From e541bb9eed964e6840ddf2cd859af3f94150dc85 Mon Sep 17 00:00:00 2001
From: Patrick Cloke <clokep@users.noreply.github.com>
Date: Tue, 31 May 2022 07:42:50 -0400
Subject: [PATCH] Rework stream token to stop caring about groups. (#12897)

---
 changelog.d/12897.removal | 1 +
 synapse/streams/events.py | 4 ++--
 synapse/types.py          | 6 +++++-
 3 files changed, 8 insertions(+), 3 deletions(-)
 create mode 100644 changelog.d/12897.removal

diff --git a/changelog.d/12897.removal b/changelog.d/12897.removal
new file mode 100644
index 0000000000..41f6fae5da
--- /dev/null
+++ b/changelog.d/12897.removal
@@ -0,0 +1 @@
+Remove support for the non-standard groups/communities feature from Synapse.
diff --git a/synapse/streams/events.py b/synapse/streams/events.py
index acf17ba623..54e0b1a23b 100644
--- a/synapse/streams/events.py
+++ b/synapse/streams/events.py
@@ -54,7 +54,6 @@ class EventSources:
         push_rules_key = self.store.get_max_push_rules_stream_id()
         to_device_key = self.store.get_to_device_stream_token()
         device_list_key = self.store.get_device_stream_token()
-        groups_key = self.store.get_group_stream_token()
 
         token = StreamToken(
             room_key=self.sources.room.get_current_key(),
@@ -65,7 +64,8 @@ class EventSources:
             push_rules_key=push_rules_key,
             to_device_key=to_device_key,
             device_list_key=device_list_key,
-            groups_key=groups_key,
+            # Groups key is unused.
+            groups_key=0,
         )
         return token
 
diff --git a/synapse/types.py b/synapse/types.py
index 091cc611ab..0586d2cbb9 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -639,7 +639,7 @@ class StreamToken:
         6. `push_rules_key`: `541479`
         7. `to_device_key`: `274711`
         8. `device_list_key`: `265584`
-        9. `groups_key`: `1`
+        9. `groups_key`: `1` (note that this key is now unused)
 
     You can see how many of these keys correspond to the various
     fields in a "/sync" response:
@@ -691,6 +691,7 @@ class StreamToken:
     push_rules_key: int
     to_device_key: int
     device_list_key: int
+    # Note that the groups key is no longer used and may have bogus values.
     groups_key: int
 
     _SEPARATOR = "_"
@@ -722,6 +723,9 @@ class StreamToken:
                 str(self.push_rules_key),
                 str(self.to_device_key),
                 str(self.device_list_key),
+                # Note that the groups key is no longer used, but it is still
+                # serialized so that there will not be confusion in the future
+                # if additional tokens are added.
                 str(self.groups_key),
             ]
         )