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.transport.nio;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.nio.ByteBuffer;
  import java.nio.channels.Channel;
  import java.nio.channels.ClosedChannelException;
  import java.nio.channels.ReadableByteChannel;
  import java.nio.channels.SelectionKey;
  import java.nio.channels.Selector;
  import java.nio.channels.SocketChannel;
  
  /**
   * Implementation of InputStream using Java NIO channel,direct buffer and
   * Selector
   */
  public class NIOBufferedInputStream extends InputStream {
  
      private final static int BUFFER_SIZE = 8192;
  
      private SocketChannel sc = null;
  
      private ByteBuffer bb = null;
  
      private Selector rs = null;
  
      public NIOBufferedInputStream(ReadableByteChannel channel, int size)
              throws ClosedChannelException, IOException {
  
          if (size <= 0) {
              throw new IllegalArgumentException("Buffer size <= 0");
          }
  
          this.bb = ByteBuffer.allocateDirect(size);
          this.sc = (SocketChannel) channel;
  
          this.sc.configureBlocking(false);
  
          this.rs = Selector.open();
  
          sc.register(rs, SelectionKey.OP_READ);
  
          bb.position(0);
          bb.limit(0);
      }
  
      public NIOBufferedInputStream(ReadableByteChannel channel)
              throws ClosedChannelException, IOException {
          this(channel, BUFFER_SIZE);
      }
  
      public int available() throws IOException {
          if (!rs.isOpen())
              throw new IOException("Input Stream Closed");
  
          return bb.remaining();
      }
  
      public void close() throws IOException {
          if (rs.isOpen()) {
              rs.close();
  
              if (sc.isOpen()) {
                  sc.socket().shutdownInput();
                  sc.socket().close();
              }
  
              bb = null;
              sc = null;
          }
      }
  
      public int read() throws IOException {
          if (!rs.isOpen())
              throw new IOException("Input Stream Closed");
  
          if (!bb.hasRemaining()) {
              try {
                  fill(1);
              } catch (ClosedChannelException e) {
                  close();
                  return -1;
              }
          }
  
          return (bb.get() & 0xFF);
      }
  
      public int read(byte[] b, int off, int len) throws IOException {
          int bytesCopied = -1;
  
          if (!rs.isOpen())
              throw new IOException("Input Stream Closed");
  
          while (bytesCopied == -1) {
              if (bb.hasRemaining()) {
                  bytesCopied = (len < bb.remaining() ? len : bb.remaining());
                  bb.get(b, off, bytesCopied);
              } else {
                  try {
                      fill(1);
                  } catch (ClosedChannelException e) {
                      close();
                      return -1;
                  }
              }
          }
  
          return bytesCopied;
      }
  
      public long skip(long n) throws IOException {
          long skiped = 0;
  
          if (!rs.isOpen())
              throw new IOException("Input Stream Closed");
  
          while (n > 0) {
              if (n <= bb.remaining()) {
                  skiped += n;
                  bb.position(bb.position() + (int) n);
                  n = 0;
              } else {
                  skiped += bb.remaining();
                  n -= bb.remaining();
  
                  bb.position(bb.limit());
  
                  try {
                      fill((int) n);
                  } catch (ClosedChannelException e) {
                      close();
                      return skiped;
                  }
              }
          }
  
          return skiped;
      }
  
      private void fill(int n) throws IOException, ClosedChannelException {
          int bytesRead = -1;
  
          if ((n <= 0) || (n <= bb.remaining()))
              return;
  
          bb.compact();
  
          n = (bb.remaining() < n ? bb.remaining() : n);
  
          for (;;) {
              bytesRead = sc.read(bb);
  
              if (bytesRead == -1)
                  throw new ClosedChannelException();
  
              n -= bytesRead;
  
              if (n <= 0)
                  break;
  
              rs.select(0);
              rs.selectedKeys().clear();
          }
  
          bb.flip();
      }
  }