Add EQC test case for AP mode repair w/ part. sim.

test/machi_ap_repair_eqc.erl

@@ -0,0 +1,568 @@
+%% -------------------------------------------------------------------
+%%
+%% Copyright (c) 2007-2015 Basho Technologies, Inc.  All Rights Reserved.
+%%
+%% This file is provided to you 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.
+%%
+%% -------------------------------------------------------------------
+
+%% EQC single-threaded and concurrent test for file operations and repair
+%% under simulated network partition.
+
+%% The main purpose is to confirm no dataloss, i.e. every chunk that
+%% has been successfully written (ACK received) by append/write
+%% opration will be read after partition heals.
+%%
+%% All updating -- append, write and trim -- operations are executed
+%% through CR client, not directly by flu1 client, in order to be
+%% end-to-end test (in single chain point of veiw.) There may be churn
+%% for projections by simulated network partition.
+%%
+%% Test steps
+%% 1. Setup single chain.
+%% 2. Execute updating operations and simulated partition (by eqc_statem).
+%%    Every updating results are recorded in ETS tables.
+%% 3. When {error, timeout|partition} happens, trigger management tick for
+%%    every chain manager process.
+%% 4. After commands are executed, remove patition and wait for the chain
+%%    without down nodes nor repairing nodes.
+%% 5. Asserting written results so that each record be read from the
+%%    chain and data be the same with written one.
+
+%% Improvements to-do's
+%% - Use higher concurrency, e.g. 10+
+%% - Random length for binary to write
+%% - Operations other than append, write, trim
+%% - Use checksum instead of binary to save memory
+%% - More variety for partitioning pattern: non-constant failure
+
+-module(machi_ap_repair_eqc).
+
+-ifdef(TEST).
+-ifdef(EQC).
+-compile(export_all).
+-include("machi.hrl").
+-include("machi_projection.hrl").
+-include("machi_verbose.hrl").
+-include_lib("eqc/include/eqc.hrl").
+-include_lib("eqc/include/eqc_statem.hrl").
+-include_lib("eunit/include/eunit.hrl").
+
+%% ETS table names
+-define(WRITTEN_TAB,  written).  % Successfully written data
+-define(ACCPT_TAB,    accpt).    % Errors with no harm, e.g. timeout
+-define(FAILED_TAB,   failed).   % Uncategorized errors, when happenes
+                                 % it should be re-categorized to accept or critical
+-define(CRITICAL_TAB, critical). % Critical errors, e.g. double write to the same key
+
+-define(QC_OUT(P),
+        eqc:on_output(fun(Str, Args) -> io:format(user, Str, Args) end, P)).
+
+%% EUNIT TEST DEFINITION
+prop_repair_test_() ->
+    {PropTO, EUnitTO} = eqc_timeout(60),
+    Verbose = eqc_verbose(),
+    {spawn,
+     [{timeout, EUnitTO,
+       ?_assertEqual(
+          true,
+          eqc:quickcheck(eqc:testing_time(
+                           PropTO, ?QC_OUT(noshrink(prop_repair(Verbose))))))}]}.
+
+prop_repair_par_test_() ->
+    {PropTO, EUnitTO} = eqc_timeout(60),
+    Verbose = eqc_verbose(),
+    {spawn,
+     [{timeout, EUnitTO,
+       ?_assertEqual(
+          true,
+          eqc:quickcheck(eqc:testing_time(
+                           PropTO, ?QC_OUT(noshrink(prop_repair_par(Verbose))))))}]}.
+
+%% SHELL HELPERS
+test() -> test(100).
+test(N) -> test(N, true).
+test(N, Verbose) -> quickcheck(numtests(N, noshrink(prop_repair_par(Verbose)))).
+check() -> check(prop_repair_par(true), current_counterexample()).
+
+-record(state, {num,             % Number of FLU servers
+                seed,            % Seed for partition simulator
+                verbose=false,   % Verbose output for debugging
+                flu_names,       % List of FLU names
+                mgr_names,       % List of chain manager names
+                fc_list,         % List of FLU1 proxy clients
+                cr_list}).       % List of CR clients
+
+weight(_S, change_partition) ->  20;
+weight(_S, _)                -> 100.
+
+%% append
+
+append_args(#state{cr_list=CRList}=S) ->
+    [elements(CRList), chunk(), S].
+
+append({_SimSelfName, C}, Bin, #state{verbose=V}=S) ->
+    Prefix = <<"pre">>,
+    Len = byte_size(Bin),
+    Res = (catch machi_cr_client:append_chunk(C, Prefix, Bin, {sec(1), sec(1)})),
+    case Res of
+        {ok, {_Off, Len, _FileName}=Key} ->
+            case ets:insert_new(?WRITTEN_TAB, {Key, Bin}) of
+                true ->
+                    [?V("<o>", []) || V],
+                    ok;
+                false ->
+                    %% The Key is alread written, WHY!!!????
+                    case ets:lookup(?WRITTEN_TAB, Key) of
+                        [{Key, Bin}] ->
+                            %% TODO: The identical binary is alread inserted in
+                            %%  written table. Is this acceptable??? Hmm, maybe NO...
+                            [?V("<dws:~w>", [Key]) || V],
+                            true = ets:insert_new(?ACCPT_TAB,
+                                                  {make_ref(), double_write_same, Key}),
+                            {acceptable_error, doublewrite_the_same};
+                        [{Key, OtherBin}] ->
+                            [?V("<dwd:~w:~w>", [Key, {OtherBin, Bin}]) || V],
+                            true = ets:insert_new(?CRITICAL_TAB,
+                                                  {make_ref(), double_write_diff, Key}),
+                            R = {critical_error,
+                                 {doublewrite_diff, Key, {OtherBin, Bin}}},
+                            %% TODO: when double write happens, it seems that
+                            %% repair process got stack with endless loop. To
+                            %% avoit it, return error here.
+                            %% If this error/1 will be removed, one can possibly
+                            %% know double write frequency/rate.
+                            error(R)
+                    end
+            end;
+        {error, partition} -> 
+            [?V("<pt>", []) || V],
+            true = ets:insert_new(?ACCPT_TAB, {make_ref(), timeout}),
+            _ = tick(S),
+            {acceptable_error, partition};
+        {'EXIT', {timeout, _}} ->
+            [?V("<to:~w:~w>", [_SimSelfName, C]) || V],
+            true = ets:insert_new(?ACCPT_TAB, {make_ref(), timeout}),
+            _ = tick(S),
+            {acceptable_error, timeout};
+        {ok, {_Off, UnexpectedLen, _FileName}=Key} ->
+            [?V("<XX>", []) || V],
+            true = ets:insert_new(?CRITICAL_TAB, {make_ref(), unexpected_len, Key}),
+            {critical_error, {unexpected_len, Key, Len, UnexpectedLen}};
+        {error, _Reason} = Error ->
+            [?V("<er>", []) || V],
+            true = ets:insert_new(?FAILED_TAB, {make_ref(), Error}),
+            {other_error, Error};
+        Other ->
+            [?V("<er>", []) || V],
+            true = ets:insert_new(?FAILED_TAB, {make_ref(), Other}),
+            {other_error, Other}
+    end.
+
+%% change partition
+
+change_partition_args(#state{flu_names=FLUNames}=S) ->
+    %% [partition(FLUNames), S].
+    [partition_sym(FLUNames), S].
+
+change_partition(Partition,
+                 #state{verbose=Verbose, flu_names=FLUNames}=S) ->
+    [case Partition of
+         [] -> ?V("## Turn OFF partition: ~w~n", [Partition]);
+         _  -> ?V("## Turn ON  partition: ~w~n", [Partition])
+     end || Verbose],
+    machi_partition_simulator:always_these_partitions(Partition),
+    _ = machi_partition_simulator:get(FLUNames),
+    %% Don't wait for stable chain, tick will be executed on demand
+    %% in append oprations
+    _ = tick(S),
+    ok.
+
+%% Generators
+
+num() ->
+    choose(2, 5).
+    %% return(3).
+
+%% Generator for possibly assymmetric partition information
+partition(FLUNames) ->
+    frequency([{10, return([])},
+               {20, non_empty(sublist(flu_ordered_pairs(FLUNames)))}]).
+
+%% Generator for symmetric partition information
+partition_sym(FLUNames) ->
+    ?LET(Pairs, non_empty(sublist(flu_pairs(FLUNames))),
+         lists:flatmap(fun({One, Another}) -> [{One, Another}, {Another, One}] end,
+                       Pairs)).
+
+flu_ordered_pairs(FLUNames) ->
+    [{From, To} || From <- FLUNames, To <- FLUNames, From =/= To].
+
+flu_pairs(FLUNames) ->
+    [{One, Another} || One <- FLUNames, Another <- FLUNames, One > Another].
+
+chunk() ->
+    non_empty(binary(10)).
+
+%% Property
+
+prop_repair(Verbose) ->
+    error_logger:tty(false),
+    application:load(sasl),
+    application:set_env(sasl, sasl_error_logger, false),
+
+    Seed = {1445,935441,287549},
+    ?FORALL(Num, num(),
+    ?FORALL(Cmds, commands(?MODULE, initial_state(Num, Seed, Verbose)),
+            begin
+                SetupState = setup_chain(Num, Seed, Verbose),
+                {H, S1, Res} = run_commands(?MODULE, Cmds),
+                %% ?V("S1=~w~n", [S1]),
+                ?V("==== Start post operations, stabilize and confirm results~n", []),
+                {_Res2, S2} = stabilize(commands_len(Cmds), SetupState),
+                {Dataloss, Critical} = confirm_result(S2),
+                pretty_commands(
+                  ?MODULE, Cmds, {H, S1, Res},
+                  aggregate(with_title(cmds), command_names(Cmds),
+                  collect(with_title(length5), (length(Cmds) div 5) * 5,
+                          {Dataloss, Critical} =:= {0, 0})))
+            end)).
+
+prop_repair_par(Verbose) ->
+    error_logger:tty(false),
+    application:load(sasl),
+    application:set_env(sasl, sasl_error_logger, false),
+
+    Seed = {1445,935441,287549},
+    ?FORALL(Num, num(),
+    ?FORALL(Cmds,
+            %% Now try-and-err'ing, how to control command length and concurrency?
+            ?SUCHTHAT(Cmds0, ?SIZED(Size, resize(Size,
+                      parallel_commands(?MODULE, initial_state(Num, Seed, Verbose)))),
+                      commands_len(Cmds0) > 20
+                      andalso
+                      concurrency(Cmds0) > 2),
+            begin
+                CmdsLen= commands_len(Cmds),
+                SetupState = setup_chain(Num, Seed, Verbose),
+                {Seq, Par, Res} = run_parallel_commands(?MODULE, Cmds),
+                %% ?V("Seq=~w~n", [Seq]),
+                %% ?V("Par=~w~n", [Par]),
+                ?V("==== Start post operations, stabilize and confirm results~n", []),
+                {Dataloss, Critical} =
+                    case Res of
+                        ok ->
+                            {_Res2, S2} = stabilize(CmdsLen, SetupState),
+                            confirm_result(S2);
+                        _ ->
+                            ?V("Res=~w~n", [Res]),
+                            {undefined, undefined}
+                end,
+                pretty_commands(
+                  ?MODULE, Cmds, {Seq, Par, Res},
+                  aggregate(with_title(cmds), command_names(Cmds),
+                  collect(with_title(length5), (CmdsLen div 5) * 5,
+                  collect(with_title(conc),    concurrency(Cmds),
+                          {Dataloss, Critical} =:= {0, 0})))
+                 )
+            end)).
+
+%% Initilization / setup
+
+%% Fake initialization function for debugging in shell like:
+%% > eqc_gen:sample(eqc_statem:commands(machi_ap_repair_eqc)).
+%% but not so helpful.
+initial_state() ->
+    #state{cr_list=[a,b,c]}.
+
+initial_state(Num, Seed, Verbose) ->
+    AllListE = all_list_extra(Num),
+    FLUNames = [P#p_srvr.name || {P, _Dir} <- AllListE],
+    MgrNames = [{Name, machi_flu_psup:make_mgr_supname(Name)} || Name <- FLUNames],
+    Dict = orddict:from_list([{P#p_srvr.name, P} || {P, _Dir} <- AllListE]),
+
+    FCList = [begin
+                  {ok, PCPid} = machi_proxy_flu1_client:start_link(P),
+                  {Name, PCPid}
+              end || {_, #p_srvr{name=Name}=P} <- Dict],
+    %% CR clients are pooled, each has "name" which is interpreted "From"
+    %% side of simulated partition.
+    CRListCount = 10, % ad-hoc
+    SimSelfNames = lists:append(lists:duplicate(CRListCount div Num +1, FLUNames)),
+    CRList = [begin
+                  {ok, C} = machi_cr_client:start_link(
+                              [P || {_, P} <- Dict],
+                              [{use_partition_simulator, true},
+                               {simulator_self_name, SimSelfName},
+                               {simulator_members, FLUNames}]),
+                  {SimSelfName, C}
+              end || SimSelfName <- SimSelfNames],
+    #state{num=Num, seed=Seed, verbose=Verbose,
+           flu_names=FLUNames, mgr_names=MgrNames,
+           cr_list=CRList, fc_list=FCList}.
+
+setup_chain(Num, Seed, Verbose) ->
+    %% ?V("setup_chain(Num=~w, Seed=~w~nn", [Num, Seed]),
+    AllListE = all_list_extra(Num),
+    FLUNames = [P#p_srvr.name || {P, _Dir} <- AllListE],
+    MgrNames = [{Name, machi_flu_psup:make_mgr_supname(Name)} || Name <- FLUNames],
+    Dict = orddict:from_list([{P#p_srvr.name, P} || {P, _Dir} <- AllListE]),
+
+    ok = shutdown_hard(),
+    [begin
+         machi_flu1_test:clean_up_data_dir(Dir),
+         filelib:ensure_dir(Dir ++ "/not-used")
+     end || {_P, Dir} <- AllListE],
+    [catch ets:delete(T) || T <- tabs()],
+
+    [ets:new(T, [set, public, named_table,
+                 {write_concurrency, true}, {read_concurrency, true}]) ||
+        T <- tabs()],
+    {ok, _} = application:ensure_all_started(machi),
+
+    SimSpec = {part_sim,
+               {machi_partition_simulator, start_link, [{0,0,0}, 0, 100]},
+               permanent, 500, worker, []},
+    {ok, _PSimPid} = supervisor:start_child(machi_sup, SimSpec),
+    ok = machi_partition_simulator:set_seed(Seed),
+    _Partitions = machi_partition_simulator:get(FLUNames),
+
+    %% Start FLUs and setup the chain
+    FLUOpts = [{use_partition_simulator, true},
+               %% {private_write_verbose, true},
+               {active_mode, false},
+               {simulate_repair, false}],
+    [{ok, _} = machi_flu_psup:start_flu_package(Name, Port, Dir, FLUOpts) ||
+        {#p_srvr{name=Name, port=Port}, Dir} <- AllListE],
+    [machi_chain_manager1:set_chain_members(MgrName, Dict) || {_, MgrName} <- MgrNames],
+
+    State = initial_state(Num, Seed, Verbose),
+    %% Don't wait for complete chain. Even partialy completed, the chain
+    %% should work fine. Right?
+    wait_until_stable(chain_state_all_ok(FLUNames), FLUNames, MgrNames,
+                      State#state.fc_list, 20),
+    State.
+
+%% Post commands
+
+stabilize(0, S) ->
+    {ok, S};
+stabilize(_CmdsLen, #state{flu_names=FLUNames, mgr_names=MgrNames, fc_list=FCList}=S) ->
+    machi_partition_simulator:no_partitions(),
+    wait_until_stable(chain_state_all_ok(FLUNames), FLUNames, MgrNames, FCList, 100),
+    {ok, S}.
+
+chain_state_all_ok(FLUNames) ->
+    [{FLUName, {FLUNames, [], []}} || FLUName <- FLUNames].
+
+confirm_result(#state{cr_list=[{_, C}|_]}=_S) ->
+    [{written, _Written}, {accpt, Accpt},
+     {failed, Failed}, {critical, Critical}] = tab_counts(),
+    {OK, Dataloss} = confirm_written(C),
+    ?V("  Written=~w, DATALOSS=~w, Acceptable=~w~n", [OK, Dataloss, Accpt]),
+    ?V("  Failed=~w, Critical=~w~n~n", [Failed, Critical]),
+    DirBase = get_dir_base(),
+    Suffix = dump_file_suffix(),
+    case Failed of
+        0 -> ok;
+        _ ->
+            DumpFailed = filename:join(DirBase, "dump-failed-" ++ Suffix),
+            ?V("Dump failed ETS tab to: ~w~n", [DumpFailed]),
+            ets:tab2file(?FAILED_TAB, DumpFailed)
+    end,
+    case Critical of
+        0 -> ok;
+        _ ->
+            DumpCritical = filename:join(DirBase, "dump-critical-" ++ Suffix),
+            ?V("Dump critical ETS tab to: ~w~n", [DumpCritical]),
+            ets:tab2file(?CRITICAL_TAB, DumpCritical)
+    end,
+    {Dataloss, Critical}.
+
+confirm_written(C) ->
+    ets:foldl(
+      fun({Key, Bin}, {OK, NG}) ->
+              case assert_chunk(C, Key, Bin) of
+                  ok -> {OK+1, NG};
+                  {error, _} -> {OK, NG+1}
+              end
+      end, {0, 0}, ?WRITTEN_TAB).
+
+assert_chunk(C, {Off, Len, FileName}=Key, Bin) ->
+    %% TODO: This probably a bug, read_chunk respnds with filename of `string()' type
+    FileNameStr = binary_to_list(FileName),
+    %% TODO : Use CSum instead of binary (after disuccsion about CSum is calmed down?)
+    case (catch machi_cr_client:read_chunk(C, FileName, Off, Len, [], sec(3))) of
+        {ok, {[{FileNameStr, Off, Bin, _}], []}} ->
+            ok;
+        {ok, Got} ->
+            ?V("read_chunk got different binary for Key=~p~n", [Key]),
+            ?V("    Expected: ~p~n", [{[{FileNameStr, Off, Bin, <<"CSum-NYI">>}], []}]),
+            ?V("    Got:      ~p~n", [Got]),
+            {error, different_binary};
+        {error, Reason} ->
+            ?V("read_chunk error for Key=~p: ~p~n", [Key, Reason]),
+            {error, Reason};
+        Other ->
+            ?V("read_chunk other error for Key=~p: ~p~n", [Key, Other]),
+            {error, Other}
+    end.
+
+%% Internal utilities
+
+eqc_verbose() ->
+    os:getenv("EQC_VERBOSE") =:= "true".
+
+eqc_timeout(Default) ->
+    PropTimeout = case os:getenv("EQC_TIMEOUT") of
+                      false -> Default;
+                      V -> list_to_integer(V)
+                  end,
+    {PropTimeout, PropTimeout * 300}.
+
+%% Returns a list like
+%% `[{#p_srvr{name=a, port=7501, ..}, "./eqc/data.eqc.a/"}, ...]'
+all_list_extra(Num) ->
+    {PortBase, DirBase} = get_port_dir_base(),
+    [begin
+         FLUNameStr = [$a + I - 1],
+         FLUName = list_to_atom(FLUNameStr),
+         MgrName = machi_flu_psup:make_mgr_supname(FLUName),
+         {#p_srvr{name=FLUName, address="localhost", port=PortBase+I,
+                  props=[{chmgr, MgrName}]},
+          DirBase ++ "/data.eqc." ++ FLUNameStr}
+     end || I <- lists:seq(1, Num)].
+
+get_port_dir_base() ->
+    I = case os:getenv("EQC_BASE_PORT") of
+            false -> 0;
+            V -> list_to_integer(V)
+        end,
+    D = get_dir_base(),
+    {7400 + (I * 100), D ++ "/" ++ integer_to_list(I)}.
+
+get_dir_base() ->
+    case os:getenv("EQC_BASE_DIR") of
+        false -> "./eqc";
+        DD -> DD
+    end.
+
+shutdown_hard() ->
+    _STOP = application:stop(machi),
+    timer:sleep(100).
+
+tick(#state{flu_names=FLUNames, mgr_names=MgrNames,
+            fc_list=FCList, verbose=Verbose}) ->
+    tick(FLUNames, MgrNames, FCList, Verbose).
+
+tick(FLUNames, MgrNames, FCList, Verbose) ->
+    tick(FLUNames, MgrNames, 2, 100, FCList, Verbose).
+
+tick(FLUNames, MgrNames, Iter, SleepMax, FCList, Verbose) ->
+    TickFun = tick_fun(FLUNames, MgrNames, self()),
+    TickFun(Iter, 0, SleepMax),
+    [?V("## Chain state after tick()=~w~n", [chain_state(FCList)]) || Verbose].
+
+tick_fun(FLUNames, MgrNames, Parent) ->
+    fun(Iters, SleepMin, SleepMax) ->
+            %% ?V("^", []),
+            Trigger =
+                fun(FLUName, MgrName) ->
+                        random:seed(now()),
+                        [begin
+                             erlang:yield(),
+                             SleepMaxRand = random:uniform(SleepMax + 1),
+                             %% io:format(user, "{t}", []),
+                             Elapsed = machi_chain_manager1:sleep_ranked_order(
+                                         SleepMin, SleepMaxRand,
+                                         FLUName, FLUNames),
+                             MgrName ! tick_check_environment,
+                             %% Be more unfair by not sleeping here.
+                             timer:sleep(max(SleepMax - Elapsed, 1)),
+                             ok
+                         end || _ <- lists:seq(1, Iters)],
+                        Parent ! {done, self()}
+                end,
+            Pids = [{spawn(fun() -> Trigger(FLUName, MgrName) end), FLUName} ||
+                       {FLUName, MgrName} <- MgrNames ],
+            [receive
+                 {done, ThePid} ->
+                     ok
+             after 120*1000 ->
+                     exit({icky_timeout, M_name})
+             end || {ThePid, M_name} <- Pids]
+    end.
+
+wait_until_stable(ExpectedChainState, FLUNames, MgrNames, FCList) ->
+    wait_until_stable(ExpectedChainState, FLUNames, MgrNames, FCList, 20).
+
+wait_until_stable(ExpectedChainState, FLUNames, MgrNames, FCList, Retries) ->
+    TickFun = tick_fun(FLUNames, MgrNames, self()),
+    wait_until_stable1(ExpectedChainState, TickFun, FCList, Retries).
+
+wait_until_stable1(_ExpectedChainState, _TickFun, FCList, 0) ->
+    ?V("  [ERROR] wait_until_stable failed.... : ~p~n", [chain_state(FCList)]),
+    false;
+wait_until_stable1(ExpectedChainState, TickFun, FCList, Reties) ->
+    [TickFun(3, 0, 100) || _ <- lists:seq(1, 3)],
+    Normalized = normalize_chain_state(chain_state(FCList)),
+    case Normalized of
+        ExpectedChainState ->
+            ?V("  Got stable chain: ~w~n", [chain_state(FCList)]),
+            true;
+        _ ->
+            ?V("  NOT YET stable chain: ~w~n", [chain_state(FCList)]),
+            wait_until_stable1(ExpectedChainState, TickFun, FCList, Reties-1)
+    end.
+
+normalize_chain_state(ChainState) ->
+    lists:usort([{FLUName,
+                  {lists:usort(UPI), lists:usort(Repairing), lists:usort(Down)}} ||
+                    {FLUName, {_EpochNo, UPI, Repairing, Down}} <- ChainState]).
+
+chain_state(FCList) ->
+    lists:usort(
+      [case (catch machi_proxy_flu1_client:read_latest_projection(C, private, sec(5))) of
+           {ok, #projection_v1{epoch_number=EpochNo, upi=UPI,
+                               repairing=Repairing, down=Down}} ->
+               {FLUName, {EpochNo, UPI, Repairing, Down}};
+           Other ->
+               {FLUName, Other}
+       end || {FLUName, C} <- FCList]).
+
+tabs() -> [?WRITTEN_TAB, ?ACCPT_TAB, ?FAILED_TAB, ?CRITICAL_TAB].
+
+tab_counts() ->
+    [{T, ets:info(T, size)} || T <- tabs()].
+
+sec(Sec) ->
+    timer:seconds(Sec).
+
+commands_len({SeqCmds, ParCmdsList} = _Cmds) ->
+    lists:sum([length(SeqCmds) | [length(P) || P <- ParCmdsList]]);
+commands_len(Cmds) ->
+    length(Cmds).
+
+concurrency({_SeqCmds, ParCmdsList} = _Cmds) -> length(ParCmdsList);
+concurrency(_) -> 1.
+
+dump_file_suffix() ->
+    {{Year, Month, Day}, {Hour, Min, Sec}} = calendar:local_time(),
+    lists:flatten(
+      io_lib:format("~4.10.0B-~2.10.0B-~2.10.0BT~2.10.0B:~2.10.0B:~2.10.0B.000Z",
+                    [Year, Month, Day, Hour, Min, Sec])).
+
+-endif. % EQC
+-endif. % TEST