Introduce time warp safe replacement for safe_fixed option

The new time warp safe option is safe_fixed_monotonic_time which
gives erlang:monotonic_time().

The safe_fixed option was also slightly changed. It now gives
erlang:timestamp() instead of erlang:now(). This has however
not been documented, so it is considered a compatible change.

The above effects both ets, and dets.

This commit also include the bugfix OTP-13239 for
dets:info(Tab, safe_fixed). The timestamp in the result returned
by dets:info(Tab, safe_fixed) was unintentionally broken as a
result of the time API rewrites in OTP 18.0.

2 files changed, 53 insertions, 6 deletions

diff --git a/lib/stdlib/test/dets_SUITE.erl b/lib/stdlib/test/dets_SUITE.erl
index 7f5e06524a..35e587afcc 100644
--- a/lib/stdlib/test/dets_SUITE.erl
+++ b/lib/stdlib/test/dets_SUITE.erl
@@ -1876,9 +1876,33 @@ fixtable(Config, Version) when is_list(Config) ->
     {ok, _} = dets:open_file(T, [{type, duplicate_bag} | Args]),
     %% In a fixed table, delete and re-insert an object.
     ok = dets:insert(T, {1, a, b}),
+    SysBefore = erlang:timestamp(),
+    MonBefore = erlang:monotonic_time(),
     dets:safe_fixtable(T, true),
+    MonAfter = erlang:monotonic_time(),
+    SysAfter = erlang:timestamp(),
+    Self = self(),
+    {FixMonTime,[{Self,1}]} = dets:info(T,safe_fixed_monotonic_time),
+    {FixSysTime,[{Self,1}]} = dets:info(T,safe_fixed),
+    true = is_integer(FixMonTime),
+    true = MonBefore =< FixMonTime,
+    true = FixMonTime =< MonAfter,
+    {FstMs,FstS,FstUs} = FixSysTime,
+    true = is_integer(FstMs),
+    true = is_integer(FstS),
+    true = is_integer(FstUs),
+    case erlang:system_info(time_warp_mode) of
+	no_time_warp ->
+	    true = timer:now_diff(FixSysTime, SysBefore) >= 0,
+	    true = timer:now_diff(SysAfter, FixSysTime) >= 0;
+	_ ->
+	    %% ets:info(Tab,safe_fixed) not timewarp safe...
+	    ignore
+    end,
     ok = dets:match_delete(T, {1, a, b}),
     ok = dets:insert(T, {1, a, b}),
+    {FixMonTime,[{Self,1}]} = dets:info(T,safe_fixed_monotonic_time),
+    {FixSysTime,[{Self,1}]} = dets:info(T,safe_fixed),
     dets:safe_fixtable(T, false),
     1 = length(dets:match_object(T, '_')),
 
diff --git a/lib/stdlib/test/ets_SUITE.erl b/lib/stdlib/test/ets_SUITE.erl
index ae431d66d9..30a158d9e1 100644
--- a/lib/stdlib/test/ets_SUITE.erl
+++ b/lib/stdlib/test/ets_SUITE.erl
@@ -3989,15 +3989,37 @@ safe_fixtable_do(Opts) ->
     ?line true = ets:safe_fixtable(Tab, true),
     ?line receive after 1 -> ok end,
     ?line true = ets:safe_fixtable(Tab, false),
-    ?line false = ets:info(Tab,safe_fixed),
-    ?line true = ets:safe_fixtable(Tab, true),
+    false = ets:info(Tab,safe_fixed_monotonic_time),
+    false = ets:info(Tab,safe_fixed),
+    SysBefore = erlang:timestamp(),
+    MonBefore = erlang:monotonic_time(),
+    true = ets:safe_fixtable(Tab, true),
+    MonAfter = erlang:monotonic_time(),
+    SysAfter = erlang:timestamp(),
     Self = self(),
-    ?line {{_,_,_},[{Self,1}]} = ets:info(Tab,safe_fixed),
+    {FixMonTime,[{Self,1}]} = ets:info(Tab,safe_fixed_monotonic_time),
+    {FixSysTime,[{Self,1}]} = ets:info(Tab,safe_fixed),
+    true = is_integer(FixMonTime),
+    true = MonBefore =< FixMonTime,
+    true = FixMonTime =< MonAfter,
+    {FstMs,FstS,FstUs} = FixSysTime,
+    true = is_integer(FstMs),
+    true = is_integer(FstS),
+    true = is_integer(FstUs),
+    case erlang:system_info(time_warp_mode) of
+	no_time_warp ->
+	    true = timer:now_diff(FixSysTime, SysBefore) >= 0,
+	    true = timer:now_diff(SysAfter, FixSysTime) >= 0;
+	_ ->
+	    %% ets:info(Tab,safe_fixed) not timewarp safe...
+	    ignore
+    end,
     %% Test that an unjustified 'unfix' is a no-op.
     {Pid,MRef} = my_spawn_monitor(fun() -> true = ets:safe_fixtable(Tab,false) end),
     {'DOWN', MRef, process, Pid, normal} = receive M -> M end,
-    ?line true = ets:info(Tab,fixed),
-    ?line {{_,_,_},[{Self,1}]} = ets:info(Tab,safe_fixed),
+    true = ets:info(Tab,fixed),
+    {FixMonTime,[{Self,1}]} = ets:info(Tab,safe_fixed_monotonic_time),
+    {FixSysTime,[{Self,1}]} = ets:info(Tab,safe_fixed),
     %% badarg's
     ?line {'EXIT', {badarg, _}} = (catch ets:safe_fixtable(Tab, foobar)),
     ?line true = ets:info(Tab,fixed),
@@ -4043,6 +4065,7 @@ info_do(Opts) ->
     ?line undefined = ets:info(non_existing_table_xxyy,type),
     ?line undefined = ets:info(non_existing_table_xxyy,node),
     ?line undefined = ets:info(non_existing_table_xxyy,named_table),
+    ?line undefined = ets:info(non_existing_table_xxyy,safe_fixed_monotonic_time),
     ?line undefined = ets:info(non_existing_table_xxyy,safe_fixed),
     ?line verify_etsmem(EtsMem).
 
@@ -5532,7 +5555,7 @@ otp_8166_zombie_creator(T,Deleted) ->
 						  [{'=<','$1', Deleted}],
 						  [true]}]),
 	    Pid ! zombies_created,
-	    repeat_while(fun() -> case ets:info(T,safe_fixed) of
+	    repeat_while(fun() -> case ets:info(T,safe_fixed_monotonic_time) of
 				      {_,[_P1,_P2]} ->
 					  false;
 				      _ ->