Merge branch 'rickard/time_api/OTP-11997'

* rickard/time_api/OTP-11997:
  Better OS system time implementation
  Documentation adjustments
  Fix zero timout timers
  erts_sys_hrtime() for lcnt
  Better support for poor os monotonic sources

Conflicts:
	erts/preloaded/ebin/erlang.beam

1 files changed, 86 insertions, 11 deletions

diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index 880c294c73..ba5f80a9c1 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -110,10 +110,17 @@
 	  <note>
 	    <p>The value of the <c>native</c> time unit gives
 	    you more or less no information at all about the
-	    quality of time values. It sets an upper bound for
-	    the resolution as well as for the precision, but it
-	    gives absolutely no information at all about the
-	    accuracy.</p>
+	    quality of time values. It sets a limit for
+	    the
+	    <seealso marker="time_correction#Time_Resolution">resolution</seealso>
+	    as well as for the
+	    <seealso marker="time_correction#Time_Precision">precision</seealso>
+	    of time values,
+	    but it gives absolutely no information at all about the
+	    <seealso marker="time_correction#Time_Accuracy">accuracy</seealso>
+	    of time values. The resolution of the <c>native</c> time
+	    unit and the resolution of time values may differ
+	    significantly.</p>
 	  </note>
 	  </item>
 
@@ -6038,6 +6045,8 @@ ok
       <name name="system_info" arity="1" clause_i="62"/>
       <name name="system_info" arity="1" clause_i="63"/>
       <name name="system_info" arity="1" clause_i="64"/>
+      <name name="system_info" arity="1" clause_i="65"/>
+      <name name="system_info" arity="1" clause_i="66"/>
       <fsummary>Information about the system</fsummary>
       <desc>
         <p>Returns various information about the current system
@@ -6449,20 +6458,33 @@ ok
 	      <c>Function</c>.</p></item>
 
 	      <tag><c>{resolution, OsMonotonicTimeResolution}</c></tag>
-	      <item><p>Highest possible resolution of current
-	      OS monotonic time source as parts per second. If
-	      no resolution information can be retreived from
-	      the OS, <c>OsMonotonicTimeResolution</c> will be
+	      <item><p>Highest possible
+	      <seealso marker="time_correction#Time_Resolution">resolution</seealso>
+	      of current OS monotonic time source as parts per
+	      second. If no resolution information can be retreived
+	      from the OS, <c>OsMonotonicTimeResolution</c> will be
 	      set to the resolution of the time unit of
 	      <c>Function</c>s return value. That is, the actual
 	      resolution may be lower than
 	      <c>OsMonotonicTimeResolution</c>. Also note that
 	      the resolution does not say anything about the
-	      accuracy, and that the precision might not align
-	      with the resolution. You do, however, know that the
-	      precision won't be higher than
+	      <seealso marker="time_correction#Time_Accuracy">accuracy</seealso>,
+	      and that the
+	      <seealso marker="time_correction#Time_Precision">precision</seealso>
+	      might not align with the resolution. You do,
+	      however, know that the precision won't be
+	      better than
 	      <c>OsMonotonicTimeResolution</c>.</p></item>
 
+	      <tag><c>{extended, Extended}</c></tag>
+	      <item><p><c>Extended</c> equals <c>yes</c> if
+	      the range of time values has been extended;
+	      otherwise, <c>Extended</c> equals <c>no</c>. The
+	      range needs to be extended if <c>Function</c>
+	      returns values that wrap fast. This typically
+	      is the case when the return value is a 32-bit
+	      value.</p></item>
+
 	      <tag><c>{parallel, Parallel}</c></tag>
 	      <item><p><c>Parallel</c> equals <c>yes</c> if
 	      <c>Function</c> is called in parallel from multiple
@@ -6476,6 +6498,59 @@ ok
 	      <seealso marker="#type_time_unit">time unit</seealso>.</p></item>
 	    </taglist>
           </item>
+          <tag><marker id="system_info_os_system_time_source"><c>os_system_time_source</c></marker></tag>
+          <item>
+            <p>Returns a list containing information about the source of
+	    <seealso marker="erts:time_correction#OS_System_Time">OS
+	    system time</seealso> that is used by the runtime system.</p>
+	    <p>The list contains two-tuples with <c>Key</c>s
+	    as first element, and <c>Value</c>s as second element. The
+	    order if these tuples is undefined. Currently the following
+	    tuples may be part of the list, but more tuples may be
+	    introduced in the future:</p>
+	    <taglist>
+	      <tag><c>{function, Function}</c></tag>
+	      <item><p><c>Function</c> is the name of the funcion
+	      used.</p></item>
+
+	      <tag><c>{clock_id, ClockId}</c></tag>
+	      <item><p>This tuple only exist if <c>Function</c>
+	      can be used with different clocks. <c>ClockId</c>
+	      corresponds to the clock identifer used when calling
+	      <c>Function</c>.</p></item>
+
+	      <tag><c>{resolution, OsSystemTimeResolution}</c></tag>
+	      <item><p>Highest possible
+	      <seealso marker="time_correction#Time_Resolution">resolution</seealso>
+	      of current OS system time source as parts per
+	      second. If no resolution information can be retreived
+	      from the OS, <c>OsSystemTimeResolution</c> will be
+	      set to the resolution of the time unit of
+	      <c>Function</c>s return value. That is, the actual
+	      resolution may be lower than
+	      <c>OsSystemTimeResolution</c>. Also note that
+	      the resolution does not say anything about the
+	      <seealso marker="time_correction#Time_Accuracy">accuracy</seealso>,
+	      and that the
+	      <seealso marker="time_correction#Time_Precision">precision</seealso>
+	      might not align with the resolution. You do,
+	      however, know that the precision won't be
+	      better than
+	      <c>OsSystemTimeResolution</c>.</p></item>
+
+	      <tag><c>{parallel, Parallel}</c></tag>
+	      <item><p><c>Parallel</c> equals <c>yes</c> if
+	      <c>Function</c> is called in parallel from multiple
+	      threads. If it is not called in parallel, because
+	      calls needs to be serialized, <c>Parallel</c> equals
+	      <c>no</c>.</p></item>
+
+	      <tag><c>{time, OsSystemTime}</c></tag>
+	      <item><p><c>OsSystemTime</c> equals current OS
+	      system time in <c>native</c>
+	      <seealso marker="#type_time_unit">time unit</seealso>.</p></item>
+	    </taglist>
+          </item>
 	  <tag><marker id="system_info_port_parallelism"><c>port_parallelism</c></marker></tag>
 	  <item><p>Returns the default port parallelism scheduling hint used.
 	  For more information see the