From c9b67977e08e658e7f30c1a341350771238129a4 Mon Sep 17 00:00:00 2001
From: Erica Z <zerica@callcc.eu>
Date: Tue, 15 Oct 2024 22:14:37 +0200
Subject: [PATCH] improve async queue logic hopefully

---
 src/playbin.vala | 42 +++++++++---------------------------------
 1 file changed, 9 insertions(+), 33 deletions(-)

diff --git a/src/playbin.vala b/src/playbin.vala
index 1f648b8..1ace5cf 100644
--- a/src/playbin.vala
+++ b/src/playbin.vala
@@ -46,7 +46,7 @@ class Playbin : Object {
     public Playbin (ListModel play_queue) {
         this.play_queue = play_queue;
 
-        this.next_uri = new AsyncQueue<string?> ();
+        this.next_uri = new AsyncQueue<string> ();
         this.next_uri.push ("");
 
         // gstreamer docs: GNOME-based applications, for example, will usually
@@ -78,30 +78,21 @@ class Playbin : Object {
             } else if (this.playing_index+1 == position) {
                 // next track was changed
                 // try to fix up gapless transition
-                this.next_uri.lock ();
-                switch (this.next_uri.length_unlocked ()) {
-                case 1:
+                string? next_uri = this.next_uri.try_pop ();
+                if (next_uri != null) {
                     // we're in luck, about-to-finish hasn't been triggered yet
                     // we can get away with replacing it
-                    this.next_uri.try_pop_unlocked ();
                     if (this.playing_index+1 < play_queue.get_n_items ()) {
                         Song song = (Song) play_queue.get_item (this.playing_index+1);
-                        this.next_uri.push_unlocked (this.api.stream_uri (song.id));
+                        this.next_uri.push (this.api.stream_uri (song.id));
                     } else {
-                        this.next_uri.push_unlocked ("");
+                        this.next_uri.push ("");
                     }
-                    break;
-
-                case 0:
+                } else {
                     // about-to-finish already triggered
                     // we'll need to stop the new track when it starts playing
                     assert (false); // TODO
-                    break;
-
-                default:
-                    error ("invalid next_uri queue length %u\n", this.next_uri.length_unlocked ());
                 }
-                this.next_uri.unlock ();
             }
         });
 
@@ -193,29 +184,14 @@ class Playbin : Object {
         this.playbin.set_state (Gst.State.PLAYING);
         this.next_gapless = false;
 
-        this.next_uri.lock ();
-        switch (this.next_uri.length_unlocked ()) {
-          case 1:
+        string? next_uri = this.next_uri.try_pop ();
+        if (next_uri != null) {
             // we're in luck, about-to-finish hasn't been triggered yet
-            this.next_uri.try_pop_unlocked ();
-            break;
-
-          case 0:
+        } else {
             // about-to-finish already triggered
             // we'll need to stop the new track when it starts playing
             assert (false); // TODO
-            break;
-
-          case -1:
-            // about-to-finish is blocked
-            // extremely stupid edge case
-            assert (false); // TODO
-            break;
-
-          default:
-            error ("invalid next_uri queue length %u\n", this.next_uri.length_unlocked ());
         }
-        this.next_uri.unlock ();
     }
 
     // ASSUMPTION: about-to-finish will be signalled exactly once per track