact@thomasletan.fr>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
defmodule Lkn.Core.Pool.Supervisor do
@moduledoc false
use Supervisor
@name Lkn.Core.Pool.Supervisor
def start_link(_arg \\ []) do
Supervisor.start_link(__MODULE__, [], name: @name)
end
def init(_) do
children = [
supervisor(Lkn.Core.Pool, [])
]
supervise(children, strategy: :simple_one_for_one)
end
end
defmodule Lkn.Core.Pool.GenServer do
@moduledoc false
require Logger
alias Lkn.Core, as: L
alias Lkn.Core.Instance
alias Lkn.Core.Name
alias Lkn.Core.Puppeteer
use GenServer
defmodule State do
@moduledoc false
defstruct [
:map_key,
:instances,
]
@type t :: %State{
map_key: L.Map.k,
instances: [Instance.k],
}
@spec new(L.Map.k) :: t
def new(map_key) do
%State{
map_key: map_key,
instances: [],
}
end
@spec supervise?(t, Instance.k) :: boolean
def supervise?(state, instance_key) do
Enum.member?(state.instances, instance_key)
end
@spec add_instance(t, Instance.k) :: t
def add_instance(state, instance_key) do
%State{state|instances: [instance_key|state.instances]}
end
@spec remove_instance(t, Instance.k) :: t
def remove_instance(state, instance_key) do
%State{state|instances: List.delete(state.instances, instance_key)}
end
@spec find_instance(t, Puppeteer.k, Puppeteer.m) :: {t, Instance.k}
def find_instance(state, puppeteer_key, puppeteer_mod) do
find_instance_or_spawn(state, state.instances, puppeteer_key, puppeteer_mod)
end
@spec find_instance_or_spawn(t, [Instance.k], Puppeteer.k, Puppeteer.m) :: {t, Instance.k}
defp find_instance_or_spawn(state, [instance_key|instances], puppeteer_key, puppeteer_mod) do
if Instance.register_puppeteer(instance_key, puppeteer_key, puppeteer_mod) do
{state, instance_key}
else
find_instance_or_spawn(state, instances, puppeteer_key, puppeteer_mod)
end
end
defp find_instance_or_spawn(state, [], puppeteer_key, puppeteer_mod) do
instance_key = UUID.uuid4()
{:ok, _} = Instance.spawn_instance(state.map_key, instance_key)
if !Instance.register_puppeteer(instance_key, puppeteer_key, puppeteer_mod) do
Logger.error("[lkn.core]: [Pool(#{inspect(state.map_key)})] spawns an instance that refuses to register a new puppeteer")
raise "New spawned instance refuses to register a new puppeteer"
end
{add_instance(state, instance_key), instance_key}
end
end
@doc false
def start_link(map_key) do
GenServer.start_link(__MODULE__, map_key, name: Name.pool(map_key))
end
def init(map_key) do
{:ok, State.new(map_key)}
end
def handle_call({:register, puppeteer_key, puppeteer_module}, _from, state) do
{state, instance_key} = State.find_instance(state, puppeteer_key, puppeteer_module)
{:reply, instance_key, state}
end
def handle_cast({:kill_request, instance_key}, state) do
if State.supervise?(state, instance_key) do
if Instance.kill(instance_key) do
{:noreply, State.remove_instance(state, instance_key)}
else
{:noreply, state}
end
else
Logger.warn("[lkn.core]: [Pool(#{inspect state.map_key})] receives a request to kill [Instance(#{inspect instance_key})] but it does not supervise it.")
{:noreply, state}
end
end
end
defmodule Lkn.Core.Pool do
use Supervisor
@moduledoc """
A specialized Supervisor which spawns new Map Instance when required.
"""
alias Lkn.Core.Name
@doc false
def start_link(map_key) do
Supervisor.start_link(__MODULE__, map_key)
end
def init(map_key) do
children = [
supervisor(Lkn.Core.Instance.Supervisor, [map_key]),
worker(Lkn.Core.Pool.GenServer, [map_key]),
]
supervise(children, strategy: :one_for_all)
end
@doc false
@spec kill_request(L.Map.k, Instance.k) :: :ok
def kill_request(map_key, instance_key) do
GenServer.cast(Name.pool(map_key), {:kill_request, instance_key})
end
@doc """
Register a given Puppeteer to an Instance of a given Map.
If required, the Pool will spawn a new Instance, so the Puppeteer do not have
to worry about that. The Pool will return the Instance key.
"""
@spec register_puppeteer(Lkn.Core.Map.k, Lkn.Core.Puppeteer.k, Lkn.Core.Puppeteer.m) :: Lkn.Core.Instance.k
def register_puppeteer(map_key, puppeteer_key, puppeteer_module) do
instance_key = GenServer.call(Name.pool(map_key), {:register, puppeteer_key, puppeteer_module})
Registry.register(Lkn.Core.Notifier, Name.notify_group(instance_key), puppeteer_key)
instance_key
end
@doc """
Spwans a new Instances Pool for a given `Lkn.Core.Map`.
The Map is expected to be alive before this function is called. After that, it
is possible for a Puppeteer to join an Instance of this Map using
`register_puppeteer`.
__Note:__ The Pool lives inside a dedicated Supervisor tree.
"""
@spec spawn_pool(Lkn.Core.Map.k) :: :ok
def spawn_pool(map_key) do
{:ok, _} = Supervisor.start_child(Lkn.Core.Pool.Supervisor, [map_key])
:ok
end
end
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