From 8951bf1aa58a4c3b6886b95e51be86eb5a691eb2 Mon Sep 17 00:00:00 2001
From: Asaf Gartner <asaf@handmadedev.org>
Date: Sun, 27 Mar 2022 20:30:24 +0300
Subject: [PATCH] Timers timers timers

---
 src/twitch/twitch.go | 53 +++++++++++++++++++++++++++++++++++---------
 1 file changed, 43 insertions(+), 10 deletions(-)

diff --git a/src/twitch/twitch.go b/src/twitch/twitch.go
index e641a63e..99279cb3 100644
--- a/src/twitch/twitch.go
+++ b/src/twitch/twitch.go
@@ -56,21 +56,59 @@ func MonitorTwitchSubscriptions(ctx context.Context, dbConn *pgxpool.Pool) <-cha
 		monitorTicker := time.NewTicker(2 * time.Hour)
 		firstRunChannel := make(chan struct{}, 1)
 		firstRunChannel <- struct{}{}
+
+		timers := make([]*time.Timer, 0)
+		expiredTimers := make(chan *time.Timer, 10)
 		for {
 			select {
 			case <-ctx.Done():
+				for _, timer := range timers {
+					timer.Stop()
+				}
 				return
+			case expired := <-expiredTimers:
+				for idx, timer := range timers {
+					if timer == expired {
+						timers = append(timers[:idx], timers[idx+1:]...)
+						break
+					}
+				}
 			case <-firstRunChannel:
 				syncWithTwitch(ctx, dbConn, true)
 			case <-monitorTicker.C:
 				syncWithTwitch(ctx, dbConn, true)
 			case <-linksChangedChannel:
-				syncWithTwitch(ctx, dbConn, false)
+				// NOTE(asaf): Since we update links inside transactions for users/projects
+				//             we won't see the updated list of links until the transaction is committed.
+				//             Waiting 5 seconds is just a quick workaround for that. It's not
+				//             convenient to only trigger this after the transaction is committed.
+				var timer *time.Timer
+				t := time.AfterFunc(5*time.Second, func() {
+					expiredTimers <- timer
+					syncWithTwitch(ctx, dbConn, false)
+				})
+				timer = t
+				timers = append(timers, t)
 			case notification := <-twitchNotificationChannel:
 				if notification.Type == notificationTypeRevocation {
 					syncWithTwitch(ctx, dbConn, false)
 				} else {
-					processEventSubNotification(ctx, dbConn, &notification)
+					if notification.Type == notificationTypeChannelUpdate {
+						// NOTE(asaf): The twitch API (getStreamStatus) lags behind the notification and
+						//             would return old data if we called it immediately, so we have to
+						//             wait a bit before we process the notification. We can get the
+						//             category from the notification, but not the tags (or the up-to-date title),
+						//             so we can't really skip this.
+						var timer *time.Timer
+						t := time.AfterFunc(3*time.Minute, func() {
+							expiredTimers <- timer
+							processEventSubNotification(ctx, dbConn, &notification)
+						})
+						timer = t
+						timers = append(timers, t)
+					} else {
+						processEventSubNotification(ctx, dbConn, &notification)
+					}
 				}
 			}
 		}
@@ -144,14 +182,9 @@ func UserOrProjectLinksUpdated(twitchLoginsPreChange, twitchLoginsPostChange []s
 				}
 			}
 		}
-		if twitchChanged {
-			// NOTE(asaf): Since we update links inside transactions for users/projects
-			//             we won't see the updated list of links until the transaction is committed.
-			//             Waiting 10 seconds is just a quick workaround for that. It's not
-			//             convenient to only trigger this after the transaction is committed.
-			time.AfterFunc(10*time.Second, func() {
-				linksChangedChannel <- struct{}{}
-			})
+		select {
+		case linksChangedChannel <- struct{}{}:
+		default:
 		}
 	}
 }