atom to string conversion benchmark

gistfile1.hrl

-module(msr_subst).

-export([doit/0, props/0]).

doit() ->
    timer:start(),
    Data = data(),
    io:format("check_prop: ~p~n", [check_prop(Data)]),
    io:format("check_dict: ~p~n", [check_dict(Data)]),
    io:format("check_match: ~p~n", [check_match(Data)]),
    io:format("check_match2: ~p~n", [check_match2(Data)]),
    ok.

props() ->
    [
        {filename, "Filename"},
        {maintainer, "Maintainer"},
        {description, "Description"},
        {package, "Package"},
        {section, "Section"},
        {'installed-size', "Installed-Size"},
        {priority, "Priority"},
        {suggests, "Suggests"},
        {depends, "Depends"},
        {version, "Version"},
        {source, "Source"},
        {architecture, "Architecture"}
    ].

check_prop(Data) ->
    measure(fun check_prop/3, Data, props()).

check_dict(Data) ->
    measure(fun check_dict/3, Data, dict:from_list(props())).

check_match(Data) ->
    measure(fun check_match/3, Data, none).

check_match2(Data) ->
    measure(fun check_match2/3, Data, none).

measure(Fun, Arg1, Arg2) ->
    Start = erlang:now(),
    many_runs(Fun, Arg1, Arg2, 1000000),
    timer:now_diff(erlang:now(), Start).

many_runs(_, _, _, 0) ->
    ok;
many_runs(Fun, Data1, Data2, N) ->
    Fun(Data1, Data2, []),
    many_runs(Fun, Data1, Data2, N-1).

check_match([], _, Acc) ->
    lists:reverse(Acc);
check_match([{Key, Data}=Head | Rest], Blah, Acc) ->
    check_match(Rest, Blah, [case Key of
        filename ->
            {"Filename", Data};

        maintainer ->
            {"Maintainer", Data};

        description ->
            {"Description", Data};

        package ->
            {"Package", Data};

        section ->
            {"Section", Data};

        'installed-size' ->
            {"Installed-Size", Data};

        priority ->
            {"Priority", Data};

        suggests ->
            {"Suggests", Data};

        depends ->
            {"Depends", Data};

        version ->
            {"Version", Data};

        source ->
            {"Source", Data};

        architecture ->
            {"Architecture", Data};

        _ ->
            Head
    end | Acc]).

do_case(Key) ->
    case Key of
        filename ->
            "Filename";

        maintainer ->
            "Maintainer";

        description ->
            "Description";

        package ->
            "Package";

        section ->
            "Section";

        'installed-size' ->
            "Installed-Size";

        priority ->
            "Priority";

        suggests ->
            "Suggests";

        depends ->
            "Depends";

        version ->
            "Version";

        source ->
            "Source";

        architecture ->
            "Architecture";

        _ ->
            Key
    end.

check_match2([], _, Acc) ->
    lists:reverse(Acc);
check_match2([{Key, Data} | Rest], Blah, Acc) ->
    check_match2(Rest, Blah, [{do_case(Key), Data} | Acc]).

check_prop([], _, Acc) ->
    lists:reverse(Acc);
check_prop([{Key, Data} | Rest], Props, Acc) ->
    check_prop(Rest, Props, [{proplists:get_value(Key, Props, Key), Data} | Acc]).

check_dict([], _, Acc) ->
    lists:reverse(Acc);
check_dict([{Key, Data} | Rest], Props, Acc) ->
    check_dict(Rest, Props, [{dict:fetch(Key, Props), Data} | Acc]).

data() ->
    [
        {filename,<<"libgda4-dev_4.0.4-0maemo0_i386.deb">>},
        {maintainer,[<<"Gustavo R. Montesino <grmontesino@ig.com.br>">>]},
        {description, [
            <<"Development files for GNOME Data Access library for GNOME2">>,
            <<"GNOME Data Access is an attempt to provide uniform access to">>,
            <<"different kinds of data sources (databases, information servers,">>,
            <<"mail spools, etc).">>,
            <<"It is a complete architecture that provides all you need to">>,
            <<"access your data.">>,<<".">>,
            <<"This library is made for GNOME2, but it doesn't require GNOME2 libraries.">>,
            <<".">>,
            <<"This package contains the header files and libraries which">>,
            <<"you need for development.">>
        ]},
        {package,<<"libgda4-dev">>},
        {section,<<"libdevel">>},
        {'installed-size',<<"2432">>},
        {priority,<<"optional">>},
        {suggests,[<<"libgda4-doc">>]},
        {depends, [
            <<"libgda4-4 (= 4.0.4-0maemo0)">>,
            <<"libglib2.0-dev (>= 2.2.0)">>,
            <<"libxslt1-dev">>
        ]},
        {version,<<"4.0.4-0maemo0">>},
        {source,<<"libgda4">>},
        {architecture,<<"i386">>}
    ].