RTC: Add a limit for the default provider

packages/core-data/src/reducer.js

@@ -16,6 +16,7 @@ import { createUndoManager } from '@wordpress/undo-manager';
 import { ifMatchingAction, replaceAction } from './utils';
 import { reducer as queriedDataReducer } from './queried-data';
 import { rootEntitiesConfig, DEFAULT_ENTITY_KEY } from './entities';
+import { ConnectionErrorCode } from './sync';
 
 /** @typedef {import('./types').AnyFunction} AnyFunction */
 
@@ -706,6 +707,16 @@ export function collaborationSupported( state = true, action ) {
 	switch ( action.type ) {
 		case 'SET_COLLABORATION_SUPPORTED':
 			return action.supported;
+
+		case 'SET_SYNC_CONNECTION_STATUS':
+			if (
+				ConnectionErrorCode.DOCUMENT_SIZE_LIMIT_EXCEEDED ===
+				action.status?.error?.code
+			) {
+				return false;
+			}
+
+			return state;
 	}
 	return state;
 }

packages/core-data/src/sync.ts

@@ -12,6 +12,7 @@ import {
 import { unlock } from './lock-unlock';
 
 const {
+	ConnectionErrorCode,
 	createSyncManager,
 	Delta,
 	CRDT_DOC_META_PERSISTENCE_KEY,
@@ -22,6 +23,7 @@ const {
 } = unlock( syncPrivateApis );
 
 export {
+	ConnectionErrorCode,
 	Delta,
 	CRDT_DOC_META_PERSISTENCE_KEY,
 	CRDT_RECORD_MAP_KEY,

packages/editor/src/components/post-locked-modal/index.js

@@ -16,21 +16,39 @@ import { addAction, removeAction } from '@wordpress/hooks';
 import { useInstanceId } from '@wordpress/compose';
 import { store as coreStore } from '@wordpress/core-data';
 import { unlock } from '../../lock-unlock';
+import { DOCUMENT_SIZE_LIMIT_EXCEEDED } from '../../utils/sync-error-messages';
 
 /**
  * Internal dependencies
  */
 import { store as editorStore } from '../../store';
 
 function CollaborationContext() {
-	const isCollaborationSupported = useSelect( ( select ) => {
-		return unlock( select( coreStore ) ).isCollaborationSupported();
-	}, [] );
+	const { isCollaborationSupported, syncConnectionStatus } = useSelect(
+		( select ) => {
+			const selectors = unlock( select( coreStore ) );
+			return {
+				isCollaborationSupported: selectors.isCollaborationSupported(),
+				syncConnectionStatus: selectors.getSyncConnectionStatus(),
+			};
+		},
+		[]
+	);
 
 	if ( isCollaborationSupported ) {
 		return null;
 	}
 
+	if ( DOCUMENT_SIZE_LIMIT_EXCEEDED === syncConnectionStatus?.error?.code ) {
+		return (
+			<p>
+				{ __(
+					'Because this post is too large for real-time collaboration, only one person can edit at a time.'
+				) }
+			</p>
+		);
+	}
+
 	return (
 		<p>
 			{ __(

packages/editor/src/components/sync-connection-modal/index.js

@@ -46,16 +46,24 @@ const DISCONNECTED_DEBOUNCE_MS = 2000;
  * @return {Element|null} The modal component or null if not disconnected.
  */
 export function SyncConnectionModal() {
-	const { connectionState, postType } = useSelect( ( selectFn ) => {
-		const currentPostType = selectFn( editorStore ).getCurrentPostType();
-		return {
-			connectionState:
-				selectFn( coreDataStore ).getSyncConnectionStatus() || null,
-			postType: currentPostType
-				? selectFn( coreDataStore ).getPostType( currentPostType )
-				: null,
-		};
-	}, [] );
+	const { connectionState, isCollaborationEnabled, postType } = useSelect(
+		( selectFn ) => {
+			const currentPostType =
+				selectFn( editorStore ).getCurrentPostType();
+			return {
+				connectionState:
+					selectFn( coreDataStore ).getSyncConnectionStatus() || null,
+				isCollaborationEnabled:
+					selectFn(
+						editorStore
+					).isCollaborationEnabledForCurrentPost(),
+				postType: currentPostType
+					? selectFn( coreDataStore ).getPostType( currentPostType )
+					: null,
+			};
+		},
+		[]
+	);
 
 	const { secondsRemaining, markRetrying } = useRetryCountdown(
 		connectionState?.retryInMs,
@@ -115,7 +123,7 @@ export function SyncConnectionModal() {
 		};
 	}, [ connectionStatus, connectionErrorCode ] );
 
-	if ( ! syncConnectionMessage ) {
+	if ( ! syncConnectionMessage || ! isCollaborationEnabled ) {
 		return null;
 	}
 

packages/editor/src/utils/sync-error-messages.js

@@ -3,35 +3,45 @@
  */
 import { __ } from '@wordpress/i18n';
 
+// These error codes are defined in the sync package:
+// packages/sync/src/errors.ts
+export const AUTHENTICATION_FAILED = 'authentication-failed';
+export const CONNECTION_EXPIRED = 'connection-expired';
+export const CONNECTION_LIMIT_EXCEEDED = 'connection-limit-exceeded';
+export const DOCUMENT_SIZE_LIMIT_EXCEEDED = 'document-size-limit-exceeded';
+export const UNKNOWN_ERROR = 'unknown-error';
+
 /**
  * Default error messages for known error codes.
  */
 const ERROR_MESSAGES = {
-	'authentication-failed': {
+	[ AUTHENTICATION_FAILED ]: {
 		title: __( 'Unable to connect' ),
 		description: __(
 			"Real-time collaboration couldn't verify your permissions. " +
 				'Check that you have access to edit this post, or contact your site administrator.'
 		),
 		canRetry: false,
 	},
-	'connection-expired': {
+	[ CONNECTION_EXPIRED ]: {
 		title: __( 'Connection expired' ),
 		description: __(
 			'Your connection to real-time collaboration has timed out. ' +
 				'Editing is paused to prevent conflicts with other editors.'
 		),
 		canRetry: true,
 	},
-	'connection-limit-exceeded': {
+	[ CONNECTION_LIMIT_EXCEEDED ]: {
 		title: __( 'Too many editors connected' ),
 		description: __(
 			'Real-time collaboration has reached its connection limit. ' +
 				'Try again later or contact your site administrator.'
 		),
 		canRetry: true,
 	},
-	'unknown-error': {
+	// DOCUMENT_SIZE_LIMIT_EXCEEDED is not included here because it results in
+	// collaboration being disabled entirely.
+	[ UNKNOWN_ERROR ]: {
 		title: __( 'Connection lost' ),
 		description: __(
 			'The connection to real-time collaboration was interrupted. ' +
@@ -54,5 +64,5 @@ export function getSyncErrorMessages( error ) {
 		return ERROR_MESSAGES[ error.code ];
 	}
 
-	return ERROR_MESSAGES[ 'unknown-error' ];
+	return ERROR_MESSAGES[ UNKNOWN_ERROR ];
 }

packages/editor/src/utils/test/sync-error-messages.js

@@ -8,6 +8,7 @@ describe( 'getSyncErrorMessages', () => {
 		'authentication-failed',
 		'connection-expired',
 		'connection-limit-exceeded',
+		'document-size-limit-exceeded',
 		'unknown-error',
 	] )(
 		'should return title, description, and canRetry for "%s"',

packages/sync/src/errors.ts

@@ -0,0 +1,17 @@
+export enum ConnectionErrorCode {
+	AUTHENTICATION_FAILED = 'authentication-failed',
+	CONNECTION_EXPIRED = 'connection-expired',
+	CONNECTION_LIMIT_EXCEEDED = 'connection-limit-exceeded',
+	DOCUMENT_SIZE_LIMIT_EXCEEDED = 'document-size-limit-exceeded',
+	UNKNOWN_ERROR = 'unknown-error',
+}
+
+export class ConnectionError extends Error {
+	constructor(
+		public code: ConnectionErrorCode = ConnectionErrorCode.UNKNOWN_ERROR,
+		message?: string
+	) {
+		super( message );
+		this.name = 'ConnectionError';
+	}
+}

packages/sync/src/private-apis.ts

@@ -7,6 +7,7 @@ import {
 	LOCAL_EDITOR_ORIGIN,
 	LOCAL_UNDO_IGNORED_ORIGIN,
 } from './config';
+import { ConnectionErrorCode } from './errors';
 import { lock } from './lock-unlock';
 import { createSyncManager } from './manager';
 import { pollingManager } from './providers/http-polling/polling-manager';
@@ -22,4 +23,5 @@ lock( privateApis, {
 	LOCAL_EDITOR_ORIGIN,
 	LOCAL_UNDO_IGNORED_ORIGIN,
 	retrySyncConnection: () => pollingManager.retryNow(),
+	ConnectionErrorCode,
 } );

packages/sync/src/providers/http-polling/config.ts

@@ -0,0 +1,7 @@
+export const MAX_ERROR_BACKOFF_IN_MS = 30 * 1000; // 30 seconds
+export const MAX_UPDATE_SIZE_IN_BYTES = 1 * 1024 * 1024; // 1 MB
+export const POLLING_INTERVAL_IN_MS = 1000; // 1 second or 1000 milliseconds
+export const POLLING_INTERVAL_WITH_COLLABORATORS_IN_MS = 250; // 250 milliseconds
+// Must be less than the server-side AWARENESS_TIMEOUT (30 s) to avoid
+// false disconnects when the tab is in the background.
+export const POLLING_INTERVAL_BACKGROUND_TAB_IN_MS = 25 * 1000; // 25 seconds

packages/sync/src/providers/http-polling/polling-manager.ts

@@ -11,6 +11,14 @@ import * as syncProtocol from 'y-protocols/sync';
 /**
  * Internal dependencies
  */
+import {
+	MAX_ERROR_BACKOFF_IN_MS,
+	MAX_UPDATE_SIZE_IN_BYTES,
+	POLLING_INTERVAL_IN_MS,
+	POLLING_INTERVAL_WITH_COLLABORATORS_IN_MS,
+	POLLING_INTERVAL_BACKGROUND_TAB_IN_MS,
+} from './config';
+import { ConnectionError, ConnectionErrorCode } from '../../errors';
 import type { ConnectionStatus } from '../../types';
 import {
 	type AwarenessState,
@@ -28,12 +36,6 @@ import {
 	postSyncUpdateNonBlocking,
 } from './utils';
 
-const POLLING_INTERVAL_IN_MS = 1000; // 1 second or 1000 milliseconds
-const POLLING_INTERVAL_WITH_COLLABORATORS_IN_MS = 250; // 250 milliseconds
-// Must be less than the server-side AWARENESS_TIMEOUT (30 s) to avoid
-// false disconnects when the tab is in the background.
-const POLLING_INTERVAL_BACKGROUND_TAB_IN_MS = 25 * 1000; // 25 seconds
-const MAX_ERROR_BACKOFF_IN_MS = 30 * 1000; // 30 seconds
 const POLLING_MANAGER_ORIGIN = 'polling-manager';
 
 type LogFunction = ( message: string, debug?: object ) => void;
@@ -146,7 +148,9 @@ function processAwarenessUpdate(
 
 	// Removed clients are missing from the server state.
 	const removed = new Set< number >(
-		currentStates.keys().filter( ( clientId ) => ! state[ clientId ] )
+		Array.from( currentStates.keys() ).filter(
+			( clientId ) => ! state[ clientId ]
+		)
 	);
 
 	Object.entries( state ).forEach( ( [ clientIdString, awarenessState ] ) => {
@@ -459,6 +463,7 @@ function poll(): void {
 	// Start polling.
 	void start();
 }
+
 function registerRoom( {
 	room,
 	doc,
@@ -483,6 +488,29 @@ function registerRoom( {
 			return;
 		}
 
+		if ( update.byteLength > MAX_UPDATE_SIZE_IN_BYTES ) {
+			const state = roomStates.get( room );
+			if ( ! state ) {
+				return;
+			}
+
+			state.log( 'Document size limit exceeded', {
+				maxUpdateSizeInBytes: MAX_UPDATE_SIZE_IN_BYTES,
+				updateSizeInBytes: update.byteLength,
+			} );
+
+			state.onStatusChange( {
+				status: 'disconnected',
+				error: new ConnectionError(
+					ConnectionErrorCode.DOCUMENT_SIZE_LIMIT_EXCEEDED,
+					'Document size limit exceeded'
+				),
+			} );
+
+			// This is an unrecoverable error. Unregister the room to prevent syncing.
+			unregisterRoom( room );
+		}
+
 		// Tag local document changes as 'update' type.
 		updateQueue.add( createSyncUpdate( update, SyncUpdateType.UPDATE ) );
 	}