Disable caching in /sync corner case (#16080)
Fixes #15502
2 files changed, 11 insertions, 10 deletions
diff --git a/changelog.d/16080.bugfix b/changelog.d/16080.bugfix
new file mode 100644
index 0000000000..1ad6fb3c52
--- /dev/null
+++ b/changelog.d/16080.bugfix
@@ -0,0 +1 @@
+Fix a long-standing bu in `/sync` where timeout=0 does not skip caching, resulting in slow calls in cases where there are no new changes. Contributed by @PlasmaIntec.
\ No newline at end of file
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 8174248387..60a9f341b5 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -387,16 +387,16 @@ class SyncHandler:
from_token=since_token,
)
- # if nothing has happened in any of the users' rooms since /sync was called,
- # the resultant next_batch will be the same as since_token (since the result
- # is generated when wait_for_events is first called, and not regenerated
- # when wait_for_events times out).
- #
- # If that happens, we mustn't cache it, so that when the client comes back
- # with the same cache token, we don't immediately return the same empty
- # result, causing a tightloop. (#8518)
- if result.next_batch == since_token:
- cache_context.should_cache = False
+ # if nothing has happened in any of the users' rooms since /sync was called,
+ # the resultant next_batch will be the same as since_token (since the result
+ # is generated when wait_for_events is first called, and not regenerated
+ # when wait_for_events times out).
+ #
+ # If that happens, we mustn't cache it, so that when the client comes back
+ # with the same cache token, we don't immediately return the same empty
+ # result, causing a tightloop. (#8518)
+ if result.next_batch == since_token:
+ cache_context.should_cache = False
if result:
if sync_config.filter_collection.lazy_load_members():
|
