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/**
 * 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.hadoop.net;

import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import java.io.InputStream;
import java.net.Socket;
import java.net.SocketTimeoutException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.SelectableChannel;
import java.nio.channels.SelectionKey;

/**
 * This implements an input stream that can have a timeout while reading.
 * This sets non-blocking flag on the socket channel.
 * So after create this object, read() on 
 * {@link Socket#getInputStream()} and write() on 
 * {@link Socket#getOutputStream()} for the associated socket will throw 
 * IllegalBlockingModeException. 
 * Please use {@link SocketOutputStream} for writing.
 */
@InterfaceAudience.LimitedPrivate("HDFS")
public class SocketInputStream extends InputStream
                               implements ReadableByteChannel {

  private Reader reader;

  private static class Reader extends SocketIOWithTimeout {
    ReadableByteChannel channel;
    
    Reader(ReadableByteChannel channel, long timeout) throws IOException {
      super((SelectableChannel)channel, timeout);
      this.channel = channel;
    }
    
    @Override
    int performIO(ByteBuffer buf) throws IOException {
      return channel.read(buf);
    }
  }
  
  /**
   * Create a new input stream with the given timeout. If the timeout
   * is zero, it will be treated as infinite timeout. The socket's
   * channel will be configured to be non-blocking.
   * 
   * @param channel 
   *        Channel for reading, should also be a {@link SelectableChannel}.
   *        The channel will be configured to be non-blocking.
   * @param timeout timeout in milliseconds. must not be negative.
   * @throws IOException
   */
  public SocketInputStream(ReadableByteChannel channel, long timeout)
                                                        throws IOException {
    SocketIOWithTimeout.checkChannelValidity(channel);
    reader = new Reader(channel, timeout);
  }

  /**
   * Same as SocketInputStream(socket.getChannel(), timeout): 

* * Create a new input stream with the given timeout. If the timeout * is zero, it will be treated as infinite timeout. The socket's * channel will be configured to be non-blocking. * * @see SocketInputStream#SocketInputStream(ReadableByteChannel, long) * * @param socket should have a channel associated with it. * @param timeout timeout timeout in milliseconds. must not be negative. * @throws IOException */ public SocketInputStream(Socket socket, long timeout) throws IOException { this(socket.getChannel(), timeout); } /** * Same as SocketInputStream(socket.getChannel(), socket.getSoTimeout()) * :

* * Create a new input stream with the given timeout. If the timeout * is zero, it will be treated as infinite timeout. The socket's * channel will be configured to be non-blocking. * @see SocketInputStream#SocketInputStream(ReadableByteChannel, long) * * @param socket should have a channel associated with it. * @throws IOException */ public SocketInputStream(Socket socket) throws IOException { this(socket.getChannel(), socket.getSoTimeout()); } @Override public int read() throws IOException { /* Allocation can be removed if required. * probably no need to optimize or encourage single byte read. */ byte[] buf = new byte[1]; int ret = read(buf, 0, 1); if (ret > 0) { return (int)(buf[0] & 0xff); } if (ret != -1) { // unexpected throw new IOException("Could not read from stream"); } return ret; } @Override public int read(byte[] b, int off, int len) throws IOException { return read(ByteBuffer.wrap(b, off, len)); } @Override public synchronized void close() throws IOException { /* close the channel since Socket.getInputStream().close() * closes the socket. */ reader.channel.close(); reader.close(); } /** * Returns underlying channel used by inputstream. * This is useful in certain cases like channel for * {@link FileChannel#transferFrom(ReadableByteChannel, long, long)}. */ public ReadableByteChannel getChannel() { return reader.channel; } //ReadableByteChannel interface @Override public boolean isOpen() { return reader.isOpen(); } @Override public int read(ByteBuffer dst) throws IOException { return reader.doIO(dst, SelectionKey.OP_READ); } /** * waits for the underlying channel to be ready for reading. * The timeout specified for this stream applies to this wait. * * @throws SocketTimeoutException * if select on the channel times out. * @throws IOException * if any other I/O error occurs. */ public void waitForReadable() throws IOException { reader.waitForIO(SelectionKey.OP_READ); } public void setTimeout(long timeoutMs) { reader.setTimeout(timeoutMs); } }




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