CRDT LF Hive

CRDT LF Hive

A Hive storage implementation for CRDT LF objects, providing efficient persistence for Change and Snapshot objects with document-scoped organization.

Features

Complete Hive Adapters: All necessary type adapters for CRDT objects (Change, Snapshot, PeerId, OperationId, VersionVector, etc.)
Easy Initialization: One-line setup with CRDTHive.initialize()
Flexible Data Serialization: Choose between JSON encoding or custom Hive adapters for generic data types
Document-Scoped Storage: Optional utilities that organize data by document ID for better isolation and performance
Batch Operations: Efficient bulk save/load operations for changes and snapshots

Quick Start

1. Initialize Hive with CRDT Adapters

import 'package:hive/hive.dart';
import 'package:crdt_lf_hive/crdt_lf_hive.dart';

void main() async {
  // Initialize Hive
  Hive.init('./my_app_data');
  
  // Register all CRDT adapters
  CRDTHive.initialize();
  
  // Your app code here...
}

2. Basic Usage with Manual Box Management

import 'package:crdt_lf/crdt_lf.dart';
import 'package:hive/hive.dart';

// Open boxes manually
final changeBox = await Hive.openBox<Change>('changes');
final snapshotBox = await Hive.openBox<Snapshot>('snapshots');

// Store and retrieve changes
final change = /* your change */;
await changeBox.put(change.id.toString(), change);
final retrievedChange = changeBox.get(change.id.toString());

3. Using Document-Scoped Storage (Recommended)

import 'package:crdt_lf/crdt_lf.dart';
import 'package:crdt_lf_hive/crdt_lf_hive.dart';

final documentId = 'my-document-id';

// Open storage for a specific document
final changeStorage = await CRDTHive.openChangeStorageForDocument(documentId);
final snapshotStorage = await CRDTHive.openSnapshotStorageForDocument(documentId);

// Or open both at once
final documentStorage = await CRDTHive.openStorageForDocument(documentId);

Document-Scoped Storage

The library provides optional storage utilities that organize data by document ID. Each document gets its own dedicated Hive boxes, improving isolation and performance.

CRDTChangeStorage

Manages Change objects for a specific document:

final changeStorage = await CRDTHive.openChangeStorageForDocument('doc-123');

// Save individual changes
await changeStorage.saveChange(change);

// Batch save multiple changes
await changeStorage.saveChanges([change1, change2, change3]);

// Load all changes for the document
final changes = changeStorage.getChanges();

// Delete changes
await changeStorage.deleteChange(change);
await changeStorage.deleteChanges([change1, change2]);

// Storage info
print('Total changes: ${changeStorage.count}');
print('Is empty: ${changeStorage.isEmpty}');

CRDTSnapshotStorage

Manages Snapshot objects for a specific document:

final snapshotStorage = await CRDTHive.openSnapshotStorageForDocument('doc-123');

// Save snapshots
await snapshotStorage.saveSnapshot(snapshot);
await snapshotStorage.saveSnapshots([snapshot1, snapshot2]);

// Retrieve snapshots
final snapshot = snapshotStorage.getSnapshot('snapshot-id');
final allSnapshots = snapshotStorage.getSnapshots();

// Check existence
if (snapshotStorage.containsSnapshot('snapshot-id')) {
  // Snapshot exists
}

Data Serialization Options

The useDataAdapter parameter in CRDTHive.initialize() controls how generic data types in CRDT operations are serialized:

Default Mode (useDataAdapter: false)

Generic data is serialized using JSON encoding:

CRDTHive.initialize(); // useDataAdapter defaults to false

// Data like List<String>, Map<String, dynamic> will be JSON-encoded
final listHandler = CRDTListHandler<String>(document, 'items');
listHandler.insert(0, 'Hello World'); // Stored as JSON

Custom Adapter Mode (useDataAdapter: true)

Generic data uses custom Hive adapters for better performance and type safety:

class MyCustomDataAdapter extends TypeAdapter<MyCustomData> {
  @override
  final int typeId = 200;

  @override
  ListValue read(BinaryReader reader) {
    // ...
  }

  @override
  void write(BinaryWriter writer, ListValue obj) {
    // ...
  }
}

// Register your custom adapters first
Hive.registerAdapter(MyCustomDataAdapter());

// Then initialize with custom adapter support
CRDTHive.initialize(useDataAdapter: true);

// Now your custom types will use their adapters
final listHandler = CRDTListHandler<MyCustomData>(document, 'items');
listHandler.insert(0, MyCustomData(value: 'test')); // Uses MyCustomDataAdapter

Examples

Storage example

A complete example with a custom data type and adapter is available here.

Server (+ storage) and clients

A complete example of a server with a persistent registry of documents and clients that can connect to the server and sync their data is available here.

Box Naming Convention

When using document-scoped storage, boxes are named using the pattern:

Changes: {boxName}_{documentId} (default: changes_{documentId})
Snapshots: {boxName}_{documentId} (default: snapshots_{documentId})

This ensures each document has isolated storage while allowing custom box name prefixes.

Storage Management

Cleanup Operations

// Close all CRDT-related boxes
await CRDTHive.closeAllBoxes();

// Delete all data for a specific document
await CRDTHive.deleteDocumentData('doc-123');

// Delete a specific box
await CRDTHive.deleteBox('changes_doc-123');

Box Customization

// Custom box names
final changeStorage = await CRDTHive.openChangeStorageForDocument(
  'doc-123',
  boxName: 'my_custom_changes',
);

final documentStorage = await CRDTHive.openStorageForDocument(
  'doc-123',
  changesBoxName: 'custom_changes',
  snapshotsBoxName: 'custom_snapshots',
);

Important Notes

Document-scoped storage utilities are optional - you can manage Hive boxes manually if preferred
Custom box organization - the provided utilities use a specific box-per-document pattern, but you can implement your own organization strategy
Type ID conflicts - ensure your custom adapters use unique type IDs

Roadmap

A roadmap is available in the project page. The roadmap provides a high-level overview of the project's goals and the current status of the project.

Packages

Other bricks of the crdt "system" are: