Merge branch 'sverker/erts/monitored_by-docs/ERL-648/OTP-15180' into maint

* sverker/erts/monitored_by-docs/ERL-648/OTP-15180:
  os_mon: Fix volatile test cpu_sup_SUITE:util_api
  erts: Fix spec and docs for process_info 'monitored_by'

4 files changed, 24 insertions, 12 deletions

diff --git a/erts/doc/src/erl_nif.xml b/erts/doc/src/erl_nif.xml
index a8eff43623..0fff8f7cad 100644
--- a/erts/doc/src/erl_nif.xml
+++ b/erts/doc/src/erl_nif.xml
@@ -194,7 +194,7 @@ ok
         <p>Binaries are sequences of whole bytes. Bitstrings with an arbitrary
           bit length have no support yet.</p>
       </item>
-      <tag>Resource objects</tag>
+      <tag><marker id="resource_objects"/>Resource objects</tag>
       <item>
         <p>The use of resource objects is a safe way to return pointers to
           native data structures from a NIF. A resource object is
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index 73800687b7..8e014c3010 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -197,6 +197,15 @@
       </desc>
     </datatype>
 
+    <datatype>
+      <name name="nif_resource"></name>
+      <desc>
+        <p>An opaque handle identifing a
+	<seealso marker="erl_nif#resource_objects">NIF resource object
+	</seealso>.</p>
+      </desc>
+    </datatype>
+
   </datatypes>
 
   <funcs>
@@ -5288,10 +5297,10 @@ RealSystem = system + MissedSystem</code>
             <p><c><anno>MinBinVHeapSize</anno></c> is the minimum binary virtual
               heap size for the process.</p>
           </item>
-          <tag><c>{monitored_by, <anno>Pids</anno>}</c></tag>
+          <tag><c>{monitored_by, <anno>MonitoredBy</anno>}</c></tag>
           <item>
-            <p>A list of process identifiers monitoring the process (with
-              <c>monitor/2</c>).</p>
+            <p>A list of identifiers for all the processes, ports and NIF
+	    resources, that are monitoring the process.</p>
           </item>
           <tag><c>{monitors, <anno>Monitors</anno>}</c></tag>
           <item>
diff --git a/erts/preloaded/src/erlang.erl b/erts/preloaded/src/erlang.erl
index 75f6901258..1ed6b6b284 100644
--- a/erts/preloaded/src/erlang.erl
+++ b/erts/preloaded/src/erlang.erl
@@ -86,15 +86,15 @@
       | 'nano_seconds'.
 
 -opaque prepared_code() :: reference().
-
 -export_type([prepared_code/0]).
 
--opaque dist_handle() :: atom().
+-opaque nif_resource() :: reference().
+-export_type([nif_resource/0]).
 
+-opaque dist_handle() :: atom().
 -export_type([dist_handle/0]).
 
 -type iovec() :: [binary()].
-
 -export_type([iovec/0]).
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -2316,7 +2316,7 @@ process_flag(_Flag, _Value) ->
       {min_heap_size, MinHeapSize :: non_neg_integer()} |
       {min_bin_vheap_size, MinBinVHeapSize :: non_neg_integer()} |
       {max_heap_size, MaxHeapSize :: max_heap_size()} |
-      {monitored_by, Pids :: [pid()]} |
+      {monitored_by, MonitoredBy :: [pid() | port() | nif_resource()]} |
       {monitors,
        Monitors :: [{process | port, Pid :: pid() | port() |
                                      {RegName :: atom(), Node :: node()}}]} |
diff --git a/lib/os_mon/test/cpu_sup_SUITE.erl b/lib/os_mon/test/cpu_sup_SUITE.erl
index 7122d23503..ba28f31f26 100644
--- a/lib/os_mon/test/cpu_sup_SUITE.erl
+++ b/lib/os_mon/test/cpu_sup_SUITE.erl
@@ -122,19 +122,19 @@ util_api(Config) when is_list(Config) ->
 
     %% util([])
     {all, Busy1, NonBusy1, []} = cpu_sup:util([]),
-    100.00 = Busy1 + NonBusy1,
+    true = tiny_diff(100.00, Busy1 + NonBusy1),
 
     %% util([detailed])
     {Cpus2, Busy2, NonBusy2, []} = cpu_sup:util([detailed]),
     true = lists:all(fun(X) -> is_integer(X) end, Cpus2),
     true = lists:all(BusyP, Busy2),
     true = lists:all(NonBusyP, NonBusy2),
-    100.00 = lists:foldl(Sum,0,Busy2)+lists:foldl(Sum,0,NonBusy2),
+    true = tiny_diff(100.00, lists:foldl(Sum,0,Busy2)+lists:foldl(Sum,0,NonBusy2)),
 
     %% util([per_cpu])
     [{Cpu3, Busy3, NonBusy3, []}|_] = cpu_sup:util([per_cpu]),
     true = is_integer(Cpu3),
-    100.00 = Busy3 + NonBusy3,
+    true = tiny_diff(100.00, Busy3 + NonBusy3),
 
     %% util([detailed, per_cpu])
     [{Cpu4, Busy4, NonBusy4, []}|_] =
@@ -142,7 +142,7 @@ util_api(Config) when is_list(Config) ->
     true = is_integer(Cpu4),
     true = lists:all(BusyP, Busy2),
     true = lists:all(NonBusyP, NonBusy2),
-    100.00 = lists:foldl(Sum,0,Busy4)+lists:foldl(Sum,0,NonBusy4),
+    true = tiny_diff(100.00, lists:foldl(Sum,0,Busy4)+lists:foldl(Sum,0,NonBusy4)),
 
     %% bad util/1 calls
     {'EXIT',{badarg,_}} = (catch cpu_sup:util(detailed)),
@@ -150,6 +150,9 @@ util_api(Config) when is_list(Config) ->
 
     ok.
 
+tiny_diff(A, B) ->
+    (abs(A - B) < 1.0e-11).
+
 -define(SPIN_TIME, 1000).
 
 %% Test utilization values