Add support for evicting cache entries based on last access time.

docs/sample_config.yaml

@@ -673,35 +673,35 @@ retention:
 #event_cache_size: 10K
 
 caches:
-   # Controls the global cache factor, which is the default cache factor
-   # for all caches if a specific factor for that cache is not otherwise
-   # set.
-   #
-   # This can also be set by the "SYNAPSE_CACHE_FACTOR" environment
-   # variable. Setting by environment variable takes priority over
-   # setting through the config file.
-   #
-   # Defaults to 0.5, which will half the size of all caches.
-   #
-   #global_factor: 1.0
+    # Controls the global cache factor, which is the default cache factor
+    # for all caches if a specific factor for that cache is not otherwise
+    # set.
+    #
+    # This can also be set by the "SYNAPSE_CACHE_FACTOR" environment
+    # variable. Setting by environment variable takes priority over
+    # setting through the config file.
+    #
+    # Defaults to 0.5, which will half the size of all caches.
+    #
+    #global_factor: 1.0
 
-   # A dictionary of cache name to cache factor for that individual
-   # cache. Overrides the global cache factor for a given cache.
-   #
-   # These can also be set through environment variables comprised
-   # of "SYNAPSE_CACHE_FACTOR_" + the name of the cache in capital
-   # letters and underscores. Setting by environment variable
-   # takes priority over setting through the config file.
-   # Ex. SYNAPSE_CACHE_FACTOR_GET_USERS_WHO_SHARE_ROOM_WITH_USER=2.0
-   #
-   # Some caches have '*' and other characters that are not
-   # alphanumeric or underscores. These caches can be named with or
-   # without the special characters stripped. For example, to specify
-   # the cache factor for `*stateGroupCache*` via an environment
-   # variable would be `SYNAPSE_CACHE_FACTOR_STATEGROUPCACHE=2.0`.
-   #
-   per_cache_factors:
-     #get_users_who_share_room_with_user: 2.0
+    # A dictionary of cache name to cache factor for that individual
+    # cache. Overrides the global cache factor for a given cache.
+    #
+    # These can also be set through environment variables comprised
+    # of "SYNAPSE_CACHE_FACTOR_" + the name of the cache in capital
+    # letters and underscores. Setting by environment variable
+    # takes priority over setting through the config file.
+    # Ex. SYNAPSE_CACHE_FACTOR_GET_USERS_WHO_SHARE_ROOM_WITH_USER=2.0
+    #
+    # Some caches have '*' and other characters that are not
+    # alphanumeric or underscores. These caches can be named with or
+    # without the special characters stripped. For example, to specify
+    # the cache factor for `*stateGroupCache*` via an environment
+    # variable would be `SYNAPSE_CACHE_FACTOR_STATEGROUPCACHE=2.0`.
+    #
+    per_cache_factors:
+        #get_users_who_share_room_with_user: 2.0
 
     # Controls how long an entry can be in a cache without having been
     # accessed before being evicted. Defaults to None, which means

synapse/config/cache.py

@@ -116,35 +116,35 @@ def generate_config_section(self, **kwargs):
         #event_cache_size: 10K
 
         caches:
-           # Controls the global cache factor, which is the default cache factor
-           # for all caches if a specific factor for that cache is not otherwise
-           # set.
-           #
-           # This can also be set by the "SYNAPSE_CACHE_FACTOR" environment
-           # variable. Setting by environment variable takes priority over
-           # setting through the config file.
-           #
-           # Defaults to 0.5, which will half the size of all caches.
-           #
-           #global_factor: 1.0
-
-           # A dictionary of cache name to cache factor for that individual
-           # cache. Overrides the global cache factor for a given cache.
-           #
-           # These can also be set through environment variables comprised
-           # of "SYNAPSE_CACHE_FACTOR_" + the name of the cache in capital
-           # letters and underscores. Setting by environment variable
-           # takes priority over setting through the config file.
-           # Ex. SYNAPSE_CACHE_FACTOR_GET_USERS_WHO_SHARE_ROOM_WITH_USER=2.0
-           #
-           # Some caches have '*' and other characters that are not
-           # alphanumeric or underscores. These caches can be named with or
-           # without the special characters stripped. For example, to specify
-           # the cache factor for `*stateGroupCache*` via an environment
-           # variable would be `SYNAPSE_CACHE_FACTOR_STATEGROUPCACHE=2.0`.
-           #
-           per_cache_factors:
-             #get_users_who_share_room_with_user: 2.0
+            # Controls the global cache factor, which is the default cache factor
+            # for all caches if a specific factor for that cache is not otherwise
+            # set.
+            #
+            # This can also be set by the "SYNAPSE_CACHE_FACTOR" environment
+            # variable. Setting by environment variable takes priority over
+            # setting through the config file.
+            #
+            # Defaults to 0.5, which will half the size of all caches.
+            #
+            #global_factor: 1.0
+
+            # A dictionary of cache name to cache factor for that individual
+            # cache. Overrides the global cache factor for a given cache.
+            #
+            # These can also be set through environment variables comprised
+            # of "SYNAPSE_CACHE_FACTOR_" + the name of the cache in capital
+            # letters and underscores. Setting by environment variable
+            # takes priority over setting through the config file.
+            # Ex. SYNAPSE_CACHE_FACTOR_GET_USERS_WHO_SHARE_ROOM_WITH_USER=2.0
+            #
+            # Some caches have '*' and other characters that are not
+            # alphanumeric or underscores. These caches can be named with or
+            # without the special characters stripped. For example, to specify
+            # the cache factor for `*stateGroupCache*` via an environment
+            # variable would be `SYNAPSE_CACHE_FACTOR_STATEGROUPCACHE=2.0`.
+            #
+            per_cache_factors:
+                #get_users_who_share_room_with_user: 2.0
 
             # Controls how long an entry can be in a cache without having been
             # accessed before being evicted. Defaults to None, which means