improvement: better memory usage and admin commands to analyze it

src/service/globals/data.rs

@@ -15,7 +15,8 @@ pub trait Data: Send + Sync {
     fn current_count(&self) -> Result<u64>;
     async fn watch(&self, user_id: &UserId, device_id: &DeviceId) -> Result<()>;
     fn cleanup(&self) -> Result<()>;
-    fn memory_usage(&self) -> Result<String>;
+    fn memory_usage(&self) -> String;
+    fn clear_caches(&self, amount: u32);
     fn load_keypair(&self) -> Result<Ed25519KeyPair>;
     fn remove_keypair(&self) -> Result<()>;
     fn add_signing_key(

src/service/globals/mod.rs

@@ -214,10 +214,6 @@ impl Service {
         self.db.cleanup()
     }
 
-    pub fn memory_usage(&self) -> Result<String> {
-        self.db.memory_usage()
-    }
-
     pub fn server_name(&self) -> &ServerName {
         self.config.server_name.as_ref()
     }