chore(retainer): get rid of qlc usage

apps/emqx_retainer/src/emqx_retainer.app.src

@@ -2,7 +2,7 @@
 {application, emqx_retainer, [
     {description, "EMQX Retainer"},
     % strict semver, bump manually!
-    {vsn, "5.0.21"},
+    {vsn, "5.0.22"},
     {modules, []},
     {registered, [emqx_retainer_sup]},
     {applications, [kernel, stdlib, emqx, emqx_ctl]},

apps/emqx_retainer/src/emqx_retainer_dispatcher.erl

@@ -255,6 +255,8 @@ deliver([], Context, Pid, Topic, Cursor, Limiter) ->
 deliver(Result, Context, Pid, Topic, Cursor, Limiter) ->
     case erlang:is_process_alive(Pid) of
         false ->
+            ok = close_cursor(Cursor),
+            ?tp(debug, retainer_dispatcher_no_receiver, #{topic => Topic}),
             {ok, Limiter};
         _ ->
             DeliverNum = emqx_conf:get([retainer, flow_control, batch_deliver_number], undefined),
@@ -272,6 +274,11 @@ deliver(Result, Context, Pid, Topic, Cursor, Limiter) ->
             end
     end.
 
+close_cursor({{qlc_cursor, _} = Cursor, _}) ->
+    qlc:delete_cursor(Cursor);
+close_cursor(_Cursor) ->
+    ok.
+
 do_deliver([], _DeliverNum, _Pid, _Topic, Limiter) ->
     {ok, Limiter};
 do_deliver(Msgs, DeliverNum, Pid, Topic, Limiter) ->

apps/emqx_retainer/src/emqx_retainer_mnesia.erl

@@ -22,7 +22,6 @@
 -include_lib("emqx/include/logger.hrl").
 -include_lib("snabbkaffe/include/snabbkaffe.hrl").
 -include_lib("stdlib/include/ms_transform.hrl").
--include_lib("stdlib/include/qlc.hrl").
 
 %% emqx_retainer callbacks
 -export([
@@ -60,7 +59,6 @@
 
 -define(META_KEY, index_meta).
 
--define(CLEAR_BATCH_SIZE, 1000).
 -define(REINDEX_BATCH_SIZE, 1000).
 -define(REINDEX_DISPATCH_WAIT, 30000).
 -define(REINDEX_RPC_RETRY_INTERVAL, 1000).
@@ -167,15 +165,20 @@ clear_expired(_) ->
 
 clear_expired() ->
     NowMs = erlang:system_time(millisecond),
-    QH = qlc:q([
-        RetainedMsg
-     || #retained_message{
-            expiry_time = ExpiryTime
-        } = RetainedMsg <- ets:table(?TAB_MESSAGE),
-        (ExpiryTime =/= 0) and (ExpiryTime < NowMs)
-    ]),
-    QC = qlc:cursor(QH),
-    clear_batch(dirty_indices(write), QC).
+    S0 = ets_stream(?TAB_MESSAGE),
+    S1 = stream_filter(
+        fun(#retained_message{expiry_time = ExpiryTime}) ->
+            ExpiryTime =/= 0 andalso ExpiryTime < NowMs
+        end,
+        S0
+    ),
+    DirtyWriteIndices = dirty_indices(write),
+    stream_foreach(
+        fun(RetainedMsg) ->
+            delete_message_with_indices(RetainedMsg, DirtyWriteIndices)
+        end,
+        S1
+    ).
 
 delete_message(_State, Topic) ->
     Tokens = topic_to_tokens(Topic),
@@ -183,13 +186,11 @@ delete_message(_State, Topic) ->
         false ->
             ok = delete_message_by_topic(Tokens, dirty_indices(write));
         true ->
-            QH = search_table(Tokens, 0),
-            qlc:fold(
-                fun(RetainedMsg, _) ->
-                    ok = delete_message_with_indices(RetainedMsg, dirty_indices(write))
-                end,
-                undefined,
-                QH
+            S = search_stream(Tokens, 0),
+            DirtyWriteIndices = dirty_indices(write),
+            stream_foreach(
+                fun(RetainedMsg) -> delete_message_with_indices(RetainedMsg, DirtyWriteIndices) end,
+                S
             )
     end.
 
@@ -199,54 +200,49 @@ read_message(_State, Topic) ->
 match_messages(_State, Topic, undefined) ->
     Tokens = topic_to_tokens(Topic),
     Now = erlang:system_time(millisecond),
-    QH = msg_table(search_table(Tokens, Now)),
+    S = msg_stream(search_stream(Tokens, Now)),
     case batch_read_number() of
         all_remaining ->
-            {ok, qlc:eval(QH), undefined};
+            {ok, emqx_utils_stream:consume(S), undefined};
         BatchNum when is_integer(BatchNum) ->
-            Cursor = qlc:cursor(QH),
-            match_messages(undefined, Topic, {Cursor, BatchNum})
+            match_messages(undefined, Topic, {S, BatchNum})
     end;
-match_messages(_State, _Topic, {Cursor, BatchNum}) ->
-    case qlc_next_answers(Cursor, BatchNum) of
-        {closed, Rows} ->
-            {ok, Rows, undefined};
-        {more, Rows} ->
-            {ok, Rows, {Cursor, BatchNum}}
+match_messages(_State, _Topic, {S0, BatchNum}) ->
+    case emqx_utils_stream:consume(BatchNum, S0) of
+        {Rows, S1} ->
+            {ok, Rows, {S1, BatchNum}};
+        Rows when is_list(Rows) ->
+            {ok, Rows, undefined}
     end.
 
 page_read(_State, Topic, Page, Limit) ->
     Now = erlang:system_time(millisecond),
-    QH =
+    S0 =
         case Topic of
             undefined ->
-                msg_table(search_table(undefined, ['#'], Now));
+                msg_stream(search_stream(undefined, ['#'], Now));
             _ ->
                 Tokens = topic_to_tokens(Topic),
-                msg_table(search_table(Tokens, Now))
+                msg_stream(search_stream(Tokens, Now))
         end,
-    OrderedQH = qlc:sort(QH, {order, fun compare_message/2}),
-    Cursor = qlc:cursor(OrderedQH),
+    %% This is very inefficient, but we are limited with inherited API
+    S1 = emqx_utils_stream:list(
+        lists:sort(
+            fun compare_message/2,
+            emqx_utils_stream:consume(S0)
+        )
+    ),
     NSkip = (Page - 1) * Limit,
-    SkipResult =
-        case NSkip > 0 of
-            true ->
-                {Result, _} = qlc_next_answers(Cursor, NSkip),
-                Result;
-            false ->
-                more
-        end,
-    case SkipResult of
-        closed ->
-            {ok, false, []};
-        more ->
-            case qlc_next_answers(Cursor, Limit) of
-                {closed, Rows} ->
-                    {ok, false, Rows};
-                {more, Rows} ->
-                    qlc:delete_cursor(Cursor),
-                    {ok, true, Rows}
-            end
+    case emqx_utils_stream:consume(NSkip, S1) of
+        {_, S2} ->
+            case emqx_utils_stream:consume(Limit, S2) of
+                {Rows, _S3} ->
+                    {ok, true, Rows};
+                Rows when is_list(Rows) ->
+                    {ok, false, Rows}
+            end;
+        Rows when is_list(Rows) ->
+            {ok, false, []}
     end.
 
 clean(_) ->
@@ -318,58 +314,63 @@ do_store_retained_index(Key, ExpiryTime) ->
     },
     mnesia:write(?TAB_INDEX, RetainedIndex, write).
 
-msg_table(SearchTable) ->
-    qlc:q([
-        Msg
-     || #retained_message{
-            msg = Msg
-        } <- SearchTable
-    ]).
+msg_stream(SearchStream) ->
+    emqx_utils_stream:map(
+        fun(#retained_message{msg = Msg}) -> Msg end,
+        SearchStream
+    ).
 
-search_table(Tokens, Now) ->
+search_stream(Tokens, Now) ->
     Indices = dirty_indices(read),
     Index = emqx_retainer_index:select_index(Tokens, Indices),
-    search_table(Index, Tokens, Now).
+    search_stream(Index, Tokens, Now).
 
-search_table(undefined, Tokens, Now) ->
+search_stream(undefined, Tokens, Now) ->
     Ms = make_message_match_spec(Tokens, Now),
-    ets:table(?TAB_MESSAGE, [{traverse, {select, Ms}}]);
-search_table(Index, FilterTokens, Now) ->
+    emqx_utils_stream:ets(
+        fun
+            (undefined) -> ets:select(?TAB_MESSAGE, Ms, 1);
+            (Cont) -> ets:select(Cont)
+        end
+    );
+search_stream(Index, FilterTokens, Now) ->
     {Ms, IsExactMs} = make_index_match_spec(Index, FilterTokens, Now),
-    Topics = [
-        emqx_retainer_index:restore_topic(Key)
-     || #retained_index{key = Key} <- ets:select(?TAB_INDEX, Ms)
-    ],
-    RetainedMsgQH = qlc:q([
-        ets:lookup(?TAB_MESSAGE, TopicTokens)
-     || TopicTokens <- Topics, match(IsExactMs, TopicTokens, FilterTokens)
-    ]),
-    qlc:q([
-        RetainedMsg
-     || [
-            #retained_message{
-                expiry_time = ExpiryTime
-            } = RetainedMsg
-        ] <- RetainedMsgQH,
-        (ExpiryTime == 0) or (ExpiryTime > Now)
-    ]).
+    IndexRecordStream = emqx_utils_stream:ets(
+        fun
+            (undefined) -> ets:select(?TAB_INDEX, Ms, 1);
+            (Cont) -> ets:select(Cont)
+        end
+    ),
+    TopicStream = emqx_utils_stream:map(
+        fun(#retained_index{key = Key}) -> emqx_retainer_index:restore_topic(Key) end,
+        IndexRecordStream
+    ),
+    MatchingTopicStream = stream_filter(
+        fun(TopicTokens) -> match(IsExactMs, TopicTokens, FilterTokens) end,
+        TopicStream
+    ),
+    LookedUpRetainMsgStream = emqx_utils_stream:map(
+        fun(TopicTokens) -> ets:lookup(?TAB_MESSAGE, TopicTokens) end,
+        MatchingTopicStream
+    ),
+    FoundAndValidLookedUpRetainMsgStream = stream_filter(
+        fun
+            ([#retained_message{expiry_time = ExpiryTime}]) ->
+                ExpiryTime =:= 0 orelse ExpiryTime >= Now;
+            ([]) ->
+                false
+        end,
+        LookedUpRetainMsgStream
+    ),
+    RetainMsgStream = emqx_utils_stream:map(
+        fun([RetainedMsg]) -> RetainedMsg end,
+        FoundAndValidLookedUpRetainMsgStream
+    ),
+    RetainMsgStream.
 
 match(_IsExactMs = true, _TopicTokens, _FilterTokens) -> true;
 match(_IsExactMs = false, TopicTokens, FilterTokens) -> emqx_topic:match(TopicTokens, FilterTokens).
 
-clear_batch(Indices, QC) ->
-    {Result, Rows} = qlc_next_answers(QC, ?CLEAR_BATCH_SIZE),
-    lists:foreach(
-        fun(RetainedMsg) ->
-            delete_message_with_indices(RetainedMsg, Indices)
-        end,
-        Rows
-    ),
-    case Result of
-        closed -> ok;
-        more -> clear_batch(Indices, QC)
-    end.
-
 delete_message_by_topic(TopicTokens, Indices) ->
     case mnesia:dirty_read(?TAB_MESSAGE, TopicTokens) of
         [] -> ok;
@@ -409,21 +410,6 @@ read_messages(Topic) ->
             end
     end.
 
-qlc_next_answers(QC, N) ->
-    case qlc:next_answers(QC, N) of
-        NextAnswers when
-            is_list(NextAnswers) andalso
-                length(NextAnswers) < N
-        ->
-            qlc:delete_cursor(QC),
-            {closed, NextAnswers};
-        NextAnswers when is_list(NextAnswers) ->
-            {more, NextAnswers};
-        {error, Module, Reason} ->
-            qlc:delete_cursor(QC),
-            error({qlc_error, Module, Reason})
-    end.
-
 make_message_match_spec(Tokens, NowMs) ->
     Cond = emqx_retainer_index:condition(Tokens),
     MsHd = #retained_message{topic = Cond, msg = '_', expiry_time = '$3'},
@@ -552,8 +538,11 @@ reindex(NewIndices, Force, StatusFun) when
             {atomic, ok} = mria:clear_table(?TAB_INDEX),
 
             %% Fill index records in batches.
-            QH = qlc:q([Topic || #retained_message{topic = Topic} <- ets:table(?TAB_MESSAGE)]),
-            ok = reindex_batch(qlc:cursor(QH), 0, StatusFun),
+            TopicStream = emqx_utils_stream:map(
+                fun(#retained_message{topic = Topic}) -> Topic end,
+                ets_stream(?TAB_MESSAGE)
+            ),
+            ok = reindex_batch(TopicStream, 0, StatusFun),
 
             %% Enable read indices and unlock reindexing.
             finalize_reindex();
@@ -631,12 +620,12 @@ reindex_topic(Indices, Topic) ->
             ok
     end.
 
-reindex_batch(QC, Done, StatusFun) ->
-    case mria:transaction(?RETAINER_SHARD, fun ?MODULE:do_reindex_batch/2, [QC, Done]) of
-        {atomic, {more, NewDone}} ->
+reindex_batch(Stream0, Done, StatusFun) ->
+    case mria:transaction(?RETAINER_SHARD, fun ?MODULE:do_reindex_batch/2, [Stream0, Done]) of
+        {atomic, {more, NewDone, Stream1}} ->
             _ = StatusFun(NewDone),
-            reindex_batch(QC, NewDone, StatusFun);
-        {atomic, {closed, NewDone}} ->
+            reindex_batch(Stream1, NewDone, StatusFun);
+        {atomic, {done, NewDone}} ->
             _ = StatusFun(NewDone),
             ok;
         {aborted, Reason} ->
@@ -647,14 +636,26 @@ reindex_batch(QC, Done, StatusFun) ->
             {error, Reason}
     end.
 
-do_reindex_batch(QC, Done) ->
+do_reindex_batch(Stream0, Done) ->
     Indices = db_indices(write),
-    {Status, Topics} = qlc_next_answers(QC, ?REINDEX_BATCH_SIZE),
+    Result = emqx_utils_stream:consume(?REINDEX_BATCH_SIZE, Stream0),
+    Topics =
+        case Result of
+            {Rows, _Stream1} ->
+                Rows;
+            Rows when is_list(Rows) ->
+                Rows
+        end,
     ok = lists:foreach(
         fun(Topic) -> reindex_topic(Indices, Topic) end,
         Topics
     ),
-    {Status, Done + length(Topics)}.
+    case Result of
+        {_Rows, Stream1} ->
+            {more, Done + length(Topics), Stream1};
+        _Rows ->
+            {done, Done + length(Topics)}
+    end.
 
 wait_dispatch_complete(Timeout) ->
     Nodes = mria:running_nodes(),
@@ -690,3 +691,37 @@ are_indices_updated(Indices) ->
         _ ->
             false
     end.
+
+ets_stream(Tab) ->
+    emqx_utils_stream:ets(
+        fun
+            (undefined) -> ets:match_object(Tab, '$1', 1);
+            (Cont) -> ets:match_object(Cont)
+        end
+    ).
+
+stream_foreach(F, S) ->
+    case emqx_utils_stream:next(S) of
+        [X | Rest] ->
+            F(X),
+            stream_foreach(F, Rest);
+        [] ->
+            ok
+    end.
+
+%% TODO: move to emqx_utils_stream
+stream_filter(F, S) ->
+    FilterNext = fun FilterNext(St) ->
+        case emqx_utils_stream:next(St) of
+            [X | Rest] ->
+                case F(X) of
+                    true ->
+                        [X | stream_filter(F, Rest)];
+                    false ->
+                        FilterNext(Rest)
+                end;
+            [] ->
+                []
+        end
+    end,
+    fun() -> FilterNext(S) end.

apps/emqx_retainer/test/emqx_retainer_SUITE.erl

@@ -21,6 +21,7 @@
 
 -include("emqx_retainer.hrl").
 
+-include_lib("emqx/include/asserts.hrl").
 -include_lib("eunit/include/eunit.hrl").
 -include_lib("common_test/include/ct.hrl").
 -include_lib("snabbkaffe/include/snabbkaffe.hrl").
@@ -77,31 +78,25 @@ end_per_suite(Config) ->
     emqx_cth_suite:stop(?config(suite_apps, Config)).
 
 init_per_group(mnesia_without_indices, Config) ->
-    mnesia:clear_table(?TAB_INDEX_META),
-    mnesia:clear_table(?TAB_INDEX),
-    mnesia:clear_table(?TAB_MESSAGE),
-    Config;
+    [{index, false} | Config];
 init_per_group(mnesia_reindex, Config) ->
-    emqx_retainer_mnesia:populate_index_meta(),
-    mnesia:clear_table(?TAB_INDEX),
-    mnesia:clear_table(?TAB_MESSAGE),
     Config;
 init_per_group(_, Config) ->
-    emqx_retainer_mnesia:populate_index_meta(),
-    mnesia:clear_table(?TAB_INDEX),
-    mnesia:clear_table(?TAB_MESSAGE),
     Config.
 
 end_per_group(_Group, Config) ->
     emqx_retainer_mnesia:populate_index_meta(),
     Config.
 
-init_per_testcase(t_get_basic_usage_info, Config) ->
+init_per_testcase(_TestCase, Config) ->
+    case ?config(index, Config) of
+        false ->
+            mnesia:clear_table(?TAB_INDEX_META);
+        _ ->
+            emqx_retainer_mnesia:populate_index_meta()
+    end,
     mnesia:clear_table(?TAB_INDEX),
     mnesia:clear_table(?TAB_MESSAGE),
-    emqx_retainer_mnesia:populate_index_meta(),
-    Config;
-init_per_testcase(_TestCase, Config) ->
     Config.
 
 app_spec() ->
@@ -309,7 +304,7 @@ t_message_expiry(Config) ->
 
         ok = emqtt:disconnect(C1)
     end,
-    with_conf(ConfMod, Case).
+    with_conf(Config, ConfMod, Case).
 
 t_message_expiry_2(Config) ->
     ConfMod = fun(Conf) ->
@@ -331,9 +326,9 @@ t_message_expiry_2(Config) ->
 
         ok = emqtt:disconnect(C1)
     end,
-    with_conf(ConfMod, Case).
+    with_conf(Config, ConfMod, Case).
 
-t_table_full(_) ->
+t_table_full(Config) ->
     ConfMod = fun(Conf) ->
         Conf#{<<"backend">> => #{<<"max_retained_messages">> => <<"1">>}}
     end,
@@ -350,7 +345,7 @@ t_table_full(_) ->
 
         ok = emqtt:disconnect(C1)
     end,
-    with_conf(ConfMod, Case).
+    with_conf(Config, ConfMod, Case).
 
 t_clean(Config) ->
     {ok, C1} = emqtt:start_link([{clean_start, true}, {proto_ver, v5}]),
@@ -445,7 +440,7 @@ t_flow_control(_) ->
     Diff = End - Begin,
 
     ?assert(
-        Diff > timer:seconds(2.5) andalso Diff < timer:seconds(3.9),
+        Diff > timer:seconds(2.5) andalso Diff < timer:seconds(4),
         lists:flatten(io_lib:format("Diff is :~p~n", [Diff]))
     ),
 
@@ -461,7 +456,7 @@ t_flow_control(_) ->
     }),
     ok.
 
-t_clear_expired(_) ->
+t_clear_expired(Config) ->
     ConfMod = fun(Conf) ->
         Conf#{
             <<"msg_clear_interval">> := <<"1s">>,
@@ -497,9 +492,9 @@ t_clear_expired(_) ->
 
         ok = emqtt:disconnect(C1)
     end,
-    with_conf(ConfMod, Case).
+    with_conf(Config, ConfMod, Case).
 
-t_max_payload_size(_) ->
+t_max_payload_size(Config) ->
     ConfMod = fun(Conf) -> Conf#{<<"max_payload_size">> := <<"1kb">>} end,
     Case = fun() ->
         emqx_retainer:clean(),
@@ -528,7 +523,7 @@ t_max_payload_size(_) ->
 
         ok = emqtt:disconnect(C1)
     end,
-    with_conf(ConfMod, Case).
+    with_conf(Config, ConfMod, Case).
 
 t_page_read(_) ->
     {ok, C1} = emqtt:start_link([{clean_start, true}, {proto_ver, v5}]),
@@ -835,10 +830,11 @@ receive_messages(Count, Msgs) ->
         Msgs
     end.
 
-with_conf(ConfMod, Case) ->
+with_conf(CTConfig, ConfMod, Case) ->
     Conf = emqx:get_raw_config([retainer]),
     NewConf = ConfMod(Conf),
     emqx_retainer:update_config(NewConf),
+    ?config(index, CTConfig) =:= false andalso mria:clear_table(?TAB_INDEX_META),
     try
         Case(),
         {ok, _} = emqx_retainer:update_config(Conf)