content: /**
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.activemq;
  
  import java.util.List;
  import jakarta.jms.JMSException;
  import org.apache.activemq.command.ConsumerId;
  import org.apache.activemq.command.MessageDispatch;
  import org.apache.activemq.thread.Task;
  import org.apache.activemq.thread.TaskRunner;
  import org.apache.activemq.util.JMSExceptionSupport;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * A utility class used by the Session for dispatching messages asynchronously
   * to consumers
   *
   * @see jakarta.jms.Session
   */
  public class ActiveMQSessionExecutor implements Task {
      private static final Logger LOG = LoggerFactory.getLogger(ActiveMQSessionExecutor.class);
  
      private final ActiveMQSession session;
      private final MessageDispatchChannel messageQueue;
      private boolean dispatchedBySessionPool;
      private volatile TaskRunner taskRunner;
      private boolean startedOrWarnedThatNotStarted;
  
      ActiveMQSessionExecutor(ActiveMQSession session) {
          this.session = session;
          if (this.session.connection != null && this.session.connection.isMessagePrioritySupported()) {
             this.messageQueue = new SimplePriorityMessageDispatchChannel();
          }else {
              this.messageQueue = new FifoMessageDispatchChannel();
          }
      }
  
      void setDispatchedBySessionPool(boolean value) {
          dispatchedBySessionPool = value;
          wakeup();
      }
  
      void execute(MessageDispatch message) throws InterruptedException {
  
          if (!startedOrWarnedThatNotStarted) {
  
              ActiveMQConnection connection = session.connection;
              long aboutUnstartedConnectionTimeout = connection.getWarnAboutUnstartedConnectionTimeout();
              if (connection.isStarted() || aboutUnstartedConnectionTimeout < 0L) {
                  startedOrWarnedThatNotStarted = true;
              } else {
                  long elapsedTime = System.currentTimeMillis() - connection.getTimeCreated();
  
                  // lets only warn when a significant amount of time has passed
                  // just in case its normal operation
                  if (elapsedTime > aboutUnstartedConnectionTimeout) {
                      LOG.warn("Received a message on a connection which is not yet started. Have you forgotten to call Connection.start()? Connection: " + connection
                               + " Received: " + message);
                      startedOrWarnedThatNotStarted = true;
                  }
              }
          }
  
          if (!session.isSessionAsyncDispatch() && !dispatchedBySessionPool) {
              dispatch(message);
          } else {
              messageQueue.enqueue(message);
              wakeup();
          }
      }
  
      public void wakeup() {
          if (!dispatchedBySessionPool) {
              if (session.isSessionAsyncDispatch()) {
                  try {
                      TaskRunner taskRunner = this.taskRunner;
                      if (taskRunner == null) {
                          synchronized (this) {
                              if (this.taskRunner == null) {
                                  if (!isRunning()) {
                                      // stop has been called
                                      return;
                                  }
                                  this.taskRunner = session.connection.getSessionTaskRunner().createTaskRunner(this,
                                          "ActiveMQ Session: " + session.getSessionId());
                              }
                              taskRunner = this.taskRunner;
                          }
                      }
                      taskRunner.wakeup();
                  } catch (InterruptedException e) {
                      Thread.currentThread().interrupt();
                  }
              } else {
                  while (iterate()) {
                  }
              }
          }
      }
  
      void executeFirst(MessageDispatch message) {
          messageQueue.enqueueFirst(message);
          wakeup();
      }
  
      public boolean hasUncomsumedMessages() {
          return !messageQueue.isClosed() && messageQueue.isRunning() && !messageQueue.isEmpty();
      }
  
      void dispatch(MessageDispatch message) {
          // TODO - we should use a Map for this indexed by consumerId
          for (ActiveMQMessageConsumer consumer : this.session.consumers) {
              ConsumerId consumerId = message.getConsumerId();
              if (consumerId.equals(consumer.getConsumerId())) {
                  consumer.dispatch(message);
                  break;
              }
          }
      }
  
      synchronized void start() {
          if (!messageQueue.isRunning()) {
              messageQueue.start();
              if (hasUncomsumedMessages()) {
                  wakeup();
              }
          }
      }
  
      void stop() throws JMSException {
          try {
              if (messageQueue.isRunning()) {
                  synchronized(this) {
                      messageQueue.stop();
                      if (this.taskRunner != null) {
                          this.taskRunner.shutdown();
                          this.taskRunner = null;
                      }
                  }
              }
          } catch (InterruptedException e) {
              Thread.currentThread().interrupt();
              throw JMSExceptionSupport.create(e);
          }
      }
  
      boolean isRunning() {
          return messageQueue.isRunning();
      }
  
      void close() {
          messageQueue.close();
      }
  
      void clear() {
          messageQueue.clear();
      }
  
      MessageDispatch dequeueNoWait() {
          return messageQueue.dequeueNoWait();
      }
  
      protected void clearMessagesInProgress() {
          messageQueue.clear();
      }
  
      public boolean isEmpty() {
          return messageQueue.isEmpty();
      }
  
      public boolean iterate() {
  
          // Deliver any messages queued on the consumer to their listeners.
          for (ActiveMQMessageConsumer consumer : this.session.consumers) {
              if (consumer.iterate()) {
                  return true;
              }
          }
  
          // No messages left queued on the listeners.. so now dispatch messages
          // queued on the session
          MessageDispatch message = messageQueue.dequeueNoWait();
          if (message == null) {
              return false;
          } else {
              dispatch(message);
              return !messageQueue.isEmpty();
          }
      }
  
      List<MessageDispatch> getUnconsumedMessages() {
          return messageQueue.removeAll();
      }
      
      void waitForQueueRestart() throws InterruptedException {
          synchronized (messageQueue.getMutex()) {
              while (messageQueue.isRunning() == false) {
                  if (messageQueue.isClosed()) {
                      break;
                  }
                  messageQueue.getMutex().wait();
              }
          }
      }
  }
  