Error in concurrent editing and styling (Edit+Style) handling about yorkie HOT 2 CLOSED

Case 'insert-front + style'

Description

During concurrent editing and styling of a document, there is an issue where the style attribute is applied to newly inserted nodes. This behavior is unexpected and incorrect.

Steps to Reproduce

1. Set the initial state of the document as follows:

      0               1 2    3               4 5    6               7 8    9
<root> <p color="red"> a </p> <p color="red"> b </p> <p color="red"> c </p> </root>
<root>
  <p color="red">a</p>
  <p color="red">b</p>
  <p color="red">c</p>
</root>

2. Perform the following changes concurrently:
   • Client1's local change: Edit(Insert) <p italic="true">d</p> at [3, 3]
   • Client2's local change: Style attribute "bold"="aa" at [3, 6]
3. Sync Client1 and Client2

Current Result

The results after applying and syncing local changes to each client are as follows:

Client1:

• After Edit(local change)

<root>
  <p color="red">a</p>
  <p italic="true">d</p>
  <p color="red">b</p>
  <p color="red">c</p>
</root>

• Edit after Style(sync)

<root>
  <p color="red">a</p>
  <p "bold"="aa" italic="true">d</p>
  <p "bold"="aa" color="red">b</p>
  <p color="red">c</p>
</root>

Client2:

• After Style(local change)

<root>
  <p color="red">a</p>
  <p "bold"="aa" color="red">b</p>
  <p color="red">c</p>
</root>

• Style after Edit(sync)

<root>
  <p color="red">a</p>
  <p italic="true">d</p>
  <p "bold"="aa" color="red">b</p>
  <p color="red">c</p>
</root>

Suggestion

1. Lamport clock comparison

It is important to differentiate between nodes that have been newly inserted and existing nodes during the concurrent editing and styling process. This distinction will help in precisely applying style operations within the appropriate scope.

By applying the rules below, all failure cases for style-related tests that occurred in the previously written tree-concurrency-test can be resolved.

• Before
  

  yorkie/pkg/document/crdt/tree.go

  Lines 859 to 871 in a8f6bc2

  	err = t.traverseInPosRange(fromParent, fromLeft, toParent, toLeft,
  	func(token index.TreeToken[*TreeNode], _ bool) {
  	node := token.Node
  	if !node.IsRemoved() && !node.IsText() && len(attributes) > 0 {
  	if node.Attrs == nil {
  	node.Attrs = NewRHT()
  	}
  	for key, value := range attributes {
  	node.Attrs.Set(key, value, editedAt)
  	}
  	}
  	})

• After

	err = t.traverseInPosRange(fromParent, fromLeft, toParent, toLeft,
		func(token index.TreeToken[*TreeNode], _ bool) {
			node := token.Node
			if !node.IsRemoved() && !node.IsText() && len(attributes) > 0 {
				if editedAt.After(node.ID.CreatedAt) {
					return
				}

				// ...
			}
		})

Since the priority of the Lamport timestamp does not guarantee concurrent causality, this method does not solve the problem.

from yorkie.

• Go SDK: #854
• JS SDK: yorkie-team/yorkie-js-sdk#803
• Android SDK: yorkie-team/yorkie-android-sdk#178
• iOS SDK: yorkie-team/yorkie-ios-sdk#166

from yorkie.