From 6487aac5977cf470bc6a2cd0964da2850ee38717 Mon Sep 17 00:00:00 2001 From: Rickard Green Date: Thu, 30 Oct 2014 23:57:01 +0100 Subject: Introduce a new time API The old time API is based on erlang:now/0. The major issue with erlang:now/0 is that it was intended to be used for so many unrelated things. This tied these unrelated operations together and unnecessarily caused performance, scalability as well as accuracy, and precision issues for operations that do not need to have such issues. The new API spreads different functionality over multiple functions in order to improve on this. The new API consists of a number of new BIFs: - erlang:convert_time_unit/3 - erlang:monotonic_time/0 - erlang:monotonic_time/1 - erlang:system_time/0 - erlang:system_time/1 - erlang:time_offset/0 - erlang:time_offset/1 - erlang:timestamp/0 - erlang:unique_integer/0 - erlang:unique_integer/1 - os:system_time/0 - os:system_time/1 and a number of extensions of existing BIFs: - erlang:monitor(time_offset, clock_service) - erlang:system_flag(time_offset, finalize) - erlang:system_info(os_monotonic_time_source) - erlang:system_info(time_offset) - erlang:system_info(time_warp_mode) - erlang:system_info(time_correction) - erlang:system_info(start_time) See the "Time and Time Correction in Erlang" chapter of the ERTS User's Guide for more information. --- lib/kernel/doc/src/os.xml | 48 ++++++++++++++++++++++++++++++++++++++++++----- lib/kernel/src/os.erl | 14 +++++++++++++- 2 files changed, 56 insertions(+), 6 deletions(-) (limited to 'lib/kernel') diff --git a/lib/kernel/doc/src/os.xml b/lib/kernel/doc/src/os.xml index 2b57e75023..763bf01cc9 100644 --- a/lib/kernel/doc/src/os.xml +++ b/lib/kernel/doc/src/os.xml @@ -128,15 +128,50 @@ DirOut = os:cmd("dir"), % on Win32 platform environment is set using wide character interfaces.

+ + + Current OS system time + +

Returns current + OS system time + in native + time unit.

+ +

This time is not a monotonically increasing time.

 + + + + + Current OS system time + +

Returns current + OS system time + converted into the Unit passed as argument.

+ +

Calling os:system_time(Unit) is equivalent to: + erlang:convert_time_unit(os:system_time(), + native, Unit).

+ +

This time is not a monotonically increasing time.

 + + Timestamp = {MegaSecs, Secs, MicroSecs} - Returna a timestamp from the OS in the erlang:now/0 format + Current OS system time on the erlang:timestamp/0 format -

Returns a tuple in the same format as erlang:now/0. The difference is that this function returns what the operating system thinks (a.k.a. the wall clock time) without any attempts at time correction. The result of two different calls to this function is not guaranteed to be different.

-

The most obvious use for this function is logging. The tuple can be used together with the function calendar:now_to_universal_time/1 -or calendar:now_to_local_time/1 to get calendar time. Using the calendar time together with the MicroSecs part of the return tuple from this function allows you to log timestamps in high resolution and consistent with the time in the rest of the operating system.

-

Example of code formatting a string in the format "DD Mon YYYY HH:MM:SS.mmmmmm", where DD is the day of month, Mon is the textual month name, YYYY is the year, HH:MM:SS is the time and mmmmmm is the microseconds in six positions:

+

Returns current + OS system time + in the same format as erlang:timestamp/0. + The tuple can be used together with the function + calendar:now_to_universal_time/1 + or calendar:now_to_local_time/1 to + get calendar time. Using the calendar time together with the MicroSecs part of the return + tuple from this function allows you to log timestamps in high resolution and consistent with the + time in the rest of the operating system.

+

Example of code formatting a string in the format "DD Mon YYYY HH:MM:SS.mmmmmm", where + DD is the day of month, Mon is the textual month name, YYYY is the year, HH:MM:SS is the time and + mmmmmm is the microseconds in six positions:

-module(print_time). -export([format_utc_timestamp/0]). @@ -155,6 +190,9 @@ format_utc_timestamp() -> 1> io:format("~s~n",[print_time:format_utc_timestamp()]). 29 Apr 2009 9:55:30.051711 +

OS system time can also be retreived by + os:system_time/0, + and os:system_time/1.

 diff --git a/lib/kernel/src/os.erl b/lib/kernel/src/os.erl index 187fd0001b..3d308a43b0 100644 --- a/lib/kernel/src/os.erl +++ b/lib/kernel/src/os.erl @@ -26,7 +26,8 @@ %%% BIFs --export([getenv/0, getenv/1, getpid/0, putenv/2, timestamp/0, unsetenv/1]). +-export([getenv/0, getenv/1, getpid/0, putenv/2, system_time/0, system_time/1, + timestamp/0, unsetenv/1]). -spec getenv() -> [string()]. @@ -52,6 +53,17 @@ getpid() -> putenv(_, _) -> erlang:nif_error(undef). +-spec system_time() -> integer(). + +system_time() -> + erlang:nif_error(undef). + +-spec system_time(Unit) -> integer() when + Unit :: erlang:time_unit(). + +system_time(_Unit) -> + erlang:nif_error(undef). + -spec timestamp() -> Timestamp when Timestamp :: erlang:timestamp(). -- cgit v1.2.3 From fbaa0becc787e73fa539e0d497b0d74be27c9534 Mon Sep 17 00:00:00 2001 From: Rickard Green Date: Wed, 17 Dec 2014 22:18:27 +0100 Subject: Replace usage of erlang:now() with usage of new API --- lib/kernel/src/auth.erl | 4 ++-- lib/kernel/src/dist_util.erl | 6 ++++-- lib/kernel/src/global.erl | 18 ++++++++++-------- lib/kernel/src/inet_db.erl | 3 +-- lib/kernel/src/inet_res.erl | 14 +++++++++----- lib/kernel/src/kernel.app.src | 2 +- lib/kernel/src/pg2.erl | 11 +++++++---- 7 files changed, 34 insertions(+), 24 deletions(-) (limited to 'lib/kernel') diff --git a/lib/kernel/src/auth.erl b/lib/kernel/src/auth.erl index eda35147d3..dbc486bee1 100644 --- a/lib/kernel/src/auth.erl +++ b/lib/kernel/src/auth.erl @@ -370,8 +370,8 @@ check_cookie1([], Result) -> %% Creates a new, random cookie. create_cookie(Name) -> - {_, S1, S2} = now(), - Seed = S2*10000+S1, + Seed = abs(erlang:monotonic_time() + bxor erlang:unique_integer()), Cookie = random_cookie(20, Seed, []), case file:open(Name, [write, raw]) of {ok, File} -> diff --git a/lib/kernel/src/dist_util.erl b/lib/kernel/src/dist_util.erl index b127fe2e33..6b510bd0c3 100644 --- a/lib/kernel/src/dist_util.erl +++ b/lib/kernel/src/dist_util.erl @@ -298,7 +298,7 @@ shutdown(_Module, _Line, _Data, Reason) -> exit(Reason). %% Use this line to debug connection. %% Set net_kernel verbose = 1 as well. -%% exit({Reason, ?MODULE, _Line, _Data, erlang:now()}). +%% exit({Reason, ?MODULE, _Line, _Data, erlang:timestamp()}). flush_down() -> @@ -373,7 +373,9 @@ gen_digest(Challenge, Cookie) when is_integer(Challenge), is_atom(Cookie) -> %% gen_challenge() returns a "random" number %% --------------------------------------------------------------- gen_challenge() -> - {A,B,C} = erlang:now(), + A = erlang:phash2([erlang:node()]), + B = erlang:monotonic_time(), + C = erlang:unique_integer(), {D,_} = erlang:statistics(reductions), {E,_} = erlang:statistics(runtime), {F,_} = erlang:statistics(wall_clock), diff --git a/lib/kernel/src/global.erl b/lib/kernel/src/global.erl index 0a4edea452..6c36d417a2 100644 --- a/lib/kernel/src/global.erl +++ b/lib/kernel/src/global.erl @@ -881,11 +881,12 @@ handle_info({nodeup, Node}, S0) when S0#state.connect_all -> false -> resend_pre_connect(Node), - %% now() is used as a tag to separate different synch sessions + %% erlang:unique_integer([monotonic]) is used as a tag to + %% separate different synch sessions %% from each others. Global could be confused at bursty nodeups %% because it couldn't separate the messages between the different %% synch sessions started by a nodeup. - MyTag = now(), + MyTag = erlang:unique_integer([monotonic]), put({sync_tag_my, Node}, MyTag), ?trace({sending_nodeup_to_locker, {node,Node},{mytag,MyTag}}), S1#state.the_locker ! {nodeup, Node, MyTag}, @@ -1772,8 +1773,8 @@ update_locker_known(Upd, S) -> S#multi{known = Known, the_boss = TheBoss}. random_element(L) -> - {A,B,C} = now(), - E = (A+B+C) rem length(L), + E = abs(erlang:monotonic_time() + bxor erlang:unique_integer()) rem length(L), lists:nth(E+1, L). exclude_known(Others, Known) -> @@ -2072,9 +2073,10 @@ random_sleep(Times) -> end, case get(random_seed) of undefined -> - {A1, A2, A3} = now(), - _ = random:seed(A1, A2, A3 + erlang:phash(node(), 100000)), - ok; + _ = random:seed(erlang:phash2([erlang:node()]), + erlang:monotonic_time(), + erlang:unique_integer()), + ok; _ -> ok end, %% First time 1/4 seconds, then doubling each time up to 8 seconds max. @@ -2106,7 +2108,7 @@ trace_message(S, M, X) -> S#state{trace = [trace_message(M, X) | S#state.trace]}. trace_message(M, X) -> - {node(), now(), M, nodes(), X}. + {node(), erlang:timestamp(), M, nodes(), X}. %%----------------------------------------------------------------- %% Each sync process corresponds to one call to sync. Each such diff --git a/lib/kernel/src/inet_db.erl b/lib/kernel/src/inet_db.erl index 2ebdc0f554..abe207295f 100644 --- a/lib/kernel/src/inet_db.erl +++ b/lib/kernel/src/inet_db.erl @@ -1372,8 +1372,7 @@ cache_rr(_Db, Cache, RR) -> ets:insert(Cache, RR). times() -> - {Mega,Secs,_} = erlang:now(), - Mega*1000000 + Secs. + erlang:monotonic_time(1). %% lookup and remove old entries diff --git a/lib/kernel/src/inet_res.erl b/lib/kernel/src/inet_res.erl index 6037da1d22..410128a16a 100644 --- a/lib/kernel/src/inet_res.erl +++ b/lib/kernel/src/inet_res.erl @@ -715,10 +715,10 @@ udp_send(#sock{inet=I}, {A,B,C,D}=IP, Port, Buffer) udp_recv(#sock{inet6=I}, {A,B,C,D,E,F,G,H}=IP, Port, Timeout, Decode) when ?ip6(A,B,C,D,E,F,G,H), ?port(Port) -> - do_udp_recv(I, IP, Port, Timeout, Decode, erlang:now(), Timeout); + do_udp_recv(I, IP, Port, Timeout, Decode, time_now(), Timeout); udp_recv(#sock{inet=I}, {A,B,C,D}=IP, Port, Timeout, Decode) when ?ip(A,B,C,D), ?port(Port) -> - do_udp_recv(I, IP, Port, Timeout, Decode, erlang:now(), Timeout). + do_udp_recv(I, IP, Port, Timeout, Decode, time_now(), Timeout). do_udp_recv(_I, _IP, _Port, 0, _Decode, _Start, _T) -> timeout; @@ -742,7 +742,7 @@ do_udp_recv(I, IP, Port, Timeout, Decode, Start, T) -> NewTimeout = erlang:max(0, Timeout - 50), do_udp_recv(I, IP, Port, NewTimeout, Decode, Start, T); false -> - Now = erlang:now(), + Now = time_now(), NewT = erlang:max(0, Timeout - now_ms(Now, Start)), do_udp_recv(I, IP, Port, Timeout, Decode, Start, NewT); Result -> @@ -1057,5 +1057,9 @@ dns_msg(Msg) -> end. -compile({inline, [now_ms/2]}). -now_ms({Meg1,Sec1,Mic1}, {Meg0,Sec0,Mic0}) -> - ((Meg1-Meg0)*1000000 + (Sec1-Sec0))*1000 + ((Mic1-Mic0) div 1000). +now_ms(Int1, Int0) -> + Int1 - Int0. + +-compile({inline, [time_now/0]}). +time_now() -> + erlang:monotonic_time(1000). diff --git a/lib/kernel/src/kernel.app.src b/lib/kernel/src/kernel.app.src index 9f6c0f4624..0cb10791d7 100644 --- a/lib/kernel/src/kernel.app.src +++ b/lib/kernel/src/kernel.app.src @@ -115,6 +115,6 @@ {applications, []}, {env, [{error_logger, tty}]}, {mod, {kernel, []}}, - {runtime_dependencies, ["erts-6.1.2", "stdlib-2.0", "sasl-2.4"]} + {runtime_dependencies, ["erts-7.0", "stdlib-2.0", "sasl-2.4"]} ] }. diff --git a/lib/kernel/src/pg2.erl b/lib/kernel/src/pg2.erl index b562d4ffd2..70d7a75671 100644 --- a/lib/kernel/src/pg2.erl +++ b/lib/kernel/src/pg2.erl @@ -140,19 +140,22 @@ get_closest_pid(Name) -> [Pid] -> Pid; [] -> - {_,_,X} = erlang:now(), case get_members(Name) of [] -> {error, {no_process, Name}}; Members -> - lists:nth((X rem length(Members))+1, Members) + random_element(Members) end; Members when is_list(Members) -> - {_,_,X} = erlang:now(), - lists:nth((X rem length(Members))+1, Members); + random_element(Members); Else -> Else end. +random_element(List) -> + X = abs(erlang:monotonic_time() + bxor erlang:unique_integer()), + lists:nth((X rem length(List)) + 1, List). + %%% %%% Callback functions from gen_server %%% -- cgit v1.2.3