fix(ds): Optimize hot loop of skipstream storage layout

apps/emqx_durable_storage/src/emqx_ds_storage_skipstream_lts.erl

@@ -293,6 +293,21 @@ delete_next(Shard, S, It0, Selector, BatchSize, Now, IsCurrent) ->
 %% Internal functions
 %%================================================================================
 
+%% Loop context:
+-record(ctx, {
+    shard,
+    %% Generation runtime state
+    s,
+    %% RocksDB iterators:
+    iters,
+    %% Cached topic structure for the static index:
+    topic_structure,
+    %% Maximum time:
+    tmax,
+    %% Compressed topic filter, split into words:
+    filter
+}).
+
 get_streams(Trie, TopicFilter) ->
     lists:map(
         fun({Static, _Varying}) ->
@@ -316,34 +331,19 @@ serialize(#s{serialization_schema = SSchema, with_guid = WithGuid}, Varying, Msg
     emqx_ds_msg_serializer:serialize(SSchema, Msg).
 
 enrich(
-    Shard,
-    #s{trie = Trie, with_guid = WithGuid},
+    #ctx{shard = Shard, topic_structure = Structure, s = #s{with_guid = WithGuid}},
     DSKey,
-    StaticKey,
     Msg0
 ) ->
-    case emqx_ds_lts:reverse_lookup(Trie, StaticKey) of
-        {ok, Structure} ->
-            %% Reconstruct the original topic from the static topic
-            %% index and varying parts:
-            Topic = emqx_topic:join(
-                emqx_ds_lts:decompress_topic(Structure, words(Msg0#message.topic))
-            ),
-            Msg0#message{
-                topic = Topic,
-                id =
-                    case WithGuid of
-                        true -> Msg0#message.id;
-                        false -> fake_guid(Shard, DSKey)
-                    end
-            };
-        undefined ->
-            Err = #{
-                msg => "LTS trie missing key",
-                key => StaticKey
-            },
-            throw({unrecoverable, Err})
-    end.
+    Topic = emqx_topic:join(emqx_ds_lts:decompress_topic(Structure, words(Msg0#message.topic))),
+    Msg0#message{
+        topic = Topic,
+        id =
+            case WithGuid of
+                true -> Msg0#message.id;
+                false -> fake_guid(Shard, DSKey)
+            end
+    }.
 
 deserialize(
     #s{serialization_schema = SSchema},
@@ -437,15 +437,41 @@ do_init_iterators(S, Static, [], _WildcardLevel) ->
         }
     ].
 
-next_loop(Shard, S, It = #it{ts = TS}, Iterators, BatchSize, TMax) ->
-    next_loop(Shard, S, It, Iterators, BatchSize, TMax, {seek, TS}, []).
+next_loop(
+    Shard,
+    S = #s{trie = Trie},
+    It = #it{static_index = StaticIdx, ts = TS, compressed_tf = CompressedTF},
+    Iterators,
+    BatchSize,
+    TMax
+) ->
+    TopicStructure =
+        case emqx_ds_lts:reverse_lookup(Trie, StaticIdx) of
+            {ok, Rev} ->
+                Rev;
+            undefined ->
+                throw(#{
+                    msg => "LTS trie missing key",
+                    key => StaticIdx
+                })
+        end,
+    Ctx = #ctx{
+        shard = Shard,
+        s = S,
+        iters = Iterators,
+        topic_structure = TopicStructure,
+        filter = words(CompressedTF),
+        tmax = TMax
+    },
+    next_loop(Ctx, It, BatchSize, {seek, TS}, []).
 
-next_loop(_Shard, _S, It, _Iterators, 0, _TMax, Op, Acc) ->
+next_loop(_Ctx, It, 0, Op, Acc) ->
     finalize_loop(It, Op, Acc);
-next_loop(Shard, S, It0, Iterators, BatchSize, TMax, Op, Acc) ->
+next_loop(Ctx, It0, BatchSize, Op, Acc) ->
     %% ?tp(notice, skipstream_loop, #{
     %%     ts => It0#it.ts, tf => It0#it.compressed_tf, bs => BatchSize, tmax => TMax, op => Op
     %% }),
+    #ctx{s = S, tmax = TMax, iters = Iterators} = Ctx,
     #it{static_index = StaticIdx, compressed_tf = CompressedTF} = It0,
     case next_step(S, StaticIdx, CompressedTF, Iterators, undefined, Op) of
         none ->
@@ -463,12 +489,12 @@ next_loop(Shard, S, It0, Iterators, BatchSize, TMax, Op, Acc) ->
         {seek, TS} ->
             %% ?tp(notice, skipstream_loop_result, #{r => seek, ts => TS}),
             It = It0#it{ts = TS},
-            next_loop(Shard, S, It, Iterators, BatchSize, TMax, {seek, TS}, Acc);
+            next_loop(Ctx, It, BatchSize, {seek, TS}, Acc);
         {ok, TS, DSKey, Msg0} ->
             %% ?tp(notice, skipstream_loop_result, #{r => ok, ts => TS, key => Key}),
-            Message = enrich(Shard, S, DSKey, StaticIdx, Msg0),
+            Message = enrich(Ctx, DSKey, Msg0),
             It = It0#it{ts = TS},
-            next_loop(Shard, S, It, Iterators, BatchSize - 1, TMax, next, [{DSKey, Message} | Acc])
+            next_loop(Ctx, It, BatchSize - 1, next, [{DSKey, Message} | Acc])
     end.
 
 finalize_loop(It0, Op, Acc) ->