refactor SimplePool automatic reconnection.

pool.go

@@ -79,15 +79,6 @@ func (pool *SimplePool) subMany(ctx context.Context, urls []string, filters Filt
 	ticker := time.NewTicker(seenAlreadyDropTick)
 	eose := false
 
-	updateSince := func() {
-		// After reconnection, update the since in the filter so that
-		// old events are not retrieved.
-		now := Now()
-		for i := range filters {
-			filters[i].Since = &now
-		}
-	}
-
 	pending := xsync.NewCounter()
 	pending.Add(int64(len(urls)))
 	for _, url := range urls {
@@ -107,26 +98,25 @@ func (pool *SimplePool) subMany(ctx context.Context, urls []string, filters Filt
 				default:
 				}
 
+				var sub *Subscription
+
 				relay, err := pool.EnsureRelay(nm)
 				if err != nil {
 					time.Sleep(3 * time.Second)
-					updateSince()
-					continue
+					goto reconnect
 				}
 
-				sub, err := relay.Subscribe(ctx, filters)
+				sub, err = relay.Subscribe(ctx, filters)
 				if err != nil {
 					time.Sleep(3 * time.Second)
-					updateSince()
-					continue
+					goto reconnect
 				}
 
-			loop:
 				for {
 					select {
 					case evt, more := <-sub.Events:
 						if !more {
-							break loop
+							goto reconnect
 						}
 						if unique {
 							if _, seen := seenAlready.LoadOrStore(evt.ID, evt.CreatedAt); seen {
@@ -156,7 +146,13 @@ func (pool *SimplePool) subMany(ctx context.Context, urls []string, filters Filt
 						return
 					}
 				}
-				updateSince()
+
+			reconnect:
+				// when attempting to reconnect update the `since` in filters so old events are not retrieved
+				now := Now()
+				for i := range filters {
+					filters[i].Since = &now
+				}
 			}
 		}(NormalizeURL(url))
 	}