Don't delete old game cache if it's in use by another server

Author: yungcomputerchair

src-tauri/src/lib.rs

@@ -429,17 +429,17 @@ async fn prep_launch(
                                 "Upgraded cache from parent version {} for {}",
                                 parent_uuid, version_uuid
                             );
-                            if state.config.launcher.delete_old_game_caches {
+
+                            if state.config.launcher.delete_old_game_caches
+                                && state.get_version_use_count(parent_uuid) == 0
+                            {
                                 if let Err(e) = util::delete_dir(&parent_cache_dir) {
                                     warn!(
                                         "Failed to delete cache for parent version {}: {}",
                                         parent_uuid, e
                                     );
                                 } else {
-                                    info!(
-                                        "Deleted cache for parent version {}",
-                                        parent_uuid
-                                    );
+                                    info!("Deleted cache for parent version {}", parent_uuid);
                                 }
                             }
                         }

src-tauri/src/state.rs

@@ -179,6 +179,23 @@ impl AppState {
         versions.extend(imported);
         Ok(num_imported)
     }
+
+    pub fn get_version_use_count(&self, uuid: Uuid) -> usize {
+        self.servers
+            .servers
+            .iter()
+            .filter(|s| match &s.info {
+                ServerInfo::Simple { version, .. } => version == &uuid.to_string(),
+                // for endpoint servers, this is less straightforward since we don't know the versions
+                // until we query the endpoint, and we really don't want to query every endpoint server to get this info.
+                // we can use the user's preferred version as a best guess here
+                // and it'll be fine since most cache upgrades happen only when a version is deprecated by a server anyway.
+                ServerInfo::Endpoint {
+                    preferred_version, ..
+                } => preferred_version.as_ref() == Some(&uuid.to_string()),
+            })
+            .count()
+    }
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone, Default)]