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fixpoint lib solver variables registry_variable.ex
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lib/solver/variables/registry_variable.ex

defmodule CPSolver.Variable.Agent do
alias CPSolver.DefaultDomain, as: Domain
alias CPSolver.Store.Registry, as: StoreRegistry
alias CPSolver.Variable
alias CPSolver.Utils
require Logger
@behaviour GenServer
def create(%{id: id} = variable) do
{:ok, _} = Registry.register(StoreRegistry, id, self())
{:ok, _pid} =
GenServer.start_link(__MODULE__, variable, name: StoreRegistry.variable_proc_id(variable))
end
def dispose(variable) do
topic = {variable, variable.id}
Enum.each(Utils.subscribers(topic), fn s -> Utils.unsubscribe(s, topic) end)
GenServer.cast(StoreRegistry.variable_proc_id(variable), :dispose)
end
def alive?(variable) do
case GenServer.whereis(StoreRegistry.variable_proc_id(variable)) do
nil -> false
pid -> Process.alive?(pid)
end
end
@impl true
@spec init(atom | %{:domain => any, optional(any) => any}) :: {:ok, :gb_sets.set(any)}
def init(variable) do
{:ok, Domain.new(variable.domain)}
end
def operation(var, operation, args \\ []) do
GenServer.call(StoreRegistry.variable_proc_id(var), {var, operation, args})
end
@impl true
def handle_call({var, op, _args}, _from, :fail) do
handle_op_on_failed_var(var, op)
{:reply, :fail, :fail}
end
## Read ops
def handle_call({_var, :domain, _args}, _from, domain) do
{:reply, domain, domain}
end
def handle_call({_var, op, args}, _from, domain)
when op in [:size, :fixed?, :min, :max, :contains?] do
{:reply, apply(Domain, op, [domain | args]), domain}
end
## Write ops
def handle_call({var, op, args}, _from, domain)
when op in [:remove, :removeAbove, :removeBelow, :fix] do
{result, updated_domain} =
case apply(Domain, op, [domain | args]) do
:fail ->
{:fail, :fail}
|> tap(fn _ -> handle_failure(var) end)
:none ->
{:no_change, domain}
|> tap(fn _ -> handle_domain_no_change(var) end)
{domain_change, new_domain} ->
{domain_change, new_domain}
|> tap(fn _ -> handle_domain_change(domain_change, var, new_domain) end)
end
{:reply, result, updated_domain}
end
@impl true
def handle_cast(:dispose, state) do
{:stop, :normal, state}
end
defp handle_op_on_failed_var(var, operation) do
Logger.warning(
"Attempt to request #{inspect(operation)} on failed variable #{inspect(var.id)}"
)
end
defp handle_failure(var) do
Logger.debug("Failure for variable #{inspect(var.id)}")
## TODO: notify space (and maybe don't notify propagators)
publish(var, {:fail, var.id})
end
defp handle_domain_no_change(_var) do
:ok
end
defp handle_domain_change(domain_change, var, _domain) do
publish(var, {domain_change, var.id})
|> tap(fn _ ->
Logger.debug("Domain change (#{domain_change}) for #{inspect(var.id)}")
maybe_unsubscribe_all(domain_change, var)
end)
end
defp publish(var, message) do
Variable.publish(var, message)
end
defp maybe_unsubscribe_all(:fixed, var) do
Enum.each(Variable.subscribers(var), fn pid -> Variable.unsubscribe(pid, var) end)
end
defp maybe_unsubscribe_all(_, _var) do
:ok
end
end