HtPipe prevents the entire Elixir from terminating abnormaly by NIFs.

README.md

AbortNif with HtPipe

HtPipe prevents the entire Elixir from terminating abnormaly by NIFs.

Installation and Usage

1. mix new abort_nif --sup
2. cd abort_nif
3. edit the following files.

• mix.exs
• lib/abort_nif/application.ex
• lib/abort_nif.ex
• Makefile
• libnif.c

4. mix deps.get
5. iex --name main_node --cookie cookie -S mix

Scenario 1

AbortNif has push/1 and pop/0 functions:

iex(main_node@yourhost.local)1> AbortNif.pop()
:empty
iex(main_node@yourhost.local)2> AbortNif.push(1)
:ok
iex(main_node@yourhost.local)3> AbortNif.push(2)
:ok
iex(main_node@yourhost.local)4> AbortNif.pop()  
2
iex(main_node@yourhost.local)5> AbortNif.pop()  
1
iex(main_node@yourhost.local)6> AbortNif.pop()  
:empty

Scenario 2

AbortNif aborts by abort_soft/0 and restart soon by the supervisor. The state will be empty by restarting:

iex(main_node@yourhost.local)1> AbortNif.push(1)
:ok
iex(main_node@yourhost.local)2> AbortNif.push(2)
:ok
iex(main_node@yourhost.local)3> AbortNif.abort_soft()
:ok
iex(main_node@yourhost.local)4> AbortNif.pop()       
:empty

Scenario 3

AbortNif aborts by abort_hard/0 by NIF and restart soon by the supervisor of HtPipe, with some error message from Logger. The state will be empty by restarting

iex(main_node@yourhost.local)1> AbortNif.push(1)
:ok
iex(main_node@yourhost.local)2> AbortNif.push(2)
:ok
iex(main_node@yourhost.local)3> AbortNif.abort_hard()
:ok
iex(main_node@yourhost.local)4> 
05:28:26.650 [error] Process #PID<20680.102.0> on node :"htp_worker_main_node@zackym2air01.local" raised an exception
** (UndefinedFunctionError) function HtPipe.worker/3 is undefined or private
    (ht_pipe 0.1.0-dev) HtPipe.worker(#PID<0.220.0>, 5000, #Function<0.51034852/0 in AbortNif.handle_cast/2>)
05:28:31.759 [error] GenServer AbortNif terminating
** (stop) bad return value: nil
Last message: {:"$gen_cast", :abort_hard}
State: [2, 1]
AbortNif.pop
:empty

abort_nif.ex

defmodule AbortNif do
  require Logger
  use GenServer

  @moduledoc """
  Documentation for `AbortNif`.
  """

  @on_load :load_nif

  @doc false
  def load_nif() do
    nif_file = ~c'#{Application.app_dir(:abort_nif, "priv/libnif")}'

    case :erlang.load_nif(nif_file, 0) do
      :ok -> :ok
      {:error, {:reload, _}} -> :ok
      {:error, reason} -> Logger.error("Failed to load NIF: #{inspect(reason)}")
    end
  end

  def abort_nif(), do: exit(:nif_not_loaded)

  @impl true
  def init(stack) do
    {:ok, stack}
  end

  @impl true
  def handle_call(:pop, _from, [head | tail]) do
    {:reply, head, tail}
  end

  @impl true
  def handle_call(:pop, _from, []) do
    {:reply, :empty, []}
  end

  @impl true
  def handle_cast({:push, element}, state) do
    {:noreply, [element | state]}
  end

  @impl true
  def handle_cast(:abort_soft, _state) do
    exit({:shutdown, :abort_soft})
  end

  @impl true
  def handle_cast(:abort_hard, _state) do
    HtPipe.htp(fn -> abort_nif() end, spawn: :os)
  end

  @spec start_link(maybe_improper_list) :: :ignore | {:error, any} | {:ok, pid}
  def start_link(default) when is_list(default) do
    GenServer.start_link(__MODULE__, default, name: __MODULE__)
  end

  def pop() do
    GenServer.call(__MODULE__, :pop)
  end

  def push(element) do
    GenServer.cast(__MODULE__, {:push, element})
  end

  def abort_soft() do
    GenServer.cast(__MODULE__, :abort_soft)
  end

  def abort_hard() do
    GenServer.cast(__MODULE__, :abort_hard)
  end

  @doc """
  Hello world.

  ## Examples

      iex> AbortNif.hello()
      :world

  """
  def hello do
    :world
  end
end

application.ex

defmodule AbortNif.Application do
  # See https://hexdocs.pm/elixir/Application.html
  # for more information on OTP Applications
  @moduledoc false

  use Application

  @impl true
  def start(_type, _args) do
    children = [
      # Starts a worker by calling: AbortNif.Worker.start_link(arg)
      # {AbortNif.Worker, arg}
      AbortNif
    ]

    # See https://hexdocs.pm/elixir/Supervisor.html
    # for other strategies and supported options
    opts = [strategy: :one_for_one, name: AbortNif.Supervisor]
    Supervisor.start_link(children, opts)
  end
end

libnif.c

#include <stdlib.h>
#include <erl_nif.h>

static ERL_NIF_TERM abort_nif(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
{
    abort();
}

static ErlNifFunc nif_funcs [] =
{
    {"abort_nif", 0, abort_nif}
};

ERL_NIF_INIT(Elixir.AbortNif, nif_funcs, NULL, NULL, NULL, NULL)

Makefile

.phony: all clean

PRIV = $(MIX_APP_PATH)/priv
BUILD = $(MIX_APP_PATH)/obj
NIF = $(PRIV)/libnif.so

ifeq ($(CROSSCOMPILE),)
ifeq ($(shell uname -s),Linux)
LDFLAGS += -fPIC -shared
CFLAFGS += -fPIC
else
LDFLAGS += -undefined dynamic_lookup -dynamiclib
endif
else
LDFLAGS += -fPIC -shared
CFLAGS += -fPIC
endif

ifeq ($(ERL_EI_INCLUDE_DIR),)
ERLANG_PATH = $(shell elixir --eval ':code.root_dir |> to_string() |> IO.puts()')
ifeq ($(ERLANG_PATH),)
$(error Could not find the Elixir installation. Check to see that 'elixir')
endif
ERL_EI_INCLUDE_DIR = $(ERLANG_PATH)/usr/include
ERL_EI_LIBDIR = $(ERLANG_PATH)/usr/lib
endif

ERL_CFLAGS ?= -I$(ERL_EI_INCLUDE_DIR)
ERL_LDFLAGS ?= -L$(ERL_EI_LIBDIR)


C_SRC = c_src/libnif.c
C_OBJ = $(C_SRC:c_src/%.c=$(BUILD)/%.o)

all: $(PRIV) $(BUILD) $(NIF)

$(PRIV) $(BUILD):
	mkdir -p $@

$(BUILD)/%.o: c_src/%.c
	@echo " CC $(notdir $@)"
	$(CC) -c $(ERL_CFLAGS) $(CFLAGS) -o $@ $<

$(NIF): $(C_OBJ)
	@echo " LD $(notdir $@)"
	$(CC) -o $@ $(ERL_LDFLAGS) $(LDFLAGS) $^

clean:
	$(RM) $(NIF) $(C_OBJ)
	

mix.exs

defmodule AbortNif.MixProject do
  use Mix.Project

  def project do
    [
      app: :abort_nif,
      version: "0.1.0",
      elixir: "~> 1.13",
      start_permanent: Mix.env() == :prod,
      deps: deps(),
      compilers: [:elixir_make] ++ Mix.compilers,
      deps: package()
    ]
  end

  # Run "mix help compile.app" to learn about applications.
  def application do
    [
      extra_applications: [:logger],
      mod: {AbortNif.Application, []}
    ]
  end

  # Run "mix help deps" to learn about dependencies.
  defp deps do
    [
      # {:dep_from_hexpm, "~> 0.3.0"},
      # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
      {:elixir_make, "~> 0.6", runtime: false},
      {:ht_pipe, "~> 0.1.0-dev", github: "zeam-vm/ht_pipe", branch: "main"}
    ]
  end

  defp package do
    [
      files: [
        "lib",
        "LICENSE",
        "mix.exs",
        "README.md",
        "c_src/*.[ch]",
        "Makefile"
      ]
    ]
  end
end