fix warnings.

frontend/rust-lib/flowy-document/src/services/doc/revision/cache/memory.rs

@@ -39,7 +39,7 @@ impl RevisionMemoryCache {
                 return;
             }
         }
-        // FIXME: Remove outdated revisions to reduce memory usage
+        // TODO: Remove outdated revisions to reduce memory usage
         self.revs_map.insert(record.revision.rev_id, record.clone());
         self.pending_write_revs.write().await.push(record.revision.rev_id);
         self.make_checkpoint().await;
@@ -92,7 +92,7 @@ impl RevisionMemoryCache {
         *self.defer_save.write().await = Some(tokio::spawn(async move {
             tokio::time::sleep(Duration::from_millis(300)).await;
             let mut revs_write_guard = pending_write_revs.write().await;
-            // FIXME:
+            // TODO:
             // It may cause performance issues because we hold the write lock of the
             // rev_order and the lock will be released after the checkpoint has been written
             // to the disk.

frontend/rust-lib/flowy-document/src/services/doc/web_socket/web_socket.rs

@@ -272,7 +272,7 @@ impl CombinedSink {
         }
     }
 
-    // FIXME: return Option<&DocumentWSData> would be better
+    // TODO: return Option<&DocumentWSData> would be better
     pub(crate) async fn front(&self) -> Option<DocumentWSData> { self.shared.read().await.front().cloned() }
 
     pub(crate) async fn push_front(&self, data: DocumentWSData) { self.shared.write().await.push_front(data); }