#!/usr/bin/env escript
%% -*- mode: erlang -*-
%%! -pa ranch/ebin -sname ranch_race +P 1000000 +A 200 +K true -env ERL_MAX_PORTS 1000000

%% This script is tested only in Linux environment.
%% I could not make it work with Mac OS (it limits connection rate).
%%
%% Warning: you are likely going to hit max open files limit.
%% Before running this script you should raise max fds by executing:
%%      sudo -E -- bash -c "ulimit -n 1000000; sudo -E -u $USER bash --login"

-module(ranch_race).
-mode(compile).

-export([main/1]).

-export([stress_worker/1]).

%-behaviour(ranch_protocol).
-export([start_link/4]).
%-behaviour(gen_server).
-export([init/1, handle_info/2, terminate/2]).

%% escript entry function
main([]) ->
    start_stress(2000),
    receive
        stop -> exit({shutdown, stopped})
    end.

start_stress(WorkerCount) ->
    {ok, Port} = start_listener(),
    _ = [spawn_link(?MODULE, stress_worker, [Port]) || _ <- lists:seq(1, WorkerCount)],
    ok.

start_listener() ->
    application:load(sasl),
    application:set_env(sasl, errlog_type, error),
    application:ensure_all_started(sasl),

    application:ensure_all_started(ranch),
    {ok, _} = ranch:start_listener(?MODULE, 1000, ranch_tcp, [{port, 0}, {max_connections, infinity}, {reuseaddr, true}], ?MODULE, []),
    {ok, ranch:get_port(?MODULE)}.


stress_worker(Port) ->
    {ok, S} = gen_tcp:connect("localhost", Port, [{active, false}, {reuseaddr, true}]),
    gen_tcp:close(S),
    ?MODULE:stress_worker(Port).


%%% Ranch protocol based on gen_server like described at http://ninenines.eu/docs/en/ranch/HEAD/guide/protocols/
start_link(Ref, Socket, Transport, _Opts) ->
    gen_server:start_link(?MODULE, [Ref, Socket, Transport], []).

init([Ref, Socket, Transport]) ->
    {ok, {state, Ref, Socket, Transport}, 0}.

handle_info(timeout, State={state, Ref, _Socket, _Transport}) ->
    ok = ranch:accept_ack(Ref),
    {stop, {shutdown, got_timeout}, State};
handle_info(Message, State) ->
    io:format("Got unexpected message: ~120p~n", [Message]),
    {stop, {shutdown, unexpected_message}, State}.

terminate(_, _) -> ok.