Merge branch 'anders/diameter/17/time/OTP-12926' into maint-17

* anders/diameter/17/time/OTP-12926:
  Simplify time manipulation
  Remove use of monotonic time in pre-18 code
  Remove unnecessary redefinition of erlang:max/2

9 files changed, 11 insertions, 122 deletions

diff --git a/lib/diameter/src/base/diameter_config.erl b/lib/diameter/src/base/diameter_config.erl
index 8ac3b9d6ca..89b26707ad 100644
--- a/lib/diameter/src/base/diameter_config.erl
+++ b/lib/diameter/src/base/diameter_config.erl
@@ -37,8 +37,7 @@
 -module(diameter_config).
 -behaviour(gen_server).
 
--compile({no_auto_import, [monitor/2, now/0]}).
--import(diameter_lib, [now/0]).
+-compile({no_auto_import, [monitor/2]}).
 
 -export([start_service/2,
          stop_service/1,
diff --git a/lib/diameter/src/base/diameter_lib.erl b/lib/diameter/src/base/diameter_lib.erl
index b9b3e21788..26cc6137a2 100644
--- a/lib/diameter/src/base/diameter_lib.erl
+++ b/lib/diameter/src/base/diameter_lib.erl
@@ -18,18 +18,12 @@
 %%
 
 -module(diameter_lib).
--compile({no_auto_import, [now/0]}).
 
 -export([info_report/2,
          error_report/2,
          warning_report/2,
-         now/0,
-         timestamp/1,
          now_diff/1,
-         micro_diff/1,
-         micro_diff/2,
          time/1,
-         seed/0,
          eval/1,
          eval_name/1,
          get_stacktrace/0,
@@ -98,49 +92,10 @@ fmt(T) ->
     end.
 
 %% ---------------------------------------------------------------------------
-%% # now/0
-%% ---------------------------------------------------------------------------
-
--type timestamp() :: {non_neg_integer(), 0..999999, 0..999999}.
--type now() :: integer() %% monotonic time
-             | timestamp().
-
--spec now()
-   -> now().
-
-%% Use monotonic time if it exists, fall back to erlang:now()
-%% otherwise.
-
-now() ->
-    try
-        erlang:monotonic_time() 
-    catch
-        error: undef -> erlang:now()
-    end.
-
-%% ---------------------------------------------------------------------------
-%% # timestamp/1
-%% ---------------------------------------------------------------------------
-
--spec timestamp(NowT :: now())
-   -> timestamp().
-
-timestamp({_,_,_} = T) ->  %% erlang:now()
-    T;
-
-timestamp(MonoT) ->  %% monotonic time
-    MicroSecs = monotonic_to_microseconds(MonoT + erlang:time_offset()),
-    Secs = MicroSecs div 1000000,
-    {Secs div 1000000, Secs rem 1000000, MicroSecs rem 1000000}.
-
-monotonic_to_microseconds(MonoT) ->
-    erlang:convert_time_unit(MonoT, native, micro_seconds).
-
-%% ---------------------------------------------------------------------------
 %% # now_diff/1
 %% ---------------------------------------------------------------------------
 
--spec now_diff(NowT :: now())
+-spec now_diff(NowT :: erlang:timestamp())
    -> {Hours, Mins, Secs, MicroSecs}
  when Hours :: non_neg_integer(),
       Mins  :: 0..59,
@@ -151,36 +106,7 @@ monotonic_to_microseconds(MonoT) ->
 %% instead of as integer microseconds.
 
 now_diff(Time) ->
-    time(micro_diff(Time)).
-
-%% ---------------------------------------------------------------------------
-%% # micro_diff/1
-%% ---------------------------------------------------------------------------
-
--spec micro_diff(NowT :: now())
-   -> MicroSecs
- when MicroSecs :: non_neg_integer().
-
-micro_diff({_,_,_} = T0) ->
-    timer:now_diff(erlang:now(), T0);
-
-micro_diff(T0) ->  %% monotonic time
-    monotonic_to_microseconds(erlang:monotonic_time() - T0).
-
-%% ---------------------------------------------------------------------------
-%% # micro_diff/2
-%% ---------------------------------------------------------------------------
-
--spec micro_diff(T1 :: now(), T0 :: now())
-   -> MicroSecs
- when MicroSecs :: non_neg_integer().
-
-micro_diff(T1, T0)
-  when is_integer(T1), is_integer(T0) ->  %% monotonic time
-    monotonic_to_microseconds(T1 - T0);
-
-micro_diff(T1, T0) ->  %% at least one erlang:now()
-    timer:now_diff(timestamp(T1), timestamp(T0)).
+    time(timer:now_diff(now(), Time)).
 
 %% ---------------------------------------------------------------------------
 %% # time/1
@@ -190,7 +116,7 @@ micro_diff(T1, T0) ->  %% at least one erlang:now()
 
 -spec time(NowT | Diff)
    -> {Hours, Mins, Secs, MicroSecs}
- when NowT  :: timestamp(),
+ when NowT  :: erlang:timestamp(),
       Diff  :: non_neg_integer(),
       Hours :: non_neg_integer(),
       Mins  :: 0..59,
@@ -209,27 +135,6 @@ time(Micro) ->  %% elapsed time
     {H, M, S, Micro rem 1000000}.
 
 %% ---------------------------------------------------------------------------
-%% # seed/0
-%% ---------------------------------------------------------------------------
-
--spec seed()
-   -> {timestamp(), {integer(), integer(), integer()}}.
-
-%% Return an argument for random:seed/1.
-
-seed() ->
-    T = now(),
-    {timestamp(T), seed(T)}.
-
-%% seed/1
-
-seed({_,_,_} = T) ->
-    T;
-
-seed(T) ->  %% monotonic time
-    {erlang:phash2(node()), T, erlang:unique_integer()}.
-
-%% ---------------------------------------------------------------------------
 %% # eval/1
 %%
 %% Evaluate a function in various forms.
diff --git a/lib/diameter/src/base/diameter_peer.erl b/lib/diameter/src/base/diameter_peer.erl
index b31aa65ce3..1ae8b567b1 100644
--- a/lib/diameter/src/base/diameter_peer.erl
+++ b/lib/diameter/src/base/diameter_peer.erl
@@ -20,9 +20,6 @@
 -module(diameter_peer).
 -behaviour(gen_server).
 
--compile({no_auto_import, [now/0]}).
--import(diameter_lib, [now/0]).
-
 %% Interface towards transport modules ...
 -export([recv/2,
          up/1,
diff --git a/lib/diameter/src/base/diameter_reg.erl b/lib/diameter/src/base/diameter_reg.erl
index f785777874..6bb4710e63 100644
--- a/lib/diameter/src/base/diameter_reg.erl
+++ b/lib/diameter/src/base/diameter_reg.erl
@@ -24,8 +24,7 @@
 -module(diameter_reg).
 -behaviour(gen_server).
 
--compile({no_auto_import, [monitor/2, now/0]}).
--import(diameter_lib, [now/0]).
+-compile({no_auto_import, [monitor/2]}).
 
 -export([add/1,
          add_new/1,
diff --git a/lib/diameter/src/base/diameter_service.erl b/lib/diameter/src/base/diameter_service.erl
index 86e744dfbe..a31cef2c8c 100644
--- a/lib/diameter/src/base/diameter_service.erl
+++ b/lib/diameter/src/base/diameter_service.erl
@@ -24,9 +24,6 @@
 -module(diameter_service).
 -behaviour(gen_server).
 
--compile({no_auto_import, [now/0]}).
--import(diameter_lib, [now/0]).
-
 %% towards diameter_service_sup
 -export([start_link/1]).
 
@@ -1218,7 +1215,7 @@ connect_timer(Opts, Def0) ->
 %% continuous restarted in case of faulty config or other problems.
 tc(Time, Tc) ->
     choose(Tc > ?RESTART_TC
-             orelse diameter_lib:micro_diff(Time) > 1000*?RESTART_TC,
+             orelse timer:now_diff(now(), Time) > 1000*?RESTART_TC,
            Tc,
            ?RESTART_TC).
 
diff --git a/lib/diameter/src/base/diameter_session.erl b/lib/diameter/src/base/diameter_session.erl
index c5ea0428b5..3b236f109a 100644
--- a/lib/diameter/src/base/diameter_session.erl
+++ b/lib/diameter/src/base/diameter_session.erl
@@ -157,8 +157,8 @@ session_id(Host) ->
 %% ---------------------------------------------------------------------------
 
 init() ->
-    {Now, Seed} = diameter_lib:seed(),
-    random:seed(Seed),
+    Now = now(),
+    random:seed(Now),
     Time = time32(Now),
     Seq  = (?INT32 band (Time bsl 20)) bor (random:uniform(1 bsl 20) - 1),
     ets:insert(diameter_sequence, [{origin_state_id, Time},
diff --git a/lib/diameter/src/base/diameter_stats.erl b/lib/diameter/src/base/diameter_stats.erl
index 79a5c7b947..c4526d3a08 100644
--- a/lib/diameter/src/base/diameter_stats.erl
+++ b/lib/diameter/src/base/diameter_stats.erl
@@ -24,9 +24,6 @@
 -module(diameter_stats).
 -behaviour(gen_server).
 
--compile({no_auto_import, [now/0]}).
--import(diameter_lib, [now/0]).
-
 -export([reg/2, reg/1,
          incr/3, incr/1,
          read/1,
diff --git a/lib/diameter/src/base/diameter_sync.erl b/lib/diameter/src/base/diameter_sync.erl
index 90eabece3d..cee06b9e96 100644
--- a/lib/diameter/src/base/diameter_sync.erl
+++ b/lib/diameter/src/base/diameter_sync.erl
@@ -27,9 +27,6 @@
 -module(diameter_sync).
 -behaviour(gen_server).
 
--compile({no_auto_import, [now/0]}).
--import(diameter_lib, [now/0]).
-
 -export([call/4, call/5,
          cast/4, cast/5,
          carp/1, carp/2]).
diff --git a/lib/diameter/src/base/diameter_watchdog.erl b/lib/diameter/src/base/diameter_watchdog.erl
index ac03ab1260..885dc6c801 100644
--- a/lib/diameter/src/base/diameter_watchdog.erl
+++ b/lib/diameter/src/base/diameter_watchdog.erl
@@ -66,7 +66,6 @@
          parent = self() :: pid(),              %% service process
          transport       :: pid() | undefined,  %% peer_fsm process
          tref :: reference()      %% reference for current watchdog timer
-               | integer()        %% monotonic time
                | tuple()          %% now()
                | undefined,
          dictionary :: module(),  %% common dictionary
@@ -125,8 +124,7 @@ i({Ack, T, Pid, {RecvData,
                  = Svc}}) ->
     monitor(process, Pid),
     wait(Ack, Pid),
-    {_, Seed} = diameter_lib:seed(),
-    random:seed(Seed),
+    random:seed(now()),
     putr(restart, {T, Opts, Svc, SvcOpts}),  %% save seeing it in trace
     putr(dwr, dwr(Caps)),                    %%
     {_,_} = Mask = proplists:get_value(sequence, SvcOpts),
@@ -459,7 +457,7 @@ transition({timeout, TRef, tw}, #watchdog{tref = TRef} = S) ->
 %% Message has arrived since the timer was started: subtract time
 %% already elapsed from new timer.
 transition({timeout, _, tw}, #watchdog{tref = T0} = S) ->
-    set_watchdog(diameter_lib:micro_diff(T0) div 1000, S);
+    set_watchdog(timer:now_diff(now(), T0) div 1000, S);
 
 %% State query.
 transition({state, Pid}, #watchdog{status = S}) ->
@@ -541,7 +539,7 @@ set_watchdog(#watchdog{tref = undefined} = S) ->
 
 %% Timer already set: start at new one only at expiry.
 set_watchdog(#watchdog{} = S) ->
-    S#watchdog{tref = diameter_lib:now()};
+    S#watchdog{tref = now()};
 
 set_watchdog(stop = No) ->
     No.