Change CacheMetrics to be quicker

We change it so that each cache has an individual CacheMetric, instead
of having one global CacheMetric. This means that when a cache tries to
increment a counter it does not need to go through so many indirections.

1 files changed, 15 insertions, 5 deletions

diff --git a/synapse/util/caches/__init__.py b/synapse/util/caches/__init__.py
index d53569ca49..ebd715c5dc 100644
--- a/synapse/util/caches/__init__.py
+++ b/synapse/util/caches/__init__.py
@@ -24,11 +24,21 @@ DEBUG_CACHES = False
 metrics = synapse.metrics.get_metrics_for("synapse.util.caches")
 
 caches_by_name = {}
-cache_counter = metrics.register_cache(
-    "cache",
-    lambda: {(name,): len(caches_by_name[name]) for name in caches_by_name.keys()},
-    labels=["name"],
-)
+# cache_counter = metrics.register_cache(
+#     "cache",
+#     lambda: {(name,): len(caches_by_name[name]) for name in caches_by_name.keys()},
+#     labels=["name"],
+# )
+
+
+def register_cache(name, cache):
+    caches_by_name[name] = cache
+    return metrics.register_cache(
+        "cache",
+        lambda: len(cache),
+        name,
+    )
+
 
 _string_cache = LruCache(int(5000 * CACHE_SIZE_FACTOR))
 caches_by_name["string_cache"] = _string_cache