Merge branch 'bjorn/erts/persistent_terms/OTP-14669' into maint

* bjorn/erts/persistent_terms/OTP-14669:
  Implement a tab for persistent terms in crashdump viewer
  Add tests of persistent terms for crashdump_viewer
  Add a persistent term storage
  Refactor releasing of literals
  Extend the sharing-preserving routines to optionally copy literals

2 files changed, 615 insertions, 0 deletions

diff --git a/erts/emulator/test/Makefile b/erts/emulator/test/Makefile
index bf00de2204..d201ea6ee1 100644
--- a/erts/emulator/test/Makefile
+++ b/erts/emulator/test/Makefile
@@ -92,6 +92,7 @@ MODULES= \
 	port_SUITE \
 	port_bif_SUITE \
 	prim_eval_SUITE \
+	persistent_term_SUITE \
 	process_SUITE \
 	pseudoknot_SUITE \
 	receive_SUITE \
diff --git a/erts/emulator/test/persistent_term_SUITE.erl b/erts/emulator/test/persistent_term_SUITE.erl
new file mode 100644
index 0000000000..58cd3276b0
--- /dev/null
+++ b/erts/emulator/test/persistent_term_SUITE.erl
@@ -0,0 +1,614 @@
+%%
+%% %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
+%5
+%%     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(persistent_term_SUITE).
+-include_lib("common_test/include/ct.hrl").
+
+-export([all/0,suite/0,
+	 basic/1,purging/1,sharing/1,get_trapping/1,
+         info/1,info_trapping/1,killed_while_trapping/1,
+         off_heap_values/1,keys/1,collisions/1,
+         init_restart/1]).
+
+%%
+-export([test_init_restart_cmd/1]).
+
+suite() ->
+    [{ct_hooks,[ts_install_cth]},
+     {timetrap,{minutes,10}}].
+
+all() ->
+    [basic,purging,sharing,get_trapping,info,info_trapping,
+     killed_while_trapping,off_heap_values,keys,collisions,
+     init_restart].
+
+basic(_Config) ->
+    Chk = chk(),
+    N = 777,
+    Seq = lists:seq(1, N),
+    par(2, N, Seq),
+    seq(3, Seq),
+    seq(3, Seq),                                %Same values.
+    _ = [begin
+             Key = {?MODULE,{key,I}},
+             true = persistent_term:erase(Key),
+             false = persistent_term:erase(Key),
+             {'EXIT',{badarg,_}} = (catch persistent_term:get(Key))
+         end || I <- Seq],
+    [] = [P || {{?MODULE,_},_}=P <- persistent_term:get()],
+    chk(Chk).
+
+par(C, N, Seq) ->
+    _ = [spawn_link(fun() ->
+                            ok = persistent_term:put({?MODULE,{key,I}},
+                                                     {value,C*I})
+                    end) || I <- Seq],
+    Result = wait(N),
+    _ = [begin
+             Double = C*I,
+             {{?MODULE,{key,I}},{value,Double}} = Res
+         end || {I,Res} <- lists:zip(Seq, Result)],
+    ok.
+
+seq(C, Seq) ->
+    _ = [ok = persistent_term:put({?MODULE,{key,I}}, {value,C*I}) ||
+            I <- Seq],
+    All = persistent_term:get(),
+    All = [P || {{?MODULE,_},_}=P <- persistent_term:get()],
+    All = [{Key,persistent_term:get(Key)} || {Key,_} <- All],
+    Result = lists:sort(All),
+    _ = [begin
+             Double = C*I,
+             {{?MODULE,{key,I}},{value,Double}} = Res
+         end || {I,Res} <- lists:zip(Seq, Result)],
+    ok.
+
+wait(N) ->
+    All = [P || {{?MODULE,_},_}=P <- persistent_term:get()],
+    case length(All) of
+        N ->
+            All = [{Key,persistent_term:get(Key)} || {Key,_} <- All],
+            lists:sort(All);
+        _ ->
+            receive after 10 -> ok end,
+            wait(N)
+    end.
+
+%% Make sure that terms that have been erased are copied into all
+%% processes that still hold a pointer to them.
+
+purging(_Config) ->
+    Chk = chk(),
+    do_purging(fun(K) -> persistent_term:put(K, {?MODULE,new}) end,
+               replaced),
+    do_purging(fun persistent_term:erase/1, erased),
+    chk(Chk).
+
+do_purging(Eraser, Type) ->
+    Parent = self(),
+    Key = {?MODULE,?FUNCTION_NAME},
+    ok = persistent_term:put(Key, {term,[<<"abc",0:777/unit:8>>]}),
+    Ps0 = [spawn_monitor(fun() -> purging_tester(Parent, Key) end) ||
+              _ <- lists:seq(1, 50)],
+    Ps = maps:from_list(Ps0),
+    purging_recv(gotten, Ps),
+    Eraser(Key),
+    _ = [P ! {Parent,Type} || P <- maps:keys(Ps)],
+    purging_wait(Ps).
+
+purging_recv(Tag, Ps) when map_size(Ps) > 0 ->
+    receive
+        {Pid,Tag} ->
+            true = is_map_key(Pid, Ps),
+            purging_recv(Tag, maps:remove(Pid, Ps))
+    end;
+purging_recv(_, _) -> ok.
+
+purging_wait(Ps) when map_size(Ps) > 0 ->
+    receive
+        {'DOWN',Ref,process,Pid,Reason} ->
+            normal = Reason,
+            Ref = map_get(Pid, Ps),
+            purging_wait(maps:remove(Pid, Ps))
+    end;
+purging_wait(_) -> ok.
+
+purging_tester(Parent, Key) ->
+    Term = persistent_term:get(Key),
+    purging_check_term(Term),
+    0 = erts_debug:size_shared(Term),
+    Parent ! {self(),gotten},
+    receive
+        {Parent,erased} ->
+            {'EXIT',{badarg,_}} = (catch persistent_term:get(Key)),
+            purging_tester_1(Term);
+        {Parent,replaced} ->
+            {?MODULE,new} = persistent_term:get(Key),
+            purging_tester_1(Term)
+    end.
+
+%% Wait for the term to be copied into this process.
+purging_tester_1(Term) ->
+    purging_check_term(Term),
+    receive after 1 -> ok end,
+    case erts_debug:size_shared(Term) of
+        0 ->
+            purging_tester_1(Term);
+        Size ->
+            %% The term has been copied into this process.
+            purging_check_term(Term),
+            Size = erts_debug:size(Term)
+    end.
+
+purging_check_term({term,[<<"abc",0:777/unit:8>>]}) ->
+    ok.
+
+%% Test that sharing is preserved when storing terms.
+
+sharing(_Config) ->
+    Chk = chk(),
+    Depth = 10,
+    Size = 2*Depth,
+    Shared = lists:foldl(fun(_, A) -> [A|A] end,
+                         [], lists:seq(1, Depth)),
+    Size = erts_debug:size(Shared),
+    Key = {?MODULE,?FUNCTION_NAME},
+    ok = persistent_term:put(Key, Shared),
+    SharedStored = persistent_term:get(Key),
+    Size = erts_debug:size(SharedStored),
+    0 = erts_debug:size_shared(SharedStored),
+
+    {Pid,Ref} = spawn_monitor(fun() ->
+                                      Term = persistent_term:get(Key),
+                                      Size = erts_debug:size(Term),
+                                      0 = erts_debug:size_shared(Term),
+                                      true = Term =:= SharedStored
+                              end),
+    receive
+        {'DOWN',Ref,process,Pid,normal} ->
+            true = persistent_term:erase(Key),
+            Size = erts_debug:size(SharedStored),
+            chk(Chk)
+    end.
+
+%% Test trapping of persistent_term:get/0.
+
+get_trapping(_Config) ->
+    Chk = chk(),
+
+    %% Assume that the get/0 traps after 4000 iterations
+    %% in a non-debug emulator.
+    N = case test_server:timetrap_scale_factor() of
+            1 -> 10000;
+            _ -> 1000
+        end,
+    spawn_link(fun() -> get_trapping_create(N) end),
+    All = do_get_trapping(N, []),
+    N = get_trapping_check_result(lists:sort(All), 1),
+    erlang:garbage_collect(),
+    get_trapping_erase(N),
+    chk(Chk).
+
+do_get_trapping(N, Prev) ->
+    case persistent_term:get() of
+        Prev when length(Prev) >= N ->
+            All = [P || {{?MODULE,{get_trapping,_}},_}=P <- Prev],
+            case length(All) of
+                N -> All;
+                _ -> do_get_trapping(N, Prev)
+            end;
+        New ->
+            receive after 1 -> ok end,
+            do_get_trapping(N, New)
+    end.
+
+get_trapping_create(0) ->
+    ok;
+get_trapping_create(N) ->
+    ok = persistent_term:put({?MODULE,{get_trapping,N}}, N),
+    get_trapping_create(N-1).
+
+get_trapping_check_result([{{?MODULE,{get_trapping,N}},N}|T], N) ->
+    get_trapping_check_result(T, N+1);
+get_trapping_check_result([], N) -> N-1.
+
+get_trapping_erase(0) ->
+    ok;
+get_trapping_erase(N) ->
+    true = persistent_term:erase({?MODULE,{get_trapping,N}}),
+    get_trapping_erase(N-1).
+
+%% Test retrieving information about persistent terms.
+
+info(_Config) ->
+    Chk = chk(),
+
+    %% White box test of info/0.
+    N = 100,
+    try
+        Overhead = info_literal_area_overhead(),
+        io:format("Overhead = ~p\n", [Overhead]),
+        info_wb(N, Overhead, info_info())
+    after
+        _ = [_ = persistent_term:erase({?MODULE,I}) ||
+                I <- lists:seq(1, N)]
+    end,
+
+    chk(Chk).
+
+%% White box test of persistent_term:info/0. We take into account
+%% that there might already exist persistent terms (created by the
+%% OTP standard libraries), but we assume that they are not
+%% changed during the execution of this test case.
+
+info_wb(0, _, _) ->
+    ok;
+info_wb(N, Overhead, {BaseCount,BaseMemory}) ->
+    Key = {?MODULE,N},
+    Value = lists:seq(1, N),
+    ok = persistent_term:put(Key, Value),
+
+    %% Calculate the extra memory needed for this term.
+    WordSize = erlang:system_info(wordsize),
+    ExtraMemory = Overhead + 2 * N * WordSize,
+
+    %% Call persistent_term:info/0.
+    {Count,Memory} = info_info(),
+
+    %% There should be one more persistent term.
+    Count = BaseCount + 1,
+
+    %% Verify that the amount of memory is correct.
+    case BaseMemory + ExtraMemory of
+        Memory ->
+            %% Exactly right. The size of the hash table was not changed.
+            ok;
+        Expected ->
+            %% The size of the hash table has been doubled to avoid filling
+            %% the table to more than 50 percent. The previous number
+            %% of entries must have been exactly half the size of the
+            %% hash table. The expected number of extra words added by
+            %% the resizing will be twice that number.
+            ExtraWords = BaseCount * 2,
+            true = ExtraWords * WordSize =:= (Memory - Expected)
+    end,
+    info_wb(N-1, Overhead, {Count,Memory}).
+
+info_info() ->
+    #{count:=Count,memory:=Memory} = persistent_term:info(),
+    true = is_integer(Count) andalso Count >= 0,
+    true = is_integer(Memory) andalso Memory >= 0,
+    {Count,Memory}.
+
+%% Calculate the number of extra bytes needed for storing each term in
+%% the literal, assuming that the key is a tuple of size 2 with
+%% immediate elements. The calculated number is the size of the
+%% ErtsLiteralArea struct excluding the storage for the literal term
+%% itself.
+
+info_literal_area_overhead() ->
+    Key1 = {?MODULE,1},
+    Key2 = {?MODULE,2},
+    #{memory:=Mem0} = persistent_term:info(),
+    ok = persistent_term:put(Key1, literal),
+    #{memory:=Mem1} = persistent_term:info(),
+    ok = persistent_term:put(Key2, literal),
+    #{memory:=Mem2} = persistent_term:info(),
+    true = persistent_term:erase(Key1),
+    true = persistent_term:erase(Key2),
+
+    %% The size of the hash table may have doubled when inserting
+    %% one of the keys. To avoiding counting the change in the hash
+    %% table size, take the smaller size increase.
+    min(Mem2-Mem1, Mem1-Mem0).
+
+%% Test trapping of persistent_term:info/0.
+
+info_trapping(_Config) ->
+    Chk = chk(),
+
+    %% Assume that the info/0 traps after 4000 iterations
+    %% in a non-debug emulator.
+    N = case test_server:timetrap_scale_factor() of
+            1 -> 10000;
+            _ -> 1000
+        end,
+    spawn_link(fun() -> info_trapping_create(N) end),
+    All = do_info_trapping(N, 0),
+    N = info_trapping_check_result(lists:sort(All), 1),
+    erlang:garbage_collect(),
+    info_trapping_erase(N),
+    chk(Chk).
+
+do_info_trapping(N, PrevMem) ->
+    case info_info() of
+        {N,Mem} ->
+            true = Mem >= PrevMem,
+            All = [P || {{?MODULE,{info_trapping,_}},_}=P <- persistent_term:get()],
+            case length(All) of
+                N -> All;
+                _ -> do_info_trapping(N, PrevMem)
+            end;
+        {_,Mem} ->
+            true = Mem >= PrevMem,
+            receive after 1 -> ok end,
+            do_info_trapping(N, Mem)
+    end.
+
+info_trapping_create(0) ->
+    ok;
+info_trapping_create(N) ->
+    ok = persistent_term:put({?MODULE,{info_trapping,N}}, N),
+    info_trapping_create(N-1).
+
+info_trapping_check_result([{{?MODULE,{info_trapping,N}},N}|T], N) ->
+    info_trapping_check_result(T, N+1);
+info_trapping_check_result([], N) -> N-1.
+
+info_trapping_erase(0) ->
+    ok;
+info_trapping_erase(N) ->
+    true = persistent_term:erase({?MODULE,{info_trapping,N}}),
+    info_trapping_erase(N-1).
+
+%% Test that hash tables are deallocated if a process running
+%% persistent_term:get/0 is killed.
+
+killed_while_trapping(_Config) ->
+    Chk = chk(),
+    N = case test_server:timetrap_scale_factor() of
+            1 -> 20000;
+            _ -> 2000
+        end,
+    kwt_put(N),
+    kwt_spawn(10),
+    kwt_erase(N),
+    chk(Chk).
+
+kwt_put(0) ->
+    ok;
+kwt_put(N) ->
+    ok = persistent_term:put({?MODULE,{kwt,N}}, N),
+    kwt_put(N-1).
+
+kwt_spawn(0) ->
+    ok;
+kwt_spawn(N) ->
+    Pids = [spawn(fun kwt_getter/0) || _ <- lists:seq(1, 20)],
+    erlang:yield(),
+    _ = [exit(Pid, kill) || Pid <- Pids],
+    kwt_spawn(N-1).
+
+kwt_getter() ->
+    _ = persistent_term:get(),
+    kwt_getter().
+
+kwt_erase(0) ->
+    ok;
+kwt_erase(N) ->
+    true = persistent_term:erase({?MODULE,{kwt,N}}),
+    kwt_erase(N-1).
+
+%% Test storing off heap values (such as ref-counted binaries).
+
+off_heap_values(_Config) ->
+    Chk = chk(),
+    Key = {?MODULE,?FUNCTION_NAME},
+    Val = {a,list_to_binary(lists:seq(0, 255)),make_ref(),fun() -> ok end},
+    ok = persistent_term:put(Key, Val),
+    FetchedVal = persistent_term:get(Key),
+    Val = FetchedVal,
+    true = persistent_term:erase(Key),
+    off_heap_values_wait(FetchedVal, Val),
+    chk(Chk).
+
+off_heap_values_wait(FetchedVal, Val) ->
+    case erts_debug:size_shared(FetchedVal) of
+        0 ->
+            Val = FetchedVal,
+            ok;
+        _ ->
+            erlang:yield(),
+            off_heap_values_wait(FetchedVal, Val)
+    end.
+
+%% Test some more data types as keys. Use the module name as a key
+%% to minimize the risk of collision with any key used
+%% by the OTP libraries.
+
+keys(_Config) ->
+    Chk = chk(),
+    do_key(?MODULE),
+    do_key([?MODULE]),
+    do_key(?MODULE_STRING),
+    do_key(list_to_binary(?MODULE_STRING)),
+    chk(Chk).
+
+do_key(Key) ->
+    Val = term_to_binary(Key),
+    ok = persistent_term:put(Key, Val),
+    StoredVal = persistent_term:get(Key),
+    Val = StoredVal,
+    true = persistent_term:erase(Key).
+
+%% Create persistent terms with keys that are known to collide.
+%% Delete them in random order, making sure that all others
+%% terms can still be found.
+
+collisions(_Config) ->
+    Chk = chk(),
+
+    %% Create persistent terms with random keys.
+    Keys = lists:flatten(colliding_keys()),
+    Kvs = [{K,rand:uniform(1000)} || K <- Keys],
+    _ = [ok = persistent_term:put(K, V) || {K,V} <- Kvs],
+    _ = [V = persistent_term:get(K) || {K,V} <- Kvs],
+
+    %% Now delete the persistent terms in random order.
+    collisions_delete(lists:keysort(2, Kvs)),
+
+    chk(Chk).
+
+collisions_delete([{Key,Val}|Kvs]) ->
+    Val = persistent_term:get(Key),
+    true = persistent_term:erase(Key),
+    true = lists:sort(persistent_term:get()) =:= lists:sort(Kvs),
+    _ = [V = persistent_term:get(K) || {K,V} <- Kvs],
+    collisions_delete(Kvs);
+collisions_delete([]) ->
+    ok.
+
+colliding_keys() ->
+    %% Collisions found by Jesper L. Andersen for breaking maps.
+    L = [[764492191,2361333849],
+         [49527266765044,90940896816021,20062927283041,267080852079651],
+         [249858369443708,206247021789428,20287304470696,25847120931175],
+         [10645228898670,224705626119556,267405565521452,258214397180678],
+         [264783762221048,166955943492306,98802957003141,102012488332476],
+         [69425677456944,177142907243411,137138950917722,228865047699598],
+         [116031213307147,29203342183358,37406949328742,255198080174323],
+         [200358182338308,235207156008390,120922906095920,116215987197289],
+         [58728890318426,68877471005069,176496507286088,221041411345780],
+         [91094120814795,50665258299931,256093108116737,19777509566621],
+         [74646746200247,98350487270564,154448261001199,39881047281135],
+         [23408943649483,164410325820923,248161749770122,274558342231648],
+         [169531547115055,213630535746863,235098262267796,200508473898303],
+         [235098564415817,85039146398174,51721575960328,173069189684390],
+         [176136386396069,155368359051606,147817099696487,265419485459634],
+         [137542881551462,40028925519736,70525669519846,63445773516557],
+         [173854695142814,114282444507812,149945832627054,99605565798831],
+         [177686773562184,127158716984798,132495543008547],
+         [227073396444896,139667311071766,158915951283562],
+         [26212438434289,94902985796531,198145776057315],
+         [266279278943923,58550737262493,74297973216378],
+         [32373606512065,131854353044428,184642643042326],
+         [34335377662439,85341895822066,273492717750246]],
+
+    %% Verify that the keys still collide (this will fail if the
+    %% internal hash function has been changed).
+    erts_debug:set_internal_state(available_internal_state, true),
+    try
+        case erlang:system_info(wordsize) of
+            8 ->
+                verify_colliding_keys(L);
+            4 ->
+                %% Not guaranteed to collide on a 32-bit system.
+                ok
+        end
+    after
+        erts_debug:set_internal_state(available_internal_state, false)
+    end,
+
+    L.
+
+verify_colliding_keys([[K|Ks]|Gs]) ->
+    Hash = internal_hash(K),
+    [Hash] = lists:usort([internal_hash(Key) || Key <- Ks]),
+    verify_colliding_keys(Gs);
+verify_colliding_keys([]) ->
+    ok.
+
+internal_hash(Term) ->
+    erts_debug:get_internal_state({internal_hash,Term}).
+
+%% Test that all persistent terms are erased by init:restart/0.
+
+init_restart(_Config) ->
+    File = "command_file",
+    ok = file:write_file(File, term_to_binary(restart)),
+    {ok,[[Erl]]} = init:get_argument(progname),
+    ModPath = filename:dirname(code:which(?MODULE)),
+    Cmd = Erl ++ " -pa " ++ ModPath ++ " -noshell "
+        "-run " ++ ?MODULE_STRING ++ " test_init_restart_cmd " ++
+        File,
+    io:format("~s\n", [Cmd]),
+    Expected = "12ok",
+    case os:cmd(Cmd) of
+        Expected ->
+            ok;
+        Actual ->
+            io:format("Expected: ~s", [Expected]),
+            io:format("Actual:   ~s\n", [Actual]),
+            ct:fail(unexpected_output)
+    end.
+
+test_init_restart_cmd([File]) ->
+    try
+        do_test_init_restart_cmd(File)
+    catch
+        C:R ->
+            io:format("\n~p ~p\n", [C,R]),
+            halt()
+    end,
+    receive
+        _ -> ok
+    end.
+
+do_test_init_restart_cmd(File) ->
+    {ok,Bin} = file:read_file(File),
+    Seq = lists:seq(1, 50),
+    case binary_to_term(Bin) of
+        restart ->
+            _ = [persistent_term:put({?MODULE,I}, {value,I}) ||
+                    I <- Seq],
+            ok = file:write_file(File, term_to_binary(was_restarted)),
+            io:put_chars("1"),
+            init:restart(),
+            receive
+                _ -> ok
+            end;
+        was_restarted ->
+            io:put_chars("2"),
+            ok = file:delete(File),
+            _ = [begin
+                     Key = {?MODULE,I},
+                     {'EXIT',{badarg,_}} = (catch persistent_term:get(Key))
+                 end || I <- Seq],
+            io:put_chars("ok"),
+            init:stop()
+    end.
+
+%% Check that there is the same number of persistents terms before
+%% and after each test case.
+
+chk() ->
+    persistent_term:info().
+
+chk(Chk) ->
+    Chk = persistent_term:info(),
+    Key = {?MODULE,?FUNCTION_NAME},
+    ok = persistent_term:put(Key, {term,Chk}),
+    Term = persistent_term:get(Key),
+    true = persistent_term:erase(Key),
+    chk_not_stuck(Term),
+    ok.
+
+chk_not_stuck(Term) ->
+    %% Hash tables to be deleted are put onto a queue.
+    %% Make sure that the queue isn't stuck by a table with
+    %% a non-zero ref count.
+
+    case erts_debug:size_shared(Term) of
+        0 ->
+            erlang:yield(),
+            chk_not_stuck(Term);
+        _ ->
+            ok
+    end.