Merge branch 'bjorn/use-monotonic-time'

* bjorn/use-monotonic-time:
  supervisor: Correct restart handling
  test_server: Use erlang:monotonic_time/0
  compile: Teach 'time' option to show three significant decimals
  timer: Use monotonic_time/0 in tc/1,2,3

3 files changed, 50 insertions, 17 deletions

diff --git a/lib/stdlib/src/supervisor.erl b/lib/stdlib/src/supervisor.erl
index 7c0cd8b26a..67655b1145 100644
--- a/lib/stdlib/src/supervisor.erl
+++ b/lib/stdlib/src/supervisor.erl
@@ -1403,13 +1403,8 @@ add_restart([R|Restarts], Now, Period) ->
 add_restart([], _, _) ->
     [].
 
-inPeriod(Time, Now, Period) ->
-    case Time - Now of
-	T when T > Period ->
-	    false;
-	_ ->
-	    true
-    end.
+inPeriod(Then, Now, Period) ->
+    Now =< Then + Period.
 
 %%% ------------------------------------------------------
 %%% Error and progress reporting.
diff --git a/lib/stdlib/src/timer.erl b/lib/stdlib/src/timer.erl
index 19d803345e..c266177b4d 100644
--- a/lib/stdlib/src/timer.erl
+++ b/lib/stdlib/src/timer.erl
@@ -161,10 +161,11 @@ sleep(T) ->
       Time :: integer(),
       Value :: term().
 tc(F) ->
-    Before = os:timestamp(),
+    T1 = erlang:monotonic_time(),
     Val = F(),
-    After = os:timestamp(),
-    {now_diff(After, Before), Val}.
+    T2 = erlang:monotonic_time(),
+    Time = erlang:convert_time_unit(T2 - T1, native, micro_seconds),
+    {Time, Val}.
 
 %%
 %% Measure the execution time (in microseconds) for Fun(Args).
@@ -175,10 +176,11 @@ tc(F) ->
       Time :: integer(),
       Value :: term().
 tc(F, A) ->
-    Before = os:timestamp(),
+    T1 = erlang:monotonic_time(),
     Val = apply(F, A),
-    After = os:timestamp(),
-    {now_diff(After, Before), Val}.
+    T2 = erlang:monotonic_time(),
+    Time = erlang:convert_time_unit(T2 - T1, native, micro_seconds),
+    {Time, Val}.
 
 %%
 %% Measure the execution time (in microseconds) for an MFA.
@@ -190,10 +192,11 @@ tc(F, A) ->
       Time :: integer(),
       Value :: term().
 tc(M, F, A) ->
-    Before = os:timestamp(),
+    T1 = erlang:monotonic_time(),
     Val = apply(M, F, A),
-    After = os:timestamp(),
-    {now_diff(After, Before), Val}.
+    T2 = erlang:monotonic_time(),
+    Time = erlang:convert_time_unit(T2 - T1, native, micro_seconds),
+    {Time, Val}.
 
 %%
 %% Calculate the time difference (in microseconds) of two
diff --git a/lib/stdlib/test/supervisor_SUITE.erl b/lib/stdlib/test/supervisor_SUITE.erl
index c98654aef7..9dcf19707c 100644
--- a/lib/stdlib/test/supervisor_SUITE.erl
+++ b/lib/stdlib/test/supervisor_SUITE.erl
@@ -53,7 +53,8 @@
 	  temporary_abnormal/1, temporary_bystander/1]).
 
 %% Restart strategy tests 
--export([ one_for_one/1,
+-export([ multiple_restarts/1,
+	  one_for_one/1,
 	  one_for_one_escalation/1, one_for_all/1,
 	  one_for_all_escalation/1, one_for_all_other_child_fails_restart/1,
 	  simple_one_for_one/1, simple_one_for_one_escalation/1,
@@ -78,6 +79,7 @@ suite() ->
 all() -> 
     [{group, sup_start}, {group, sup_start_map}, {group, sup_stop}, child_adm,
      child_adm_simple, extra_return, child_specs, sup_flags,
+     multiple_restarts,
      {group, restart_one_for_one},
      {group, restart_one_for_all},
      {group, restart_simple_one_for_one},
@@ -873,6 +875,39 @@ temporary_bystander(_Config) ->
     [{child1, _, _, _}] = supervisor:which_children(SupPid2).
 
 %%-------------------------------------------------------------------------
+%% Test restarting a process multiple times, being careful not
+%% to exceed the maximum restart frquency.
+multiple_restarts(Config) when is_list(Config) ->
+    process_flag(trap_exit, true),
+    Child1 = #{id => child1,
+	       start => {supervisor_1, start_child, []},
+	       restart => permanent,
+	       shutdown => brutal_kill,
+	       type => worker,
+	       modules => []},
+    SupFlags = #{strategy => one_for_one,
+		 intensity => 1,
+		 period => 1},
+    {ok, SupPid} = start_link({ok, {SupFlags, []}}),
+    {ok, CPid1} = supervisor:start_child(sup_test, Child1),
+
+    %% Terminate the process several times, but being careful
+    %% not to exceed the maximum restart intensity.
+    terminate(SupPid, CPid1, child1, abnormal),
+    _ = [begin
+	     receive after 2100 -> ok end,
+	     [{_, Pid, _, _}|_] = supervisor:which_children(sup_test),
+	     terminate(SupPid, Pid, child1, abnormal)
+	 end || _ <- [1,2,3]],
+
+    %% Verify that the supervisor is still alive and clean up.
+    ok = supervisor:terminate_child(SupPid, child1),
+    ok = supervisor:delete_child(SupPid, child1),
+    exit(SupPid, kill),
+    ok.
+
+
+%%-------------------------------------------------------------------------
 %% Test the one_for_one base case.
 one_for_one(Config) when is_list(Config) ->
     process_flag(trap_exit, true),