More fixes for crashes caused by using disposed track (#497)

* More fixes for crashes caused by using disposed track

* Add withRTCTrack method to refactor the isDisposed usage

* spotless

+---
+"client-sdk-android": patch
+---
+
+More fixes for crashes caused by using disposed track

 [versions]
-webrtc = "125.6422.04"
+webrtc = "125.6422.05"
 
 androidJainSipRi = "1.3.0-91"
 androidx-activity = "1.9.0"

@@ -16,7 +16,6 @@
 
 package io.livekit.android.room.track
 
-import io.livekit.android.webrtc.peerconnection.executeBlockingOnRTCThread
 import livekit.org.webrtc.AudioTrack
 import livekit.org.webrtc.AudioTrackSink
 import livekit.org.webrtc.RtpReceiver
@@ -39,23 +38,19 @@ class RemoteAudioTrack(
      * to use the data after this function returns.
      */
     fun addSink(sink: AudioTrackSink) {
-        executeBlockingOnRTCThread {
-            if (!isDisposed) {
+        withRTCTrack {
             rtcTrack.addSink(sink)
         }
     }
-    }
 
     /**
      * Removes a previously added sink.
      */
     fun removeSink(sink: AudioTrackSink) {
-        executeBlockingOnRTCThread {
-            if (!isDisposed) {
+        withRTCTrack {
             rtcTrack.removeSink(sink)
         }
     }
-    }
 
     /**
      * Sets the volume.
@@ -66,10 +61,8 @@ class RemoteAudioTrack(
      * * values greater than 1 will boost the volume of the track.
      */
     fun setVolume(volume: Double) {
-        executeBlockingOnRTCThread {
-            if (!isDisposed) {
+        withRTCTrack {
             rtcTrack.setVolume(volume)
         }
     }
-    }
 }

@@ -27,6 +27,9 @@ import livekit.LivekitRtc
 import livekit.org.webrtc.MediaStreamTrack
 import livekit.org.webrtc.RTCStatsCollectorCallback
 import livekit.org.webrtc.RTCStatsReport
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
 
 abstract class Track(
     name: String,
@@ -50,32 +53,13 @@ abstract class Track(
         internal set
 
     var enabled: Boolean
-        get() = executeBlockingOnRTCThread {
-            if (!isDisposed) {
-                rtcTrack.enabled()
-            } else {
-                false
-            }
-        }
-        set(value) {
-            executeBlockingOnRTCThread {
-                if (!isDisposed) {
-                    rtcTrack.setEnabled(value)
-                }
-            }
-        }
+        get() = withRTCTrack(defaultValue = false) { rtcTrack.enabled() }
+        set(value) = withRTCTrack { rtcTrack.setEnabled(value) }
 
     var statsGetter: RTCStatsGetter? = null
 
-    /**
-     * [MediaStreamTrack] doesn't expose a way to tell if it's disposed. Track it here.
-     * This can only be safely accessed on the rtc thread.
-     *
-     * Note: [MediaStreamTrack] can still be disposed if we don't own it, so this isn't necessarily safe,
-     * however generally all the tracks passed into this class are owned by this class.
-     */
-    internal var isDisposed = false
-        private set
+    internal val isDisposed
+        get() = rtcTrack.isDisposed
 
     /**
      * Return the [RTCStatsReport] for this track, or null if none is available.
@@ -193,11 +177,31 @@ abstract class Track(
      * Disposes the track. LiveKit will generally take care of disposing tracks for you.
      */
     open fun dispose() {
-        executeBlockingOnRTCThread {
-            isDisposed = true
+        withRTCTrack {
             rtcTrack.dispose()
         }
     }
+
+    @OptIn(ExperimentalContracts::class)
+    internal inline fun <T> withRTCTrack(crossinline action: MediaStreamTrack.() -> T) {
+        contract { callsInPlace(action, InvocationKind.AT_MOST_ONCE) }
+        withRTCTrack(Unit, action)
+    }
+
+    @OptIn(ExperimentalContracts::class)
+    internal inline fun <T> withRTCTrack(defaultValue: T, crossinline action: MediaStreamTrack.() -> T): T {
+        contract { callsInPlace(action, InvocationKind.AT_MOST_ONCE) }
+        if (isDisposed) {
+            return defaultValue
+        }
+        return executeBlockingOnRTCThread {
+            return@executeBlockingOnRTCThread if (isDisposed) {
+                defaultValue
+            } else {
+                action(rtcTrack)
+            }
+        }
+    }
 }
 
 sealed class TrackException(message: String? = null, cause: Throwable? = null) :

@@ -28,13 +28,11 @@ abstract class VideoTrack(name: String, override val rtcTrack: VideoTrack) :
      * Add a [VideoSink] that will receive frames.
      */
     open fun addRenderer(renderer: VideoSink) {
-        executeBlockingOnRTCThread {
-            if (!isDisposed) {
+        withRTCTrack {
             sinks.add(renderer)
             rtcTrack.addSink(renderer)
         }
     }
-    }
 
     /**
      * Remove a previously added [VideoSink].
@@ -43,8 +41,8 @@ abstract class VideoTrack(name: String, override val rtcTrack: VideoTrack) :
         executeBlockingOnRTCThread {
             if (!isDisposed) {
                 rtcTrack.removeSink(renderer)
-                sinks.remove(renderer)
             }
+            sinks.remove(renderer)
         }
     }
 

@@ -47,4 +47,8 @@ class MockMediaStreamTrack(
         }
         disposed = true
     }
+
+    override fun isDisposed(): Boolean {
+        return disposed
+    }
 }