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.

1 files changed, 29 insertions, 18 deletions

diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index d11f6b0c6d..19a8e1f789 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -495,24 +495,35 @@
           <c><![CDATA[werl]]></c>, not <c><![CDATA[erl]]></c> (<c><![CDATA[oldshell]]></c>). Note also that
           <c><![CDATA[Ctrl-Break]]></c> is used instead of <c><![CDATA[Ctrl-C]]></c> on Windows.</p>
       </item>
-      <tag><marker id="+c"><c><![CDATA[+c]]></c></marker></tag>
-      <item>
-        <p>Disable compensation for sudden changes of system time.</p>
-        <p>Normally, <c><![CDATA[erlang:now/0]]></c> will not immediately reflect
-          sudden changes in the system time, in order to keep timers
-          (including <c><![CDATA[receive-after]]></c>) working. Instead, the time
-          maintained by <c><![CDATA[erlang:now/0]]></c> is slowly adjusted towards
-          the new system time. (Slowly means in one percent adjustments;
-          if the time is off by one minute, the time will be adjusted
-          in 100 minutes.)</p>
-        <p>When the <c><![CDATA[+c]]></c> option is given, this slow adjustment
-          will not take place. Instead <c><![CDATA[erlang:now/0]]></c> will always
-          reflect the current system time. Note that timers are based
-          on <c><![CDATA[erlang:now/0]]></c>. If the system time jumps, timers
-          then time out at the wrong time.</p>
-        <p><em>NOTE</em>: You can check whether the adjustment is enabled or
-          disabled by calling
-	  <seealso marker="erlang#system_info_tolerant_timeofday">erlang:system_info(tolerant_timeofday)</seealso>.</p>
+      <tag><marker id="+c"><c><![CDATA[+c true | false]]></c></marker></tag>
+      <item>
+        <p>Enable or disable
+	<seealso marker="time_correction#Time_Correction">time correction</seealso>:</p>
+	<taglist>
+	  <tag><c>true</c></tag>
+	  <item><p>Enable time correction. This is the default if
+	  time correction is supported on the specific platform.</p></item>
+
+	  <tag><c>false</c></tag>
+	  <item><p>Disable time correction.</p></item>
+	</taglist>
+	<p>For backwards compatibility, the boolean value can be omitted.
+	This is interpreted as <c>+c false</c>.
+	</p>
+      </item>
+      <tag><marker id="+C_"><c><![CDATA[+C no_time_warp | single_time_warp | multi_time_warp]]></c></marker></tag>
+      <item>
+        <p>Set
+	<seealso marker="time_correction#Time_Warp_Modes">time warp mode</seealso>:
+	</p>
+	<taglist>
+	  <tag><c>no_time_warp</c></tag>
+	  <item><p><seealso marker="time_correction#No_Time_Warp_Mode">No Time Warp Mode</seealso> (the default)</p></item>
+	  <tag><c>single_time_warp</c></tag>
+	  <item><p><seealso marker="time_correction#Single_Time_Warp_Mode">Single Time Warp Mode</seealso></p></item>
+	  <tag><c>multi_time_warp</c></tag>
+	  <item><p><seealso marker="time_correction#Multi_Time_Warp_Mode">Multi Time Warp Mode</seealso></p></item>
+	</taglist>
       </item>
       <tag><c><![CDATA[+d]]></c></tag>
       <item>