remove poll altogether

client/lib/patch-db.ts

@@ -1,5 +1,5 @@
-import { EMPTY, map, merge, Observable, shareReplay, Subject } from 'rxjs'
-import { catchError, filter, switchMap, tap } from 'rxjs/operators'
+import { map, shareReplay, Subject, timer } from 'rxjs'
+import { catchError, concatMap, tap } from 'rxjs/operators'
 import { Store } from './store'
 import { DBCache, Http } from './types'
 import { Source } from './source/source'
@@ -7,27 +7,21 @@ import { Source } from './source/source'
 export class PatchDB<T> {
   public store: Store<T> = new Store(this.http, this.initialCache)
   public connectionError$ = new Subject<any>()
-  public cache$ = this.sources$.pipe(
-    switchMap(sources =>
-      merge(...sources.map(s => s.watch$(this.store))).pipe(
-        catchError(e => {
-          this.connectionError$.next(e)
-
-          return EMPTY
-        }),
-      ),
-    ),
-    tap(_ => this.connectionError$.next(null)),
-    filter(Boolean),
-    map(res => {
-      this.store.update(res)
-      return this.store.cache
+  public cache$ = this.source.watch$(this.store).pipe(
+    catchError((e, watch$) => {
+      this.connectionError$.next(e)
+      return timer(4000).pipe(concatMap(() => watch$))
     }),
+    tap(res => {
+      this.connectionError$.next(null)
+      this.store.update(res)
+    }),
+    map(_ => this.store.cache),
     shareReplay(1),
   )
 
   constructor(
-    private readonly sources$: Observable<Source<T>[]>,
+    private readonly source: Source<T>,
     private readonly http: Http<T>,
     private readonly initialCache: DBCache<T>,
   ) {}