Fix EOS loop freeze and playback rate not sticking on start

Throttle the EOS loop-restart seek so a fast-looping clip can't fire
back-to-back blocking flush seeks on gnome-shell's main loop, which
was severe enough to freeze the whole desktop. Also apply the
configured playback rate immediately on start instead of only from
the first loop restart.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

lib/liveWallpaper.js

@@ -78,6 +78,8 @@ export class LiveWallpaperManager {
 
         this._settingsSignals = [];
         this._busWatchId = 0;
+        this._eosSeekTimeoutId = 0;
+        this._lastEosSeekTimeMs = 0;
         this._monitorsChangedId = 0;
         this._fullscreenChangedId = 0;
         this._upowerProxy = null;
@@ -277,6 +279,11 @@ export class LiveWallpaperManager {
             this._applyMute();
             const stateChangeResult = this._playbin.set_state(Gst.State.PLAYING);
             this._logger.debug(`playbin.set_state(PLAYING) returned ${stateChangeResult}`);
+            // set_state(PLAYING) alone always starts at native rate 1.0 —
+            // without this, a configured custom speed only ever took effect
+            // once the first EOS loop-restart seek ran.
+            if (this._settings.get_double(SettingsKey.LIVE_WALLPAPER_PLAYBACK_RATE) !== 1.0)
+                this._seekToLoopStart();
 
             this._frameCount = 0;
             this._pollCount = 0;
@@ -399,13 +406,9 @@ export class LiveWallpaperManager {
     _onBusMessage(message) {
         const Gst = this._Gst;
         switch (message.type) {
-        case Gst.MessageType.EOS: {
+        case Gst.MessageType.EOS:
-            const rate = this._settings.get_double(SettingsKey.LIVE_WALLPAPER_PLAYBACK_RATE);
+            this._loopPlayback();
-            this._playbin.seek(
-                rate, Gst.Format.TIME, Gst.SeekFlags.FLUSH | Gst.SeekFlags.KEY_UNIT,
-                Gst.SeekType.SET, 0, Gst.SeekType.NONE, -1);
             break;
-        }
         case Gst.MessageType.ERROR: {
             const [error, debug] = message.parse_error();
             this._logger.error(error, `Live wallpaper playback error (${debug ?? 'no debug info'})`);
@@ -426,6 +429,48 @@ export class LiveWallpaperManager {
         }
     }
 
+    /**
+     * Restarts playback at EOS. `seek()` with GST_SEEK_FLAG_FLUSH blocks
+     * the calling thread until the pipeline flushes — and since this whole
+     * extension runs on gnome-shell's own main loop, that blocks the entire
+     * desktop for as long as it takes. At rate 1.0 that's one blocking call
+     * per full playthrough, tolerable; at higher rates a short clip loops
+     * (and EOS fires) many times a second, turning it into a sustained
+     * back-to-back stall that reads as a hard freeze. Throttling to at most
+     * one restart per EOS_SEEK_MIN_INTERVAL_MS gives the main loop room to
+     * breathe between them.
+     */
+    _loopPlayback() {
+        const nowMs = GLib.get_monotonic_time() / 1000;
+        const elapsedMs = nowMs - this._lastEosSeekTimeMs;
+        const minIntervalMs = 150;
+
+        if (elapsedMs >= minIntervalMs) {
+            this._seekToLoopStart();
+            return;
+        }
+
+        if (this._eosSeekTimeoutId)
+            return;
+        this._eosSeekTimeoutId = GLib.timeout_add(GLib.PRIORITY_DEFAULT, minIntervalMs - elapsedMs, () => {
+            this._eosSeekTimeoutId = 0;
+            this._seekToLoopStart();
+            return GLib.SOURCE_REMOVE;
+        });
+    }
+
+    _seekToLoopStart() {
+        if (!this._playbin)
+            return;
+
+        this._lastEosSeekTimeMs = GLib.get_monotonic_time() / 1000;
+        const Gst = this._Gst;
+        const rate = this._settings.get_double(SettingsKey.LIVE_WALLPAPER_PLAYBACK_RATE);
+        this._playbin.seek(
+            rate, Gst.Format.TIME, Gst.SeekFlags.FLUSH | Gst.SeekFlags.KEY_UNIT,
+            Gst.SeekType.SET, 0, Gst.SeekType.NONE, -1);
+    }
+
     _stateName(state) {
         const Gst = this._Gst;
         return Object.keys(Gst.State).find(name => Gst.State[name] === state) ?? String(state);
@@ -610,6 +655,11 @@ export class LiveWallpaperManager {
             this._pollTimeoutId = 0;
         }
 
+        if (this._eosSeekTimeoutId) {
+            GLib.source_remove(this._eosSeekTimeoutId);
+            this._eosSeekTimeoutId = 0;
+        }
+
         if (this._playbin) {
             const Gst = this._Gst;
             const bus = this._playbin.get_bus();