Move event_cache_size to CacheConfig

docs/sample_config.yaml

@@ -634,10 +634,6 @@ database:
   args:
     database: DATADIR/homeserver.db
 
-# Number of events to cache in memory.
-#
-#event_cache_size: 10K
-
 
 ## Logging ##
 
@@ -1979,6 +1975,12 @@ opentracing:
 
 # Caching can be configured through the following options.
 #
+
+# The number of events to cache in memory. Not affected by the
+# caches.global_factor.
+#
+#event_cache_size: 10K
+
 caches:
    # Controls the global cache factor. This can be overridden by the
    # "SYNAPSE_CACHE_FACTOR" environment variable.

synapse/config/cache.py

@@ -74,6 +74,12 @@ class CacheConfig(Config):
 
         # Caching can be configured through the following options.
         #
+
+        # The number of events to cache in memory. Not affected by the
+        # caches.global_factor.
+        #
+        #event_cache_size: 10K
+
         caches:
            # Controls the global cache factor. This can be overridden by the
            # "SYNAPSE_CACHE_FACTOR" environment variable.

synapse/config/database.py

@@ -68,10 +68,6 @@ database:
   name: sqlite3
   args:
     database: %(database_path)s
-
-# Number of events to cache in memory.
-#
-#event_cache_size: 10K
 """