[Multi-Tab] Master Election (#501)

Author: schmidt-sebastian

packages/firestore/src/core/firestore_client.ts

@@ -241,7 +241,12 @@ export class FirestoreClient {
     const serializer = new JsonProtoSerializer(this.databaseInfo.databaseId, {
       useProto3Json: true
     });
-    this.persistence = new IndexedDbPersistence(storagePrefix, serializer);
+    this.persistence = new IndexedDbPersistence(
+      storagePrefix,
+      this.platform,
+      this.asyncQueue,
+      serializer
+    );
     return this.persistence.start();
   }
 
@@ -252,7 +257,7 @@ export class FirestoreClient {
    */
   private startMemoryPersistence(): Promise<void> {
     this.garbageCollector = new EagerGarbageCollector();
-    this.persistence = new MemoryPersistence();
+    this.persistence = new MemoryPersistence(this.asyncQueue);
     return this.persistence.start();
   }
 
@@ -309,6 +314,13 @@ export class FirestoreClient {
       })
       .then(() => {
         return this.remoteStore.start();
+      })
+      .then(() => {
+        // NOTE: This will immediately call the listener, so we make sure to
+        // set it after localStore / remoteStore are started.
+        this.persistence.setPrimaryStateListener(isPrimary =>
+          this.syncEngine.applyPrimaryState(isPrimary)
+        );
       });
   }
 

packages/firestore/src/core/sync_engine.ts

@@ -121,13 +121,19 @@ export class SyncEngine implements RemoteSyncer {
     [uidKey: string]: SortedMap<BatchId, Deferred<void>>;
   };
   private targetIdGenerator = TargetIdGenerator.forSyncEngine();
+  private isPrimary = false;
 
   constructor(
     private localStore: LocalStore,
     private remoteStore: RemoteStore,
     private currentUser: User
   ) {}
 
+  // Only used for testing.
+  get isPrimaryClient() {
+    return this.isPrimary;
+  }
+
   /** Subscribes view and error handler. Can be called only once. */
   subscribe(viewHandler: ViewHandler, errorHandler: ErrorHandler): void {
     assert(
@@ -616,4 +622,9 @@ export class SyncEngine implements RemoteSyncer {
         return this.remoteStore.handleUserChange(user);
       });
   }
+
+  applyPrimaryState(isPrimary: boolean): Promise<void> {
+    this.isPrimary = isPrimary;
+    return Promise.resolve();
+  }
 }