124 lines
3.9 KiB
TypeScript
124 lines
3.9 KiB
TypeScript
import { RoomSnapshot, TLSocketRoom } from '@tldraw/sync-core'
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import {
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TLRecord,
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createTLSchema,
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// defaultBindingSchemas,
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defaultShapeSchemas,
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} from '@tldraw/tlschema'
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import { AutoRouter, IRequest, error } from 'itty-router'
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import throttle from 'lodash.throttle'
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import { Environment } from './types'
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// add custom shapes and bindings here if needed:
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const schema = createTLSchema({
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shapes: { ...defaultShapeSchemas },
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// bindings: { ...defaultBindingSchemas },
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})
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// each whiteboard room is hosted in a DurableObject:
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// https://developers.cloudflare.com/durable-objects/
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// there's only ever one durable object instance per room. it keeps all the room state in memory and
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// handles websocket connections. periodically, it persists the room state to the R2 bucket.
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export class TldrawDurableObject {
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private r2: R2Bucket
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// the room ID will be missing whilst the room is being initialized
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private roomId: string | null = null
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// when we load the room from the R2 bucket, we keep it here. it's a promise so we only ever
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// load it once.
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private roomPromise: Promise<TLSocketRoom<TLRecord, void>> | null = null
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constructor(
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private readonly ctx: DurableObjectState,
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env: Environment
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) {
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this.r2 = env.TLDRAW_BUCKET
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ctx.blockConcurrencyWhile(async () => {
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this.roomId = ((await this.ctx.storage.get('roomId')) ?? null) as string | null
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})
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}
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private readonly router = AutoRouter({
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catch: (e) => {
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console.log(e)
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return error(e)
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},
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})
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// when we get a connection request, we stash the room id if needed and handle the connection
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.get('/connect/:roomId', async (request) => {
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if (!this.roomId) {
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await this.ctx.blockConcurrencyWhile(async () => {
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await this.ctx.storage.put('roomId', request.params.roomId)
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this.roomId = request.params.roomId
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})
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}
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return this.handleConnect(request)
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})
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// `fetch` is the entry point for all requests to the Durable Object
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fetch(request: Request): Response | Promise<Response> {
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return this.router.fetch(request)
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}
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// what happens when someone tries to connect to this room?
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async handleConnect(request: IRequest): Promise<Response> {
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// extract query params from request
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const sessionId = request.query.sessionId as string
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if (!sessionId) return error(400, 'Missing sessionId')
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// Create the websocket pair for the client
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const { 0: clientWebSocket, 1: serverWebSocket } = new WebSocketPair()
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serverWebSocket.accept()
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// load the room, or retrieve it if it's already loaded
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const room = await this.getRoom()
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// connect the client to the room
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room.handleSocketConnect({ sessionId, socket: serverWebSocket })
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// return the websocket connection to the client
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return new Response(null, { status: 101, webSocket: clientWebSocket })
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}
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getRoom() {
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const roomId = this.roomId
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if (!roomId) throw new Error('Missing roomId')
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if (!this.roomPromise) {
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this.roomPromise = (async () => {
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// fetch the room from R2
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const roomFromBucket = await this.r2.get(`rooms/${roomId}`)
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// if it doesn't exist, we'll just create a new empty room
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const initialSnapshot = roomFromBucket
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? ((await roomFromBucket.json()) as RoomSnapshot)
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: undefined
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// create a new TLSocketRoom. This handles all the sync protocol & websocket connections.
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// it's up to us to persist the room state to R2 when needed though.
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return new TLSocketRoom<TLRecord, void>({
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schema,
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initialSnapshot,
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onDataChange: () => {
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// and persist whenever the data in the room changes
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this.schedulePersistToR2()
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},
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})
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})()
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}
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return this.roomPromise
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}
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// we throttle persistance so it only happens every 10 seconds
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schedulePersistToR2 = throttle(async () => {
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if (!this.roomPromise || !this.roomId) return
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const room = await this.getRoom()
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// convert the room to JSON and upload it to R2
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const snapshot = JSON.stringify(room.getCurrentSnapshot())
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await this.r2.put(`rooms/${this.roomId}`, snapshot)
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}, 10_000)
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}
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