Merge branch 'john/erts/runtime-lcnt' into maint

* john/erts/runtime-lcnt:

  Document rt_mask and add warnings about copy_save
  Add an emulator test suite for lock counting
  Break erts_debug:lock_counters/1 into separate BIFs
  Allow toggling lock counting at runtime
  Move lock flags to a common header
  Enable register_SUITE for lcnt builds
  Enable lcnt smoke test on all builds that have lcnt enabled
  Make lock counter info independent of the locks being counted

OTP-14412
OTP-13170
OTP-14413

1 files changed, 156 insertions, 0 deletions

diff --git a/erts/emulator/test/lcnt_SUITE.erl b/erts/emulator/test/lcnt_SUITE.erl
new file mode 100644
index 0000000000..504b9b54cf
--- /dev/null
+++ b/erts/emulator/test/lcnt_SUITE.erl
@@ -0,0 +1,156 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2017. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+
+-module(lcnt_SUITE).
+
+-include_lib("common_test/include/ct.hrl").
+
+-export(
+    [all/0, suite/0,
+     init_per_suite/1, end_per_suite/1,
+     init_per_testcase/2, end_per_testcase/2]).
+
+-export(
+    [toggle_lock_counting/1, error_on_invalid_category/1, preserve_locks/1]).
+
+suite() ->
+    [{ct_hooks,[ts_install_cth]},
+     {timetrap, {seconds, 10}}].
+
+all() ->
+    [toggle_lock_counting, error_on_invalid_category, preserve_locks].
+
+init_per_suite(Config) ->
+    case erlang:system_info(lock_counting) of
+        true ->
+            %% The tests will run straight over these properties, so we have to
+            %% preserve them to avoid tainting the other tests.
+            OldCopySave = erts_debug:lcnt_control(copy_save),
+            OldMask = erts_debug:lcnt_control(mask),
+            [{lcnt_SUITE, {OldCopySave, OldMask}} | Config];
+        _ ->
+            {skip, "Lock counting is not enabled"}
+    end.
+
+end_per_suite(Config) ->
+    {OldCopySave, OldMask} = proplists:get_value(lcnt_SUITE, Config),
+
+    erts_debug:lcnt_control(copy_save, OldCopySave),
+    OldCopySave = erts_debug:lcnt_control(copy_save),
+
+    erts_debug:lcnt_control(mask, OldMask),
+    OldMask = erts_debug:lcnt_control(mask),
+
+    erts_debug:lcnt_clear(),
+    ok.
+
+init_per_testcase(_Case, Config) ->
+    disable_lock_counting(),
+    Config.
+
+end_per_testcase(_Case, _Config) ->
+    ok.
+
+disable_lock_counting() ->
+    ok = erts_debug:lcnt_control(copy_save, false),
+    ok = erts_debug:lcnt_control(mask, []),
+    ok = erts_debug:lcnt_clear(),
+
+    %% Sanity check.
+    false = erts_debug:lcnt_control(copy_save),
+    [] = erts_debug:lcnt_control(mask),
+
+    %% The above commands rely on some lazy operations, so we'll have to wait
+    %% for the list to clear.
+    ok = wait_for_empty_lock_list().
+
+wait_for_empty_lock_list() ->
+    wait_for_empty_lock_list(10).
+wait_for_empty_lock_list(Tries) when Tries > 0 ->
+    try_flush_cleanup_ops(),
+    case erts_debug:lcnt_collect() of
+        [{duration, _}, {locks, []}] ->
+            ok;
+        _ ->
+            timer:sleep(50),
+            wait_for_empty_lock_list(Tries - 1)
+    end;
+wait_for_empty_lock_list(0) ->
+    ct:fail("Lock list failed to clear after disabling lock counting.").
+
+%% Queue up a lot of thread progress cleanup ops in a vain attempt to
+%% flush the lock list.
+try_flush_cleanup_ops() ->
+    false = lists:member(process, erts_debug:lcnt_control(mask)),
+    [spawn(fun() -> ok end) || _ <- lists:seq(1, 1000)].
+
+%%
+%% Test cases
+%%
+
+toggle_lock_counting(Config) when is_list(Config) ->
+    Categories =
+        [allocator, db, debug, distribution, generic, io, process, scheduler],
+    lists:foreach(
+        fun(Category) ->
+            Locks = get_lock_info_for(Category),
+            if
+                Locks =/= [] ->
+                    disable_lock_counting();
+                Locks =:= [] ->
+                    ct:fail("Failed to toggle ~p locks.", [Category])
+            end
+        end, Categories).
+
+get_lock_info_for(Categories) when is_list(Categories) ->
+    ok = erts_debug:lcnt_control(mask, Categories),
+    [{duration, _}, {locks, Locks}] = erts_debug:lcnt_collect(),
+    Locks;
+
+get_lock_info_for(Category) when is_atom(Category) ->
+    get_lock_info_for([Category]).
+
+preserve_locks(Config) when is_list(Config) ->
+    erts_debug:lcnt_control(mask, [process]),
+
+    erts_debug:lcnt_control(copy_save, true),
+    [spawn(fun() -> ok end) || _ <- lists:seq(1, 1000)],
+
+    %% Wait for the processes to be fully destroyed before disabling copy_save,
+    %% then remove all active locks from the list. (There's no foolproof method
+    %% to do this; sleeping before/after is the best way we have)
+    timer:sleep(500),
+
+    erts_debug:lcnt_control(copy_save, false),
+    erts_debug:lcnt_control(mask, []),
+
+    try_flush_cleanup_ops(),
+    timer:sleep(500),
+
+    case erts_debug:lcnt_collect() of
+        [{duration, _}, {locks, Locks}] when length(Locks) > 0 ->
+            ct:pal("Preserved ~p locks.", [length(Locks)]);
+        [{duration, _}, {locks, []}] ->
+            ct:fail("copy_save didn't preserve any locks.")
+    end.
+
+error_on_invalid_category(Config) when is_list(Config) ->
+    {error, badarg, q_invalid} = erts_debug:lcnt_control(mask, [q_invalid]),
+    ok.