fix: getFreeTrack() would return a track it just returned when the timing coincides

src/net/torvald/terrarum/audio/AudioMixer.kt

@@ -124,7 +124,7 @@ class AudioMixer : Disposable {
      */
     fun getFreeTrackNoMatterWhat(): TerrarumAudioMixerTrack {
         synchronized(this) {
-            return getFreeTrack() ?: dynamicTracks.minBy { it.playStartedTime }
+            return getFreeTrack() ?: dynamicTracks.minBy { it.playStartedTime }.also { it.checkedOutTime = System.nanoTime() }
         }
     }
 
@@ -134,7 +134,10 @@ class AudioMixer : Disposable {
     fun getFreeTrack(): TerrarumAudioMixerTrack? {
         synchronized(this) {
             return dynamicTracks.filter { it.trackingTarget == null && !it.isPlaying }
-                .minByOrNull { it.playStartedTime }
+                .minByOrNull { maxOf(it.checkedOutTime, it.playStartedTime) }
+                .also {
+                    it?.checkedOutTime = System.nanoTime()
+                }
         }
     }
 

src/net/torvald/terrarum/audio/MixerTrackProcessor.kt

@@ -381,15 +381,6 @@ class MixerTrackProcessor(bufferSize: Int, val rate: Int, val track: TerrarumAud
 }
 
 
-private fun <T> Queue<T>.removeFirstOrElse(function: () -> T): T {
-    return if (this.isEmpty) {
-        this.removeFirst()
-    }
-    else {
-        function()
-    }
-}
-
 
 class FeedSamplesToAdev(val bufferSize: Int, val rate: Int, val track: TerrarumAudioMixerTrack) : Runnable {
     init {

src/net/torvald/terrarum/audio/TerrarumAudioMixerTrack.kt

@@ -65,7 +65,7 @@ class TerrarumAudioMixerTrack(
 
     internal val streamPlaying = AtomicBoolean(false)
     var playStartedTime = 0L; internal set
-
+    var checkedOutTime = 0L; internal set
 
     fun copyStatusTo(other: TerrarumAudioMixerTrack) {
         other.pullNextTrack = this.pullNextTrack
@@ -163,7 +163,7 @@ class TerrarumAudioMixerTrack(
 
     fun stop() {
         printdbg("TerrarumAudioMixerTrack $name", "Stop music (mixertrack=${this.name}, musictrack=$currentTrack)")
-        printStackTrace("TerrarumAudioMixerTrack $name")
+//        printStackTrace("TerrarumAudioMixerTrack $name")
 
         currentTrack?.reset()