LevelDB database adapter for Yjs
LevelDB is a fast embedded database. It is the underlying technology of IndexedDB.
Internally, y-leveldb uses level which
allows to exchange the storage medium for a different supported database.
Hence this adapter also supports rocksdb, lmdb, and many more..
- Persistent storage for the server
- Exchangeable storage medium
- Can be used in y-websocket
- A single y-leveldb instance can handle many documents.
Use it
npm install y-leveldb --save
import * as Y from 'yjs'
import { LeveldbPersistence } from 'y-leveldb'
const persistence = new LeveldbPersistence('./storage-location')
const ydoc = new Y.Doc()
ydoc.getArray('arr').insert(0, [1, 2, 3])
ydoc.getArray('arr').toArray() // => [1, 2, 3]
// store document updates retrieved from other clients
persistence.storeUpdate('my-doc', Y.encodeStateAsUpdate(ydoc))
// when you want to sync, or store data to a database,
// retrieve the temporary Y.Doc to consume data
const ydocPersisted = await persistence.getYDoc('my-doc')
ydocPersisted.getArray('arr') // [1, 2, 3]
API
persistence = LeveldbPersistence(storageLocation, [{ [level] }])
Create a y-leveldb persistence instance.
You can use any levelup-compatible adapter.
import { LeveldbPersistence } from 'y-leveldb'
import level from 'level-mem'
const persistence = new LeveldbPersistence('./storage-location', { level })
persistence.getYDoc(docName: string): Promise<Y.Doc>
Create a Y.Doc instance with the data persisted in leveldb. Use this to
temporarily create a Yjs document to sync changes or extract data.
persistence.storeUpdate(docName: string, update: Uint8Array): Promise
Store a single document update to the database.
persistence.getStateVector(docName: string): Promise<Uint8Array>
The state vector (describing the state of the persisted document - see
Yjs docs) is maintained in a separate
field and constantly updated.
This allows you to sync changes without actually creating a Yjs document.
persistence.getDiff(docName: string, stateVector: Uint8Array): Promise<Uint8Array>
Get the differences directly from the database. The same as
Y.encodeStateAsUpdate(ydoc, stateVector).
persistence.clearDocument(docName: string): Promise
Delete a document, and all associated data from the database.
persistence.setMeta(docName: string, metaKey: string, value: any): Promise
Persist some meta information in the database and associate it with a document.
It is up to you what you store here. You could, for example, store credentials
here.
persistence.getMeta(docName: string, metaKey: string): Promise<any|undefined>
Retrieve a store meta value from the database. Returns undefined if the
metaKey doesn't exist.
persistence.delMeta(docName: string, metaKey: string): Promise
Delete a store meta value.
persistence.getAllDocNames(docName: string): Promise<Array<string>>
Retrieve the names of all stored documents.
persistence.getAllDocStateVectors(docName: string): Promise<Array<{ name:string,clock:number,sv:Uint8Array}
Retrieve the state vectors of all stored documents. You can use this to sync
two y-leveldb instances.
Note: The state vectors might be outdated if the associated document is not
yet flushed. So use with caution.
persistence.flushDocument(docName: string): Promise (dev only)
Internally y-leveldb stores incremental updates. You can merge all document
updates to a single entry. You probably never have to use this.
License
y-leveldb is licensed under the MIT License.
kevin.jahns@protonmail.com
