fix: tracker skip applied deletion error

crates/fuzz/src/crdt_fuzzer.rs

@@ -559,6 +559,7 @@ where
  #[allow(clippy::redundant_clone)]
  let mut actions_clone = actions.clone();
  let action_ref: usize = (&mut actions_clone) as *mut _ as usize;
+ eprintln!("Initializing");
  #[allow(clippy::blocks_in_conditions)]
  if std::panic::catch_unwind(|| {
  // SAFETY: test
@@ -573,6 +574,7 @@ where
  return;
  }
 
+ eprintln!("Started!");
  let minified = Arc::new(Mutex::new(actions.clone()));
  let candidates = Arc::new(Mutex::new(VecDeque::new()));
  println!("Setup candidates...");
@@ -644,7 +646,7 @@ where
  }
 
  for thread in threads.into_iter() {
- thread.join().unwrap();
+ thread.join().unwrap_or_default();
  }
 
  let minified = normalize(site_num, &mut minified.try_lock().unwrap());

crates/fuzz/tests/test.rs

@@ -12908,6 +12908,202 @@ fn movable_list_undo_impl_1() {
  )
 }
 
+#[test]
+fn movable_list_err() {
+ test_multi_sites(
+ 5,
+ vec![FuzzTarget::All],
+ &mut [
+ Handle {
+ site: 29,
+ target: 29,
+ container: 29,
+ action: Generic(GenericAction {
+ value: Container(MovableList),
+ bool: true,
+ key: 488447261,
+ pos: 2097865012304223517,
+ length: 876435809836317,
+ prop: 2097865012304216064,
+ }),
+ },
+ Handle {
+ site: 29,
+ target: 29,
+ container: 29,
+ action: Generic(GenericAction {
+ value: Container(Unknown(226)),
+ bool: false,
+ key: 16850407,
+ pos: 2097865012304223517,
+ length: 10416984306455747869,
+ prop: 2097900196676341904,
+ }),
+ },
+ Handle {
+ site: 29,
+ target: 29,
+ container: 29,
+ action: Generic(GenericAction {
+ value: I32(797),
+ bool: false,
+ key: 488447261,
+ pos: 2097865012304223517,
+ length: 10416984306455747869,
+ prop: 2097865012304253072,
+ }),
+ },
+ Handle {
+ site: 29,
+ target: 29,
+ container: 29,
+ action: Generic(GenericAction {
+ value: I32(488447261),
+ bool: true,
+ key: 488447261,
+ pos: 1542381706525,
+ length: 10416835838496021789,
+ prop: 2097865012311789712,
+ }),
+ },
+ Handle {
+ site: 29,
+ target: 29,
+ container: 29,
+ action: Generic(GenericAction {
+ value: Container(Unknown(226)),
+ bool: false,
+ key: 16850407,
+ pos: 2097865012304223517,
+ length: 10416984306455747869,
+ prop: 2097900196676341904,
+ }),
+ },
+ Handle {
+ site: 29,
+ target: 29,
+ container: 29,
+ action: Generic(GenericAction {
+ value: Container(MovableList),
+ bool: true,
+ key: 488447261,
+ pos: 2097865012304223725,
+ length: 876435809836317,
+ prop: 2097865012304216064,
+ }),
+ },
+ Handle {
+ site: 29,
+ target: 201,
+ container: 201,
+ action: Generic(GenericAction {
+ value: I32(488447261),
+ bool: true,
+ key: 488447261,
+ pos: 2097865012304223517,
+ length: 2097865012421664029,
+ prop: 10416984888674156829,
+ }),
+ },
+ Handle {
+ site: 29,
+ target: 29,
+ container: 29,
+ action: Generic(GenericAction {
+ value: Container(Unknown(226)),
+ bool: false,
+ key: 16850407,
+ pos: 2097865012304223517,
+ length: 10416984306455747869,
+ prop: 2097900196676341904,
+ }),
+ },
+ Handle {
+ site: 29,
+ target: 30,
+ container: 29,
+ action: Generic(GenericAction {
+ value: I32(797),
+ bool: false,
+ key: 488453429,
+ pos: 2097865012304223517,
+ length: 10416984306455747869,
+ prop: 2097865012304253072,
+ }),
+ },
+ Handle {
+ site: 29,
+ target: 29,
+ container: 29,
+ action: Generic(GenericAction {
+ value: I32(488447261),
+ bool: true,
+ key: 488447261,
+ pos: 1542381706525,
+ length: 10416835838496021789,
+ prop: 2097865012311789712,
+ }),
+ },
+ Handle {
+ site: 29,
+ target: 29,
+ container: 29,
+ action: Generic(GenericAction {
+ value: I32(488447261),
+ bool: true,
+ key: 488447261,
+ pos: 2097872708885617949,
+ length: 10416984306455747869,
+ prop: 2097865012304253072,
+ }),
+ },
+ Handle {
+ site: 29,
+ target: 29,
+ container: 1,
+ action: Generic(GenericAction {
+ value: I32(488447261),
+ bool: true,
+ key: 488447261,
+ pos: 2097865012304223517,
+ length: 2097865012421664029,
+ prop: 10416984888674156829,
+ }),
+ },
+ Handle {
+ site: 29,
+ target: 29,
+ container: 29,
+ action: Generic(GenericAction {
+ value: Container(Unknown(226)),
+ bool: false,
+ key: 16850407,
+ pos: 2097865012304223517,
+ length: 10416984306455747869,
+ prop: 2097900196676341904,
+ }),
+ },
+ Handle {
+ site: 29,
+ target: 29,
+ container: 29,
+ action: Generic(GenericAction {
+ value: I32(797),
+ bool: false,
+ key: 488447261,
+ pos: 2097865012304223517,
+ length: 10416984306455747869,
+ prop: 2097865012304253072,
+ }),
+ },
+ SyncAllUndo {
+ site: 144,
+ op_len: 488447376,
+ },
+ ],
+ )
+}
+
 #[test]
 fn minify() {
  minify_error(

crates/loro-internal/src/container/list/list_op.rs

@@ -135,6 +135,7 @@ impl HasLength for DeleteSpan {
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
 pub struct DeleteSpanWithId {
  /// This is the target id with the smallest counter no matter whether the span is reversed.
+ /// So it's always the id of the leftmost element of the target span.
  pub id_start: ID,
  /// The deleted position span
  pub span: DeleteSpan,

crates/loro-internal/src/container/richtext/tracker.rs

@@ -153,6 +153,12 @@ impl Tracker {
  /// If `reverse` is true, the deletion happens from the end of the range to the start.
  /// So the first op is the one that deletes element at `pos+len-1`, the last op
  /// is the one that deletes element at `pos`.
+ ///
+ /// - op_id: the first op that perform the deletion
+ /// - target_start_id: in the target deleted span, it's the first id of the span
+ /// - pos: the start pos of the deletion in the target span
+ /// - len: the length of the deletion span
+ /// - reverse: if true, the kth op delete the last kth element of the span
  pub(crate) fn delete(
  &mut self,
  mut op_id: ID,
@@ -165,7 +171,13 @@ impl Tracker {
  // the op is partially included, need to slice the op
  let start = (applied_counter_end - op_id.counter) as usize;
  op_id.counter = applied_counter_end;
- target_start_id = target_start_id.inc(start as i32);
+ if !reverse {
+ target_start_id = target_start_id.inc(start as i32);
+ }
+ // Okay, this looks pretty weird, but it's correct.
+ // If it's reverse, we don't need to change the target_start_id, because target_start_id always pointing towards the
+ // leftmost element of the span. After applying the initial part of the deletion, which starts from the right side,
+ // the target_start_id will be still pointing towards the same leftmost element, thus no need to change.
  len -= start;
  // If reverse, don't need to change the pos, because it's deleting backwards.
  // If not reverse, we don't need to change the pos either, because the `start` chars after it are already deleted