feat: cache topic and subscription reads

server/store/group_message_runtime_test.go

@@ -409,3 +409,28 @@ func TestInvalidateGroupSettingsUsesTopicCacheKey(t *testing.T) {
 		t.Fatalf("unexpected deleted objects: %#v", runtime.deletedObjects)
 	}
 }
+
+func TestTopicAndSubscriptionCacheTTLIsShort(t *testing.T) {
+	runtime := &redisGroupMessageRuntime{cfg: redisConfig{CacheTTL: 300, ShortTTL: 600}}
+	for _, namespace := range []string{cacheNamespaceTopic, cacheNamespaceSub} {
+		if got := runtime.cacheTTL(namespace); got != time.Minute {
+			t.Fatalf("cache TTL for %s = %v, want 1m", namespace, got)
+		}
+	}
+	if got := runtime.cacheTTL(cacheNamespaceGroupSettings); got != 5*time.Minute {
+		t.Fatalf("cache TTL for group settings = %v, want 5m", got)
+	}
+}
+
+func TestInvalidateSubscriptionCacheWithZeroUserDeletesTopicPrefix(t *testing.T) {
+	oldRuntime := groupMsgRuntime
+	runtime := newTestGroupMessageRuntime()
+	groupMsgRuntime = runtime
+	t.Cleanup(func() { groupMsgRuntime = oldRuntime })
+
+	invalidateSubscriptionCache(7, "grpAlpha", types.ZeroUid)
+	want := []string{"grpAlpha:", "chnAlpha:"}
+	if len(runtime.deletedPrefixes) != len(want) || runtime.deletedPrefixes[0] != want[0] || runtime.deletedPrefixes[1] != want[1] {
+		t.Fatalf("unexpected deleted prefixes: %#v", runtime.deletedPrefixes)
+	}
+}