code: /* Copyright (c) 2013, Cornell University
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   *     * Redistributions of source code must retain the above copyright notice,
   *       this list of conditions and the following disclaimer.
   *     * Redistributions in binary form must reproduce the above copyright
   *       notice, this list of conditions and the following disclaimer in the
   *       documentation and/or other materials provided with the distribution.
   *     * Neither the name of HyperDex nor the names of its contributors may be
   *       used to endorse or promote products derived from this software without
   *       specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   */
  
  package org.hyperdex.client;
  
  import java.util.LinkedList;
  import java.util.Queue;
  
  public class Iterator implements Operation
  {
      private long ptr = 0;
      private Client c;
      private Queue<Object> backlogged;
  
      public Iterator(Client c)
      {
          this.c = c;
          this.backlogged = new LinkedList<Object>();
          _create();
      }
  
      protected void finalize() throws Throwable
      {
          try
          {
              destroy();
          }
          finally
          {
              super.finalize();
          }
      }
  
      public synchronized void destroy()
      {
          if (ptr != 0)
          {
              _destroy();
              ptr = 0;
          }
      }
  
      /* ctor/dtor */
      private native void _create();
      private native void _destroy();
  
      /* Other calls */
      public Boolean hasNext() throws HyperDexClientException
      {
          while (!finished() && backlogged.isEmpty())
          {
              this.c.loop();
          }
  
          return !backlogged.isEmpty();
      }
  
      public Object next()
      {
          return backlogged.poll();
      }
  
      private native boolean finished();
      public native void callback();
  
      /* Utilities */
      private void appendBacklogged(Object ret)
      {
          backlogged.add(ret);
      }
  }
  