From d9c9706c05a0f617e9de45434e53a4f363b40a0c Mon Sep 17 00:00:00 2001
From: Eric Eastwood <erice@element.io>
Date: Thu, 26 Mar 2026 11:28:35 -0500
Subject: [PATCH] Debug why we pad

---
 scripts-dev/complement.sh      | 24 ++++++++++++------------
 synapse/handlers/federation.py | 23 ++++++++++++++++++++++-
 synapse/handlers/pagination.py |  7 +++++++
 3 files changed, 41 insertions(+), 13 deletions(-)

diff --git a/scripts-dev/complement.sh b/scripts-dev/complement.sh
index cca87d42a9..db83e87ad2 100755
--- a/scripts-dev/complement.sh
+++ b/scripts-dev/complement.sh
@@ -274,18 +274,18 @@ main() {
   # We pick and choose the specific MSC's that Synapse supports.
   default_complement_test_packages=(
     ./tests/csapi
-    ./tests
-    ./tests/msc3874
-    ./tests/msc3890
-    ./tests/msc3391
-    ./tests/msc3757
-    ./tests/msc3930
-    ./tests/msc3902
-    ./tests/msc3967
-    ./tests/msc4140
-    ./tests/msc4155
-    ./tests/msc4306
-    ./tests/msc4222
+    # ./tests
+    # ./tests/msc3874
+    # ./tests/msc3890
+    # ./tests/msc3391
+    # ./tests/msc3757
+    # ./tests/msc3930
+    # ./tests/msc3902
+    # ./tests/msc3967
+    # ./tests/msc4140
+    # ./tests/msc4155
+    # ./tests/msc4306
+    # ./tests/msc4222
   )
 
   # Export the list of test packages as a space-separated environment variable, so other
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index f173166be1..982f2a62fe 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -255,7 +255,8 @@ class FederationHandler:
                 room_id=room_id,
                 # Per the docstring, it's best to pad the `current_depth` by the
                 # number of messages you plan to backfill from these points.
-                current_depth=current_depth + limit,
+                # current_depth=current_depth + limit,
+                current_depth=current_depth,
                 # We only need to end up with 5 extremities combined with the
                 # insertion event extremities to make the `/backfill` request
                 # but fetch an order of magnitude more to make sure there is
@@ -267,6 +268,25 @@ class FederationHandler:
             )
         ]
 
+        all_backwards_extremities = [
+            _BackfillPoint(event_id, depth, _BackfillPointType.BACKWARDS_EXTREMITY)
+            for event_id, depth in await self.store.get_backfill_points_in_room(
+                room_id=room_id,
+                current_depth=999999,
+                limit=50,
+            )
+        ]
+        logger.info(
+            "asdf all_backwards_extremities=%s",
+            all_backwards_extremities,
+        )
+
+        logger.info(
+            "asdf current_depth=%s backwards_extremities=%s",
+            current_depth,
+            backwards_extremities,
+        )
+
         # we now have a list of potential places to backpaginate from. We prefer to
         # start with the most recent (ie, max depth), so let's sort the list.
         sorted_backfill_points: list[_BackfillPoint] = sorted(
@@ -313,6 +333,7 @@ class FederationHandler:
             logger.debug(
                 "_maybe_backfill_inner: all backfill points are *after* current depth. Trying again with later backfill points."
             )
+            logger.info("asdf: backfill in the background")
             self.hs.run_as_background_process(
                 "_maybe_backfill_inner_anyway_with_max_depth",
                 self.maybe_backfill,
diff --git a/synapse/handlers/pagination.py b/synapse/handlers/pagination.py
index a55dcc78b0..6cc51123f9 100644
--- a/synapse/handlers/pagination.py
+++ b/synapse/handlers/pagination.py
@@ -566,6 +566,13 @@ class PaginationHandler:
                     StreamKeyType.ROOM, leave_token
                 )
 
+        logger.info(
+            "asdf get_messages backfill=%s pagin_config.from_token=%s curr_topo=%s",
+            backfill,
+            pagin_config.from_token,
+            curr_topo,
+        )
+
         to_room_key = None
         if pagin_config.to_token:
             to_room_key = pagin_config.to_token.room_key