Stop using thread pools

mobile/src/main/java/be/mygod/librootkotlinx/RootServer.kt

@@ -404,7 +404,7 @@ class RootServer {
                 mainInitialized.await()
                 CoroutineScope(Dispatchers.Main.immediate + job)
             }
-            val callbackWorker = newSingleThreadContext("callbackWorker")
+            val callbackWorker = Dispatchers.IO.limitedParallelism(1)
             // access to cancellables shall be wrapped in defaultWorker
             val cancellables = LongSparseArray<() -> Unit>()
 

mobile/src/main/java/be/mygod/vpnhotspot/LocalOnlyHotspotService.kt

@@ -59,7 +59,7 @@ class LocalOnlyHotspotService : IpNeighbourMonitoringService(), CoroutineScope {
     /**
      * Writes and critical reads to routingManager should be protected with this context.
      */
-    private val dispatcher = newSingleThreadContext("LocalOnlyHotspotService")
+    private val dispatcher = Dispatchers.IO.limitedParallelism(1)
     override val coroutineContext = dispatcher + Job()
     private var routingManager: RoutingManager? = null
     private var timeoutMonitor: TetherTimeoutMonitor? = null
@@ -167,10 +167,7 @@ class LocalOnlyHotspotService : IpNeighbourMonitoringService(), CoroutineScope {
         launch {
             routingManager?.stop()
             routingManager = null
-            if (exit) {
-                cancel()
-                dispatcher.close()
-            }
+            if (exit) cancel()
         }
     }
 }

mobile/src/main/java/be/mygod/vpnhotspot/RepeaterService.kt

@@ -241,7 +241,7 @@ class RepeaterService : Service(), CoroutineScope, WifiP2pManager.ChannelListene
     /**
      * Writes and critical reads to routingManager should be protected with this context.
      */
-    private val dispatcher = newSingleThreadContext("RepeaterService")
+    private val dispatcher = Dispatchers.IO.limitedParallelism(1)
     override val coroutineContext = dispatcher + Job()
     private var routingManager: RoutingManager? = null
     private var persistNextGroup = false
@@ -529,7 +529,6 @@ class RepeaterService : Service(), CoroutineScope, WifiP2pManager.ChannelListene
         launch {    // force clean to prevent leakage
             cleanLocked()
             cancel()
-            dispatcher.close()
         }
         app.pref.unregisterOnSharedPreferenceChangeListener(this)
         if (Build.VERSION.SDK_INT < 29) unregisterReceiver(deviceListener)

mobile/src/main/java/be/mygod/vpnhotspot/TetheringService.kt

@@ -55,7 +55,7 @@ class TetheringService : IpNeighbourMonitoringService(), TetheringManager.Tether
     /**
      * Writes and critical reads to downstreams should be protected with this context.
      */
-    private val dispatcher = newSingleThreadContext("TetheringService")
+    private val dispatcher = Dispatchers.IO.limitedParallelism(1)
     override val coroutineContext = dispatcher + Job()
     private val binder = Binder()
     private val downstreams = ConcurrentHashMap<String, Downstream>()
@@ -144,7 +144,6 @@ class TetheringService : IpNeighbourMonitoringService(), TetheringManager.Tether
             unregisterReceiver()
             downstreams.values.forEach { it.stop() }    // force clean to prevent leakage
             cancel()
-            dispatcher.close()
         }
         super.onDestroy()
     }