Expose creation of a frozen document service factory. (#25653)

Exposing creation of a frozen document service factory via standalone
function. Given Pages container load flow, this is the step of less
friction where we can enforce storage only in containers that were
loaded with pending local state.

Author: dannimad

packages/loader/container-loader/api-report/container-loader.legacy.alpha.api.md

@@ -23,6 +23,9 @@ export interface ContainerAlpha extends IContainer {
 // @beta @legacy
 export function createDetachedContainer(createDetachedContainerProps: ICreateDetachedContainerProps): Promise<IContainer>;
 
+// @alpha @legacy
+export function createFrozenDocumentServiceFactory(factory?: IDocumentServiceFactory | Promise<IDocumentServiceFactory>): IDocumentServiceFactory;
+
 // @beta @legacy (undocumented)
 export interface IBaseProtocolHandler {
     // (undocumented)

packages/loader/container-loader/src/createAndLoadContainerUtils.ts

@@ -21,7 +21,7 @@ import type {
 	IUrlResolver,
 } from "@fluidframework/driver-definitions/internal";
 
-import { FrozenDocumentServiceFactory } from "./frozenServices.js";
+import { createFrozenDocumentServiceFactory } from "./frozenServices.js";
 import { Loader } from "./loader.js";
 import type { ProtocolHandlerBuilder } from "./protocol.js";
 
@@ -197,6 +197,6 @@ export async function loadFrozenContainerFromPendingState(
 ): Promise<IContainer> {
 	return loadExistingContainer({
 		...props,
-		documentServiceFactory: new FrozenDocumentServiceFactory(props.documentServiceFactory),
+		documentServiceFactory: createFrozenDocumentServiceFactory(props.documentServiceFactory),
 	});
 }

packages/loader/container-loader/src/frozenServices.ts

@@ -5,6 +5,7 @@
 
 import { TypedEventEmitter } from "@fluid-internal/client-utils";
 import type { IDisposable } from "@fluidframework/core-interfaces";
+import { isPromiseLike } from "@fluidframework/core-utils/internal";
 import {
 	ScopeType,
 	type ConnectionMode,
@@ -28,13 +29,38 @@ import {
 
 import type { IConnectionStateChangeReason } from "./contracts.js";
 
+/**
+ * Creation of a FrozenDocumentServiceFactory which wraps an existing
+ * DocumentServiceFactory to provide a storage-only document service.
+ *
+ * @param documentServiceFactory - The underlying DocumentServiceFactory to wrap.
+ * @returns A FrozenDocumentServiceFactory
+ * @legacy @alpha
+ */
+export function createFrozenDocumentServiceFactory(
+	factory?: IDocumentServiceFactory | Promise<IDocumentServiceFactory>,
+): IDocumentServiceFactory {
+	// Sync path
+	return factory instanceof FrozenDocumentServiceFactory
+		? factory
+		: new FrozenDocumentServiceFactory(factory);
+}
+
 export class FrozenDocumentServiceFactory implements IDocumentServiceFactory {
-	constructor(private readonly documentServiceFactory?: IDocumentServiceFactory) {}
+	constructor(
+		private readonly documentServiceFactory?:
+			| IDocumentServiceFactory
+			| Promise<IDocumentServiceFactory>,
+	) {}
 
 	async createDocumentService(resolvedUrl: IResolvedUrl): Promise<IDocumentService> {
+		let factory = this.documentServiceFactory;
+		if (isPromiseLike(factory)) {
+			factory = await this.documentServiceFactory;
+		}
 		return new FrozenDocumentService(
 			resolvedUrl,
-			await this.documentServiceFactory?.createDocumentService(resolvedUrl),
+			await factory?.createDocumentService(resolvedUrl),
 		);
 	}
 	async createContainer(): Promise<IDocumentService> {

packages/loader/container-loader/src/index.ts

@@ -5,6 +5,7 @@
 
 export { ConnectionState } from "./connectionState.js";
 export { type ContainerAlpha, waitContainerToCatchUp, asLegacyAlpha } from "./container.js";
+export { createFrozenDocumentServiceFactory } from "./frozenServices.js";
 export {
 	createDetachedContainer,
 	loadExistingContainer,