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Diffstat (limited to 'erts/example/time_compat.erl')
| -rw-r--r-- | erts/example/time_compat.erl | 302 |
1 files changed, 302 insertions, 0 deletions
diff --git a/erts/example/time_compat.erl b/erts/example/time_compat.erl new file mode 100644 index 0000000000..d582117ceb --- /dev/null +++ b/erts/example/time_compat.erl @@ -0,0 +1,302 @@ +%% +%% %CopyrightBegin% +%% +%% Copyright Ericsson AB 2014. All Rights Reserved. +%% +%% The contents of this file are subject to the Erlang Public License, +%% Version 1.1, (the "License"); you may not use this file except in +%% compliance with the License. You should have received a copy of the +%% Erlang Public License along with this software. If not, it can be +%% retrieved online at http://www.erlang.org/. +%% +%% Software distributed under the License is distributed on an "AS IS" +%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See +%% the License for the specific language governing rights 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 == 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. |