start client engine only once

client/src/plugins/engine.js

@@ -5,15 +5,36 @@ export default (context, inject) => {
 
   const engine = {
     lastFetched: [0, 0, 0, 0, 0],
+    isActive: false,
+    shouldStop: false,
+
     async start() {
       if (!store.state.engine.user) {
         if (!await this.fetchUserInfo()) {
           window.location.href = "/"
         }
       }
+      if (this.isActive) {
+        console.warn('attempt to start already running engine!')
+        return
+      }
+
+      this.isActive = true
       this.fetchUpdate()
     },
+
+    stop() {
+      if (!this.isActive) return
+      this.shouldStop = true
+    },
+
     async fetchUpdate() {
+      if (this.shouldStop || !this.isActive) {
+        this.isActive = false
+        this.shouldStop = false
+        return
+      }
+
       let delay = 0
       try {
         const url = buildUrl($config.serverBaseUrl, {