core: make sync hub connection more reliable

packages/core/api/sync/index.js

@@ -135,7 +135,6 @@ class Sync {
         }
       })
       .withHubProtocol(new MessagePackHubProtocol({ ignoreUndefined: true }))
-      .withAutomaticReconnect()
       .build();
 
     EV.subscribe(EVENTS.userLoggedOut, async () => {
@@ -143,6 +142,10 @@ class Sync {
       this.autoSync.stop();
     });
 
+    this.connection.onclose((error) => {
+      this.logger.error(error || new Error("Connection closed."));
+    });
+
     this.connection.on("SyncItem", async (syncStatus) => {
       await this.onSyncItem(syncStatus);
       sendSyncProgressEvent(
@@ -167,11 +170,6 @@ class Sync {
   async start(full, force, serverLastSynced) {
     this.logger.info("Starting sync", { full, force, serverLastSynced });
 
-    this.connection.onclose((error) => {
-      this.logger.error(error || new Error("Connection closed."));
-      throw new Error("Connection closed.");
-    });
-
     const { lastSynced, oldLastSynced } = await this.init(force);
     this.logger.info("Initialized sync", { lastSynced, oldLastSynced });
 
@@ -405,12 +403,15 @@ class Sync {
   }
 
   async checkConnection() {
-    try {
-      if (this.connection.state !== signalr.HubConnectionState.Connected) {
-        if (this.connection.state !== signalr.HubConnectionState.Disconnected) {
-          await this.connection.stop();
-        }
+    const CONNECTED_STATES = [
+      signalr.HubConnectionState.Connected,
+      signalr.HubConnectionState.Connecting,
+      signalr.HubConnectionState.Reconnecting,
+      signalr.HubConnectionState.Disconnecting
+    ];
 
+    try {
+      if (!CONNECTED_STATES.includes(this.connection.state)) {
         await promiseTimeout(15000, this.connection.start());
       }
     } catch (e) {