From 948ee9b34f34a55cb4b70b7077a849c7dc7a5f18 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?John=20H=C3=B6gberg?= Date: Fri, 21 Jul 2017 14:20:16 +0200 Subject: Replace the zlib driver with a NIF All operations will now yield appropriately, allowing them to be used freely in concurrent applications. This commit also deprecates the functions listed below, although they won't raise deprecation warnings until OTP 21: zlib:adler32 zlib:crc32 zlib:inflateChunk zlib:getBufSize zlib:setBufSize The behavior of throwing an error when a dictionary is required for decompression has also been deprecated. --- lib/kernel/test/Makefile | 4 +- lib/kernel/test/kernel_bench.spec | 1 + lib/kernel/test/zlib_SUITE.erl | 351 +++++++++++++++++++++++++++----------- 3 files changed, 258 insertions(+), 98 deletions(-) create mode 100644 lib/kernel/test/kernel_bench.spec (limited to 'lib/kernel') diff --git a/lib/kernel/test/Makefile b/lib/kernel/test/Makefile index b9942e899f..efe3a68531 100644 --- a/lib/kernel/test/Makefile +++ b/lib/kernel/test/Makefile @@ -148,8 +148,8 @@ release_tests_spec: make_emakefile $(INSTALL_DIR) "$(RELSYSDIR)" $(INSTALL_DATA) $(ERL_FILES) "$(RELSYSDIR)" $(INSTALL_DATA) $(APP_FILES) "$(RELSYSDIR)" - $(INSTALL_DATA) kernel.spec kernel_smoke.spec $(EMAKEFILE)\ - $(COVERFILE) "$(RELSYSDIR)" + $(INSTALL_DATA) kernel.spec kernel_smoke.spec kernel_bench.spec \ + $(EMAKEFILE) $(COVERFILE) "$(RELSYSDIR)" chmod -R u+w "$(RELSYSDIR)" @tar cf - *_SUITE_data | (cd "$(RELSYSDIR)"; tar xf -) diff --git a/lib/kernel/test/kernel_bench.spec b/lib/kernel/test/kernel_bench.spec new file mode 100644 index 0000000000..8de60dae31 --- /dev/null +++ b/lib/kernel/test/kernel_bench.spec @@ -0,0 +1 @@ +{groups,"../kernel_test",zlib_SUITE,[bench]}. diff --git a/lib/kernel/test/zlib_SUITE.erl b/lib/kernel/test/zlib_SUITE.erl index 4b67fce9a8..efbbc805a0 100644 --- a/lib/kernel/test/zlib_SUITE.erl +++ b/lib/kernel/test/zlib_SUITE.erl @@ -21,6 +21,7 @@ -module(zlib_SUITE). -include_lib("common_test/include/ct.hrl"). +-include_lib("common_test/include/ct_event.hrl"). -compile(export_all). @@ -43,7 +44,7 @@ end end()). --define(BARG, {'EXIT',{badarg,[{zlib,_,_,_}|_]}}). +-define(BARG, {'EXIT',{badarg,[{_,_,_,_}|_]}}). -define(DATA_ERROR, {'EXIT',{data_error,[{zlib,_,_,_}|_]}}). init_per_testcase(_Func, Config) -> @@ -74,7 +75,8 @@ suite() -> {timetrap,{minutes,1}}]. all() -> - [{group, api}, {group, examples}, {group, func}, smp, + [{group, api}, {group, examples}, {group, func}, + {group, bench}, smp, otp_9981, otp_7359]. @@ -84,14 +86,19 @@ groups() -> api_deflateSetDictionary, api_deflateReset, api_deflateParams, api_deflate, api_deflateEnd, api_inflateInit, api_inflateSetDictionary, api_inflateGetDictionary, - api_inflateSync, api_inflateReset, api_inflate, api_inflateChunk, - api_inflateEnd, api_setBufsz, api_getBufsz, api_crc32, - api_adler32, api_getQSize, api_un_compress, api_un_zip, + api_inflateReset, api_inflate2, api_inflate3, api_inflateChunk, + api_safeInflate, api_inflateEnd, api_crc32, + api_adler32, api_un_compress, api_un_zip, api_g_un_zip]}, {examples, [], [intro]}, {func, [], [zip_usage, gz_usage, gz_usage2, compress_usage, - dictionary_usage, large_deflate, crc, adler]}]. + dictionary_usage, large_deflate, crc, adler, + only_allow_owner, sub_heap_binaries]}, + {bench, + [inflate_bench_zeroed, inflate_bench_rand, + deflate_bench_zeroed, deflate_bench_rand, + chunk_bench_zeroed, chunk_bench_rand]}]. init_per_suite(Config) -> Config. @@ -244,7 +251,7 @@ api_deflateEnd(Config) when is_list(Config) -> Z1 = zlib:open(), ?m(ok, zlib:deflateInit(Z1, default)), ?m(ok, zlib:deflateEnd(Z1)), - ?m({'EXIT', {einval,_}}, zlib:deflateEnd(Z1)), %% ?? + ?m(?BARG, zlib:deflateEnd(Z1)), ?m(?BARG, zlib:deflateEnd(gurka)), ?m(ok, zlib:deflateInit(Z1, default)), ?m(B when is_list(B), zlib:deflate(Z1, <<"Kilroy was here">>)), @@ -261,7 +268,7 @@ api_inflateInit(Config) when is_list(Config) -> Z1 = zlib:open(), ?m(?BARG, zlib:inflateInit(gurka)), ?m(ok, zlib:inflateInit(Z1)), - ?m({'EXIT',{einval,_}}, zlib:inflateInit(Z1, 15)), %% ?? + ?m(?BARG, zlib:inflateInit(Z1, 15)), lists:foreach(fun(Wbits) -> Z11 = zlib:open(), ?m(ok, zlib:inflateInit(Z11,Wbits)), @@ -291,12 +298,13 @@ api_inflateSetDictionary(Config) when is_list(Config) -> %% Test inflateGetDictionary. api_inflateGetDictionary(Config) when is_list(Config) -> Z1 = zlib:open(), + zlib:inflateInit(Z1), IsOperationSupported = case catch zlib:inflateGetDictionary(Z1) of - {'EXIT',{einval,_}} -> true; - {'EXIT',{enotsup,_}} -> false + ?BARG -> false; + _ -> true end, - _ = zlib:close(Z1), + zlib:close(Z1), api_inflateGetDictionary_if_supported(IsOperationSupported). api_inflateGetDictionary_if_supported(false) -> @@ -306,45 +314,42 @@ api_inflateGetDictionary_if_supported(true) -> Z1 = zlib:open(), ?m(ok, zlib:deflateInit(Z1)), Dict = <<"foobar barfoo foo bar far boo">>, - ?m(_, zlib:deflateSetDictionary(Z1, Dict)), + Checksum = zlib:deflateSetDictionary(Z1, Dict), Payload = <<"foobarbarbar">>, Compressed = zlib:deflate(Z1, Payload, finish), ?m(ok, zlib:close(Z1)), - % Decompress and test dictionary extraction + % Decompress and test dictionary extraction with inflate/2 Z2 = zlib:open(), ?m(ok, zlib:inflateInit(Z2)), ?m(<<>>, iolist_to_binary(zlib:inflateGetDictionary(Z2))), ?m({'EXIT',{stream_error,_}}, zlib:inflateSetDictionary(Z2, Dict)), - ?m({'EXIT',{{need_dictionary,_},_}}, zlib:inflate(Z2, Compressed)), + ?m({'EXIT',{{need_dictionary,Checksum},_}}, zlib:inflate(Z2, Compressed)), ?m(ok, zlib:inflateSetDictionary(Z2, Dict)), ?m(Dict, iolist_to_binary(zlib:inflateGetDictionary(Z2))), - ?m(Payload, iolist_to_binary(zlib:inflate(Z2, Compressed))), + Payload = iolist_to_binary(zlib:inflate(Z2, [])), ?m(ok, zlib:close(Z2)), ?m(?BARG, zlib:inflateSetDictionary(Z2, Dict)), - ok. -%% Test inflateSync. -api_inflateSync(Config) when is_list(Config) -> - {skip,"inflateSync/1 sucks"}. -%% Z1 = zlib:open(), -%% ?m(ok, zlib:deflateInit(Z1)), -%% B1list0 = zlib:deflate(Z1, "gurkan gurra ger galna tunnor", full), -%% B2 = zlib:deflate(Z1, "grodan boll", finish), -%% io:format("~p\n", [B1list0]), -%% io:format("~p\n", [B2]), -%% ?m(ok, zlib:deflateEnd(Z1)), -%% B1 = clobber(14, list_to_binary(B1list0)), -%% Compressed = list_to_binary([B1,B2]), -%% io:format("~p\n", [Compressed]), - -%% ?m(ok, zlib:inflateInit(Z1)), -%% ?m(?BARG, zlib:inflateSync(gurka)), -%% ?m({'EXIT',{data_error,_}}, zlib:inflate(Z1, Compressed)), -%% ?m(ok, zlib:inflateSync(Z1)), -%% Ubs = zlib:inflate(Z1, []), -%% <<"grodan boll">> = list_to_binary(Ubs), -%% ?m(ok, zlib:close(Z1)). + %% ... And do the same for inflate/3 + Z3 = zlib:open(), + ?m(ok, zlib:inflateInit(Z3)), + ?m(<<>>, iolist_to_binary(zlib:inflateGetDictionary(Z3))), + ?m({'EXIT',{stream_error,_}}, zlib:inflateSetDictionary(Z3, Dict)), + + {need_dictionary, Checksum, _Output = []} = + zlib:inflate(Z3, Compressed, [{exception_on_need_dict, false}]), + + ?m(ok, zlib:inflateSetDictionary(Z3, Dict)), + ?m(Dict, iolist_to_binary(zlib:inflateGetDictionary(Z3))), + + Payload = iolist_to_binary( + zlib:inflate(Z3, [], [{exception_on_need_dict, false}])), + + ?m(ok, zlib:close(Z3)), + ?m(?BARG, zlib:inflateSetDictionary(Z3, Dict)), + + ok. clobber(N, Bin) when is_binary(Bin) -> T = list_to_tuple(binary_to_list(Bin)), @@ -362,8 +367,8 @@ api_inflateReset(Config) when is_list(Config) -> ?m(ok, zlib:inflateReset(Z1)), ?m(ok, zlib:close(Z1)). -%% Test inflate. -api_inflate(Config) when is_list(Config) -> +%% Test inflate/2 +api_inflate2(Config) when is_list(Config) -> Data = [<<1,2,2,3,3,3,4,4,4,4>>], Compressed = zlib:compress(Data), Z1 = zlib:open(), @@ -375,12 +380,32 @@ api_inflate(Config) when is_list(Config) -> ?m(Data, zlib:inflate(Z1, Compressed)), ?m(?BARG, zlib:inflate(gurka, Compressed)), ?m(?BARG, zlib:inflate(Z1, 4384)), - ?m(?BARG, zlib:inflate(Z1, [atom_list])), + ?m(?BARG, zlib:inflate(Z1, [atom_list])), ?m(ok, zlib:inflateEnd(Z1)), ?m(ok, zlib:inflateInit(Z1)), ?m({'EXIT',{data_error,_}}, zlib:inflate(Z1, <<2,1,2,1,2>>)), ?m(ok, zlib:close(Z1)). +%% Test inflate/3; same as inflate/2 but with the default options inverted. +api_inflate3(Config) when is_list(Config) -> + Data = [<<1,2,2,3,3,3,4,4,4,4>>], + Options = [{exception_on_need_dict, false}], + Compressed = zlib:compress(Data), + Z1 = zlib:open(), + ?m(ok, zlib:inflateInit(Z1)), + ?m([], zlib:inflate(Z1, <<>>, Options)), + ?m(Data, zlib:inflate(Z1, Compressed)), + ?m(ok, zlib:inflateEnd(Z1)), + ?m(ok, zlib:inflateInit(Z1)), + ?m(Data, zlib:inflate(Z1, Compressed, Options)), + ?m(?BARG, zlib:inflate(gurka, Compressed, Options)), + ?m(?BARG, zlib:inflate(Z1, 4384, Options)), + ?m(?BARG, zlib:inflate(Z1, [atom_list], Options)), + ?m(ok, zlib:inflateEnd(Z1)), + ?m(ok, zlib:inflateInit(Z1)), + ?m({'EXIT',{data_error,_}}, zlib:inflate(Z1, <<2,1,2,1,2>>, Options)), + ?m(ok, zlib:close(Z1)). + %% Test inflateChunk. api_inflateChunk(Config) when is_list(Config) -> ChunkSize = 1024, @@ -388,71 +413,107 @@ api_inflateChunk(Config) when is_list(Config) -> Part1 = binary:part(Data, 0, ChunkSize), Part2 = binary:part(Data, ChunkSize, ChunkSize), Part3 = binary:part(Data, ChunkSize * 2, ChunkSize), + Compressed = zlib:compress(Data), Z1 = zlib:open(), + zlib:setBufSize(Z1, ChunkSize), + ?m(ok, zlib:inflateInit(Z1)), - ?m([], zlib:inflateChunk(Z1, <<>>)), - ?m({more, Part1}, zlib:inflateChunk(Z1, Compressed)), - ?m({more, Part2}, zlib:inflateChunk(Z1)), - ?m(Part3, zlib:inflateChunk(Z1)), - ?m(ok, zlib:inflateEnd(Z1)), + 0 = iolist_size(zlib:inflateChunk(Z1, <<>>)), + + {more, Part1AsIOList} = zlib:inflateChunk(Z1, Compressed), + {more, Part2AsIOList} = zlib:inflateChunk(Z1), + {more, Part3AsIOList} = zlib:inflateChunk(Z1), + [] = zlib:inflateChunk(Z1), + + ?m(Part1, iolist_to_binary(Part1AsIOList)), + ?m(Part2, iolist_to_binary(Part2AsIOList)), + ?m(Part3, iolist_to_binary(Part3AsIOList)), + + ?m(ok, zlib:inflateEnd(Z1)), ?m(ok, zlib:inflateInit(Z1)), - ?m({more, Part1}, zlib:inflateChunk(Z1, Compressed)), + + ?m({more, Part1AsIOList}, zlib:inflateChunk(Z1, Compressed)), ?m(ok, zlib:inflateReset(Z1)), - zlib:setBufSize(Z1, size(Data)), - ?m(Data, zlib:inflateChunk(Z1, Compressed)), - ?m(ok, zlib:inflateEnd(Z1)), + zlib:setBufSize(Z1, byte_size(Data) + 1), + DataAsIOList = zlib:inflateChunk(Z1, Compressed), + ?m(Data, iolist_to_binary(DataAsIOList)), + + ?m(ok, zlib:inflateEnd(Z1)), ?m(ok, zlib:inflateInit(Z1)), + ?m(?BARG, zlib:inflateChunk(gurka, Compressed)), ?m(?BARG, zlib:inflateChunk(Z1, 4384)), + + ?m({'EXIT',{data_error,_}}, zlib:inflateEnd(Z1)), + + ?m(ok, zlib:close(Z1)). + +%% Test safeInflate as a mirror of inflateChunk, but ignore the stuff about +%% exact chunk sizes. +api_safeInflate(Config) when is_list(Config) -> + Data = << <<(I rem 150)>> || I <- lists:seq(1, 20 bsl 10) >>, + Compressed = zlib:compress(Data), + Z1 = zlib:open(), + + ?m(ok, zlib:inflateInit(Z1)), + + SafeInflateLoop = + fun + Loop({continue, Chunk}, Output) -> + Loop(zlib:safeInflate(Z1, []), [Output, Chunk]); + Loop({finished, Chunk}, Output) -> + [Output, Chunk] + end, + + Decompressed = SafeInflateLoop(zlib:safeInflate(Z1, Compressed), []), + Data = iolist_to_binary(Decompressed), + + ?m(ok, zlib:inflateEnd(Z1)), + ?m(ok, zlib:inflateInit(Z1)), + + {continue, Partial} = zlib:safeInflate(Z1, Compressed), + PBin = iolist_to_binary(Partial), + PSize = byte_size(PBin), + <> = Data, + + ?m(ok, zlib:inflateReset(Z1)), + + {continue, Partial} = zlib:safeInflate(Z1, Compressed), + PBin = iolist_to_binary(Partial), + PSize = byte_size(PBin), + <> = Data, + + ?m(ok, zlib:inflateReset(Z1)), + + SafeInflateLoop(zlib:safeInflate(Z1, Compressed), []), + + ?m({'EXIT',{data_error,_}}, zlib:safeInflate(Z1, Compressed)), + + ?m(ok, zlib:inflateReset(Z1)), + ?m(?BARG, zlib:safeInflate(gurka, Compressed)), + ?m(?BARG, zlib:safeInflate(Z1, 4384)), ?m({'EXIT',{data_error,_}}, zlib:inflateEnd(Z1)), ?m(ok, zlib:close(Z1)). %% Test inflateEnd. api_inflateEnd(Config) when is_list(Config) -> Z1 = zlib:open(), - ?m({'EXIT',{einval,_}}, zlib:inflateEnd(Z1)), + ?m(?BARG, zlib:inflateEnd(Z1)), ?m(ok, zlib:inflateInit(Z1)), ?m(?BARG, zlib:inflateEnd(gurka)), ?m({'EXIT',{data_error,_}}, zlib:inflateEnd(Z1)), - ?m({'EXIT',{einval,_}}, zlib:inflateEnd(Z1)), + ?m(?BARG, zlib:inflateEnd(Z1)), ?m(ok, zlib:inflateInit(Z1)), ?m(B when is_list(B), zlib:inflate(Z1, zlib:compress("abc"))), ?m(ok, zlib:inflateEnd(Z1)), ?m(ok, zlib:close(Z1)). -%% Test getBufsz. -api_getBufsz(Config) when is_list(Config) -> - Z1 = zlib:open(), - ?m(Val when is_integer(Val), zlib:getBufSize(Z1)), - ?m(?BARG, zlib:getBufSize(gurka)), - ?m(ok, zlib:close(Z1)). - -%% Test setBufsz. -api_setBufsz(Config) when is_list(Config) -> - Z1 = zlib:open(), - ?m(?BARG, zlib:setBufSize(Z1, gurka)), - ?m(?BARG, zlib:setBufSize(gurka, 1232330)), - Sz = ?m( Val when is_integer(Val), zlib:getBufSize(Z1)), - ?m(ok, zlib:setBufSize(Z1, Sz*2)), - DSz = Sz*2, - ?m(DSz, zlib:getBufSize(Z1)), - ?m(ok, zlib:close(Z1)). - -%%% Debug function ?? -%% Test getQSize. -api_getQSize(Config) when is_list(Config) -> - Z1 = zlib:open(), - Q = ?m(Val when is_integer(Val), zlib:getQSize(Z1)), - io:format("QSize ~p ~n", [Q]), - ?m(?BARG, zlib:getQSize(gurka)), - ?m(ok, zlib:close(Z1)). - %% Test crc32. api_crc32(Config) when is_list(Config) -> Z1 = zlib:open(), @@ -594,24 +655,9 @@ intro(Config) when is_list(Config) -> large_deflate(Config) when is_list(Config) -> large_deflate_do(). large_deflate_do() -> - Z = zlib:open(), - Plain = rand_bytes(zlib:getBufSize(Z)*5), - ok = zlib:deflateInit(Z), - _ZlibHeader = zlib:deflate(Z, [], full), - Deflated = zlib:deflate(Z, Plain, full), - ?m(ok, zlib:close(Z)), - ?m(Plain, zlib:unzip(list_to_binary([Deflated, 3, 0]))). - -rand_bytes(Sz) -> - L = <<8,2,3,6,1,2,3,2,3,4,8,7,3,7,2,3,4,7,5,8,9,3>>, - rand_bytes(erlang:md5(L),Sz). - -rand_bytes(Bin, Sz) when byte_size(Bin) >= Sz -> - <> = Bin, - Res; -rand_bytes(Bin, Sz) -> - rand_bytes(<<(erlang:md5(Bin))/binary, Bin/binary>>, Sz). - + Plain = gen_determ_rand_bytes(64 bsl 10), + Deflated = zlib:zip(Plain), + ?m(Plain, zlib:unzip(Deflated)). %% Test a standard compressed zip file. zip_usage(Config) when is_list(Config) -> @@ -869,10 +915,14 @@ dictionary_usage({run}) -> %% Now uncompress. Z2 = zlib:open(), ?m(ok, zlib:inflateInit(Z2)), + {'EXIT',{{need_dictionary,DictID},_}} = (catch zlib:inflate(Z2, Compressed)), + ?m(ok, zlib:inflateSetDictionary(Z2, Dict)), ?m(ok, zlib:inflateSetDictionary(Z2, binary_to_list(Dict))), + Uncompressed = ?m(B when is_list(B), zlib:inflate(Z2, [])), + ?m(ok, zlib:inflateEnd(Z2)), ?m(ok, zlib:close(Z2)), ?m(Data, list_to_binary(Uncompressed)). @@ -882,6 +932,35 @@ split_bin(<>, Acc) -> split_bin(Last,Acc) -> lists:reverse([Last|Acc]). +only_allow_owner(Config) when is_list(Config) -> + Z = zlib:open(), + + ?m(ok, zlib:inflateInit(Z)), + ?m(ok, zlib:inflateReset(Z)), + + {Pid, Ref} = spawn_monitor( + fun() -> + ?m(?BARG, zlib:inflateReset(Z)) + end), + + receive + {'DOWN', Ref, process, Pid, _Reason} -> + ok + after 200 -> + ?error("Spawned worker timed out.", []) + end, + + ?m(ok, zlib:inflateReset(Z)). + +sub_heap_binaries(Config) when is_list(Config) -> + Compressed = zlib:compress(<<"gurka">>), + ConfLen = erlang:length(Config), + + HeapBin = <>, + <<_:8/integer, SubHeapBin/binary>> = HeapBin, + + ?m(<<"gurka">>, zlib:uncompress(SubHeapBin)), + ok. %% Check concurrent access to zlib driver. smp(Config) -> @@ -999,7 +1078,78 @@ otp_9981(Config) when is_list(Config) -> Ports = lists:sort(erlang:ports()), ok. +-define(BENCH_SIZE, (16 bsl 20)). + +-define(DECOMPRESS_BENCH(Name, What, Data), + Name(Config) when is_list(Config) -> + Uncompressed = Data, + Compressed = zlib:compress(Uncompressed), + What(Compressed, byte_size(Uncompressed))). + +-define(COMPRESS_BENCH(Name, What, Data), + Name(Config) when is_list(Config) -> + Compressed = Data, + What(Compressed, byte_size(Compressed))). + +?DECOMPRESS_BENCH(inflate_bench_zeroed, throughput_bench_inflate, + <<0:(8 * ?BENCH_SIZE)>>). +?DECOMPRESS_BENCH(inflate_bench_rand, throughput_bench_inflate, + gen_determ_rand_bytes(?BENCH_SIZE)). + +?DECOMPRESS_BENCH(chunk_bench_zeroed, throughput_bench_chunk, + <<0:(8 * ?BENCH_SIZE)>>). +?DECOMPRESS_BENCH(chunk_bench_rand, throughput_bench_chunk, + gen_determ_rand_bytes(?BENCH_SIZE)). + +?COMPRESS_BENCH(deflate_bench_zeroed, throughput_bench_deflate, + <<0:(8 * ?BENCH_SIZE)>>). +?COMPRESS_BENCH(deflate_bench_rand, throughput_bench_deflate, + gen_determ_rand_bytes(?BENCH_SIZE)). + +throughput_bench_inflate(Compressed, Size) -> + Z = zlib:open(), + zlib:inflateInit(Z), + + submit_throughput_results(Size, + fun() -> + zlib:inflate(Z, Compressed) + end). + +throughput_bench_deflate(Uncompressed, Size) -> + Z = zlib:open(), + zlib:deflateInit(Z), + + submit_throughput_results(Size, + fun() -> + zlib:deflate(Z, Uncompressed, finish) + end). + +throughput_bench_chunk(Compressed, Size) -> + Z = zlib:open(), + zlib:inflateInit(Z), + + ChunkLoop = + fun + Loop({more, _}) -> Loop(zlib:inflateChunk(Z)); + Loop(_) -> ok + end, + + submit_throughput_results(Size, + fun() -> + ChunkLoop(zlib:inflateChunk(Z, Compressed)) + end). + +submit_throughput_results(Size, Fun) -> + TimeTaken = measure_perf_counter(Fun, millisecond), + + KBPS = trunc((Size bsr 10) / (TimeTaken / 1000)), + ct_event:notify(#event{ name = benchmark_data, data = [{value,KBPS}] }), + {comment, io_lib:format("~p ms, ~p KBPS", [TimeTaken, KBPS])}. +measure_perf_counter(Fun, Unit) -> + Start = os:perf_counter(Unit), + Fun(), + os:perf_counter(Unit) - Start. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%% Helps with testing directly %%%%%%%%%%%%% @@ -1039,3 +1189,12 @@ expand([H|T], Acc) -> end; expand([], Acc) -> Acc. +%% Generates a bunch of statistically random bytes using the size as seed. +gen_determ_rand_bytes(Size) -> + gen_determ_rand_bytes(Size, erlang:md5_init(), <<>>). +gen_determ_rand_bytes(Size, _Context, Acc) when Size =< 0 -> + Acc; +gen_determ_rand_bytes(Size, Context0, Acc) when Size > 0 -> + Context = erlang:md5_update(Context0, <>), + Checksum = erlang:md5_final(Context), + gen_determ_rand_bytes(Size - 16, Context, <>). -- cgit v1.2.3