- name
- agent-crdt-synchronizer
- description
- Agent skill for crdt-synchronizer - invoke with $agent-crdt-synchronizer
---
name: crdt-synchronizer
type: synchronizer
color: "#4CAF50"
description: Implements Conflict-free Replicated Data Types for eventually consistent state synchronization
capabilities:
- state_based_crdts
- operation_based_crdts
- delta_synchronization
- conflict_resolution
- causal_consistency
priority: high
hooks:
pre: |
echo "🔄 CRDT Synchronizer syncing: $TASK"
# Initialize CRDT state tracking
if [[ "$TASK" == *"synchronization"* ]]; then
echo "📊 Preparing delta state computation"
fi
post: |
echo "🎯 CRDT synchronization complete"
# Verify eventual consistency
echo "✅ Validating conflict-free state convergence"
---
# CRDT Synchronizer
Implements Conflict-free Replicated Data Types for eventually consistent distributed state synchronization.
## Core Responsibilities
1. **CRDT Implementation**: Deploy state-based and operation-based conflict-free data types
2. **Data Structure Management**: Handle counters, sets, registers, and composite structures
3. **Delta Synchronization**: Implement efficient incremental state updates
4. **Conflict Resolution**: Ensure deterministic conflict-free merge operations
5. **Causal Consistency**: Maintain proper ordering of causally related operations
## Technical Implementation
### Base CRDT Framework
```javascript
class CRDTSynchronizer {
constructor(nodeId, replicationGroup) {
this.nodeId = nodeId;
this.replicationGroup = replicationGroup;
this.crdtInstances = new Map();
this.vectorClock = new VectorClock(nodeId);
this.deltaBuffer = new Map();
this.syncScheduler = new SyncScheduler();
this.causalTracker = new CausalTracker();
}
// Register CRDT instance
registerCRDT(name, crdtType, initialState = null) {
const crdt = this.createCRDTInstance(crdtType, initialState);
this.crdtInstances.set(name, crdt);
// Subscribe to CRDT changes for delta tracking
crdt.onUpdate((delta) => {
this.trackDelta(name, delta);
});
return crdt;
}
// Create specific CRDT instance
createCRDTInstance(type, initialState) {
switch (type) {
case 'G_COUNTER':
return new GCounter(this.nodeId, this.replicationGroup, initialState);
case 'PN_COUNTER':
return new PNCounter(this.nodeId, this.replicationGroup, initialState);
case 'OR_SET':
return new ORSet(this.nodeId, initialState);
case 'LWW_REGISTER':
return new LWWRegister(this.nodeId, initialState);
case 'OR_MAP':
return new ORMap(this.nodeId, this.replicationGroup, initialState);
case 'RGA':
return new RGA(this.nodeId, initialState);
default:
throw new Error(`Unknown CRDT type: ${type}`);
}
}
// Synchronize with peer nodes
async synchronize(peerNodes = null) {
const targets = peerNodes || Array.from(this.replicationGroup);
for (const peer of targets) {
if (peer !== this.nodeId) {
await this.synchronizeWithPeer(peer);
}
}
}
async synchronizeWithPeer(peerNode) {
// Get current state and deltas
const localState = this.getCurrentState();
const deltas = this.getDeltasSince(peerNode);
// Send sync request
const syncRequest = {
type: 'CRDT_SYNC_REQUEST',
sender: this.nodeId,
vectorClock: this.vectorClock.clone(),
state: localState,
deltas: deltas
};
try {
const response = await this.sendSyncRequest(peerNode, syncRequest);
await this.processSyncResponse(response);
} catch (error) {
console.error(`Sync failed with ${peerNode}:`, error);
}
}
}
```
### G-Counter Implementation
```javascript
class GCounter {
constructor(nodeId, replicationGroup, initialState = null) {
this.nodeId = nodeId;
this.replicationGroup = replicationGroup;
this.payload = new Map();
// Initialize counters for all nodes
for (const node of replicationGroup) {
this.payload.set(node, 0);
}
if (initialState) {
this.merge(initialState);
}
this.updateCallbacks = [];
}
// Increment operation (can only be performed by owner node)
increment(amount = 1) {
if (amount < 0) {
throw new Error('G-Counter only supports positive increments');
}
const oldValue = this.payload.get(this.nodeId) || 0;
const newValue = oldValue + amount;
this.payload.set(this.nodeId, newValue);
// Notify observers
this.notifyUpdate({
type: 'INCREMENT',
node: this.nodeId,
oldValue: oldValue,
newValue: newValue,
delta: amount
});
return newValue;
}
// Get current value (sum of all node counters)
value() {
return Array.from(this.payload.values()).reduce((sum, val) => sum + val, 0);
}
// Merge with another G-Counter state
merge(otherState) {
let changed = false;
for (const [node, otherValue] of otherState.payload) {
const currentValue = this.payload.get(node) || 0;
if (otherValue > currentValue) {
this.payload.set(node, otherValue);
changed = true;
}
}
if (changed) {
this.notifyUpdate({
type: 'MERGE',
mergedFrom: otherState
});
}
}
// Compare with another state
compare(otherState) {
for (const [node, otherValue] of otherState.payload) {
const currentValue = this.payload.get(node) || 0;
if (currentValue < otherValue) {
return 'LESS_THAN';
} else if (currentValue > otherValue) {
return 'GREATER_THAN';
}
}
return 'EQUAL';
}
// Clone current state
clone() {
const newCounter = new GCounter(this.nodeId, this.replicationGroup);
newCounter.payload = new Map(this.payload);
return newCounter;
}
onUpdate(callback) {
this.updateCallbacks.push(callback);
}
notifyUpdate(delta) {
this.updateCallbacks.forEach(callback => callback(delta));
}
}
```
### OR-Set Implementation
```javascript
class ORSet {
constructor(nodeId, initialState = null) {
this.nodeId = nodeId;
this.elements = new Map(); // element -> Set of unique tags
this.tombstones = new Set(); // removed element tags
this.tagCounter = 0;
if (initialState) {
this.merge(initialState);
}
this.updateCallbacks = [];
}
// Add element to set
add(element) {
const tag = this.generateUniqueTag();
if (!this.elements.has(element)) {
this.elements.set(element, new Set());
}
this.elements.get(element).add(tag);
this.notifyUpdate({
type: 'ADD',
element: element,
tag: tag
});
return tag;
}
// Remove element from set
remove(element) {
if (!this.elements.has(element)) {
return false; // Element not present
}
const tags = this.elements.get(element);
const removedTags = [];
// Add all tags to tombstones
for (const tag of tags) {
this.tombstones.add(tag);
removedTags.push(tag);
}
this.notifyUpdate({
type: 'REMOVE',
element: element,
removedTags: removedTags
});
return true;
}
// Check if element is in set
has(element) {
if (!this.elements.has(element)) {
return false;
}
const tags = this.elements.get(element);
// Element is present if it has at least one non-tombstoned tag
for (const tag of tags) {
if (!this.tombstones.has(tag)) {
return true;
}
}
return false;
}
// Get all elements in set
values() {
const result = new Set();
for (const [element, tags] of this.elements) {
// Include element if it has at least one non-tombstoned tag
for (const tag of tags) {
if (!this.tombstones.has(tag)) {
result.add(element);
break;
}
}
}
return result;
}
// Merge with another OR-Set
merge(otherState) {
let changed = false;
// Merge elements and their tags
for (const [element, otherTags] of otherState.elements) {
if (!this.elements.has(element)) {
this.elements.set(element, new Set());
}
const currentTags = this.elements.get(element);
for (const tag of otherTags) {
if (!currentTags.has(tag)) {
currentTags.add(tag);
changed = true;
}
}
}
// Merge tombstones
for (const tombstone of otherState.tombstones) {
if (!this.tombstones.has(tombstone)) {
this.tombstones.add(tombstone);
changed = true;
}
}
if (changed) {
this.notifyUpdate({
type: 'MERGE',
mergedFrom: otherState
});
}
}
generateUniqueTag() {
return `${this.nodeId}-${Date.now()}-${++this.tagCounter}`;
}
onUpdate(callback) {
this.updateCallbacks.push(callback);
}
notifyUpdate(delta) {
this.updateCallbacks.forEach(callback => callback(delta));
}
}
```
### LWW-Register Implementation
```javascript
class LWWRegister {
constructor(nodeId, initialValue = null) {
this.nodeId = nodeId;
this.value = initialValue;
this.timestamp = initialValue ? Date.now() : 0;
this.vectorClock = new VectorClock(nodeId);
this.updateCallbacks = [];
}
// Set new value with timestamp
set(newValue, timestamp = null) {
const ts = timestamp || Date.now();
if (ts > this.timestamp ||
(ts === this.timestamp && this.nodeId > this.getLastWriter())) {
const oldValue = this.value;
this.value = newValue;
this.timestamp = ts;
this.vectorClock.increment();
this.notifyUpdate({
type: 'SET',
oldValue: oldValue,
newValue: newValue,
timestamp: ts
});
}
}
// Get current value
get() {
return this.value;
}
// Merge with another LWW-Register
merge(otherRegister) {
if (otherRegister.timestamp > this.timestamp ||
(otherRegister.timestamp === this.timestamp &&
otherRegister.nodeId > this.nodeId)) {
const oldValue = this.value;
this.value = otherRegister.value;
this.timestamp = otherRegister.timestamp;
this.notifyUpdate({
type: 'MERGE',
oldValue: oldValue,
newValue: this.value,
mergedFrom: otherRegister
});
}
// Merge vector clocks
this.vectorClock.merge(otherRegister.vectorClock);
}
getLastWriter() {
// In real implementation, this would track the actual writer
return this.nodeId;
}
onUpdate(callback) {
this.updateCallbacks.push(callback);
}
notifyUpdate(delta) {
this.updateCallbacks.forEach(callback => callback(delta));
}
}
```
### RGA (Replicated Growable Array) Implementation
```javascript
class RGA {
constructor(nodeId, initialSequence = []) {
this.nodeId = nodeId;
this.sequence = [];
this.tombstones = new Set();
this.vertexCounter = 0;
// Initialize with sequence
for (const element of initialSequence) {
this.insert(this.sequence.length, element);
}
this.updateCallbacks = [];
}
// Insert element at position
insert(position, element) {
const vertex = this.createVertex(element, position);
// Find insertion point based on causal ordering
const insertionIndex = this.findInsertionIndex(vertex, position);
this.sequence.splice(insertionIndex, 0, vertex);
this.notifyUpdate({
type: 'INSERT',
position: insertionIndex,
element: element,
vertex: vertex
});
return vertex.id;
}
// Remove element at position
remove(position) {
if (position < 0 || position >= this.visibleLength()) {
throw new Error('Position out of bounds');
}
const visibleVertex = this.getVisibleVertex(position);
if (visibleVertex) {
this.tombstones.add(visibleVertex.id);
this.notifyUpdate({
type: 'REMOVE',
position: position,
vertex: visibleVertex
});
return true;
}
return false;
}
// Get visible elements (non-tombstoned)
toArray() {
return this.sequence
.filter(vertex => !this.tombstones.has(vertex.id))
.map(vertex => vertex.element);
}
// Get visible length
visibleLength() {
return this.sequence.filter(vertex => !this.tombstones.has(vertex.id)).length;
}
// Merge with another RGA
merge(otherRGA) {
let changed = false;
// Merge sequences
const mergedSequence = this.mergeSequences(this.sequence, otherRGA.sequence);
if (mergedSequence.length !== this.sequence.length) {
this.sequence = mergedSequence;
changed = true;
}
// Merge tombstones
for (const tombstone of otherRGA.tombstones) {
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