393 fix cached dataset load

src/realtimeSessions/components/RealtimeSessionIndicator.vue

@@ -73,7 +73,7 @@ export default {
         this.activeSession = this.sessionService.getActiveTopicOrSession();
         this.stopListening = this.sessionService.listen(this.onActiveSessionChange);
 
-        this.pollForSessions();
+        this.pollForSessions(true);
     },
     beforeUnmount() {
         this.stopListening?.();
@@ -84,10 +84,10 @@ export default {
         }
     },
     methods: {
-        pollForSessions() {
+        pollForSessions(resolveCachedDatasets = false ) {
             if (!this.activeSession) {
                 this.sessionService
-                    .getTopicsWithSessions()
+                    .getTopicsWithSessions( resolveCachedDatasets )
                     .then(topics => {
                         this.hasTopics = topics.length > 0;
                     });

src/services/session/SessionService.js

@@ -243,13 +243,53 @@ class SessionService {
      *
      * @returns {Promise.<Topic[]>}
      */
-    async getTopicsWithSessions() {
+    async getTopicsWithSessions(resolveCachedDatasets = false) {
         if (this.realtimeSessionConfig.disable) {
             return Promise.resolve([]);
         }
-
-        const datasets = Object.values(this.getDatasets());
-        const validUrls = datasets.map(dataset => dataset.options.sessionLADUrl).filter(url => url);
+        let datasets = [];
+        // Need to wait for MIOs to load for the cached datasets to return.
+        const cachedDatasets = new Promise((resolve) => {
+            // Check once a second
+            const pollInterval = 1000;
+            let currentLength = 0;
+            let maxIterations = 15;
+            let currentIteration = 0;
+            const checkDatasets = () => {
+                const result = Object.values(this.getDatasets());
+
+                // no datasets
+                if (result.length === 0) {
+                    // maxed out iterations, give up and resolve with empty array
+                    if (currentIteration > maxIterations) {
+                        resolve([]);
+                        return;
+                    }
+                    currentIteration++;
+                    setTimeout(checkDatasets, pollInterval);
+                } else { // we have datasets
+                    // first time we have datasets
+                    if (currentLength === 0) {
+                        currentLength = result.length;
+                        setTimeout(checkDatasets, pollInterval);
+                    } else { // we've already seen some datasets, check for stability
+                        if (result.length === currentLength) { // we have stability, resolve
+                            resolve(result);
+                        } else { // datasets still loading, wait for stability
+                            currentLength = result.length;
+                            setTimeout(checkDatasets, pollInterval);
+                        } 
+                    }
+                }
+            };
+            checkDatasets(); // Start polling
+        });
+        if (resolveCachedDatasets) {
+            datasets = await cachedDatasets;
+        } else {
+            datasets = Object.values(this.getDatasets());
+        }
+        const validUrls = datasets.map((dataset) => dataset.options.sessionLADUrl).filter(Boolean);
         const sessionLADUrls = validUrls.reduce((uniqueUrls, url) => {
             return uniqueUrls.includes(url) ? uniqueUrls : [...uniqueUrls, url];
         }, []);