[browser] Minimal blazor.boot.json integration

src/mono/wasm/runtime/blazor/BootConfig.ts

@@ -0,0 +1,89 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+import { Module } from "../imports";
+import { WebAssemblyBootResourceType } from "./WebAssemblyStartOptions";
+
+type LoadBootResourceCallback = (type: WebAssemblyBootResourceType, name: string, defaultUri: string, integrity: string) => string | Promise<Response> | null | undefined;
+
+export class BootConfigResult {
+    private constructor(public bootConfig: BootJsonData, public applicationEnvironment: string) {
+    }
+
+    static async initAsync(loadBootResource?: LoadBootResourceCallback, environment?: string): Promise<BootConfigResult> {
+        const loaderResponse = loadBootResource !== undefined ?
+            loadBootResource("manifest", "blazor.boot.json", "_framework/blazor.boot.json", "") :
+            defaultLoadBlazorBootJson("_framework/blazor.boot.json");
+
+        let bootConfigResponse: Response;
+
+        if (!loaderResponse) {
+            bootConfigResponse = await defaultLoadBlazorBootJson("_framework/blazor.boot.json");
+        } else if (typeof loaderResponse === "string") {
+            bootConfigResponse = await defaultLoadBlazorBootJson(loaderResponse);
+        } else {
+            bootConfigResponse = await loaderResponse;
+        }
+
+        const applicationEnvironment = environment || (Module.getApplicationEnvironment && Module.getApplicationEnvironment(bootConfigResponse)) || "Production";
+        const bootConfig: BootJsonData = await bootConfigResponse.json();
+        bootConfig.modifiableAssemblies = bootConfigResponse.headers.get("DOTNET-MODIFIABLE-ASSEMBLIES");
+        bootConfig.aspnetCoreBrowserTools = bootConfigResponse.headers.get("ASPNETCORE-BROWSER-TOOLS");
+
+        return new BootConfigResult(bootConfig, applicationEnvironment);
+
+        function defaultLoadBlazorBootJson(url: string): Promise<Response> {
+            return fetch(url, {
+                method: "GET",
+                credentials: "include",
+                cache: "no-cache",
+            });
+        }
+    }
+}
+
+// Keep in sync with bootJsonData from the BlazorWebAssemblySDK
+export interface BootJsonData {
+    readonly entryAssembly: string;
+    readonly resources: ResourceGroups;
+    /** Gets a value that determines if this boot config was produced from a non-published build (i.e. dotnet build or dotnet run) */
+    readonly debugBuild: boolean;
+    readonly linkerEnabled: boolean;
+    readonly cacheBootResources: boolean;
+    readonly config: string[];
+    readonly icuDataMode: ICUDataMode;
+    readonly startupMemoryCache: boolean | undefined;
+    readonly runtimeOptions: string[] | undefined;
+
+    // These properties are tacked on, and not found in the boot.json file
+    modifiableAssemblies: string | null;
+    aspnetCoreBrowserTools: string | null;
+}
+
+export type BootJsonDataExtension = { [extensionName: string]: ResourceList };
+
+export interface ResourceGroups {
+    readonly assembly: ResourceList;
+    readonly lazyAssembly: ResourceList;
+    readonly pdb?: ResourceList;
+    readonly runtime: ResourceList;
+    readonly satelliteResources?: { [cultureName: string]: ResourceList };
+    readonly libraryInitializers?: ResourceList,
+    readonly extensions?: BootJsonDataExtension
+    readonly runtimeAssets: ExtendedResourceList;
+}
+
+export type ResourceList = { [name: string]: string };
+export type ExtendedResourceList = {
+    [name: string]: {
+        hash: string,
+        behavior: string
+    }
+};
+
+export enum ICUDataMode {
+    Sharded,
+    All,
+    Invariant,
+    Custom
+}

src/mono/wasm/runtime/blazor/WebAssemblyResourceLoader.ts

@@ -0,0 +1,223 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+import { toAbsoluteUri } from "./_Polyfill";
+import { BootJsonData, ResourceList } from "./BootConfig";
+import { WebAssemblyStartOptions, WebAssemblyBootResourceType } from "./WebAssemblyStartOptions";
+const networkFetchCacheMode = "no-cache";
+
+export class WebAssemblyResourceLoader {
+    private usedCacheKeys: { [key: string]: boolean } = {};
+
+    private networkLoads: { [name: string]: LoadLogEntry } = {};
+
+    private cacheLoads: { [name: string]: LoadLogEntry } = {};
+
+    static async initAsync(bootConfig: BootJsonData, startOptions: Partial<WebAssemblyStartOptions>): Promise<WebAssemblyResourceLoader> {
+        const cache = await getCacheToUseIfEnabled(bootConfig);
+        return new WebAssemblyResourceLoader(bootConfig, cache, startOptions);
+    }
+
+    constructor(readonly bootConfig: BootJsonData, readonly cacheIfUsed: Cache | null, readonly startOptions: Partial<WebAssemblyStartOptions>) {
+    }
+
+    loadResources(resources: ResourceList, url: (name: string) => string, resourceType: WebAssemblyBootResourceType): LoadingResource[] {
+        return Object.keys(resources)
+            .map(name => this.loadResource(name, url(name), resources[name], resourceType));
+    }
+
+    loadResource(name: string, url: string, contentHash: string, resourceType: WebAssemblyBootResourceType): LoadingResource {
+        const response = this.cacheIfUsed
+            ? this.loadResourceWithCaching(this.cacheIfUsed, name, url, contentHash, resourceType)
+            : this.loadResourceWithoutCaching(name, url, contentHash, resourceType);
+
+        return { name, url: toAbsoluteUri(url), response };
+    }
+
+    logToConsole(): void {
+        const cacheLoadsEntries = Object.values(this.cacheLoads);
+        const networkLoadsEntries = Object.values(this.networkLoads);
+        const cacheResponseBytes = countTotalBytes(cacheLoadsEntries);
+        const networkResponseBytes = countTotalBytes(networkLoadsEntries);
+        const totalResponseBytes = cacheResponseBytes + networkResponseBytes;
+        if (totalResponseBytes === 0) {
+            // We have no perf stats to display, likely because caching is not in use.
+            return;
+        }
+
+        const linkerDisabledWarning = this.bootConfig.linkerEnabled ? "%c" : "\n%cThis application was built with linking (tree shaking) disabled. Published applications will be significantly smaller.";
+        console.groupCollapsed(`%cdotnet%c Loaded ${toDataSizeString(totalResponseBytes)} resources${linkerDisabledWarning}`, "background: purple; color: white; padding: 1px 3px; border-radius: 3px;", "font-weight: bold;", "font-weight: normal;");
+
+        if (cacheLoadsEntries.length) {
+            console.groupCollapsed(`Loaded ${toDataSizeString(cacheResponseBytes)} resources from cache`);
+            console.table(this.cacheLoads);
+            console.groupEnd();
+        }
+
+        if (networkLoadsEntries.length) {
+            console.groupCollapsed(`Loaded ${toDataSizeString(networkResponseBytes)} resources from network`);
+            console.table(this.networkLoads);
+            console.groupEnd();
+        }
+
+        console.groupEnd();
+    }
+
+    async purgeUnusedCacheEntriesAsync(): Promise<void> {
+        // We want to keep the cache small because, even though the browser will evict entries if it
+        // gets too big, we don't want to be considered problematic by the end user viewing storage stats
+        const cache = this.cacheIfUsed;
+        if (cache) {
+            const cachedRequests = await cache.keys();
+            const deletionPromises = cachedRequests.map(async cachedRequest => {
+                if (!(cachedRequest.url in this.usedCacheKeys)) {
+                    await cache.delete(cachedRequest);
+                }
+            });
+
+            await Promise.all(deletionPromises);
+        }
+    }
+
+    private async loadResourceWithCaching(cache: Cache, name: string, url: string, contentHash: string, resourceType: WebAssemblyBootResourceType) {
+        // Since we are going to cache the response, we require there to be a content hash for integrity
+        // checking. We don't want to cache bad responses. There should always be a hash, because the build
+        // process generates this data.
+        if (!contentHash || contentHash.length === 0) {
+            throw new Error("Content hash is required");
+        }
+
+        const cacheKey = toAbsoluteUri(`${url}.${contentHash}`);
+        this.usedCacheKeys[cacheKey] = true;
+
+        let cachedResponse: Response | undefined;
+        try {
+            cachedResponse = await cache.match(cacheKey);
+        } catch {
+            // Be tolerant to errors reading from the cache. This is a guard for https://bugs.chromium.org/p/chromium/issues/detail?id=968444 where
+            // chromium browsers may sometimes throw when working with the cache.
+        }
+
+        if (cachedResponse) {
+            // It's in the cache.
+            const responseBytes = parseInt(cachedResponse.headers.get("content-length") || "0");
+            this.cacheLoads[name] = { responseBytes };
+            return cachedResponse;
+        } else {
+            // It's not in the cache. Fetch from network.
+            const networkResponse = await this.loadResourceWithoutCaching(name, url, contentHash, resourceType);
+            this.addToCacheAsync(cache, name, cacheKey, networkResponse); // Don't await - add to cache in background
+            return networkResponse;
+        }
+    }
+
+    private loadResourceWithoutCaching(name: string, url: string, contentHash: string, resourceType: WebAssemblyBootResourceType): Promise<Response> {
+        // Allow developers to override how the resource is loaded
+        if (this.startOptions.loadBootResource) {
+            const customLoadResult = this.startOptions.loadBootResource(resourceType, name, url, contentHash);
+            if (customLoadResult instanceof Promise) {
+                // They are supplying an entire custom response, so just use that
+                return customLoadResult;
+            } else if (typeof customLoadResult === "string") {
+                // They are supplying a custom URL, so use that with the default fetch behavior
+                url = customLoadResult;
+            }
+        }
+
+        // Note that if cacheBootResources was explicitly disabled, we also bypass hash checking
+        // This is to give developers an easy opt-out from the entire caching/validation flow if
+        // there's anything they don't like about it.
+        return fetch(url, {
+            cache: networkFetchCacheMode,
+            integrity: this.bootConfig.cacheBootResources ? contentHash : undefined,
+        });
+    }
+
+    private async addToCacheAsync(cache: Cache, name: string, cacheKey: string, response: Response) {
+        // We have to clone in order to put this in the cache *and* not prevent other code from
+        // reading the original response stream.
+        const responseData = await response.clone().arrayBuffer();
+
+        // Now is an ideal moment to capture the performance stats for the request, since it
+        // only just completed and is most likely to still be in the buffer. However this is
+        // only done on a 'best effort' basis. Even if we do receive an entry, some of its
+        // properties may be blanked out if it was a CORS request.
+        const performanceEntry = getPerformanceEntry(response.url);
+        const responseBytes = (performanceEntry && performanceEntry.encodedBodySize) || undefined;
+        this.networkLoads[name] = { responseBytes };
+
+        // Add to cache as a custom response object so we can track extra data such as responseBytes
+        // We can't rely on the server sending content-length (ASP.NET Core doesn't by default)
+        const responseToCache = new Response(responseData, {
+            headers: {
+                "content-type": response.headers.get("content-type") || "",
+                "content-length": (responseBytes || response.headers.get("content-length") || "").toString(),
+            },
+        });
+
+        try {
+            await cache.put(cacheKey, responseToCache);
+        } catch {
+            // Be tolerant to errors writing to the cache. This is a guard for https://bugs.chromium.org/p/chromium/issues/detail?id=968444 where
+            // chromium browsers may sometimes throw when performing cache operations.
+        }
+    }
+}
+
+async function getCacheToUseIfEnabled(bootConfig: BootJsonData): Promise<Cache | null> {
+    // caches will be undefined if we're running on an insecure origin (secure means https or localhost)
+    if (!bootConfig.cacheBootResources || typeof caches === "undefined") {
+        return null;
+    }
+
+    // cache integrity is compromised if the first request has been served over http (except localhost)
+    // in this case, we want to disable caching and integrity validation
+    if (window.isSecureContext === false) {
+        return null;
+    }
+
+    // Define a separate cache for each base href, so we're isolated from any other
+    // Blazor application running on the same origin. We need this so that we're free
+    // to purge from the cache anything we're not using and don't let it keep growing,
+    // since we don't want to be worst offenders for space usage.
+    const relativeBaseHref = document.baseURI.substring(document.location.origin.length);
+    const cacheName = `dotnet-resources-${relativeBaseHref}`;
+
+    try {
+        // There's a Chromium bug we need to be aware of here: the CacheStorage APIs say that when
+        // caches.open(name) returns a promise that succeeds, the value is meant to be a Cache instance.
+        // However, if the browser was launched with a --user-data-dir param that's "too long" in some sense,
+        // then even through the promise resolves as success, the value given is `undefined`.
+        // See https://stackoverflow.com/a/46626574 and https://bugs.chromium.org/p/chromium/issues/detail?id=1054541
+        // If we see this happening, return "null" to mean "proceed without caching".
+        return (await caches.open(cacheName)) || null;
+    } catch {
+        // There's no known scenario where we should get an exception here, but considering the
+        // Chromium bug above, let's tolerate it and treat as "proceed without caching".
+        return null;
+    }
+}
+
+function countTotalBytes(loads: LoadLogEntry[]) {
+    return loads.reduce((prev, item) => prev + (item.responseBytes || 0), 0);
+}
+
+function toDataSizeString(byteCount: number) {
+    return `${(byteCount / (1024 * 1024)).toFixed(2)} MB`;
+}
+
+function getPerformanceEntry(url: string): PerformanceResourceTiming | undefined {
+    if (typeof performance !== "undefined") {
+        return performance.getEntriesByName(url)[0] as PerformanceResourceTiming;
+    }
+}
+
+interface LoadLogEntry {
+    responseBytes: number | undefined;
+}
+
+export interface LoadingResource {
+    name: string;
+    url: string;
+    response: Promise<Response>;
+}

src/mono/wasm/runtime/blazor/WebAssemblyStartOptions.ts

@@ -0,0 +1,30 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+export interface WebAssemblyStartOptions {
+  /**
+   * Overrides the built-in boot resource loading mechanism so that boot resources can be fetched
+   * from a custom source, such as an external CDN.
+   * @param type The type of the resource to be loaded.
+   * @param name The name of the resource to be loaded.
+   * @param defaultUri The URI from which the framework would fetch the resource by default. The URI may be relative or absolute.
+   * @param integrity The integrity string representing the expected content in the response.
+   * @returns A URI string or a Response promise to override the loading process, or null/undefined to allow the default loading behavior.
+   */
+  loadBootResource(type: WebAssemblyBootResourceType, name: string, defaultUri: string, integrity: string): string | Promise<Response> | null | undefined;
+
+  /**
+   * Override built-in environment setting on start.
+   */
+  environment?: string;
+
+  /**
+   * Gets the application culture. This is a name specified in the BCP 47 format. See https://tools.ietf.org/html/bcp47
+   */
+  applicationCulture?: string;
+}
+
+// This type doesn't have to align with anything in BootConfig.
+// Instead, this represents the public API through which certain aspects
+// of boot resource loading can be customized.
+export type WebAssemblyBootResourceType = "assembly" | "pdb" | "dotnetjs" | "dotnetwasm" | "globalization" | "manifest" | "configuration";