Introduce stale while revalidate pattern (#1555)

This Improves the frontend performance with stale while
revalidate pattern.

There are noticeable performance problems in the frontend that
needed addressing. While implementing the stale-while-revalidate
pattern to display cached responses while re-fetching up-to-date
data in the background, in the same vein we used the opportunity
to remove legacy code involving redux as much as possible,
cleaned up many components and converted them to functional
react components.

Co-authored-by: Sebastian Sdorra <sebastian.sdorra@cloudogu.com>
Co-authored-by: Eduard Heimbuch <eduard.heimbuch@cloudogu.com>

scm-ui/ui-api/src/apiclient.ts

@@ -0,0 +1,316 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+import { contextPath } from "./urls";
+import { BackendErrorContent, createBackendError, ForbiddenError, isBackendError, UnauthorizedError } from "./errors";
+
+type SubscriptionEvent = {
+  type: string;
+};
+
+type OpenEvent = SubscriptionEvent;
+
+type ErrorEvent = SubscriptionEvent & {
+  error: Error;
+};
+
+type MessageEvent = SubscriptionEvent & {
+  data: string;
+  lastEventId?: string;
+};
+
+type MessageListeners = {
+  [eventType: string]: (event: MessageEvent) => void;
+};
+
+type SubscriptionContext = {
+  onOpen?: OpenEvent;
+  onMessage: MessageListeners;
+  onError?: ErrorEvent;
+};
+
+type SubscriptionArgument = MessageListeners | SubscriptionContext;
+
+type Cancel = () => void;
+
+const sessionId = (
+  Date.now().toString(36) +
+  Math.random()
+    .toString(36)
+    .substr(2, 5)
+).toUpperCase();
+
+const extractXsrfTokenFromJwt = (jwt: string) => {
+  const parts = jwt.split(".");
+  if (parts.length === 3) {
+    return JSON.parse(atob(parts[1])).xsrf;
+  }
+};
+
+// @VisibleForTesting
+export const extractXsrfTokenFromCookie = (cookieString?: string) => {
+  if (cookieString) {
+    const cookies = cookieString.split(";");
+    for (const c of cookies) {
+      const parts = c.trim().split("=");
+      if (parts[0] === "X-Bearer-Token") {
+        return extractXsrfTokenFromJwt(parts[1]);
+      }
+    }
+  }
+};
+
+const extractXsrfToken = () => {
+  return extractXsrfTokenFromCookie(document.cookie);
+};
+
+const createRequestHeaders = () => {
+  const headers: { [key: string]: string } = {
+    // disable caching for now
+    Cache: "no-cache",
+    // identify the request as ajax request
+    "X-Requested-With": "XMLHttpRequest",
+    // identify the web interface
+    "X-SCM-Client": "WUI",
+    // identify the window session
+    "X-SCM-Session-ID": sessionId
+  };
+
+  const xsrf = extractXsrfToken();
+  if (xsrf) {
+    headers["X-XSRF-Token"] = xsrf;
+  }
+  return headers;
+};
+
+const applyFetchOptions: (p: RequestInit) => RequestInit = o => {
+  if (o.headers) {
+    o.headers = {
+      ...createRequestHeaders()
+    };
+  } else {
+    o.headers = createRequestHeaders();
+  }
+  o.credentials = "same-origin";
+  return o;
+};
+
+function handleFailure(response: Response) {
+  if (!response.ok) {
+    if (response.status === 401) {
+      throw new UnauthorizedError("Unauthorized", 401);
+    } else if (response.status === 403) {
+      throw new ForbiddenError("Forbidden", 403);
+    } else if (isBackendError(response)) {
+      return response.json().then((content: BackendErrorContent) => {
+        throw createBackendError(content, response.status);
+      });
+    } else {
+      throw new Error("server returned status code " + response.status);
+    }
+  }
+  return response;
+}
+
+export function createUrl(url: string) {
+  if (url.includes("://")) {
+    return url;
+  }
+  let urlWithStartingSlash = url;
+  if (url.indexOf("/") !== 0) {
+    urlWithStartingSlash = "/" + urlWithStartingSlash;
+  }
+  return `${contextPath}/api/v2${urlWithStartingSlash}`;
+}
+
+export function createUrlWithIdentifiers(url: string): string {
+  return createUrl(url) + "?X-SCM-Client=WUI&X-SCM-Session-ID=" + sessionId;
+}
+
+type ErrorListener = (error: Error) => void;
+
+type RequestListener = (url: string, options?: RequestInit) => void;
+
+class ApiClient {
+  errorListeners: ErrorListener[] = [];
+  requestListeners: RequestListener[] = [];
+
+  get = (url: string): Promise<Response> => {
+    return this.request(url, applyFetchOptions({}))
+      .then(handleFailure)
+      .catch(this.notifyAndRethrow);
+  };
+
+  post = (
+    url: string,
+    payload?: any,
+    contentType = "application/json",
+    additionalHeaders: Record<string, string> = {}
+  ) => {
+    return this.httpRequestWithJSONBody("POST", url, contentType, additionalHeaders, payload);
+  };
+
+  postText = (url: string, payload: string, additionalHeaders: Record<string, string> = {}) => {
+    return this.httpRequestWithTextBody("POST", url, additionalHeaders, payload);
+  };
+
+  putText = (url: string, payload: string, additionalHeaders: Record<string, string> = {}) => {
+    return this.httpRequestWithTextBody("PUT", url, additionalHeaders, payload);
+  };
+
+  postBinary = (url: string, fileAppender: (p: FormData) => void, additionalHeaders: Record<string, string> = {}) => {
+    const formData = new FormData();
+    fileAppender(formData);
+
+    const options: RequestInit = {
+      method: "POST",
+      body: formData,
+      headers: additionalHeaders
+    };
+    return this.httpRequestWithBinaryBody(options, url);
+  };
+
+  put(url: string, payload: any, contentType = "application/json", additionalHeaders: Record<string, string> = {}) {
+    return this.httpRequestWithJSONBody("PUT", url, contentType, additionalHeaders, payload);
+  }
+
+  head = (url: string) => {
+    let options: RequestInit = {
+      method: "HEAD"
+    };
+    options = applyFetchOptions(options);
+    return this.request(url, options)
+      .then(handleFailure)
+      .catch(this.notifyAndRethrow);
+  };
+
+  delete = (url: string): Promise<Response> => {
+    let options: RequestInit = {
+      method: "DELETE"
+    };
+    options = applyFetchOptions(options);
+    return this.request(url, options)
+      .then(handleFailure)
+      .catch(this.notifyAndRethrow);
+  };
+
+  httpRequestWithJSONBody = (
+    method: string,
+    url: string,
+    contentType: string,
+    additionalHeaders: Record<string, string>,
+    payload?: any
+  ): Promise<Response> => {
+    const options: RequestInit = {
+      method: method,
+      headers: additionalHeaders
+    };
+    if (payload) {
+      options.body = JSON.stringify(payload);
+    }
+    return this.httpRequestWithBinaryBody(options, url, contentType);
+  };
+
+  httpRequestWithTextBody = (
+    method: string,
+    url: string,
+    additionalHeaders: Record<string, string> = {},
+    payload: string
+  ) => {
+    const options: RequestInit = {
+      method: method,
+      headers: additionalHeaders
+    };
+    options.body = payload;
+    return this.httpRequestWithBinaryBody(options, url, "text/plain");
+  };
+
+  httpRequestWithBinaryBody = (options: RequestInit, url: string, contentType?: string) => {
+    options = applyFetchOptions(options);
+    if (contentType) {
+      if (!options.headers) {
+        options.headers = {};
+      }
+      // @ts-ignore We are sure that here we only get headers of type {[name:string]: string}
+      options.headers["Content-Type"] = contentType;
+    }
+
+    return this.request(url, options)
+      .then(handleFailure)
+      .catch(this.notifyAndRethrow);
+  };
+
+  subscribe(url: string, argument: SubscriptionArgument): Cancel {
+    const es = new EventSource(createUrlWithIdentifiers(url), {
+      withCredentials: true
+    });
+
+    let listeners: MessageListeners;
+    // type guard, to identify that argument is of type SubscriptionContext
+    if ("onMessage" in argument) {
+      listeners = (argument as SubscriptionContext).onMessage;
+      if (argument.onError) {
+        // @ts-ignore typing of EventSource is weird
+        es.onerror = argument.onError;
+      }
+      if (argument.onOpen) {
+        // @ts-ignore typing of EventSource is weird
+        es.onopen = argument.onOpen;
+      }
+    } else {
+      listeners = argument;
+    }
+
+    for (const type in listeners) {
+      // @ts-ignore typing of EventSource is weird
+      es.addEventListener(type, listeners[type]);
+    }
+
+    return () => es.close();
+  }
+
+  onRequest = (requestListener: RequestListener) => {
+    this.requestListeners.push(requestListener);
+  };
+
+  onError = (errorListener: ErrorListener) => {
+    this.errorListeners.push(errorListener);
+  };
+
+  private request = (url: string, options: RequestInit) => {
+    this.notifyRequestListeners(url, options);
+    return fetch(createUrl(url), options);
+  };
+
+  private notifyRequestListeners = (url: string, options: RequestInit) => {
+    this.requestListeners.forEach(requestListener => requestListener(url, options));
+  };
+
+  private notifyAndRethrow = (error: Error): never => {
+    this.errorListeners.forEach(errorListener => errorListener(error));
+    throw error;
+  };
+}
+
+export const apiClient = new ApiClient();