1 files changed, 73 insertions, 0 deletions
diff --git a/app/assets/javascripts/lib/utils/poll.js b/app/assets/javascripts/lib/utils/poll.js
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index 00000000000..c30a1fcb5da
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+++ b/app/assets/javascripts/lib/utils/poll.js
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+import httpStatusCodes from './http_status';
+
+/**
+ * Polling utility for handling realtime updates.
+ * Service for vue resouce and method need to be provided as props
+ *
+ * @example
+ * new poll({
+ *   resource: resource,
+ *   method: 'name',
+ *   data: {page: 1, scope: 'all'},
+ *   successCallback: () => {},
+ *   errorCallback: () => {},
+ * }).makeRequest();
+ *
+ * this.service = new BoardsService(endpoint);
+ * new poll({
+ *   resource: this.service,
+ *   method: 'get',
+ *   data: {page: 1, scope: 'all'},
+ *   successCallback: () => {},
+ *   errorCallback: () => {},
+ * }).makeRequest();
+ *
+ *
+ * 1. Checks for response and headers before start polling
+ * 2. Interval is provided by `Poll-Interval` header.
+ * 3. If `Poll-Interval` is -1, we stop polling
+ * 4. If HTTP response is 200, we poll.
+ * 5. If HTTP response is different from 200, we stop polling.
+ *
+ */
+export default class Poll {
+  constructor(options = {}) {
+    this.options = options;
+    this.options.data = options.data || {};
+
+    this.intervalHeader = 'POLL-INTERVAL';
+    this.timeoutID = null;
+    this.canPoll = true;
+  }
+
+  checkConditions(response) {
+    const headers = gl.utils.normalizeHeaders(response.headers);
+    const pollInterval = headers[this.intervalHeader];
+
+    if (pollInterval > 0 && response.status === httpStatusCodes.OK && this.canPoll) {
+      this.timeoutID = setTimeout(() => {
+        this.makeRequest();
+      }, pollInterval);
+    }
+
+    this.options.successCallback(response);
+  }
+
+  makeRequest() {
+    const { resource, method, data, errorCallback } = this.options;
+
+    return resource[method](data)
+    .then(response => this.checkConditions(response))
+    .catch(error => errorCallback(error));
+  }
+
+  /**
+   * Stops the polling recursive chain
+   * and guarantees if the timeout is already running it won't make another request by
+   * cancelling the previously established timeout.
+   */
+  stop() {
+    this.canPoll = false;
+    clearTimeout(this.timeoutID);
+  }
+}