%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2009. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%

%%%-------------------------------------------------------------------
%%% File    : ehb.erl
%%% Author  : Rickard Green
%%% Description : An Erlang HackBench version
%%%
%%% Created : 24 Aug 2009 by Rickard Green
%%%-------------------------------------------------------------------

-module(ehb).

-export([bench_args/2, run/3]).

-define(ACK, 100).
-define(DATA, {a,b,c,d,e,f,g,h,i,j,k,l}). %% 104 bytes on a 64-bit machine
-define(GSIZE, 20).

bench_args(Version, Conf) ->
    {_,Cores} = lists:keyfind(number_of_cores, 1, Conf),
	[F1, F2] = case Version of
		short -> [1, 4];
		intermediate -> [2,8];
		long -> [8, 8]
	end,
	[[N,M] || N <- [F1 * Cores], M <- [F2 * Cores]].

run([N,M|_], _, _) ->
	Master = self(),
	Gs = lists:map(fun (_) -> group(Master, M) end, lists:seq(1, N)),
	lists:foreach(fun (G) -> receive {G, ready} -> ok end end, Gs),
	lists:foreach(fun (G) -> G ! {Master, go} end, Gs),
	lists:foreach(fun (G) -> receive {G, done} -> ok end end, Gs),
	ok.

group(Master, Loop) ->
	spawn_link(fun () ->
		GMaster = self(),
		Rs = lists:map(fun (_) ->
				spawn_link(fun () -> receiver(GMaster, ?GSIZE) end)
			end, lists:seq(1, ?GSIZE)),
		Ss = lists:map(fun (_) ->
				spawn_link(fun () ->
					receive {GMaster, go} -> sender(Rs,Loop) end
				end)
			end, lists:seq(1, ?GSIZE)),
		Master ! {self(), ready},
		receive {Master, go} -> ok end,
		lists:foreach(fun (S) -> S ! {GMaster, go} end, Ss),
		lists:foreach(fun (R) -> receive {R, done} -> ok end end, Rs),
		Master ! {self(), done}
	end).

sender(Rs, 0) ->
	lists:foreach(fun (R) -> R ! done end, Rs);
sender(Rs, Loop) when Loop > ?ACK ->
	sender_ack(Rs, ?ACK),
	sender(Rs, Loop - ?ACK);
sender(Rs, Loop) ->
	lists:foreach(fun (R) -> R ! ?DATA end, Rs),
	sender(Rs, Loop-1).

sender_ack(Rs, 2) ->
	lists:foreach(fun (R) ->
			R ! ?DATA,
			R ! {self(), are_you_keeping_up}
		end, Rs),
	lists:foreach(fun (R) ->
			receive {R, i_am_keeping_up} -> ok end,
			R ! ?DATA
		end, Rs),
	ok;
sender_ack(Rs, N) ->
	lists:foreach(fun (R) -> R ! ?DATA end, Rs),
	sender_ack(Rs, N-1).

receiver(GMaster, SendersLeft) ->
	receive
		done ->
			case SendersLeft of
				1 -> GMaster ! {self(), done};
				_ -> receiver(GMaster, SendersLeft - 1)
			end;
		Msg ->
			case Msg of
				{From, are_you_keeping_up} -> From ! {self(), i_am_keeping_up};
				_ -> ok
			end,
			receiver(GMaster, SendersLeft)
	end.