Fix the dead loop issue here: https://gist.github.com/sunflowerdeath/c0e2b46b6f5d2e32d368f8e04f730237
# Reason for the Dead Loop in `find_common_ancestor`
### Original Assumptions
1. **Dependency Assumption**
If a DagNode is depended upon by other nodes, the direction of this dependency will only point to before the end of the node. This assumption is used in system design.
2. **Node Overlap Assumption**
DagNodes do not overlap with each other. When retrieving DagNodes from two different positions:
- They are either completely identical
- Or they do not overlap at all
- If there is overlap, it means they are the same node
### Current Issues
1. **Issues Caused by Lazy Loading**
Due to the use of lazy loading, new situations have arisen. Initially:
- A certain DagNode is not depended upon by other DagNodes
- Therefore, the initially retrieved form is complete
2. **Impact of Subsequent Loading**
After loading additional DagNodes:
- The newly loaded DagNode may depend on the internal position of the previously complete DagNode
- This causes the originally complete DagNode to be split into multiple smaller DagNodes
3. **Violation of Original Assumptions**
In this case, when retrieving the content of the original DagNode again:
- Other DagNode dependencies may appear in the middle
- There may be overlaps on the DagNode
- This violates the original design assumptions
# Fix Approach
Remove the assumption in the original implementation that "overlapping DagNodes will not occur." When overlapping DagNodes are found, retain the shorter one and remove the longer one.
* test: fuzz gc correctly
* fix: lots of gc snapshot issues
* fix: vv to frontiers
* test: add an arbtest for gc fuzzing tests
* test: fix a few test issues
* fix: apply diff of a dangling container that was deleted before trimmed version
* feat: add old parent in tree diff
* chore: enable ci
* feat: add old_index to tree diff
* fix: new fractional index config
* fix: cargo fix
* fix: add FractionalIndexNotEnabled error
* fix: move config to tree state
* fix: error string
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Co-authored-by: Zixuan Chen <remch183@outlook.com>
