%%
%% %CopyrightBegin%
%% 
%% Copyright Ericsson AB 1997-2013. All Rights Reserved.
%% 
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%%     http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%% 
%% %CopyrightEnd%
%%

%% Test the garbage collector (or Memory Recycler)

-module(gc_SUITE).

-include_lib("common_test/include/ct.hrl").
-export([all/0, suite/0]).

-export([grow_heap/1, grow_stack/1, grow_stack_heap/1]).

suite() ->
    [{ct_hooks,[ts_install_cth]}].

all() -> 
    [grow_heap, grow_stack, grow_stack_heap].


%% Produce a growing list of elements,
%% for X calls, then drop one item per call
%% until the list is empty.
grow_heap(Config) when is_list(Config) ->
    ct:timetrap({minutes, 40}),
    ok  = grow_heap1(256),
    ok  = grow_heap1(512),
    ok  = grow_heap1(1024),
    ok  = grow_heap1(2048),
    ok.

grow_heap1(Len) ->
    io:format("~ngrow_heap with ~p items.",[Len]),
    show_heap("before:"),
    grow_heap1([], Len, 0, up),
    show_heap("after:").

grow_heap1(List, MaxLen, MaxLen, up) ->
    show_heap("top:"),
    grow_heap1(List, MaxLen, MaxLen-1, down);
grow_heap1(List, MaxLen, CurLen, up) ->
    NewList=[make_arbit()|List],
    grow_heap1(NewList, MaxLen, CurLen+1, up);
grow_heap1([], _MaxLen, _, down) ->
    ok;
grow_heap1([_|List], MaxLen, CurLen, down) ->
    C=erlang:unique_integer([positive]),
    Num     = C rem (length(List))+1,
    Elem    = lists:nth(Num, List),
    NewList = lists:delete(Elem, List),
    grow_heap1(NewList, MaxLen, CurLen-1, down).



%% Increase and decrease stack size, and
%% drop off some garbage from time to time.
grow_stack(Config) when is_list(Config) ->
    ct:timetrap({minutes, 80}),
    show_heap("before:"),
    grow_stack1(200, 0),
    show_heap("after:"),
    ok.

grow_stack1(0, _) ->
    ok;
grow_stack1(Recs, 0) ->
%    show_heap("running:"),
    grow_stack1(Recs-1, Recs),
    grow_stack1(0,0);
grow_stack1(Recs, CurRecs) ->
    grow_stack1(Recs, CurRecs-1),
    make_arbit(),
    grow_stack1(1,0),
    ok.


%% Let's see how BEAM handles this one...
%% While growing the heap, bounces the size of the
%% stack, and while reducing the heap, bounces the stack usage.
grow_stack_heap(Config) when is_list(Config) ->
    ct:timetrap({minutes, 40}),
    grow_stack_heap1(16),
    grow_stack_heap1(32),
    ok.

grow_stack_heap1(MaxLen) ->
    io:format("~ngrow_stack_heap with ~p items.",[MaxLen]),
    show_heap("before:"),
    grow_stack_heap1([], MaxLen, 0, up),
    show_heap("after:").

grow_stack_heap1(List, MaxLen, MaxLen, up) ->
    show_heap("top:"),
    grow_stack_heap1(List, MaxLen, MaxLen-1, down);
grow_stack_heap1(List, MaxLen, CurLen, up) ->
    grow_stack1(CurLen*2,0),
    grow_stack_heap1([make_arbit()|List], MaxLen, CurLen+1, up),
    ok;

grow_stack_heap1([], _MaxLen, _, down) -> ok;
grow_stack_heap1([_|List], MaxLen, CurLen, down) ->
    grow_stack1(CurLen*2,0),
    C=erlang:unique_integer([positive]),
    Num=C rem (length(List))+1,
    Elem=lists:nth(Num, List),
    NewList=lists:delete(Elem, List),
    grow_stack_heap1(NewList, MaxLen, CurLen-1, down),
    ok.


%% Create an arbitrary element/term.
make_arbit() ->
    {AA,BB,CC}=erlang:timestamp(),
    A=AA+1, B=BB+1, C=(CC+erlang:unique_integer([positive])) rem 1000000 + 1,
    New =
	case C rem 9 of
	    0 -> make_string((B div C) +5);
	    1 -> C;
	    2 -> make_ref();
	    3 -> self();
	    4 -> list_to_binary(make_string((C div B) + 12));
	    5 -> (C*B)/(A+1);
	    6 -> list_to_tuple(make_string((B div C) +5));
	    7 -> list_to_atom(make_string(((C div B) rem 254) + 2));
	    8 -> fun(X) -> {X,AA,make_string((B div C)+10)} end
	end,
    New.

%% Create an arbitrary string of a certain length.
make_string(Length) ->
    Alph="abcdefghjiklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"++
	"0123456789",
    make_string(Alph, Length, []).

make_string(_, 0, Acc) ->
    Acc;
make_string(Alph, Length, Acc) ->
    C=erlang:unique_integer([positive]),
    Pos=1+(Length*C rem length(Alph)),
    make_string(Alph, Length-1, 
		[lists:nth(Pos,Alph)|Acc]).

show_heap(String) ->
    garbage_collect(self()),
    receive after 1 -> ok end,
    {heap_size, HSize}=process_info(self(), heap_size),
    {stack_size, SSize}=process_info(self(), stack_size),
    io:format("Heap/Stack "++String++"~p/~p", [HSize, SSize]).