measures couch_config lookup throughput

config_bench.erl

-module (config_bench).
-export ([doit/2]).

doit(Conns, Reps) ->
    doit(Conns, Reps, false).

doit(Conns, Reps, AlsoWrite) ->
    Conf = couch_config:all(),
    Begin = erlang:now(),
    Self = self(),
    Writer = if AlsoWrite -> spawn(fun write_stuff/0); true -> Self end,
    [spawn(fun() -> grab(Self, Conf, Reps) end) || _I <- lists:seq(1,Conns)],
    ok = wait_result(Conns),
    Writer ! stop,
    % seconds to run the test
    timer:now_diff(erlang:now(), Begin)/1000000.

wait_result(0) ->
    ok;
wait_result(N) ->
    receive done -> wait_result(N-1) end.

write_stuff() ->
    receive stop -> ok
    after 0 ->
        couch_config:set("some_block", "foo",
            binary_to_list(couch_uuids:new())),
        write_stuff()
    end.

% lookup all config values
grab(Parent, _Conf, 0) ->
    Parent ! done;
grab(Parent, Conf, M) ->
    {Keys, _Values} = lists:unzip(Conf),
    [couch_config:get(K,V) || {K,V} <- Keys],
    grab(Parent, Conf, M-1).