%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2014. All Rights Reserved.
%%
%% Licensed 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.
%%
%% %CopyrightEnd%
%%
%%
%% If your code need to be able to execute on ERTS versions both
%% earlier and later than 7.0, the best approach is to use the new
%% time API introduced in ERTS 7.0 and implement a fallback
%% solution using the old primitives to be used on old ERTS
%% versions. This way your code can automatically take advantage
%% of the improvements in the API when available. This is an
%% example of how to implement such an API, but it can be used
%% as is if you want to. Just add this module to your project,
%% and call the API via this module instead of calling the
%% BIFs directly.
%%
-module(time_compat).
%% We don't want warnings about the use of erlang:now/0 in
%% this module.
-compile(nowarn_deprecated_function).
%%
%% We don't use
%% -compile({nowarn_deprecated_function, [{erlang, now, 0}]}).
%% since this will produce warnings when compiled on systems
%% where it has not yet been deprecated.
%%
-export([monotonic_time/0,
monotonic_time/1,
erlang_system_time/0,
erlang_system_time/1,
os_system_time/0,
os_system_time/1,
time_offset/0,
time_offset/1,
convert_time_unit/3,
timestamp/0,
unique_integer/0,
unique_integer/1,
monitor/2,
system_info/1,
system_flag/2]).
monotonic_time() ->
try
erlang:monotonic_time()
catch
error:undef ->
%% Use Erlang system time as monotonic time
erlang_system_time_fallback()
end.
monotonic_time(Unit) ->
try
erlang:monotonic_time(Unit)
catch
error:badarg ->
erlang:error(badarg, [Unit]);
error:undef ->
%% Use Erlang system time as monotonic time
STime = erlang_system_time_fallback(),
try
convert_time_unit_fallback(STime, native, Unit)
catch
error:bad_time_unit -> erlang:error(badarg, [Unit])
end
end.
erlang_system_time() ->
try
erlang:system_time()
catch
error:undef ->
erlang_system_time_fallback()
end.
erlang_system_time(Unit) ->
try
erlang:system_time(Unit)
catch
error:badarg ->
erlang:error(badarg, [Unit]);
error:undef ->
STime = erlang_system_time_fallback(),
try
convert_time_unit_fallback(STime, native, Unit)
catch
error:bad_time_unit -> erlang:error(badarg, [Unit])
end
end.
os_system_time() ->
try
os:system_time()
catch
error:undef ->
os_system_time_fallback()
end.
os_system_time(Unit) ->
try
os:system_time(Unit)
catch
error:badarg ->
erlang:error(badarg, [Unit]);
error:undef ->
STime = os_system_time_fallback(),
try
convert_time_unit_fallback(STime, native, Unit)
catch
error:bad_time_unit -> erlang:error(badarg, [Unit])
end
end.
time_offset() ->
try
erlang:time_offset()
catch
error:undef ->
%% Erlang system time and Erlang monotonic
%% time are always aligned
0
end.
time_offset(Unit) ->
try
erlang:time_offset(Unit)
catch
error:badarg ->
erlang:error(badarg, [Unit]);
error:undef ->
try
_ = integer_time_unit(Unit)
catch
error:bad_time_unit -> erlang:error(badarg, [Unit])
end,
%% Erlang system time and Erlang monotonic
%% time are always aligned
0
end.
convert_time_unit(Time, FromUnit, ToUnit) ->
try
erlang:convert_time_unit(Time, FromUnit, ToUnit)
catch
error:undef ->
try
convert_time_unit_fallback(Time, FromUnit, ToUnit)
catch
_:_ ->
erlang:error(badarg, [Time, FromUnit, ToUnit])
end;
error:Error ->
erlang:error(Error, [Time, FromUnit, ToUnit])
end.
timestamp() ->
try
erlang:timestamp()
catch
error:undef ->
erlang:now()
end.
unique_integer() ->
try
erlang:unique_integer()
catch
error:undef ->
{MS, S, US} = erlang:now(),
(MS*1000000+S)*1000000+US
end.
unique_integer(Modifiers) ->
try
erlang:unique_integer(Modifiers)
catch
error:badarg ->
erlang:error(badarg, [Modifiers]);
error:undef ->
case is_valid_modifier_list(Modifiers) of
true ->
%% now() converted to an integer
%% fullfill the requirements of
%% all modifiers: unique, positive,
%% and monotonic...
{MS, S, US} = erlang:now(),
(MS*1000000+S)*1000000+US;
false ->
erlang:error(badarg, [Modifiers])
end
end.
monitor(Type, Item) ->
try
erlang:monitor(Type, Item)
catch
error:Error ->
case {Error, Type, Item} of
{badarg, time_offset, clock_service} ->
%% Time offset is final and will never change.
%% Return a dummy reference, there will never
%% be any need for 'CHANGE' messages...
make_ref();
_ ->
erlang:error(Error, [Type, Item])
end
end.
system_info(Item) ->
try
erlang:system_info(Item)
catch
error:badarg ->
case Item of
time_correction ->
case erlang:system_info(tolerant_timeofday) of
enabled -> true;
disabled -> false
end;
time_warp_mode ->
no_time_warp;
time_offset ->
final;
NotSupArg when NotSupArg == os_monotonic_time_source;
NotSupArg == os_system_time_source;
NotSupArg == start_time ->
%% Cannot emulate this...
erlang:error(notsup, [NotSupArg]);
_ ->
erlang:error(badarg, [Item])
end;
error:Error ->
erlang:error(Error, [Item])
end.
system_flag(Flag, Value) ->
try
erlang:system_flag(Flag, Value)
catch
error:Error ->
case {Error, Flag, Value} of
{badarg, time_offset, finalize} ->
%% Time offset is final
final;
_ ->
erlang:error(Error, [Flag, Value])
end
end.
%%
%% Internal functions
%%
integer_time_unit(native) -> 1000*1000;
integer_time_unit(nano_seconds) -> 1000*1000*1000;
integer_time_unit(micro_seconds) -> 1000*1000;
integer_time_unit(milli_seconds) -> 1000;
integer_time_unit(seconds) -> 1;
integer_time_unit(I) when is_integer(I), I > 0 -> I;
integer_time_unit(BadRes) -> erlang:error(bad_time_unit, [BadRes]).
erlang_system_time_fallback() ->
{MS, S, US} = erlang:now(),
(MS*1000000+S)*1000000+US.
os_system_time_fallback() ->
{MS, S, US} = os:timestamp(),
(MS*1000000+S)*1000000+US.
convert_time_unit_fallback(Time, FromUnit, ToUnit) ->
FU = integer_time_unit(FromUnit),
TU = integer_time_unit(ToUnit),
case Time < 0 of
true -> TU*Time - (FU - 1);
false -> TU*Time
end div FU.
is_valid_modifier_list([positive|Ms]) ->
is_valid_modifier_list(Ms);
is_valid_modifier_list([monotonic|Ms]) ->
is_valid_modifier_list(Ms);
is_valid_modifier_list([]) ->
true;
is_valid_modifier_list(_) ->
false.
