diff --git a/synapse/config/cache.py b/synapse/config/cache.py
index 8d5f38b5d9..d119427ad8 100644
--- a/synapse/config/cache.py
+++ b/synapse/config/cache.py
@@ -151,6 +151,15 @@ class CacheConfig(Config):
# entries are never evicted based on time.
#
#expiry_time: 30m
+
+ # Controls how long the results of a /sync request are cached for after
+ # a successful response is returned. A higher duration can help clients with
+ # intermittent connections, at the cost of higher memory usage.
+ #
+ # By default, this is zero, which means that sync responses are not cached
+ # at all.
+ #
+ #sync_response_cache_duration: 2m
"""
def read_config(self, config, **kwargs):
@@ -212,6 +221,10 @@ class CacheConfig(Config):
else:
self.expiry_time_msec = None
+ self.sync_response_cache_duration = self.parse_duration(
+ cache_config.get("sync_response_cache_duration", 0)
+ )
+
# Resize all caches (if necessary) with the new factors we've loaded
self.resize_all_caches()
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index f30bfcc93c..590642f510 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -269,14 +269,22 @@ class SyncHandler:
self.presence_handler = hs.get_presence_handler()
self.event_sources = hs.get_event_sources()
self.clock = hs.get_clock()
- self.response_cache: ResponseCache[SyncRequestKey] = ResponseCache(
- hs.get_clock(), "sync"
- )
self.state = hs.get_state_handler()
self.auth = hs.get_auth()
self.storage = hs.get_storage()
self.state_store = self.storage.state
+ # TODO: flush cache entries on subsequent sync request.
+ # Once we get the next /sync request (ie, one with the same access token
+ # that sets 'since' to 'next_batch'), we know that device won't need a
+ # cached result any more, and we could flush the entry from the cache to save
+ # memory.
+ self.response_cache: ResponseCache[SyncRequestKey] = ResponseCache(
+ hs.get_clock(),
+ "sync",
+ timeout_ms=hs.config.caches.sync_response_cache_duration,
+ )
+
# ExpiringCache((User, Device)) -> LruCache(user_id => event_id)
self.lazy_loaded_members_cache: ExpiringCache[
Tuple[str, Optional[str]], LruCache[str, str]
|
