From 05d97397d32f24406429ea6b630da8ff921a1cf5 Mon Sep 17 00:00:00 2001
From: Andrew Mayorov <encube.ul@gmail.com>
Date: Mon, 17 Jun 2024 16:13:53 +0200
Subject: [PATCH] fix(dsstore): use correct comparison when walking over
 generations

---
 .../src/emqx_ds_storage_layer.erl             | 22 +++++++++----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/apps/emqx_durable_storage/src/emqx_ds_storage_layer.erl b/apps/emqx_durable_storage/src/emqx_ds_storage_layer.erl
index b908b2819..d6d36bf97 100644
--- a/apps/emqx_durable_storage/src/emqx_ds_storage_layer.erl
+++ b/apps/emqx_durable_storage/src/emqx_ds_storage_layer.erl
@@ -972,17 +972,17 @@ generation_get(Shard, GenId) ->
 
 -spec generations_since(shard_id(), emqx_ds:time()) -> [gen_id()].
 generations_since(Shard, Since) ->
-    Schema = get_schema_runtime(Shard),
-    maps:fold(
-        fun
-            (?GEN_KEY(GenId), #{until := Until}, Acc) when Until >= Since ->
-                [GenId | Acc];
-            (_K, _V, Acc) ->
-                Acc
-        end,
-        [],
-        Schema
-    ).
+    Schema = #{current_generation := Current} = get_schema_runtime(Shard),
+    list_generations_since(Schema, Current, Since).
+
+list_generations_since(Schema, GenId, Since) ->
+    case Schema of
+        #{?GEN_KEY(GenId) := #{until := Until}} when Until > Since ->
+            [GenId | list_generations_since(Schema, GenId - 1, Since)];
+        #{} ->
+            %% No more live generations.
+            []
+    end.
 
 format_state(#s{shard_id = ShardId, db = DB, cf_refs = CFRefs, schema = Schema, shard = Shard}) ->
     #{