906 lines
27 KiB
Elixir
906 lines
27 KiB
Elixir
defmodule GenEvent do
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# Functions from this module are deprecated in elixir_dispatch.
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@moduledoc """
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An event manager with event handlers behaviour.
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If you are interested in implementing an event manager, please read the
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"Alternatives" section below. If you have to implement an event handler to
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integrate with an existing system, such as Elixir's Logger, please use
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[`:gen_event`](`:gen_event`) instead.
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## Alternatives
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There are a few suitable alternatives to replace GenEvent. Each of them can be
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the most beneficial based on the use case.
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### Supervisor and GenServers
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One alternative to GenEvent is a very minimal solution consisting of using a
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supervisor and multiple GenServers started under it. The supervisor acts as
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the "event manager" and the children GenServers act as the "event handlers".
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This approach has some shortcomings (it provides no back-pressure for example)
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but can still replace GenEvent for low-profile usages of it. [This blog post
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by José
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Valim](https://dashbit.co/blog/replacing-genevent-by-a-supervisor-plus-genserver)
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has more detailed information on this approach.
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### GenStage
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If the use case where you were using GenEvent requires more complex logic,
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[GenStage](https://github.com/elixir-lang/gen_stage) provides a great
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alternative. GenStage is an external Elixir library maintained by the Elixir
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team; it provides a tool to implement systems that exchange events in a
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demand-driven way with built-in support for back-pressure. See the [GenStage
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documentation](https://hexdocs.pm/gen_stage) for more information.
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### `:gen_event`
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If your use case requires exactly what GenEvent provided, or you have to
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integrate with an existing `:gen_event`-based system, you can still use the
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[`:gen_event`](`:gen_event`) Erlang module.
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"""
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@moduledoc deprecated: "Use Erlang/OTP's :gen_event module instead"
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@callback init(args :: term) ::
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{:ok, state}
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| {:ok, state, :hibernate}
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| {:error, reason :: any}
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when state: any
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@callback handle_event(event :: term, state :: term) ::
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{:ok, new_state}
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| {:ok, new_state, :hibernate}
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| :remove_handler
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when new_state: term
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@callback handle_call(request :: term, state :: term) ::
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{:ok, reply, new_state}
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| {:ok, reply, new_state, :hibernate}
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| {:remove_handler, reply}
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when reply: term, new_state: term
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@callback handle_info(msg :: term, state :: term) ::
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{:ok, new_state}
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| {:ok, new_state, :hibernate}
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| :remove_handler
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when new_state: term
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@callback terminate(reason, state :: term) :: term
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when reason: :stop | {:stop, term} | :remove_handler | {:error, term} | term
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@callback code_change(old_vsn, state :: term, extra :: term) :: {:ok, new_state :: term}
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when old_vsn: term | {:down, term}
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@type on_start :: {:ok, pid} | {:error, {:already_started, pid}}
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@type name :: atom | {:global, term} | {:via, module, term}
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@type options :: [name: name]
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@type manager :: pid | name | {atom, node}
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@type handler :: atom | {atom, term}
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message = "Use one of the alternatives described in the documentation for the GenEvent module"
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@deprecated message
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@doc false
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defmacro __using__(_) do
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deprecation_message =
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"the GenEvent module is deprecated, see its documentation for alternatives"
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IO.warn(deprecation_message, __CALLER__)
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quote location: :keep do
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@behaviour :gen_event
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@doc false
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def init(args) do
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{:ok, args}
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end
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@doc false
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def handle_event(_event, state) do
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{:ok, state}
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end
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@doc false
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def handle_call(msg, state) do
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proc =
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case Process.info(self(), :registered_name) do
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{_, []} -> self()
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{_, name} -> name
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end
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# We do this to trick Dialyzer to not complain about non-local returns.
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case :erlang.phash2(1, 1) do
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0 ->
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raise "attempted to call GenEvent #{inspect(proc)} but no handle_call/2 clause was provided"
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1 ->
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{:remove_handler, {:bad_call, msg}}
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end
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end
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@doc false
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def handle_info(_msg, state) do
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{:ok, state}
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end
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@doc false
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def terminate(_reason, _state) do
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:ok
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end
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@doc false
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def code_change(_old, state, _extra) do
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{:ok, state}
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end
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defoverridable init: 1,
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handle_event: 2,
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handle_call: 2,
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handle_info: 2,
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terminate: 2,
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code_change: 3
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end
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end
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@doc false
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@deprecated message
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@spec start_link(options) :: on_start
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def start_link(options \\ []) when is_list(options) do
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do_start(:link, options)
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end
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@doc false
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@deprecated message
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@spec start(options) :: on_start
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def start(options \\ []) when is_list(options) do
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do_start(:nolink, options)
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end
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@no_callback :"no callback module"
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defp do_start(mode, options) do
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case Keyword.get(options, :name) do
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nil ->
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:gen.start(GenEvent, mode, @no_callback, [], [])
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atom when is_atom(atom) ->
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:gen.start(GenEvent, mode, {:local, atom}, @no_callback, [], [])
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{:global, _term} = tuple ->
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:gen.start(GenEvent, mode, tuple, @no_callback, [], [])
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{:via, via_module, _term} = tuple when is_atom(via_module) ->
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:gen.start(GenEvent, mode, tuple, @no_callback, [], [])
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other ->
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raise ArgumentError, """
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expected :name option to be one of the following:
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* nil
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* atom
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* {:global, term}
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* {:via, module, term}
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Got: #{inspect(other)}
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"""
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end
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end
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@doc false
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@deprecated message
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@spec stream(manager, keyword) :: GenEvent.Stream.t()
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def stream(manager, options \\ []) do
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%GenEvent.Stream{manager: manager, timeout: Keyword.get(options, :timeout, :infinity)}
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end
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@doc false
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@deprecated message
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@spec add_handler(manager, handler, term) :: :ok | {:error, term}
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def add_handler(manager, handler, args) do
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rpc(manager, {:add_handler, handler, args})
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end
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@doc false
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@deprecated message
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@spec add_mon_handler(manager, handler, term) :: :ok | {:error, term}
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def add_mon_handler(manager, handler, args) do
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rpc(manager, {:add_mon_handler, handler, args, self()})
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end
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@doc false
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@deprecated message
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@spec notify(manager, term) :: :ok
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def notify(manager, event)
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def notify({:global, name}, msg) do
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try do
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:global.send(name, {:notify, msg})
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:ok
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catch
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_, _ -> :ok
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end
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end
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def notify({:via, mod, name}, msg) when is_atom(mod) do
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try do
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mod.send(name, {:notify, msg})
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:ok
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catch
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_, _ -> :ok
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end
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end
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def notify(manager, msg)
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when is_pid(manager)
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when is_atom(manager)
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when tuple_size(manager) == 2 and is_atom(elem(manager, 0)) and is_atom(elem(manager, 1)) do
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send(manager, {:notify, msg})
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:ok
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end
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@doc false
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@deprecated message
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@spec sync_notify(manager, term) :: :ok
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def sync_notify(manager, event) do
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rpc(manager, {:sync_notify, event})
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end
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@doc false
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@deprecated message
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@spec ack_notify(manager, term) :: :ok
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def ack_notify(manager, event) do
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rpc(manager, {:ack_notify, event})
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end
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@doc false
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@deprecated message
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@spec call(manager, handler, term, timeout) :: term | {:error, term}
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def call(manager, handler, request, timeout \\ 5000) do
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try do
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:gen.call(manager, self(), {:call, handler, request}, timeout)
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catch
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:exit, reason ->
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exit({reason, {__MODULE__, :call, [manager, handler, request, timeout]}})
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else
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{:ok, res} -> res
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end
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end
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@doc false
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@deprecated message
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@spec remove_handler(manager, handler, term) :: term | {:error, term}
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def remove_handler(manager, handler, args) do
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rpc(manager, {:delete_handler, handler, args})
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end
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@doc false
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@deprecated message
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@spec swap_handler(manager, handler, term, handler, term) :: :ok | {:error, term}
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def swap_handler(manager, handler1, args1, handler2, args2) do
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rpc(manager, {:swap_handler, handler1, args1, handler2, args2})
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end
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@doc false
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@deprecated message
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@spec swap_mon_handler(manager, handler, term, handler, term) :: :ok | {:error, term}
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def swap_mon_handler(manager, handler1, args1, handler2, args2) do
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rpc(manager, {:swap_mon_handler, handler1, args1, handler2, args2, self()})
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end
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@doc false
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@deprecated message
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@spec which_handlers(manager) :: [handler]
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def which_handlers(manager) do
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rpc(manager, :which_handlers)
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end
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@doc false
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@deprecated message
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@spec stop(manager, reason :: term, timeout) :: :ok
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def stop(manager, reason \\ :normal, timeout \\ :infinity) do
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:gen.stop(manager, reason, timeout)
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end
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defp rpc(module, cmd) do
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{:ok, reply} = :gen.call(module, self(), cmd, :infinity)
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reply
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end
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## Init callbacks
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require Record
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Record.defrecordp(:handler, [:module, :id, :state, :pid, :ref])
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@doc false
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def init_it(starter, :self, name, mod, args, options) do
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init_it(starter, self(), name, mod, args, options)
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end
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def init_it(starter, parent, name, _mod, _args, options) do
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Process.put(:"$initial_call", {__MODULE__, :init_it, 6})
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debug = :gen.debug_options(name, options)
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:proc_lib.init_ack(starter, {:ok, self()})
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loop(parent, name(name), [], debug, false)
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end
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@doc false
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def init_hib(parent, name, handlers, debug) do
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fetch_msg(parent, name, handlers, debug, true)
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end
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defp name({:local, name}), do: name
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defp name({:global, name}), do: name
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defp name({:via, _, name}), do: name
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defp name(pid) when is_pid(pid), do: pid
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## Loop
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defp loop(parent, name, handlers, debug, true) do
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:proc_lib.hibernate(__MODULE__, :init_hib, [parent, name, handlers, debug])
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end
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defp loop(parent, name, handlers, debug, false) do
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fetch_msg(parent, name, handlers, debug, false)
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end
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defp fetch_msg(parent, name, handlers, debug, hib) do
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receive do
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{:system, from, req} ->
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:sys.handle_system_msg(req, from, parent, __MODULE__, debug, [name, handlers, hib], hib)
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{:EXIT, ^parent, reason} ->
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server_terminate(reason, parent, handlers, name)
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msg when debug == [] ->
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handle_msg(msg, parent, name, handlers, [])
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msg ->
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debug = :sys.handle_debug(debug, &print_event/3, name, {:in, msg})
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handle_msg(msg, parent, name, handlers, debug)
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end
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end
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defp handle_msg(msg, parent, name, handlers, debug) do
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case msg do
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{:notify, event} ->
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{hib, handlers} = server_event(:async, event, handlers, name)
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loop(parent, name, handlers, debug, hib)
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{_from, _tag, {:notify, event}} ->
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{hib, handlers} = server_event(:async, event, handlers, name)
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loop(parent, name, handlers, debug, hib)
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{_from, tag, {:ack_notify, event}} ->
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reply(tag, :ok)
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{hib, handlers} = server_event(:ack, event, handlers, name)
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loop(parent, name, handlers, debug, hib)
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{_from, tag, {:sync_notify, event}} ->
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{hib, handlers} = server_event(:sync, event, handlers, name)
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reply(tag, :ok)
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loop(parent, name, handlers, debug, hib)
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{:DOWN, ref, :process, _pid, reason} = other ->
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case handle_down(ref, reason, handlers, name) do
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{:ok, handlers} ->
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loop(parent, name, handlers, debug, false)
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:error ->
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{hib, handlers} = server_info(other, handlers, name)
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loop(parent, name, handlers, debug, hib)
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end
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{_from, tag, {:call, handler, query}} ->
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{hib, reply, handlers} = server_call(handler, query, handlers, name)
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reply(tag, reply)
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loop(parent, name, handlers, debug, hib)
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{_from, tag, {:add_handler, handler, args}} ->
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{hib, reply, handlers} = server_add_handler(handler, args, handlers)
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reply(tag, reply)
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loop(parent, name, handlers, debug, hib)
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{_from, tag, {:add_mon_handler, handler, args, notify}} ->
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{hib, reply, handlers} = server_add_mon_handler(handler, args, handlers, notify)
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reply(tag, reply)
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loop(parent, name, handlers, debug, hib)
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{_from, tag, {:add_process_handler, pid, notify}} ->
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{hib, reply, handlers} = server_add_process_handler(pid, handlers, notify)
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reply(tag, reply)
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loop(parent, name, handlers, debug, hib)
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{_from, tag, {:delete_handler, handler, args}} ->
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{reply, handlers} = server_remove_handler(handler, args, handlers, name)
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reply(tag, reply)
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loop(parent, name, handlers, debug, false)
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{_from, tag, {:swap_handler, handler1, args1, handler2, args2}} ->
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{hib, reply, handlers} =
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server_swap_handler(handler1, args1, handler2, args2, handlers, nil, name)
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reply(tag, reply)
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loop(parent, name, handlers, debug, hib)
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{_from, tag, {:swap_mon_handler, handler1, args1, handler2, args2, mon}} ->
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{hib, reply, handlers} =
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server_swap_handler(handler1, args1, handler2, args2, handlers, mon, name)
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reply(tag, reply)
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loop(parent, name, handlers, debug, hib)
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{_from, tag, :which_handlers} ->
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reply(tag, server_which_handlers(handlers))
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loop(parent, name, handlers, debug, false)
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{_from, tag, :get_modules} ->
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reply(tag, server_get_modules(handlers))
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loop(parent, name, handlers, debug, false)
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other ->
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{hib, handlers} = server_info(other, handlers, name)
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loop(parent, name, handlers, debug, hib)
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end
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end
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## System callbacks
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@doc false
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def system_continue(parent, debug, [name, handlers, hib]) do
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loop(parent, name, handlers, debug, hib)
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end
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@doc false
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def system_terminate(reason, parent, _debug, [name, handlers, _hib]) do
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server_terminate(reason, parent, handlers, name)
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end
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@doc false
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def system_code_change([name, handlers, hib], module, old_vsn, extra) do
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handlers =
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for handler <- handlers do
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if handler(handler, :module) == module do
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{:ok, state} = module.code_change(old_vsn, handler(handler, :state), extra)
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handler(handler, state: state)
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else
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handler
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end
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end
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{:ok, [name, handlers, hib]}
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end
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@doc false
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def system_get_state([_name, handlers, _hib]) do
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tuples =
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for handler(module: mod, id: id, state: state) <- handlers do
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{mod, id, state}
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end
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{:ok, tuples}
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end
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@doc false
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def system_replace_state(fun, [name, handlers, hib]) do
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{handlers, states} =
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:lists.unzip(
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for handler <- handlers do
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handler(module: mod, id: id, state: state) = handler
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cur = {mod, id, state}
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try do
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new = {^mod, ^id, new_state} = fun.(cur)
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{handler(handler, state: new_state), new}
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catch
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_, _ ->
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{handler, cur}
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end
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end
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)
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{:ok, states, [name, handlers, hib]}
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end
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# Keeping deprecated format_status/2 since the current implementation is not
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# compatible with format_status/1 and GenEvent is deprecated anyway
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@doc false
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def format_status(opt, status_data) do
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[pdict, sys_state, parent, _debug, [name, handlers, _hib]] = status_data
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header = :gen.format_status_header(~c"Status for event handler", name)
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formatted =
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for handler <- handlers do
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handler(module: module, state: state) = handler
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if function_exported?(module, :format_status, 2) do
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try do
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state = module.format_status(opt, [pdict, state])
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handler(handler, state: state)
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catch
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_, _ -> handler
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end
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else
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handler
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end
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end
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[
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header: header,
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data: [{~c"Status", sys_state}, {~c"Parent", parent}],
|
|
items: {~c"Installed handlers", formatted}
|
|
]
|
|
end
|
|
|
|
## Loop helpers
|
|
|
|
defp print_event(dev, {:in, msg}, name) do
|
|
case msg do
|
|
{:notify, event} ->
|
|
IO.puts(dev, "*DBG* #{inspect(name)} got event #{inspect(event)}")
|
|
|
|
{_, _, {:call, handler, query}} ->
|
|
IO.puts(
|
|
dev,
|
|
"*DBG* #{inspect(name)} (handler #{inspect(handler)}) got call #{inspect(query)}"
|
|
)
|
|
|
|
_ ->
|
|
IO.puts(dev, "*DBG* #{inspect(name)} got #{inspect(msg)}")
|
|
end
|
|
end
|
|
|
|
defp print_event(dev, dbg, name) do
|
|
IO.puts(dev, "*DBG* #{inspect(name)}: #{inspect(dbg)}")
|
|
end
|
|
|
|
defp server_add_handler({module, id}, args, handlers) do
|
|
handler = handler(module: module, id: {module, id})
|
|
do_add_handler(module, handler, args, handlers, :ok)
|
|
end
|
|
|
|
defp server_add_handler(module, args, handlers) do
|
|
handler = handler(module: module, id: module)
|
|
do_add_handler(module, handler, args, handlers, :ok)
|
|
end
|
|
|
|
defp server_add_mon_handler({module, id}, args, handlers, notify) do
|
|
ref = Process.monitor(notify)
|
|
handler = handler(module: module, id: {module, id}, pid: notify, ref: ref)
|
|
do_add_handler(module, handler, args, handlers, :ok)
|
|
end
|
|
|
|
defp server_add_mon_handler(module, args, handlers, notify) do
|
|
ref = Process.monitor(notify)
|
|
handler = handler(module: module, id: module, pid: notify, ref: ref)
|
|
do_add_handler(module, handler, args, handlers, :ok)
|
|
end
|
|
|
|
defp server_add_process_handler(pid, handlers, notify) do
|
|
ref = Process.monitor(pid)
|
|
handler = handler(module: GenEvent.Stream, id: {self(), ref}, pid: notify, ref: ref)
|
|
do_add_handler(GenEvent.Stream, handler, {pid, ref}, handlers, {self(), ref})
|
|
end
|
|
|
|
defp server_remove_handler(module, args, handlers, name) do
|
|
do_take_handler(module, args, handlers, name, :remove, :normal)
|
|
end
|
|
|
|
defp server_swap_handler(module1, args1, module2, args2, handlers, sup, name) do
|
|
{state, handlers} =
|
|
do_take_handler(module1, args1, handlers, name, :swapped, {:swapped, module2, sup})
|
|
|
|
if sup do
|
|
server_add_mon_handler(module2, {args2, state}, handlers, sup)
|
|
else
|
|
server_add_handler(module2, {args2, state}, handlers)
|
|
end
|
|
end
|
|
|
|
defp server_info(event, handlers, name) do
|
|
handlers = :lists.reverse(handlers)
|
|
server_notify(event, :handle_info, handlers, name, handlers, [], false)
|
|
end
|
|
|
|
defp server_event(mode, event, handlers, name) do
|
|
{handlers, streams} = server_split_process_handlers(mode, event, handlers, [], [])
|
|
{hib, handlers} = server_notify(event, :handle_event, handlers, name, handlers, [], false)
|
|
{hib, server_collect_process_handlers(mode, event, streams, handlers, name)}
|
|
end
|
|
|
|
defp server_split_process_handlers(mode, event, [handler | t], handlers, streams) do
|
|
case handler(handler, :id) do
|
|
{pid, _ref} when is_pid(pid) ->
|
|
server_process_notify(mode, event, handler)
|
|
server_split_process_handlers(mode, event, t, handlers, [handler | streams])
|
|
|
|
_ ->
|
|
server_split_process_handlers(mode, event, t, [handler | handlers], streams)
|
|
end
|
|
end
|
|
|
|
defp server_split_process_handlers(_mode, _event, [], handlers, streams) do
|
|
{handlers, streams}
|
|
end
|
|
|
|
defp server_process_notify(mode, event, handler(state: {pid, ref})) do
|
|
send(pid, {self(), {self(), ref}, {mode_to_tag(mode), event}})
|
|
end
|
|
|
|
defp mode_to_tag(:ack), do: :ack_notify
|
|
defp mode_to_tag(:sync), do: :sync_notify
|
|
defp mode_to_tag(:async), do: :notify
|
|
|
|
defp server_notify(event, fun, [handler | t], name, handlers, acc, hib) do
|
|
case server_update(handler, fun, event, name, handlers) do
|
|
{new_hib, handler} ->
|
|
server_notify(event, fun, t, name, handlers, [handler | acc], hib or new_hib)
|
|
|
|
:error ->
|
|
server_notify(event, fun, t, name, handlers, acc, hib)
|
|
end
|
|
end
|
|
|
|
defp server_notify(_, _, [], _, _, acc, hib) do
|
|
{hib, acc}
|
|
end
|
|
|
|
defp server_update(handler, fun, event, name, _handlers) do
|
|
handler(module: module, state: state) = handler
|
|
|
|
case do_handler(module, fun, [event, state]) do
|
|
{:ok, res} ->
|
|
case res do
|
|
{:ok, state} ->
|
|
{false, handler(handler, state: state)}
|
|
|
|
{:ok, state, :hibernate} ->
|
|
{true, handler(handler, state: state)}
|
|
|
|
:remove_handler ->
|
|
do_terminate(handler, :remove_handler, event, name, :normal)
|
|
:error
|
|
|
|
other ->
|
|
reason = {:bad_return_value, other}
|
|
do_terminate(handler, {:error, reason}, event, name, reason)
|
|
:error
|
|
end
|
|
|
|
{:error, reason} ->
|
|
do_terminate(handler, {:error, reason}, event, name, reason)
|
|
:error
|
|
end
|
|
end
|
|
|
|
defp server_collect_process_handlers(:async, event, [handler | t], handlers, name) do
|
|
server_collect_process_handlers(:async, event, t, [handler | handlers], name)
|
|
end
|
|
|
|
defp server_collect_process_handlers(mode, event, [handler | t], handlers, name)
|
|
when mode in [:sync, :ack] do
|
|
handler(ref: ref, id: id) = handler
|
|
|
|
receive do
|
|
{^ref, :ok} ->
|
|
server_collect_process_handlers(mode, event, t, [handler | handlers], name)
|
|
|
|
{_from, tag, {:delete_handler, ^id, args}} ->
|
|
do_terminate(handler, args, :remove, name, :normal)
|
|
reply(tag, :ok)
|
|
server_collect_process_handlers(mode, event, t, handlers, name)
|
|
|
|
{:DOWN, ^ref, _, _, reason} ->
|
|
do_terminate(handler, {:stop, reason}, :DOWN, name, :shutdown)
|
|
server_collect_process_handlers(mode, event, t, handlers, name)
|
|
end
|
|
end
|
|
|
|
defp server_collect_process_handlers(_mode, _event, [], handlers, _name) do
|
|
handlers
|
|
end
|
|
|
|
defp server_call(module, query, handlers, name) do
|
|
case :lists.keyfind(module, handler(:id) + 1, handlers) do
|
|
false ->
|
|
{false, {:error, :not_found}, handlers}
|
|
|
|
handler ->
|
|
case server_call_update(handler, query, name, handlers) do
|
|
{{hib, handler}, reply} ->
|
|
{hib, reply, :lists.keyreplace(module, handler(:id) + 1, handlers, handler)}
|
|
|
|
{:error, reply} ->
|
|
{false, reply, :lists.keydelete(module, handler(:id) + 1, handlers)}
|
|
end
|
|
end
|
|
end
|
|
|
|
defp server_call_update(handler, query, name, _handlers) do
|
|
handler(module: module, state: state) = handler
|
|
|
|
case do_handler(module, :handle_call, [query, state]) do
|
|
{:ok, res} ->
|
|
case res do
|
|
{:ok, reply, state} ->
|
|
{{false, handler(handler, state: state)}, reply}
|
|
|
|
{:ok, reply, state, :hibernate} ->
|
|
{{true, handler(handler, state: state)}, reply}
|
|
|
|
{:remove_handler, reply} ->
|
|
do_terminate(handler, :remove_handler, query, name, :normal)
|
|
{:error, reply}
|
|
|
|
other ->
|
|
reason = {:bad_return_value, other}
|
|
do_terminate(handler, {:error, reason}, query, name, reason)
|
|
{:error, {:error, reason}}
|
|
end
|
|
|
|
{:error, reason} ->
|
|
do_terminate(handler, {:error, reason}, query, name, reason)
|
|
{:error, {:error, reason}}
|
|
end
|
|
end
|
|
|
|
defp server_get_modules(handlers) do
|
|
for(handler(module: module) <- handlers, do: module)
|
|
|> :ordsets.from_list()
|
|
|> :ordsets.to_list()
|
|
end
|
|
|
|
defp server_which_handlers(handlers) do
|
|
for handler(id: id) <- handlers, do: id
|
|
end
|
|
|
|
defp server_terminate(reason, _parent, handlers, name) do
|
|
_ =
|
|
for handler <- handlers do
|
|
do_terminate(handler, :stop, :stop, name, :shutdown)
|
|
end
|
|
|
|
exit(reason)
|
|
end
|
|
|
|
defp reply({from, ref}, msg) do
|
|
send(from, {ref, msg})
|
|
end
|
|
|
|
defp handle_down(ref, reason, handlers, name) do
|
|
case :lists.keyfind(ref, handler(:ref) + 1, handlers) do
|
|
false ->
|
|
:error
|
|
|
|
handler ->
|
|
do_terminate(handler, {:stop, reason}, :DOWN, name, :shutdown)
|
|
{:ok, :lists.keydelete(ref, handler(:ref) + 1, handlers)}
|
|
end
|
|
end
|
|
|
|
defp do_add_handler(module, handler, arg, handlers, succ) do
|
|
case :lists.keyfind(handler(handler, :id), handler(:id) + 1, handlers) do
|
|
false ->
|
|
case do_handler(module, :init, [arg]) do
|
|
{:ok, res} ->
|
|
case res do
|
|
{:ok, state} ->
|
|
{false, succ, [handler(handler, state: state) | handlers]}
|
|
|
|
{:ok, state, :hibernate} ->
|
|
{true, succ, [handler(handler, state: state) | handlers]}
|
|
|
|
{:error, _} = error ->
|
|
{false, error, handlers}
|
|
|
|
other ->
|
|
{false, {:error, {:bad_return_value, other}}, handlers}
|
|
end
|
|
|
|
{:error, _} = error ->
|
|
{false, error, handlers}
|
|
end
|
|
|
|
_ ->
|
|
{false, {:error, :already_present}, handlers}
|
|
end
|
|
end
|
|
|
|
defp do_take_handler(module, args, handlers, name, last_in, reason) do
|
|
case :lists.keytake(module, handler(:id) + 1, handlers) do
|
|
{:value, handler, handlers} ->
|
|
{do_terminate(handler, args, last_in, name, reason), handlers}
|
|
|
|
false ->
|
|
{{:error, :not_found}, handlers}
|
|
end
|
|
end
|
|
|
|
defp do_terminate(handler, arg, last_in, name, reason) do
|
|
handler(module: module, state: state) = handler
|
|
|
|
res =
|
|
case do_handler(module, :terminate, [arg, state]) do
|
|
{:ok, res} -> res
|
|
{:error, _} = error -> error
|
|
end
|
|
|
|
report_terminate(handler, reason, state, last_in, name)
|
|
res
|
|
end
|
|
|
|
defp do_handler(mod, fun, args) do
|
|
try do
|
|
apply(mod, fun, args)
|
|
catch
|
|
:throw, val -> {:ok, val}
|
|
:error, val -> {:error, {val, __STACKTRACE__}}
|
|
:exit, val -> {:error, val}
|
|
else
|
|
res -> {:ok, res}
|
|
end
|
|
end
|
|
|
|
defp report_terminate(handler, reason, state, last_in, name) do
|
|
report_error(handler, reason, state, last_in, name)
|
|
|
|
if ref = handler(handler, :ref) do
|
|
Process.demonitor(ref, [:flush])
|
|
end
|
|
|
|
if pid = handler(handler, :pid) do
|
|
send(pid, {:gen_event_EXIT, handler(handler, :id), reason})
|
|
end
|
|
end
|
|
|
|
defp report_error(_handler, :normal, _, _, _), do: :ok
|
|
defp report_error(_handler, :shutdown, _, _, _), do: :ok
|
|
defp report_error(_handler, {:swapped, _, _}, _, _, _), do: :ok
|
|
|
|
defp report_error(handler, reason, state, last_in, name) do
|
|
reason =
|
|
case reason do
|
|
{:undef, [{m, f, a, _} | _] = mfas} ->
|
|
cond do
|
|
:code.is_loaded(m) == false ->
|
|
{:"module could not be loaded", mfas}
|
|
|
|
function_exported?(m, f, length(a)) ->
|
|
reason
|
|
|
|
true ->
|
|
{:"function not exported", mfas}
|
|
end
|
|
|
|
_ ->
|
|
reason
|
|
end
|
|
|
|
formatted = report_status(handler, state)
|
|
|
|
:error_logger.error_msg(
|
|
~c"** gen_event handler ~p crashed.~n" ++
|
|
~c"** Was installed in ~p~n" ++
|
|
~c"** Last event was: ~p~n" ++ ~c"** When handler state == ~p~n" ++ ~c"** Reason == ~p~n",
|
|
[handler(handler, :id), name, last_in, formatted, reason]
|
|
)
|
|
end
|
|
|
|
defp report_status(handler(module: module), state) do
|
|
if function_exported?(module, :format_status, 2) do
|
|
try do
|
|
module.format_status(:terminate, [Process.get(), state])
|
|
catch
|
|
_, _ -> state
|
|
end
|
|
else
|
|
state
|
|
end
|
|
end
|
|
end
|