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Replace MaxCreatedAtMapByActor with VersionVector (#1088)
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Refactored causal and concurrent relationship handling in text and tree
operations to use version vectors instead of MaxCreatedAtMapByActor. This
change enables more precise tracking of client Lamport times during
operations like deletion, improving concurrency management and providing
a more robust method for determining node existence.
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@chacha912
chacha912 authored Dec 9, 2024
1 parent 7ad9e71 commit 1084b8d
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Showing 23 changed files with 331 additions and 72 deletions.
2 changes: 1 addition & 1 deletion api/converter/from_bytes.go
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Original file line number Diff line number Diff line change
Expand Up @@ -334,7 +334,7 @@ func fromTextNode(
if err != nil {
return nil, err
}
textNode.Remove(removedAt, time.MaxTicket)
textNode.Remove(removedAt, time.MaxTicket, time.MaxLamport)
}
return textNode, nil
}
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2 changes: 1 addition & 1 deletion pkg/document/change/change.go
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Original file line number Diff line number Diff line change
Expand Up @@ -54,7 +54,7 @@ func New(id ID, message string, operations []operations.Operation, p *innerprese
// Execute applies this change to the given JSON root.
func (c *Change) Execute(root *crdt.Root, presences *innerpresence.Map) error {
for _, op := range c.operations {
if err := op.Execute(root); err != nil {
if err := op.Execute(root, c.ID().versionVector); err != nil {
return err
}
}
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46 changes: 38 additions & 8 deletions pkg/document/crdt/rga_tree_split.go
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Original file line number Diff line number Diff line change
Expand Up @@ -258,10 +258,18 @@ func (s *RGATreeSplitNode[V]) toTestString() string {

// Remove removes this node if it created before the time of deletion are
// deleted. It only marks the deleted time (tombstone).
func (s *RGATreeSplitNode[V]) Remove(removedAt *time.Ticket, maxCreatedAt *time.Ticket) bool {
func (s *RGATreeSplitNode[V]) Remove(removedAt *time.Ticket,
maxCreatedAt *time.Ticket, clientLamportAtChange int64) bool {
justRemoved := s.removedAt == nil

if !s.createdAt().After(maxCreatedAt) &&
var nodeExisted bool
if maxCreatedAt == nil {
nodeExisted = s.createdAt().Lamport() <= clientLamportAtChange
} else {
nodeExisted = !s.createdAt().After(maxCreatedAt)
}

if nodeExisted &&
(s.removedAt == nil || removedAt.After(s.removedAt)) {
s.removedAt = removedAt
return justRemoved
Expand All @@ -271,8 +279,16 @@ func (s *RGATreeSplitNode[V]) Remove(removedAt *time.Ticket, maxCreatedAt *time.
}

// canStyle checks if node is able to set style.
func (s *RGATreeSplitNode[V]) canStyle(editedAt *time.Ticket, maxCreatedAt *time.Ticket) bool {
return !s.createdAt().After(maxCreatedAt) &&
func (s *RGATreeSplitNode[V]) canStyle(editedAt *time.Ticket,
maxCreatedAt *time.Ticket, clientLamportAtChange int64) bool {
var nodeExisted bool
if maxCreatedAt == nil {
nodeExisted = s.createdAt().Lamport() <= clientLamportAtChange
} else {
nodeExisted = !s.createdAt().After(maxCreatedAt)
}

return nodeExisted &&
(s.removedAt == nil || editedAt.After(s.removedAt))
}

Expand Down Expand Up @@ -451,6 +467,7 @@ func (s *RGATreeSplit[V]) edit(
maxCreatedAtMapByActor map[string]*time.Ticket,
content V,
editedAt *time.Ticket,
versionVector time.VersionVector,
) (*RGATreeSplitNodePos, map[string]*time.Ticket, []GCPair, error) {
// 01. Split nodes with from and to
toLeft, toRight, err := s.findNodeWithSplit(to, editedAt)
Expand All @@ -464,7 +481,7 @@ func (s *RGATreeSplit[V]) edit(

// 02. delete between from and to
nodesToDelete := s.findBetween(fromRight, toRight)
maxCreatedAtMap, removedNodes := s.deleteNodes(nodesToDelete, maxCreatedAtMapByActor, editedAt)
maxCreatedAtMap, removedNodes := s.deleteNodes(nodesToDelete, maxCreatedAtMapByActor, editedAt, versionVector)

var caretID *RGATreeSplitNodeID
if toRight == nil {
Expand Down Expand Up @@ -506,6 +523,7 @@ func (s *RGATreeSplit[V]) deleteNodes(
candidates []*RGATreeSplitNode[V],
maxCreatedAtMapByActor map[string]*time.Ticket,
editedAt *time.Ticket,
versionVector time.VersionVector,
) (map[string]*time.Ticket, map[string]*RGATreeSplitNode[V]) {
createdAtMapByActor := make(map[string]*time.Ticket)
removedNodeMap := make(map[string]*RGATreeSplitNode[V])
Expand All @@ -523,10 +541,20 @@ func (s *RGATreeSplit[V]) deleteNodes(

for _, node := range candidates {
actorIDHex := node.createdAt().ActorIDHex()
actorID := node.createdAt().ActorID()

var maxCreatedAt *time.Ticket
if maxCreatedAtMapByActor == nil {
maxCreatedAt = time.MaxTicket
var clientLamportAtChange int64
if versionVector == nil && maxCreatedAtMapByActor == nil {
// Local edit - use version vector comparison
clientLamportAtChange = time.MaxLamport
} else if versionVector != nil {
lamport, ok := versionVector.Get(actorID)
if ok {
clientLamportAtChange = lamport
} else {
clientLamportAtChange = 0
}
} else {
createdAt, ok := maxCreatedAtMapByActor[actorIDHex]
if ok {
Expand All @@ -536,7 +564,9 @@ func (s *RGATreeSplit[V]) deleteNodes(
}
}

if node.Remove(editedAt, maxCreatedAt) {
// TODO(chacha912): maxCreatedAt can be removed after all legacy Changes
// (without version vector) are migrated to new Changes with version vector.
if node.Remove(editedAt, maxCreatedAt, clientLamportAtChange) {
maxCreatedAt := createdAtMapByActor[actorIDHex]
createdAt := node.id.createdAt
if maxCreatedAt == nil || createdAt.After(maxCreatedAt) {
Expand Down
18 changes: 9 additions & 9 deletions pkg/document/crdt/root_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -65,28 +65,28 @@ func TestRoot(t *testing.T) {
text := crdt.NewText(crdt.NewRGATreeSplit(crdt.InitialTextNode()), ctx.IssueTimeTicket())

fromPos, toPos, _ := text.CreateRange(0, 0)
_, _, pairs, err := text.Edit(fromPos, toPos, nil, "Hello World", nil, ctx.IssueTimeTicket())
_, _, pairs, err := text.Edit(fromPos, toPos, nil, "Hello World", nil, ctx.IssueTimeTicket(), nil)
assert.NoError(t, err)
registerGCPairs(root, pairs)
assert.Equal(t, "Hello World", text.String())
assert.Equal(t, 0, root.GarbageLen())

fromPos, toPos, _ = text.CreateRange(5, 10)
_, _, pairs, err = text.Edit(fromPos, toPos, nil, "Yorkie", nil, ctx.IssueTimeTicket())
_, _, pairs, err = text.Edit(fromPos, toPos, nil, "Yorkie", nil, ctx.IssueTimeTicket(), nil)
assert.NoError(t, err)
registerGCPairs(root, pairs)
assert.Equal(t, "HelloYorkied", text.String())
assert.Equal(t, 1, root.GarbageLen())

fromPos, toPos, _ = text.CreateRange(0, 5)
_, _, pairs, err = text.Edit(fromPos, toPos, nil, "", nil, ctx.IssueTimeTicket())
_, _, pairs, err = text.Edit(fromPos, toPos, nil, "", nil, ctx.IssueTimeTicket(), nil)
assert.NoError(t, err)
registerGCPairs(root, pairs)
assert.Equal(t, "Yorkied", text.String())
assert.Equal(t, 2, root.GarbageLen())

fromPos, toPos, _ = text.CreateRange(6, 7)
_, _, pairs, err = text.Edit(fromPos, toPos, nil, "", nil, ctx.IssueTimeTicket())
_, _, pairs, err = text.Edit(fromPos, toPos, nil, "", nil, ctx.IssueTimeTicket(), nil)
assert.NoError(t, err)
registerGCPairs(root, pairs)
assert.Equal(t, "Yorkie", text.String())
Expand Down Expand Up @@ -125,7 +125,7 @@ func TestRoot(t *testing.T) {

for _, tc := range steps {
fromPos, toPos, _ := text.CreateRange(tc.from, tc.to)
_, _, pairs, err := text.Edit(fromPos, toPos, nil, tc.content, nil, ctx.IssueTimeTicket())
_, _, pairs, err := text.Edit(fromPos, toPos, nil, tc.content, nil, ctx.IssueTimeTicket(), nil)
assert.NoError(t, err)
registerGCPairs(root, pairs)
assert.Equal(t, tc.want, text.String())
Expand Down Expand Up @@ -157,7 +157,7 @@ func TestRoot(t *testing.T) {

for _, tc := range steps {
fromPos, toPos, _ := text.CreateRange(tc.from, tc.to)
_, _, pairs, err := text.Edit(fromPos, toPos, nil, tc.content, nil, ctx.IssueTimeTicket())
_, _, pairs, err := text.Edit(fromPos, toPos, nil, tc.content, nil, ctx.IssueTimeTicket(), nil)
assert.NoError(t, err)
registerGCPairs(root, pairs)
assert.Equal(t, tc.want, text.String())
Expand All @@ -176,21 +176,21 @@ func TestRoot(t *testing.T) {
text := crdt.NewText(crdt.NewRGATreeSplit(crdt.InitialTextNode()), ctx.IssueTimeTicket())

fromPos, toPos, _ := text.CreateRange(0, 0)
_, _, pairs, err := text.Edit(fromPos, toPos, nil, "Hello World", nil, ctx.IssueTimeTicket())
_, _, pairs, err := text.Edit(fromPos, toPos, nil, "Hello World", nil, ctx.IssueTimeTicket(), nil)
assert.NoError(t, err)
registerGCPairs(root, pairs)
assert.Equal(t, `[{"val":"Hello World"}]`, text.Marshal())
assert.Equal(t, 0, root.GarbageLen())

fromPos, toPos, _ = text.CreateRange(6, 11)
_, _, pairs, err = text.Edit(fromPos, toPos, nil, "Yorkie", nil, ctx.IssueTimeTicket())
_, _, pairs, err = text.Edit(fromPos, toPos, nil, "Yorkie", nil, ctx.IssueTimeTicket(), nil)
assert.NoError(t, err)
registerGCPairs(root, pairs)
assert.Equal(t, `[{"val":"Hello "},{"val":"Yorkie"}]`, text.Marshal())
assert.Equal(t, 1, root.GarbageLen())

fromPos, toPos, _ = text.CreateRange(0, 6)
_, _, pairs, err = text.Edit(fromPos, toPos, nil, "", nil, ctx.IssueTimeTicket())
_, _, pairs, err = text.Edit(fromPos, toPos, nil, "", nil, ctx.IssueTimeTicket(), nil)
assert.NoError(t, err)
registerGCPairs(root, pairs)
assert.Equal(t, `[{"val":"Yorkie"}]`, text.Marshal())
Expand Down
23 changes: 19 additions & 4 deletions pkg/document/crdt/text.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -273,6 +273,7 @@ func (t *Text) Edit(
content string,
attributes map[string]string,
executedAt *time.Ticket,
versionVector time.VersionVector,
) (*RGATreeSplitNodePos, map[string]*time.Ticket, []GCPair, error) {
val := NewTextValue(content, NewRHT())
for key, value := range attributes {
Expand All @@ -285,6 +286,7 @@ func (t *Text) Edit(
maxCreatedAtMapByActor,
val,
executedAt,
versionVector,
)
}

Expand All @@ -295,6 +297,7 @@ func (t *Text) Style(
maxCreatedAtMapByActor map[string]*time.Ticket,
attributes map[string]string,
executedAt *time.Ticket,
versionVector time.VersionVector,
) (map[string]*time.Ticket, []GCPair, error) {
// 01. Split nodes with from and to
_, toRight, err := t.rgaTreeSplit.findNodeWithSplit(to, executedAt)
Expand All @@ -313,10 +316,20 @@ func (t *Text) Style(

for _, node := range nodes {
actorIDHex := node.id.createdAt.ActorIDHex()
actorID := node.id.createdAt.ActorID()

var maxCreatedAt *time.Ticket
if len(maxCreatedAtMapByActor) == 0 {
maxCreatedAt = time.MaxTicket
var clientLamportAtChange int64
if versionVector == nil && maxCreatedAtMapByActor == nil {
// Local edit - use version vector comparison
clientLamportAtChange = time.MaxLamport
} else if versionVector != nil {
lamport, ok := versionVector.Get(actorID)
if ok {
clientLamportAtChange = lamport
} else {
clientLamportAtChange = 0
}
} else {
createdAt, ok := maxCreatedAtMapByActor[actorIDHex]
if ok {
Expand All @@ -326,8 +339,10 @@ func (t *Text) Style(
}
}

if node.canStyle(executedAt, maxCreatedAt) {
maxCreatedAt = createdAtMapByActor[actorIDHex]
// TODO(chacha912): maxCreatedAt can be removed after all legacy Changes
// (without version vector) are migrated to new Changes with version vector.
if node.canStyle(executedAt, maxCreatedAt, clientLamportAtChange) {
maxCreatedAt := createdAtMapByActor[actorIDHex]
createdAt := node.id.createdAt
if maxCreatedAt == nil || createdAt.After(maxCreatedAt) {
createdAtMapByActor[actorIDHex] = createdAt
Expand Down
10 changes: 5 additions & 5 deletions pkg/document/crdt/text_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -32,12 +32,12 @@ func TestText(t *testing.T) {
text := crdt.NewText(crdt.NewRGATreeSplit(crdt.InitialTextNode()), ctx.IssueTimeTicket())

fromPos, toPos, _ := text.CreateRange(0, 0)
_, _, _, err := text.Edit(fromPos, toPos, nil, "Hello World", nil, ctx.IssueTimeTicket())
_, _, _, err := text.Edit(fromPos, toPos, nil, "Hello World", nil, ctx.IssueTimeTicket(), nil)
assert.NoError(t, err)
assert.Equal(t, `[{"val":"Hello World"}]`, text.Marshal())

fromPos, toPos, _ = text.CreateRange(6, 11)
_, _, _, err = text.Edit(fromPos, toPos, nil, "Yorkie", nil, ctx.IssueTimeTicket())
_, _, _, err = text.Edit(fromPos, toPos, nil, "Yorkie", nil, ctx.IssueTimeTicket(), nil)
assert.NoError(t, err)
assert.Equal(t, `[{"val":"Hello "},{"val":"Yorkie"}]`, text.Marshal())
})
Expand Down Expand Up @@ -70,17 +70,17 @@ func TestText(t *testing.T) {
text := crdt.NewText(crdt.NewRGATreeSplit(crdt.InitialTextNode()), ctx.IssueTimeTicket())

fromPos, toPos, _ := text.CreateRange(0, 0)
_, _, _, err := text.Edit(fromPos, toPos, nil, "Hello World", nil, ctx.IssueTimeTicket())
_, _, _, err := text.Edit(fromPos, toPos, nil, "Hello World", nil, ctx.IssueTimeTicket(), nil)
assert.NoError(t, err)
assert.Equal(t, `[{"val":"Hello World"}]`, text.Marshal())

fromPos, toPos, _ = text.CreateRange(6, 11)
_, _, _, err = text.Edit(fromPos, toPos, nil, "Yorkie", nil, ctx.IssueTimeTicket())
_, _, _, err = text.Edit(fromPos, toPos, nil, "Yorkie", nil, ctx.IssueTimeTicket(), nil)
assert.NoError(t, err)
assert.Equal(t, `[{"val":"Hello "},{"val":"Yorkie"}]`, text.Marshal())

fromPos, toPos, _ = text.CreateRange(0, 1)
_, _, err = text.Style(fromPos, toPos, nil, map[string]string{"b": "1"}, ctx.IssueTimeTicket())
_, _, err = text.Style(fromPos, toPos, nil, map[string]string{"b": "1"}, ctx.IssueTimeTicket(), nil)
assert.NoError(t, err)
assert.Equal(
t,
Expand Down
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