From e6d19a18b7c1057c2b4493f8db822c82bb0dbe0d Mon Sep 17 00:00:00 2001
From: Anders Svensson <anders@erlang.org>
Date: Mon, 9 Feb 2015 00:36:56 +0100
Subject: Use new time api in implementation

In particular, deal with the deprecation of erlang:now/0 in OTP 18. Be
backwards compatible with older releases: the new api is only used when
available.

The test suites have not been modified.
---
 lib/diameter/src/base/diameter_lib.erl | 109 +++++++++++++++++++++++++++++++--
 1 file changed, 103 insertions(+), 6 deletions(-)

(limited to 'lib/diameter/src/base/diameter_lib.erl')

diff --git a/lib/diameter/src/base/diameter_lib.erl b/lib/diameter/src/base/diameter_lib.erl
index 23eba7e80c..6dd1d5f6ed 100644
--- a/lib/diameter/src/base/diameter_lib.erl
+++ b/lib/diameter/src/base/diameter_lib.erl
@@ -18,12 +18,18 @@
 %%
 
 -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,
@@ -91,14 +97,51 @@ fmt(T) ->
             "p"
     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 = erlang:convert_time_resolution(MonoT + erlang:time_offset(),
+                                               erlang:time_resolution(),
+                                               1000000),
+    Secs = MicroSecs div 1000000,
+    {Secs div 1000000, Secs rem 1000000, MicroSecs rem 1000000}.
+
 %% ---------------------------------------------------------------------------
 %% # now_diff/1
 %% ---------------------------------------------------------------------------
 
--spec now_diff(NowT)
+-spec now_diff(NowT :: now())
    -> {Hours, Mins, Secs, MicroSecs}
- when NowT  :: {non_neg_integer(), 0..999999, 0..999999},
-      Hours :: non_neg_integer(),
+ when Hours :: non_neg_integer(),
       Mins  :: 0..59,
       Secs  :: 0..59,
       MicroSecs :: 0..999999.
@@ -106,8 +149,41 @@ fmt(T) ->
 %% Return timer:now_diff(now(), NowT) as an {H, M, S, MicroS} tuple
 %% instead of as integer microseconds.
 
-now_diff({_,_,_} = Time) ->
-    time(timer:now_diff(now(), Time)).
+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
+    erlang:convert_time_resolution(erlang:monotonic_time() - T0,
+                                   erlang:time_resolution(),
+                                   1000000).
+
+%% ---------------------------------------------------------------------------
+%% # 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
+    erlang:convert_time_resolution(T1 - T0,
+                                   erlang:time_resolution(),
+                                   1000000);
+
+micro_diff(T1, T0) ->  %% at least one erlang:now()
+    timer:now_diff(timestamp(T1), timestamp(T0)).
 
 %% ---------------------------------------------------------------------------
 %% # time/1
@@ -117,7 +193,7 @@ now_diff({_,_,_} = Time) ->
 
 -spec time(NowT | Diff)
    -> {Hours, Mins, Secs, MicroSecs}
- when NowT  :: {non_neg_integer(), 0..999999, 0..999999},
+ when NowT  :: timestamp(),
       Diff  :: non_neg_integer(),
       Hours :: non_neg_integer(),
       Mins  :: 0..59,
@@ -135,6 +211,27 @@ time(Micro) ->  %% elapsed time
     S = Seconds rem 60,
     {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
 %%
-- 
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