lock concurrent fetch_or_creates to prevent inconsistencies

src/database/hierarchies.rs

@@ -145,6 +145,10 @@ pub async fn list_node<C: Connection<Backend = Sqlite>>(
         .collect::<Vec<Entry>>())
 }
 
+lazy_static! {
+    static ref FETCH_CREATE_LOCK: Mutex<()> = Mutex::new(());
+}
+
 pub fn fetch_or_create_dir<C: Connection<Backend = Sqlite>>(
     connection: &C,
     parent: Option<Address>,
@@ -156,6 +160,11 @@ pub fn fetch_or_create_dir<C: Connection<Backend = Sqlite>>(
         None => trace!("FETCHING/CREATING /{:#}", directory),
     }
 
+    let _lock;
+    if create {
+        _lock = FETCH_CREATE_LOCK.lock().unwrap();
+    }
+
     let matching_directories = query(
         connection,
         Query::SingleQuery(QueryPart::Matches(EntryQuery {
@@ -220,8 +229,9 @@ pub fn fetch_or_create_dir<C: Connection<Backend = Sqlite>>(
         }
         1 => Ok(valid_directories[0].clone()),
         _ => Err(anyhow!(format!(
-            "Invalid database state - more than one directory matches the query {:?}/{:#}!", parent, directory)
+            "Invalid database state - more than one directory matches the query {:?}/{:#}!",
-        )),
+            parent, directory
+        ))),
     }
 }
 
@@ -269,8 +279,7 @@ pub fn resolve_path_cached<C: Connection<Backend = Sqlite>>(
             result.push(address.clone());
         } else {
             drop(cache_lock);
-            let address =
+            let address = fetch_or_create_dir(connection, parent, node, create)?;
-                fetch_or_create_dir(connection, parent, node, create)?;
             result.push(address.clone());
             cache.lock().unwrap().put(key, address);
         }