re-enable synchronous mode more robustly through a drop guard

src/filesystem.rs

@@ -78,6 +78,26 @@ pub async fn rescan_vault(
             .unwrap();
     }
 }
+struct PragmaSynchronousGuard<'a>(&'a DbPool);
+
+impl Drop for PragmaSynchronousGuard<'_> {
+    fn drop(&mut self) {
+        debug!("Re-enabling synchronous mode.");
+        let connection = self.0.get();
+        let res: Result<_, String> = match connection {
+            Ok(connection) => connection
+                .execute("PRAGMA synchronous = NORMAL;")
+                .map_err(|err| format!("{}", err)),
+            Err(err) => Err(format!("{}", err)),
+        };
+        if let Err(err) = res {
+            error!(
+                "Error setting synchronous mode back to NORMAL! Data loss possible! {}",
+                err
+            );
+        }
+    }
+}
 
 type UpdatePathResult = Result<UpdatePathOutcome>;
 
@@ -105,6 +125,7 @@ fn _rescan_vault<T: AsRef<Path>>(
     // Disable syncing in SQLite for the duration of the import
     debug!("Disabling SQLite synchronous mode");
     pool.get()?.execute("PRAGMA synchronous = OFF;")?;
+    let _guard = PragmaSynchronousGuard(&pool);
 
     // Walk through the vault, find all paths
     debug!("Traversing vault directory");
@@ -153,6 +174,8 @@ fn _rescan_vault<T: AsRef<Path>>(
         })
         .collect();
 
+    debug!("Processing done, cleaning up...");
+
     let existing_files = existing_files.read().unwrap();
 
     let connection = pool.get()?;
@@ -199,8 +222,7 @@ fn _rescan_vault<T: AsRef<Path>>(
     }
 
     // Re-enable SQLite syncing
-    debug!("Re-enabling synchronous mode.");
-    pool.get()?.execute("PRAGMA synchronous = NORMAL;")?;
+    drop(_guard);
 
     info!(
         "Finished updating {} ({} created, {} deleted, {} left unchanged). Took {}s.",