%% Copyright (c) 2011, Loïc Hoguin <[email protected]>
%%
%% Permission to use, copy, modify, and/or distribute this software for any
%% purpose with or without fee is hereby granted, provided that the above
%% copyright notice and this permission notice appear in all copies.
%%
%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
%% @doc Date and time related functions.
%%
%% While a gen_server process runs in the background to update
%% the cache of formatted dates every second, all API calls are
%% local and directly read from the ETS cache table, providing
%% fast time and date computations.
-module(cowboy_clock).
-behaviour(gen_server).
-export([start_link/0, stop/0, rfc1123/0]). %% API.
-export([init/1, handle_call/3, handle_cast/2,
handle_info/2, terminate/2, code_change/3]). %% gen_server.
%% @todo Use calendar types whenever they get exported.
-type year() :: non_neg_integer().
-type month() :: 1..12.
-type day() :: 1..31.
-type hour() :: 0..23.
-type minute() :: 0..59.
-type second() :: 0..59.
-type daynum() :: 1..7.
-type date() :: {year(), month(), day()}.
-type time() :: {hour(), minute(), second()}.
-type datetime() :: {date(), time()}.
-record(state, {
universaltime = undefined :: undefined | datetime(),
rfc1123 = <<>> :: binary(),
tref = undefined :: undefined | timer:tref()
}).
-define(SERVER, ?MODULE).
-define(TABLE, ?MODULE).
-include_lib("eunit/include/eunit.hrl").
%% API.
%% @private
-spec start_link() -> {ok, pid()}.
start_link() ->
gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
%% @private
-spec stop() -> stopped.
stop() ->
gen_server:call(?SERVER, stop).
%% @doc Return the current date and time formatted according to RFC-1123.
%%
%% This format is used in the <em>'Date'</em> header sent with HTTP responses.
-spec rfc1123() -> binary().
rfc1123() ->
ets:lookup_element(?TABLE, rfc1123, 2).
%% gen_server.
%% @private
-spec init([]) -> {ok, #state{}}.
init([]) ->
?TABLE = ets:new(?TABLE, [set, protected,
named_table, {read_concurrency, true}]),
T = erlang:universaltime(),
B = update_rfc1123(<<>>, undefined, T),
{ok, TRef} = timer:send_interval(1000, update),
ets:insert(?TABLE, {rfc1123, B}),
{ok, #state{universaltime=T, rfc1123=B, tref=TRef}}.
%% @private
-spec handle_call(_, _, State)
-> {reply, ignored, State} | {stop, normal, stopped, State}.
handle_call(stop, _From, State=#state{tref=TRef}) ->
{ok, cancel} = timer:cancel(TRef),
{stop, normal, stopped, State};
handle_call(_Request, _From, State) ->
{reply, ignored, State}.
%% @private
-spec handle_cast(_, State) -> {noreply, State}.
handle_cast(_Msg, State) ->
{noreply, State}.
%% @private
-spec handle_info(_, State) -> {noreply, State}.
handle_info(update, #state{universaltime=Prev, rfc1123=B1, tref=TRef}) ->
T = erlang:universaltime(),
B2 = update_rfc1123(B1, Prev, T),
ets:insert(?TABLE, {rfc1123, B2}),
{noreply, #state{universaltime=T, rfc1123=B2, tref=TRef}};
handle_info(_Info, State) ->
{noreply, State}.
%% @private
-spec terminate(_, _) -> ok.
terminate(_Reason, _State) ->
ok.
%% @private
-spec code_change(_, State, _) -> {ok, State}.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%% Internal.
-spec update_rfc1123(binary(), undefined | datetime(), datetime()) -> binary().
update_rfc1123(Bin, Now, Now) ->
Bin;
update_rfc1123(<< Keep:23/binary, _/bits >>,
{Date, {H, M, _}}, {Date, {H, M, S}}) ->
<< Keep/binary, (pad_int(S))/binary, " GMT" >>;
update_rfc1123(<< Keep:20/binary, _/bits >>,
{Date, {H, _, _}}, {Date, {H, M, S}}) ->
<< Keep/binary, (pad_int(M))/binary, $:, (pad_int(S))/binary, " GMT" >>;
update_rfc1123(<< Keep:17/binary, _/bits >>, {Date, _}, {Date, {H, M, S}}) ->
<< Keep/binary, (pad_int(H))/binary, $:, (pad_int(M))/binary,
$:, (pad_int(S))/binary, " GMT" >>;
update_rfc1123(<< _:7/binary, Keep:10/binary, _/bits >>,
{{Y, Mo, _}, _}, {Date = {Y, Mo, D}, {H, M, S}}) ->
Wday = calendar:day_of_the_week(Date),
<< (weekday(Wday))/binary, ", ", (pad_int(D))/binary, Keep/binary,
(pad_int(H))/binary, $:, (pad_int(M))/binary,
$:, (pad_int(S))/binary, " GMT" >>;
update_rfc1123(<< _:11/binary, Keep:6/binary, _/bits >>,
{{Y, _, _}, _}, {Date = {Y, Mo, D}, {H, M, S}}) ->
Wday = calendar:day_of_the_week(Date),
<< (weekday(Wday))/binary, ", ", (pad_int(D))/binary, " ",
(month(Mo))/binary, Keep/binary,
(pad_int(H))/binary, $:, (pad_int(M))/binary,
$:, (pad_int(S))/binary, " GMT" >>;
update_rfc1123(_, _, {Date = {Y, Mo, D}, {H, M, S}}) ->
Wday = calendar:day_of_the_week(Date),
<< (weekday(Wday))/binary, ", ", (pad_int(D))/binary, " ",
(month(Mo))/binary, " ", (list_to_binary(integer_to_list(Y)))/binary,
" ", (pad_int(H))/binary, $:, (pad_int(M))/binary,
$:, (pad_int(S))/binary, " GMT" >>.
%% Following suggestion by MononcQc on #erlounge.
-spec pad_int(0..59) -> binary().
pad_int(X) when X < 10 ->
<< $0, ($0 + X) >>;
pad_int(X) ->
list_to_binary(integer_to_list(X)).
-spec weekday(daynum()) -> <<_:24>>.
weekday(1) -> <<"Mon">>;
weekday(2) -> <<"Tue">>;
weekday(3) -> <<"Wed">>;
weekday(4) -> <<"Thu">>;
weekday(5) -> <<"Fri">>;
weekday(6) -> <<"Sat">>;
weekday(7) -> <<"Sun">>.
-spec month(month()) -> <<_:24>>.
month( 1) -> <<"Jan">>;
month( 2) -> <<"Feb">>;
month( 3) -> <<"Mar">>;
month( 4) -> <<"Apr">>;
month( 5) -> <<"May">>;
month( 6) -> <<"Jun">>;
month( 7) -> <<"Jul">>;
month( 8) -> <<"Aug">>;
month( 9) -> <<"Sep">>;
month(10) -> <<"Oct">>;
month(11) -> <<"Nov">>;
month(12) -> <<"Dec">>.
%% Tests.
-ifdef(TEST).
update_rfc1123_test_() ->
Tests = [
{<<"Sat, 14 May 2011 14:25:33 GMT">>, undefined,
{{2011, 5, 14}, {14, 25, 33}}, <<>>},
{<<"Sat, 14 May 2011 14:25:33 GMT">>, {{2011, 5, 14}, {14, 25, 33}},
{{2011, 5, 14}, {14, 25, 33}}, <<"Sat, 14 May 2011 14:25:33 GMT">>},
{<<"Sat, 14 May 2011 14:25:34 GMT">>, {{2011, 5, 14}, {14, 25, 33}},
{{2011, 5, 14}, {14, 25, 34}}, <<"Sat, 14 May 2011 14:25:33 GMT">>},
{<<"Sat, 14 May 2011 14:26:00 GMT">>, {{2011, 5, 14}, {14, 25, 59}},
{{2011, 5, 14}, {14, 26, 0}}, <<"Sat, 14 May 2011 14:25:59 GMT">>},
{<<"Sat, 14 May 2011 15:00:00 GMT">>, {{2011, 5, 14}, {14, 59, 59}},
{{2011, 5, 14}, {15, 0, 0}}, <<"Sat, 14 May 2011 14:59:59 GMT">>},
{<<"Sun, 15 May 2011 00:00:00 GMT">>, {{2011, 5, 14}, {23, 59, 59}},
{{2011, 5, 15}, { 0, 0, 0}}, <<"Sat, 14 May 2011 23:59:59 GMT">>},
{<<"Wed, 01 Jun 2011 00:00:00 GMT">>, {{2011, 5, 31}, {23, 59, 59}},
{{2011, 6, 1}, { 0, 0, 0}}, <<"Tue, 31 May 2011 23:59:59 GMT">>},
{<<"Sun, 01 Jan 2012 00:00:00 GMT">>, {{2011, 5, 31}, {23, 59, 59}},
{{2012, 1, 1}, { 0, 0, 0}}, <<"Sat, 31 Dec 2011 23:59:59 GMT">>}
],
[{R, fun() -> R = update_rfc1123(B, P, N) end} || {R, P, N, B} <- Tests].
pad_int_test_() ->
Tests = [
{ 0, <<"00">>}, { 1, <<"01">>}, { 2, <<"02">>}, { 3, <<"03">>},
{ 4, <<"04">>}, { 5, <<"05">>}, { 6, <<"06">>}, { 7, <<"07">>},
{ 8, <<"08">>}, { 9, <<"09">>}, {10, <<"10">>}, {11, <<"11">>},
{12, <<"12">>}, {13, <<"13">>}, {14, <<"14">>}, {15, <<"15">>},
{16, <<"16">>}, {17, <<"17">>}, {18, <<"18">>}, {19, <<"19">>},
{20, <<"20">>}, {21, <<"21">>}, {22, <<"22">>}, {23, <<"23">>},
{24, <<"24">>}, {25, <<"25">>}, {26, <<"26">>}, {27, <<"27">>},
{28, <<"28">>}, {29, <<"29">>}, {30, <<"30">>}, {31, <<"31">>},
{32, <<"32">>}, {33, <<"33">>}, {34, <<"34">>}, {35, <<"35">>},
{36, <<"36">>}, {37, <<"37">>}, {38, <<"38">>}, {39, <<"39">>},
{40, <<"40">>}, {41, <<"41">>}, {42, <<"42">>}, {43, <<"43">>},
{44, <<"44">>}, {45, <<"45">>}, {46, <<"46">>}, {47, <<"47">>},
{48, <<"48">>}, {49, <<"49">>}, {50, <<"50">>}, {51, <<"51">>},
{52, <<"52">>}, {53, <<"53">>}, {54, <<"54">>}, {55, <<"55">>},
{56, <<"56">>}, {57, <<"57">>}, {58, <<"58">>}, {59, <<"59">>}
],
[{I, fun() -> O = pad_int(I) end} || {I, O} <- Tests].
-endif.
