From 56b2672f9260d3262ce5e243ac4e3ba06dc36194 Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Thu, 7 Jul 2022 14:27:58 +0100
Subject: [PATCH] Tweak max age handling, config key name

---
 dendrite-sample.monolith.yaml      |  7 ++++---
 dendrite-sample.polylith.yaml      |  7 ++++---
 internal/caching/impl_ristretto.go | 11 +++++++++--
 setup/config/config_global.go      |  4 ++--
 4 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/dendrite-sample.monolith.yaml b/dendrite-sample.monolith.yaml
index 88f259ef6..c8c06d6c5 100644
--- a/dendrite-sample.monolith.yaml
+++ b/dendrite-sample.monolith.yaml
@@ -41,15 +41,16 @@ global:
     max_idle_conns: 5
     conn_max_lifetime: -1
 
-  # Configuration for in-process caches, to help speed up processing transactions
-  # and reducing load on the database.
+  # Configuration for in-memory caches. Caches can often improve performance by
+  # keeping frequently accessed items (like events, identifiers etc.) in memory
+  # rather than having to read them from the database.
   cache:
     # The estimated maximum size for the global cache in bytes, or in terabytes,
     # gigabytes, megabytes or kilobytes when the appropriate 'tb', 'gb', 'mb' or
     # 'kb' suffix is specified. Note that this is not a hard limit, nor is it a
     # memory limit for the entire process. A cache that is too small may ultimately
     # provide little or no benefit.
-    max_bytes_est: 1gb
+    max_size_est: 1gb
 
     # The maximum amount of time that a cache entry can live for in memory before
     # it will be evicted and/or refreshed from the database. Lower values result in
diff --git a/dendrite-sample.polylith.yaml b/dendrite-sample.polylith.yaml
index b94d828ca..c87714b51 100644
--- a/dendrite-sample.polylith.yaml
+++ b/dendrite-sample.polylith.yaml
@@ -31,15 +31,16 @@ global:
   # considered valid by other homeservers.
   key_validity_period: 168h0m0s
 
-  # Configuration for in-process caches, to help speed up processing transactions
-  # and reducing load on the database.
+  # Configuration for in-memory caches. Caches can often improve performance by
+  # keeping frequently accessed items (like events, identifiers etc.) in memory
+  # rather than having to read them from the database.
   cache:
     # The estimated maximum size for the global cache in bytes, or in terabytes,
     # gigabytes, megabytes or kilobytes when the appropriate 'tb', 'gb', 'mb' or
     # 'kb' suffix is specified. Note that this is not a hard limit, nor is it a
     # memory limit for the entire process. A cache that is too small may ultimately
     # provide little or no benefit.
-    max_bytes_est: 1gb
+    max_size_est: 1gb
 
     # The maximum amount of time that a cache entry can live for in memory before
     # it will be evicted and/or refreshed from the database. Lower values result in
diff --git a/internal/caching/impl_ristretto.go b/internal/caching/impl_ristretto.go
index 65d7af355..0db4de5e6 100644
--- a/internal/caching/impl_ristretto.go
+++ b/internal/caching/impl_ristretto.go
@@ -94,7 +94,7 @@ func NewRistrettoCache(maxCost config.DataUnit, maxAge time.Duration, enableProm
 				cache:   cache,
 				Prefix:  federationPDUsCache,
 				Mutable: true,
-				MaxAge:  time.Hour / 2,
+				MaxAge:  lesserOf(time.Hour/2, maxAge),
 			},
 		},
 		FederationEDUs: &RistrettoCostedCachePartition[int64, *gomatrixserverlib.EDU]{
@@ -102,7 +102,7 @@ func NewRistrettoCache(maxCost config.DataUnit, maxAge time.Duration, enableProm
 				cache:   cache,
 				Prefix:  federationEDUsCache,
 				Mutable: true,
-				MaxAge:  time.Hour / 2,
+				MaxAge:  lesserOf(time.Hour/2, maxAge),
 			},
 		},
 		SpaceSummaryRooms: &RistrettoCachePartition[string, gomatrixserverlib.MSC2946SpacesResponse]{
@@ -174,3 +174,10 @@ func (c *RistrettoCachePartition[K, V]) Get(key K) (value V, ok bool) {
 	value, ok = v.(V)
 	return
 }
+
+func lesserOf(a, b time.Duration) time.Duration {
+	if a < b {
+		return a
+	}
+	return b
+}
diff --git a/setup/config/config_global.go b/setup/config/config_global.go
index 525e36ed6..e1ccad7b6 100644
--- a/setup/config/config_global.go
+++ b/setup/config/config_global.go
@@ -176,7 +176,7 @@ func (c *ServerNotices) Defaults(generate bool) {
 func (c *ServerNotices) Verify(errors *ConfigErrors, isMonolith bool) {}
 
 type Cache struct {
-	EstMaxSize DataUnit      `yaml:"max_bytes_est"`
+	EstMaxSize DataUnit      `yaml:"max_size_est"`
 	MaxAge     time.Duration `yaml:"max_age"`
 }
 
@@ -186,7 +186,7 @@ func (c *Cache) Defaults(generate bool) {
 }
 
 func (c *Cache) Verify(errors *ConfigErrors, isMonolith bool) {
-	checkPositive(errors, "max_bytes_est", int64(c.EstMaxSize))
+	checkPositive(errors, "max_size_est", int64(c.EstMaxSize))
 }
 
 // ReportStats configures opt-in anonymous stats reporting.