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    1   /**
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
   10    *
   11    * Unless required by applicable law or agreed to in writing, software
   12    * distributed under the License is distributed on an "AS IS" BASIS,
   13    * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   14    * See the License for the specific language governing permissions and
   15    * limitations under the License.
   16    */
   17   package org.apache.activemq.transport.nio;
   18   
   19   import java.io.IOException;
   20   import java.nio.channels.SocketChannel;
   21   import java.util.LinkedList;
   22   import java.util.concurrent.Executor;
   23   import java.util.concurrent.ExecutorService;
   24   import java.util.concurrent.SynchronousQueue;
   25   import java.util.concurrent.ThreadFactory;
   26   import java.util.concurrent.ThreadPoolExecutor;
   27   import java.util.concurrent.TimeUnit;
   28   
   29   /**
   30    * The SelectorManager will manage one Selector and the thread that checks the
   31    * selector.
   32    * 
   33    * We may need to consider running more than one thread to check the selector if
   34    * servicing the selector takes too long.
   35    * 
   36    * @version $Rev: 46019 $ $Date: 2004-09-14 05:56:06 -0400 (Tue, 14 Sep 2004) $
   37    */
   38   public final class SelectorManager {
   39   
   40       public static final SelectorManager SINGLETON = new SelectorManager();
   41   
   42       private Executor selectorExecutor = createDefaultExecutor();
   43       private Executor channelExecutor = selectorExecutor;
   44       private LinkedList<SelectorWorker> freeWorkers = new LinkedList<SelectorWorker>();
   45       private int maxChannelsPerWorker = 1024;
   46       
   47       protected ExecutorService createDefaultExecutor() {
   48           ThreadPoolExecutor rc = new ThreadPoolExecutor(0, Integer.MAX_VALUE, 10, TimeUnit.MILLISECONDS, new SynchronousQueue<Runnable>(), new ThreadFactory() {
   49               public Thread newThread(Runnable runnable) {
   50                   return new Thread(runnable, "ActiveMQ NIO Worker");
   51               }
   52           });
   53           // rc.allowCoreThreadTimeOut(true);
   54           return rc;
   55       }
   56       
   57       public static SelectorManager getInstance() {
   58           return SINGLETON;
   59       }
   60   
   61       public interface Listener {
   62           void onSelect(SelectorSelection selector);
   63   
   64           void onError(SelectorSelection selection, Throwable error);
   65       }
   66   
   67   
   68       public synchronized SelectorSelection register(SocketChannel socketChannel, Listener listener)
   69           throws IOException {
   70   
   71           SelectorSelection selection = null;
   72           while( selection == null ) {
   73               if (freeWorkers.size() > 0) {
   74                   SelectorWorker worker = freeWorkers.getFirst();
   75                   if( worker.isReleased() ) {
   76                       freeWorkers.remove(worker);
   77                   } else {
   78                       worker.retain();
   79                       selection = new SelectorSelection(worker, socketChannel, listener);
   80                   }
   81                   
   82               } else {
   83                   // Worker starts /w retain count of 1
   84                   SelectorWorker worker = new SelectorWorker(this);
   85                   freeWorkers.addFirst(worker);
   86                   selection = new SelectorSelection(worker, socketChannel, listener);
   87               }
   88           }
   89           
   90           return selection;
   91       }
   92   
   93       synchronized void onWorkerFullEvent(SelectorWorker worker) {
   94           freeWorkers.remove(worker);
   95       }
   96   
   97       public synchronized void onWorkerEmptyEvent(SelectorWorker worker) {
   98           freeWorkers.remove(worker);
   99       }
  100   
  101       public synchronized void onWorkerNotFullEvent(SelectorWorker worker) {
  102           freeWorkers.addFirst(worker);
  103       }
  104   
  105       public Executor getChannelExecutor() {
  106           return channelExecutor;
  107       }
  108   
  109       public void setChannelExecutor(Executor channelExecutor) {
  110           this.channelExecutor = channelExecutor;
  111       }
  112   
  113       public int getMaxChannelsPerWorker() {
  114           return maxChannelsPerWorker;
  115       }
  116   
  117       public void setMaxChannelsPerWorker(int maxChannelsPerWorker) {
  118           this.maxChannelsPerWorker = maxChannelsPerWorker;
  119       }
  120   
  121       public Executor getSelectorExecutor() {
  122           return selectorExecutor;
  123       }
  124   
  125       public void setSelectorExecutor(Executor selectorExecutor) {
  126           this.selectorExecutor = selectorExecutor;
  127       }
  128   
  129   }

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