fix(transcription): Sends transcription over xmpp in separate thread.

src/main/java/org/jitsi/jigasi/transcription/AbstractTranscriptPublisher.java

@@ -21,11 +21,13 @@
 import net.java.sip.communicator.service.protocol.*;
 import net.java.sip.communicator.service.protocol.Message;
 import org.jitsi.jigasi.*;
+import org.jitsi.jigasi.util.Util;
 import org.jitsi.service.libjitsi.*;
 import org.jitsi.service.neomedia.*;
 import org.jitsi.service.neomedia.device.*;
 import org.jitsi.service.neomedia.recording.*;
 import org.jitsi.utils.logging.*;
+import org.jitsi.utils.queue.*;
 
 import java.io.*;
 import java.nio.charset.*;
@@ -157,14 +159,29 @@ public abstract class AbstractTranscriptPublisher<T>
         = Logger.getLogger(AbstractTranscriptPublisher.class);
 
     /**
-     * Aspect for successful upload of transcript
+     * A queue used to offload xmpp message sending in a new thread to avoid blocking.
      */
-    private static final String DD_ASPECT_SUCCESS = "upload_success";
+    private static final PacketQueue<Runnable> xmppInvokeQueue = new PacketQueue<>(
+            Integer.MAX_VALUE,
+            false,
+            "xmpp-transcript-publisher",
+            r -> {
+                // do process and try
+                try
+                {
+                    r.run();
 
-    /**
-     * Aspect for failed upload of transcript
-     */
-    private static final String DD_ASPECT_FAIL = "upload_fail";
+                    return true;
+                }
+                catch (Throwable e)
+                {
+                    logger.error("Error processing xmpp queue item", e);
+
+                    return false;
+                }
+            },
+            Util.createNewThreadPool("transcript-publisher-executor-pool")
+    );
 
     /**
      * Get a string which contains a time stamp and a random UUID, with an
@@ -194,13 +211,27 @@ protected static String generateHardToGuessTimeString(String prefix,
      * @param message the message to send
      */
     protected void sendMessage(ChatRoom chatRoom, T message)
+    {
+        xmppInvokeQueue.add(() -> sendMessageInternal(chatRoom, message));
+    }
+
+    private void sendMessageInternal(ChatRoom chatRoom, T message)
     {
         if (chatRoom == null)
         {
             logger.error("Cannot send message as chatRoom is null");
             return;
         }
 
+        if (!chatRoom.isJoined())
+        {
+            if (logger.isDebugEnabled())
+            {
+                logger.debug("Skip sending message to room which we left!");
+            }
+            return;
+        }
+
         String messageString = message.toString();
         Message chatRoomMessage = chatRoom.createMessage(messageString);
         try
@@ -222,6 +253,11 @@ protected void sendMessage(ChatRoom chatRoom, T message)
      * @param jsonMessage the json message to send
      */
     protected void sendJsonMessage(ChatRoom chatRoom, T jsonMessage)
+    {
+        xmppInvokeQueue.add(() -> sendJsonMessageInternal(chatRoom, jsonMessage));
+    }
+
+    private void sendJsonMessageInternal(ChatRoom chatRoom, T jsonMessage)
     {
         if (chatRoom == null)
         {