Use snapshots for sending order to improve send efficiency.

app/src/main/java/com/futo/platformplayer/sync/internal/SyncSession.kt

@@ -17,6 +17,8 @@ interface IAuthorizable {
 
 class SyncSession : IAuthorizable {
     private val _channels: MutableList<IChannel> = mutableListOf()
+    @Volatile
+    private var _snapshot: Array<IChannel> = emptyArray()
     private var _authorized: Boolean = false
     private var _remoteAuthorized: Boolean = false
     private val _onAuthorized: (session: SyncSession, isNewlyAuthorized: Boolean, isNewSession: Boolean) -> Unit
@@ -83,6 +85,8 @@ class SyncSession : IAuthorizable {
 
         synchronized(_channels) {
             _channels.add(channel)
+            _channels.sortBy { it.linkType.ordinal }
+            _snapshot = _channels.toTypedArray()
             connected = _channels.isNotEmpty()
         }
 
@@ -124,15 +128,20 @@ class SyncSession : IAuthorizable {
     fun removeChannel(channel: IChannel) {
         synchronized(_channels) {
             _channels.remove(channel)
+            _snapshot = _channels.toTypedArray()
             connected = _channels.isNotEmpty()
         }
     }
 
     fun close() {
-        synchronized(_channels) {
-            _channels.toTypedArray()
-        }.forEach { it.close() }
-
+        val toClose = synchronized(_channels) {
+            val arr = _channels.toTypedArray()
+            _channels.clear()
+            _snapshot = emptyArray()
+            connected = false
+            arr
+        }
+        toClose.forEach { it.close() }
         _onClose(this)
     }
 
@@ -209,13 +218,12 @@ class SyncSession : IAuthorizable {
 
     fun send(opcode: UByte, subOpcode: UByte, data: ByteBuffer? = null, contentEncoding: ContentEncoding? = null) {
         ensureNotMainThread()
-        val channels = synchronized(_channels) { _channels.sortedBy { it.linkType.ordinal }.toList() }
+        val channels = _snapshot
         if (channels.isEmpty()) {
-            //TODO: Should this throw?
-            Logger.v(TAG, "Packet was not sent (opcode = $opcode, subOpcode = $subOpcode) due to no connected sockets")
+            Logger.v(TAG, "Packet was not sent … no connected sockets")
             return
         }
-
+        
         var sent = false
         for (channel in channels) {
             try {