playlist retry-exhaustion handling

internal/playback/playlist_controller.go

@@ -7,10 +7,22 @@ import (
 	"time"
 )
 
-type PlaylistReadiness struct {
+type PlaylistEventKind uint8
+
+const (
+	PlaylistEventReady PlaylistEventKind = iota
+	PlaylistEventFailed
+)
+
+type PlaylistEvent struct {
 	Revision uint64
+	Kind     PlaylistEventKind
 }
 
+// PlaylistReadiness is retained as an alias for callers that only publish
+// ready events. Its zero Kind is PlaylistEventReady.
+type PlaylistReadiness = PlaylistEvent
+
 type playlistTimer interface {
 	C() <-chan time.Time
 	Stop() bool
@@ -162,6 +174,40 @@ func (c *PlaylistController) Run(
 				readiness = nil
 				continue
 			}
+			if ready.Kind == PlaylistEventFailed {
+				if ready.Revision != revision {
+					continue
+				}
+				stopTimer()
+				// A failed entry must not retain a live or apparently active
+				// duration clock, even when the policy is to wait.
+				timing = NewPlaylistTiming(revision, timing.Duration)
+				if c.playlist.OnFailure != PlaylistFailureNext {
+					c.publish(state, revision, timing)
+					continue
+				}
+				next, sessionCommand, apply, err := ApplyPlaylistSelection(
+					c.playlist,
+					state,
+					PlaylistCommand{Kind: PlaylistNext},
+					c.retry,
+				)
+				if err != nil || !apply {
+					c.publish(state, revision, timing)
+					continue
+				}
+				select {
+				case <-ctx.Done():
+					return ctx.Err()
+				case c.sessions <- sessionCommand:
+				}
+				revision++
+				state = next
+				entry, _ := next.Entry(c.playlist)
+				timing = NewPlaylistTiming(revision, entry.Duration)
+				c.publish(state, revision, timing)
+				continue
+			}
 			if timing.Paused &&
 				ready.Revision == timing.Revision &&
 				timing.Duration > 0 &&