Disable caching in /sync corner case (#16080)

Fixes #15502
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Matthew Ma 2023-08-17 02:22:50 -07:00 committed by GitHub
parent 8c3bcea2da
commit 8a4fb7a6ba
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2 changed files with 11 additions and 10 deletions

1
changelog.d/16080.bugfix Normal file
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@ -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.

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@ -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():